U.S. patent application number 14/457477 was filed with the patent office on 2016-02-18 for crosslinkable polymers.
The applicant listed for this patent is Grace Ann Bennett, Thomas B. Brust, Mark Edward Irving. Invention is credited to Grace Ann Bennett, Thomas B. Brust, Mark Edward Irving.
Application Number | 20160046748 14/457477 |
Document ID | / |
Family ID | 55174849 |
Filed Date | 2016-02-18 |
United States Patent
Application |
20160046748 |
Kind Code |
A1 |
Brust; Thomas B. ; et
al. |
February 18, 2016 |
CROSSLINKABLE POLYMERS
Abstract
Crosslinkable polymers comprise recurring units represented by:
##STR00001## wherein R, R', and R'' are independently hydrogen or
an alkyl, cyano, or halo group; R.sub.1 is hydrogen or a halo,
substituted or unsubstituted alkyl, substituted or unsubstituted
cycloalkyl, cyano, hydroxy, alkoxy, carboxy, or ester group; L is
an organic linking group; EWG represents an electron withdrawing
group having a Hammett-sigma value greater than or equal to 0.35
such that the oxygen-carbon bond in O--C(EWG)(R.sub.1) is cleavable
in the presence of a cleaving acid having a pK.sub.a of 2 or less
as measured in water; Ar is a substituted or unsubstituted arylene
group; X is NR.sub.2 or oxygen; R.sub.2 is hydrogen or an alkyl
group; t-alkyl represents a tertiary alkyl group having 4 to 6
carbon atoms, and m represents at least 1 mol % and up to and
including 100 mol %, based on the total recurring units in the
polymer.
Inventors: |
Brust; Thomas B.; (Webster,
NY) ; Bennett; Grace Ann; (Scottsville, NY) ;
Irving; Mark Edward; (Rochester, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Brust; Thomas B.
Bennett; Grace Ann
Irving; Mark Edward |
Webster
Scottsville
Rochester |
NY
NY
NY |
US
US
US |
|
|
Family ID: |
55174849 |
Appl. No.: |
14/457477 |
Filed: |
August 12, 2014 |
Current U.S.
Class: |
526/243 |
Current CPC
Class: |
C08F 28/02 20130101;
C08F 220/385 20200201; C08F 220/68 20130101; C08F 122/24 20130101;
C08F 220/387 20200201; C08F 220/382 20200201; C08F 120/38 20130101;
C08F 20/38 20130101; C08F 220/38 20130101; C08F 128/02
20130101 |
International
Class: |
C08F 220/68 20060101
C08F220/68 |
Claims
1. A polymer comprising (a) recurring units that are represented by
the following Structure (A): ##STR00006## wherein: R, R', and R''
are independently hydrogen or an alkyl, cyano, or halo group,
R.sub.1 is hydrogen or a halo, substituted or unsubstituted alkyl,
substituted or unsubstituted cycloalkyl, cyano, hydroxy, alkoxy,
carboxy, or ester group, L is an organic linking group, EWG
represents an electron withdrawing group having a Hammett-sigma
value greater than or equal to 0.35 such that the oxygen-carbon
bond in O--C(EWG)(R.sub.1) is cleavable in the presence of a
cleaving acid having a pK.sub.a of 2 or less as measured in water,
Ar is a substituted or unsubstituted arylene group, X is NR.sub.2
or oxygen, R.sub.2 is hydrogen or an alkyl group, t-alkyl
represents a tertiary alkyl group having 4 to 6 carbon atoms, and m
represents at least 1 mol % and up to and including 100 mol %,
based on the total recurring units in the polymer.
2. The polymer of claim 1, wherein R, R', and R'' are independently
hydrogen, methyl, ethyl, or chloro, R.sub.1 is hydrogen, methyl,
ethyl, or halo-substituted methyl, X is oxygen, EWG represents a
trifluoroalkyl group having 1 to 3 carbon atoms, a trichloroalkyl
group having 1 to 3 carbon atoms, cyano, nitro, carboxylic acid, or
a carboxylic acid ester, Ar is substituted or unsubstituted
phenylene, and t-alkyl represents a tertiary alkyl group having 4
or 5 carbon atoms.
3. The polymer of claim 1, wherein EWG represents a trichloromethyl
group or a trifluoromethyl group, Ar is unsubstituted phenylene,
and t-alkyl represents a tertiary butyl group.
4. The polymer of claim 1, wherein L is a carbonyloxyalkylene group
having 1 to 10 carbon atoms in the alkylene chain or a substituted
or unsubstituted arylene group.
5. The polymer of claim 1, wherein m represents at least 10 mol %
and up to and including 95 mol %, based on total recurring units in
the polymer.
6. The polymer of claim 1 further comprising (b) recurring units
comprising pendant groups that provide crosslinking in the presence
of the cleaving acid having a plc of 2 or less as measured in
water.
7. The polymer of claim 6, wherein the (b) recurring units are
present in an amount of at least 1 mol % based on the total
recurring units in the polymer.
8. The polymer of claim 6, wherein the (b) recurring units comprise
pendant glycidyl groups and are present in an amount of at least 1
mol % and up to and including 50 mol %, based on the total
recurring units in the polymer.
9. The polymer of claim 6 further comprising additional (c)
recurring units that are different from all (a) and (b) recurring
units, wherein the additional (c) recurring units are present in an
amount of at least 1 mol % and up to and including 50 mol %, based
on the total recurring units in the polymer.
10. The polymer of claim 1, wherein R, R', and R'' are
independently hydrogen or methyl, R.sub.1 is hydrogen or methyl, L
is a carbonyloxyalkylene group having 1 to 10 carbon atoms or a
substituted or unsubstituted arylene group, EWG represents a
trichloromethyl or trifluoromethyl group, X is oxygen, Ar is a
substituted or unsubstituted phenylene group, and t-alkyl
represents a tertiary alkyl group having 4 or 5 carbon atoms.
11. The polymer of claim 10, wherein EWG represents
trifluoromethyl, Ar is an unsubstituted phenylene group, and
t-alkyl represents a tertiary butyl group.
Description
RELATED APPLICATIONS
[0001] Reference is made to the following copending and commonly
assigned patent applications, the disclosures of which are
incorporated herein by reference:
[0002] U.S. Ser. No. 14/084,675 that was filed Nov. 20, 2013 by
Wexler, Bennett, and Lindner;
[0003] U.S. Ser. No. 14/084,693 that was filed Nov. 20, 2013 by
Irving, Wexler, Bennett, and Lindner;
[0004] U.S. Ser. No. 14/084,711 that was filed Nov. 20, 2013 by
Wexler, Bennett, and Lindner;
[0005] U.S. Ser. No. 14/071,765 that was filed Nov. 5, 2013 by
Brust, Irving, and Falkner; U.S. Ser. No. 14/071,879 that was filed
Nov. 5, 2013 by
[0006] Brust, Irving, Falkner, and Wyand; and
[0007] U.S. Ser. No. 14/______ filed on even date herewith by
Brust, Bennett, and Irving and entitled "Forming
Electrically-Conductive Patterns Using Crosslinkable Reactive
Polymers" (Attorney Docket No. K001788/JLT).
FIELD OF THE INVENTION
[0008] This invention relates to crosslinkable reactive polymers
that can be used a method for forming patterns that in turn can be
used for forming other material patterns such as
electrically-conductive metallic patterns, for example using
electroless plating. These crosslinkable reactive polymers contain
pendant blocked sulfonate groups, which can be unblocked to provide
pendant sulfonate or sulfonic acid groups.
BACKGROUND OF THE INVENTION
[0009] In recent decades accompanying rapid advances in
information-oriented society, there have also been rapid
technological advances to provide devices and systems for gathering
and communicating information. Of these, display devices have been
designed for television screens, commercial signage, personal and
laptop computers, personal display devices, and phones of all
types, to name the most common information sharing devices.
[0010] As the increase in the use of such devices has exploded in
frequency and necessity by displacing older technologies, there has
been a concern that electromagnetic radiation emission from such
devices may cause harm to the human body or neighboring devices or
instruments over time. To diminish the potential effects from the
electromagnetic radiation emission, display devices are designed
with various transparent conductive materials that can be used as
electromagnetic wave shielding materials.
[0011] In display devices where a continuous conductive film is not
practical for providing this protection from electromagnetic
radiation emission, it has been found that conductive mesh or
patterns can be used for this electromagnetic wave shielding
purpose.
[0012] Other technologies have been developed to provide new
microfabrication methods to provide metallic, two-dimensional, and
three-dimensional structures with conductive metals. Patterns have
been provided for these purposes using photolithography and imaging
through mask materials.
[0013] In addition, as the noted display devices have been
developed in recent years, attraction has increased greatly for the
use of touch screen technology whereby a light touch on a
transparent screen surface with a finger or stylus can create
signals to cause changes in screen views or cause the reception or
sending of information, telecommunications, interaction with the
internet, and many other features that are being developed at an
ever-increasing pace of innovation. The touch screen technology has
been made possible largely by the use of transparent conductive
grids on the primary display so that the location of the noted
touch on the screen surface can be detected by appropriate
electrical circuitry and software.
[0014] For a number of years, touch screen displays have been
prepared using indium tin oxide (ITO) coatings to create arrays of
capacitive patterns or areas used to distinguish multiple point
contacts. ITO can be readily patterned using known semiconductor
fabrication methods including photolithography and high vacuum
processing. However, the use of ITO coatings has a number of
disadvantages. Indium is an expensive rare earth metal and is
available in limited supply. Moreover, ITO is a ceramic material
and is not easily bent or flexed and such coatings require
expensive vacuum deposition methods and equipment. In addition, ITO
conductivity is relatively low, requiring short line lengths to
achieve desired response rates (upon touch). Touch screens used in
large displays are broken up into smaller segments in order to
reduce the conductive line length to provide acceptable electrical
resistance. These smaller segments require additional driving and
sensing electronics, further adding to the cost of the devices.
[0015] Silver is an ideal conductor having conductivity that is 50
to 100 times greater than that of ITO. Unlike most metal oxides,
silver oxide is still reasonably conductive and its use reduces the
problem of making reliable electrical connections. Moreover, silver
is used in many commercial applications and is available from
numerous commercial sources.
[0016] In other technologies, transparent polymeric films have been
treated with conductive metals such as silver, copper, nickel, and
aluminum by such methods as sputtering, ion plating, ion beam
assist, wet coating, as well as the vacuum deposition. However, all
of these technologies are expensive, tedious, or extremely
complicated so that the relevant industries are spending
considerable resources to design improved means for forming
conductive patterns for various devices especially touch screen
displays.
[0017] A similar level of transparency and conductivity for
patterns can be achieved by producing very fine lines of about 5-6
.mu.m in width of highly conductive material such as copper or
silver metal or conductive polymers.
[0018] Polymers that can be patternwise switched from hydrophobic
nature to hydrophilic nature are known for various uses such as
making lithographic printing plates, and such polymers typically
comprise carboxylic acid, alcohol, or amine functionality that can
be initially attached or "protected" by a chemical protective group
that renders it hydrophobic and relatively non-reactive. These
protecting groups can be removed with specific chemical triggers
such as ultraviolet irradiation, a strong acid, or basic conditions
and heat. Catalytic acids can be generated by UV light using a wide
variety of photoacid generating compounds such as sulfonium or
iodonium salts. Once the protecting groups are detached or removed,
the carboxylic acid, alcohol, or amine functionality can be
available to provide hydrophilicity and to be available for other
purposes.
[0019] Polymers containing pendant sulfonate groups rather than
carboxylic acid, alcohol, or amine groups could be useful because
of the high acidity or low pKa and high stability of the resulting
pendant sulfonic acid group, making it highly ionized under a wide
range of conditions. However, the "protection" of sulfonate groups
is known to be a problem because of the tendency for sulfonate
esters to be very reactive, making any "protecting" group unstable
to a wide variety of chemical reagents and conditions and thus
ineffective. Alternatively, the protected sulfonate-containing
polymer could readily degrade under normal environmental conditions
such as humidity and heat.
[0020] The literature relating to sulfonate "protecting" group
technology provides so assistance for this problem. Some limited
success has been reported from use of hindered alcohols such as
neopentyl, cyclopentyl, methyl tetrahydropyranyl alcohols.
Beta-halo alcohols having electron withdrawing groups, especially
beta-fluoro alcohols that destabilize the transition state of the
deprotection step (thus making the protected sulfonate more stable)
have also been reported to function under some conditions. The
fluorinated benzyl alcohol, .alpha.-(trifluoromethyl) benzyl
alcohol has been described as showing some possible use as
sulfonate protecting group. See, for example, Pauff and S. C.
Miller, Journal of Organic Chemistry, 2013, 78, 711-716; L. Rusha
and S. C. Miller, Chem. Commun., 2011, 47, 2038-2040; S. C. Miller,
Journal of Organic Chemistry, Vol. 75, No. 13, 2010.
[0021] While there are some known reactive polymers that can be
used to provide electrically-conductive patterns, there is a need
for a way to make reactive polymer patterns that can be used for
producing thin electrically-conductive lines using less expensive
materials and electroless plating techniques in order to achieve a
substantial improvement in cost, reliability, and availability of
electrically-conductive patterns for various display devices.
Moreover, it would be desirable in some applications to use
reactive polymers having "protected" pendant sulfonate groups. The
present invention addresses this need as described in considerable
detail below.
SUMMARY OF THE INVENTION
[0022] The present invention addresses problems noted above, which
invention comprises a polymer comprising (a) recurring units that
are represented by the following Structure (A):
##STR00002##
wherein: [0023] R, R', and R'' are independently hydrogen or an
alkyl, cyano, or halo group, [0024] R.sub.1 is hydrogen or a halo,
substituted or unsubstituted alkyl, substituted or unsubstituted
cycloalkyl, alkoxy, cyano, hydroxy, carboxy, or ester group, [0025]
L is an organic linking group, [0026] EWG represents an electron
withdrawing group having a Hammett-sigma value greater than or
equal to 0.35 such that the oxygen-carbon bond in O--C(EWG)
(R.sub.1) is cleavable in the presence of a cleaving acid having a
pK.sub.a of 2 or less as measured in water, [0027] Ar is a
substituted or unsubstituted arylene group, [0028] X is NR.sub.2 or
oxygen, [0029] R.sub.2 is hydrogen or an alkyl group, [0030]
t-alkyl represents a tertiary alkyl group having 4 to 6 carbon
atoms, and [0031] m represents at least 1 mol % and up to and
including 100 mol %, based on the total recurring units in the
polymer.
[0032] The crosslinkable polymers of the present invention can be
used to provide fine conductive metal lines without using
traditional high-cost semiconductor fabrication methods. These
unique reactive polymers can be reacted in the presence of a strong
acid to provide sulfonic acid or sulfonate groups to which metal
ions can be complexed, while other moieties in the reactive polymer
can provide crosslinking capability.
[0033] The unique reactive polymers of the present invention
provides these advantages and others as they can become
water-insoluble in the exposed regions of a polymeric layer, and a
water-permeable but water-insoluble pattern can be formed on a
suitable substrate. Reactive polymer in the non-exposed regions can
be readily washed away, if desired, using a suitable solvent. The
remaining metal-complexing and crosslinked polymer can then be
treated with a catalytic metal ion bath such as silver nitrate
where the metal ions will complex with the sulfonic acid or other
metal ion complexing or reactive groups in the crosslinked polymer.
These complexed metal ions can then be reduced in a suitable
reducing bath to form catalytic metal particles suitable for
electroless metal plating of a variety of metals as described
below. The UV radiation initiated crosslinking in the exposed
regions forming the desired predetermined pattern is sufficient to
keep the pattern from not dissolving in the electroless metal
plating baths, while still allowing reactants and products of the
electroless plating process to diffuse in and out of the
crosslinked polymer pattern.
[0034] The reactive polymers of the present invention therefore can
be used to produce highly conductive metal patterns that exhibit
high fidelity or correspondence to the ultraviolet radiation
exposing pattern including the ability to easily produce 5 to 6
.mu.m wide (or less) electrically-conductive metal lines that
exhibit high electrical conductivity (low resistivity).
[0035] The unique reactive polymers of this invention generally can
include an unique version of an 4-acetoxy(.alpha.-trifluoromethyl)
benzyl (ATFMB) alcohol "protecting" group to pattern-wise switch
from a non-complexing hydrophobic form to a highly complexing
hydrophilic form containing a high concentration of sulfonic acid
or sulfonate groups. This improvement is accomplished by replacing
the typical 4-acetoxy group with a t-alkoxycarbonyloxy group to
produce a new "protecting" group and by utilizing a strong acid
generating molecule such as a sulfonium or iodonium salt to trigger
the removal of the "protecting" group which then triggers a
quinone-methide reaction to de-protect the pendant sulfonic acid
groups (or sulfonate groups if neutralization occurs) in the
crosslinked polymer. The protected pendant sulfonate groups should
be much more stable to environmental conditions because a strong
acid (pK.sub.a of 2 or less) is needed to trigger such removal of
(cleaving off) the "protective" group to initiate the formation of
the pendant sulfonic acid groups or sulfonate groups.
[0036] As a result, a stable but acid-switchable reactive polymer
can be used to provide pendant sulfonic acid groups or sulfonate
groups during imagewise exposure in the presence of a strong acid,
followed by appropriate functional pattern generation. The
functional patterns can then be further used to make
electrically-conductive patterns using various conductive
metals.
DETAILED DESCRIPTION OF THE INVENTION
[0037] The following discussion is directed to various embodiments
of the present invention and while some embodiments can be more
desirable for specific uses, the disclosed embodiments should not
be interpreted or otherwise considered to limit the scope of the
present invention, as claimed below. In addition, one skilled in
the art will understand that the following disclosure has broader
application than is explicitly described and the discussion of any
embodiment.
Definitions
[0038] As used herein to define various components of the reactive
compositions, unless otherwise indicated, the singular forms "a,"
"an," and "the" are intended to include one or more of the
components (that is, including plurality referents).
[0039] Each term that is not explicitly defined in the present
application is to be understood to have a meaning that is commonly
accepted by those skilled in the art. If the construction of a term
would render it meaningless or essentially meaningless in its
context, the term's definition should be taken from a standard
dictionary.
[0040] The use of numerical values in the various ranges specified
herein, unless otherwise expressly indicated otherwise, are
considered to be approximations as though the minimum and maximum
values within the stated ranges were both preceded by the word
"about." In this manner, slight variations above and below the
stated ranges can be used to achieve substantially the same results
as the values within the ranges. In addition, the disclosure of
these ranges is intended as a continuous range including every
value between the minimum and maximum values.
[0041] Unless otherwise indicated, the term "weight %" refers to
the amount of a component or material based on the total solids of
a composition, formulation, or layer. Unless otherwise indicated,
the percentages can be the same for either a dry layer or pattern,
or for the total solids of the formulation or composition.
[0042] The term "homopolymer" is meant to refer to polymeric
materials that have the same repeating or recurring unit along a
polymer backbone. The term "copolymer" refers to polymeric
materials composed of two or more different repeating or recurring
units that are arranged in any order (randomly or otherwise) along
the polymer backbone.
[0043] For the reactive polymers of the present invention, the
various recurring units can be arranged randomly along the polymer
backbone, or there can be blocks of recurring units that occur
naturally during the polymerization process.
[0044] Recurring units in the reactive polymers are generally
derived from the corresponding ethylenically unsaturated
polymerizable monomers used in a polymerization process, which
ethylenically unsaturated polymerizable monomers have the desired
functional and pendant groups. Alternatively, desired pendant
groups can be incorporated within recurring units after
polymerization of ethylenically unsaturated polymerizable monomers
by reaction with requisite precursor pendant groups.
[0045] The term "reactive polymer" is used herein to refer to the
polymers of the present invention that have the essential
components and properties described and can be used in the methods
described herein to form electrically-conductive patterns.
[0046] By "solubility or dispersibility" in reference to the
reactive polymer, we mean that a uniform stable solution or
dispersion of reactive polymer can be prepared using a desired
solvent at a solids concentration that is useful for use in the
present invention, for example preparation of coating
formulations.
[0047] The term "aqueous-based" refers to solutions, baths, or
dispersions in which the predominant solvent, or at least 50 weight
% of the solvents, is water.
[0048] Unless otherwise indicated, the term "mol %" when used in
reference to recurring units in reactive polymers, refers to either
the nominal (theoretical) amount of a recurring unit based on the
molecular weight of ethylenically unsaturated polymerizable monomer
used in the polymerization process, or to the actual amount of
recurring unit in the resulting reactive polymer as determined
using suitable analytical techniques and equipment.
Uses
[0049] The materials and methods described or claimed herein can be
used to provide reactive polymer patterns that can be used as
patterned substrates for further chemical reactions such as the
formation of catalytic metal particles or nano-particles that can
then be used to form electrically-conductive metal patterns as
described herein, which electrically-conductive metal patterns can
be incorporated into various devices including but not limited to
touch screen or other display devices.
[0050] For example, the reactive compositions described herein can
be used for a variety of purposes where efficient
photopolymerization and metal pattern formation is needed in
various articles or devices. Such reactive compositions must be
sensitive to a chosen radiation wavelength as noted above. For
example, the reactive compositions can be used in various methods
that can provide electrically-conductive metal patterns, for
example using electroless plating procedures, which
electrically-conductive metal patterns can be incorporated into
various devices including but not limited to, touch screen or other
display devices that can be used in numerous industrial, consumer,
and commercial products.
[0051] Touch screen technology can comprise different touch sensor
configurations including capacitive and resistive touch sensors.
Capacitive touch sensors can be used in electronic devices with
touch-sensitive features. These electronic devices can include but
are not limited to, televisions, monitors, and projectors that can
be adapted to display images including text, graphics, video
images, movies, still images, and presentations. The image devices
that can be used for these display devices that can include cathode
ray tubes (CRT), projectors, flat panel liquid crystal displays
(LCD), light emitting diode (LED) systems, organic light emitting
diode (OLED) systems, plasma systems, electroluminescent displays
(ELD), and field emission displays (FED). For example, the present
invention can be used to prepare capacitive touch sensors that can
be incorporated into electronic devices with touch-sensitive
features to provide computing devices, computer displays, portable
media players including e-readers, mobile telephones and other
communicating devices.
[0052] Systems and methods of fabricating flexible and optically
compliant touch sensors in a high-volume roll-to-roll manufacturing
process wherein micro electrically-conductive features can be
created in a single pass are possible using the present invention.
The reactive compositions can be used in such systems and methods
with multiple printing members to form multiple high resolution
electrically-conductive images from predetermined designs of
patterns provided in those multiple printing members. Multiple
patterns can be printed on one or both sides of a substrate. For
example, one predetermined pattern can be printed on one side of
the substrate and a different predetermined pattern can be printed
on the opposing side of the substrate. The printed patterns of the
photopolymerizable compositions can then be further processed to
provide electrically-conductive metal patterns using electroless
metal plating.
Reactive Polymers for Pattern Formation
[0053] In general, the reactive polymers of this invention have two
essential features: (1) they have labile groups that upon exposure
to suitable radiation-induced acids are de-blocked and provide
hydrophilic sulfonic acid (or sulfonate groups if neutralization
occurs), and (2) upon such irradiation, they are capable of being
crosslinked only in exposed regions. While the reactive polymers
can be supplied as solutions in appropriate solvents, they are best
used when applied to a substrate that can have a large or small
surface, including the outer surfaces or inorganic or organic
particles and then dried.
[0054] The reactive polymers are generally vinyl polymers having a
carbon-carbon backbone and suitable pendant groups as described
below. These vinyl polymers are derived from one or more
ethylenically unsaturated polymerizable monomers using suitable
polymerization procedures including solution or emulsion
polymerization techniques using appropriate initiators,
surfactants, catalysts, and solvents, all of which would be readily
apparent to one skilled in the art from the teaching provided
herein. Specific types of recurring units described herein can be
provided in the reactive polymer in random fashion (no blocks or
recurring units formed purposely) along the reactive polymer
backbone, or there can be blocks of a specific type or types of
recurring units along the reactive polymer backbone.
[0055] The useful reactive polymers comprise at least some
recurring units that comprise pendant groups attached the polymer
backbone, which pendant groups comprise a labile group that can
provide the sulfonic acid groups (described below). The term
"labile" means that these groups can provide pendant sulfonic acid
groups upon deblocking when the reactive composition described
herein is exposed to a strong acid generated by decomposition of a
photoacid generator that has been exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm,
or more likely exposed to radiation having a .lamda..sub.max of at
least 150 nm and up to and including 330 nm (sometimes known as
"short UV"). Prior to the noted irradiation (and optional heating
described below), the labile groups are considered "blocked" or
"protected" and are not available for reaction or causing
reaction.
[0056] The reactive polymers useful in the present invention can
become de-blocked to form pendant sulfonic acid groups during the
generation of the cleaving acid (described below). Such
crosslinking does not require the presence of distinct or separate
crosslinking agents within the polymeric layer (described below),
but they can be provided if desired. Depending upon the pH of the
medium containing the de-blocked polymer, some or all of the
pendant sulfonic acid groups can become neutralized to form pendant
sulfonate groups. A skilled worker would appreciate when this might
occur for a given reactive polymer and reactive composition.
[0057] The most useful reactive polymers of this invention
(hereinafter reactive polymers) are vinyl (addition) polymers
comprising (a) recurring units that are represented by Structure
(A) as described below.
##STR00003##
[0058] In Structure (A), R, R', and R'' are independently hydrogen
or an alkyl, cyano, or halo group. Such alkyl groups can be
substituted or unsubstituted and typically have 1 to 6 carbon
atoms, or more likely 1 to 3 carbon atoms. Most likely, R, R', and
R'' are independently hydrogen, methyl, ethyl, or chloro. In most
embodiments, R, R', and R'' can independently be hydrogen or
methyl.
[0059] Additionally in Structure (A), R.sub.1 is hydrogen or a
substituted or unsubstituted alkyl group (including linear,
branched, or cyclic groups including various isomers) having 1 to
10 carbon atoms, including but not limited to chloro-, fluoro-,
cyano-, nitro-, carboxy-, hydroxy-, alkoxy-, and amino-substituted
alkyl groups. In addition R.sub.1 can be substituted or
unsubstituted cycloalkyl groups having 5 to 10 carbon atoms in the
ring, including but not limited to chloro-, fluoro-, cyano-,
nitro-, carboxy-, hydroxy-, alkoxy-, and amino-substituted
cycloalkyl groups. Moreover, R.sub.1 can be selected from halo
(fluoro or chloro), cyano, alkoxy having 1 to 6 carbon atoms,
hydroxy, carboxy, and alkyl or aryl ester groups having a suitable
number of carbon atoms. More likely, R.sub.1 is a substituted or
unsubstituted alkyl group having 1 to 6 carbon atoms (including
linear or branched non-cyclic groups) including halo-substituted
alkyl groups. Most R.sub.1 groups are hydrogen, methyl, ethyl, or
substituted methyl groups such as halo-substituted methyl
groups.
[0060] L in Structure (A) is an organic linking group comprising
one or more aliphatic groups that generally include 1 to 10 carbon,
nitrogen, or oxygen atoms in the chain and can include one or more
alkylene groups (including linear, branched, or cyclic alkylene
groups) connected or interrupted with hetero atom groups such as
oxy, carbonyl, carbonyloxy, amino, or amido groups. In most
embodiments, L comprises a combination of 1 to 10 carbon and oxygen
atoms that can include one or more alkylene groups and a
carbonyloxy group. For example, L can be a carbonyloxyalkylene
group having 1 to 10 carbon atoms in the substituted or
unsubstituted alkylene chain such as a methylene or ethylene chain.
L can also be a substituted or unsubstituted arylene groups such as
a substituted phenylene group derived from a styrene monomer.
[0061] In Structure (A), EWG represents an electron withdrawing
group having a Hammett-sigma value greater than or equal to 0.35
such that the oxygen-carbon bond in O--C(EWG)(R.sub.1) is cleavable
in the presence of a cleaving acid having a pK.sub.a of 2 or less
as measured in water. A skilled worker would be able to determine
which chemical moieties could be used as EWG groups. For example,
such useful groups include alkyl groups having at least 1 carbon
atom and at least 1 halo atom, such that most or all of the halo
atoms are attached to the same carbon atom in the alkyl group. It
is particularly useful that the halo atoms be attached to carbon
atoms as close as possible to the O--C-carbon in the
O--C(EWG)(R.sub.1) group. Useful halo atoms include fluoro, chloro,
and bromo, with fluoro atoms being particularly useful.
[0062] Representative EWG groups include but are not limited to,
trifluoroalkyl groups (linear or branched) each having 1 to 3
carbon atoms; trichloroalkyl groups (linear or branched) each
having 1 to 3 carbon atoms; cyano; nitro; carboxylic acid
(carboxy); and carboxylic acid ester groups each having at least 2
carbon atoms. In many embodiments, EWG represents a trichloromethyl
group or a trifluoromethyl group.
[0063] In addition, Ar in Structure (A) represents a substituted or
unsubstituted arylene group such as a substituted or unsubstituted
phenylene group or a substituted or unsubstituted naphthylene
group. Such divalent aromatic groups can be substituted with one or
more substituents that would be readily apparent to one skilled in
the art that would not adversely affect the effect of the cleaving
acid upon irradiation, crosslinking, metal complexation, or other
properties for which the reactive polymer is designed. In many
embodiments, Ar is unsubstituted phenylene.
[0064] Moreover, in Structure (A), X is NR.sub.2 (secondary amino
with one substituent) or O (oxy) and in most embodiments, X is
oxygen. The single substituent R.sub.2 can be hydrogen or a
substituted or unsubstituted alkyl group having 1 to 10 carbon
atoms. In many embodiments, R.sub.2 is hydrogen or methyl.
[0065] In Structure (A), t-alkyl represents a substituted or
unsubstituted tertiary alkyl group having 4 to 6 carbon atoms
including but not limited to, a tertiary alkyl ester group having 4
carbon atoms (t-butyl), 5 carbon atoms (t-pentyl or
1,1-dimethylpropyl), or 6 carbon atoms (t-hexyl,
1,1-dimethyl-n-butyl, or 1,1-dimethyl-iso-butyl) in the alkyl
moiety of the alkyl ester group. The 4 or 5 carbon atoms in the
alkyl moieties, are particularly useful and the t-butyl groups
(substituted or unsubstituted) are most useful.
[0066] As Structure (A) represents recurring units in the reactive
polymer chain, such recurring units can be present in the reactive
polymer in an amount represented by "m" that is at least 1 mol %
and up to and including 100 mol %, based on the total molar amount
of recurring units in the reactive polymer. The amount of Structure
(A) recurring units can be designed to be specific amounts
depending upon the intended use of the reactive polymer. For
example, in some embodiments where electroless metal plating is
intended using crosslinked polymers derived from reactive polymers,
m can be at least 1 mol % or at least 10 mol %, or even at least 20
mol %, and up to and including 60 mol %, or up to and including 80
mol %, or up to and including 95 mol %, or even up to and including
99 mol %, all based on the total molar amounts of recurring units
in the reactive polymer. Thus, both homopolymers and copolymers
comprising Structure (A) recurring units are contemplated in the
practice of this invention.
[0067] The reactive polymers can comprise multiple different types
of (a) recurring units that are derived from two or more different
ethylenically unsaturated polymerizable monomers, or are derived by
different reactions of the same or different precursor reactive
polymers having reactive pendant groups.
[0068] Particularly useful reactive polymers can comprise (a)
recurring units as defined by Structure (A) shown above, and (b)
recurring units comprising pendant crosslinkable groups, wherein
the (a) recurring units are present in an amount of at least 1 mol
% and up to and including 95 mol %, and the (b) recurring units are
present in an amount of at least 1 mol %, all based on the total
recurring units in the reactive polymer.
[0069] More particular, the reactive polymers can comprise (b)
recurring units in an amount of at least 1 mol % or at least 5 mol
%, or even at least 10 mol %, and up to and including 40 mol % or
up to and including 50 mol %, or even up to and including 70 mol %,
all based on the total molar amount of recurring units in the
reactive polymer, particularly where the (b) recurring units
comprise pendant glycidyl groups (as described below) comprising
ring-opening epoxy groups. Such amounts are represented as "n" in
Structure (B) shown below.
[0070] In many embodiments of the reactive polymers of this
invention, they comprise at least (b) recurring units that are
different from the (a) recurring units, which (b) recurring units
provide crosslinking during the irradiation and subsequent heating
steps described above. Useful (b) recurring units can be derived
from any ethylenically unsaturated polymerizable monomers (or
precursor monomers) comprising pendant groups that provide
crosslinking in the presence of a cleaving acid having a pK.sub.a
of 2 or less, or particularly a pK.sub.a of 0 or less, as measured
in water. Compounds that provide such cleaving acids are described
below.
[0071] For example, useful (b) recurring units can be represented
by the following Structure (B):
##STR00004##
wherein B' represents a pendant group providing crosslinking in the
presence of the cleaving acid having a pK.sub.a of 2 or less or 0
or less, when measured in water. For example, such pendant groups
can be epoxy, epithiopropyl, or aziridine groups (or combinations
thereof), with the epoxy groups being particularly useful. Such
crosslinkable groups can be directly attached to the polymer
backbone or they can be attached through a suitable divalent
linking group.
[0072] For example, some useful ethylenically unsaturated
polymerizable monomers from which the (b) recurring units can be
derived include but are not limited to, glycidyl acrylate, glycidyl
methacrylate, and can comprise pendant groups that comprise an
epoxy group (such as a glycidyl group), aziridinyl, or
epithiopropyl group. Particularly useful (b) recurring units
comprise pendant crosslinkable epoxy groups such as glycidyl groups
and can be derived from glycidyl methacrylate or glycidyl acrylate.
Other useful ethylenically unsaturated polymerizable monomers that
have acid-catalyzed crosslinking groups would be readily apparent
to one skilled in the art.
[0073] The reactive polymers can comprise multiple different types
of (b) recurring units that are derived for example from two or
more different ethylenically unsaturated polymerizable
monomers.
[0074] In addition to the (a) and (b) recurring units described
above, the reactive polymers can further comprise one or more
additional recurring units that are different from all (a) and (b)
recurring units, and herein identified as optional (c) recurring
units. A skilled polymer chemist would understand how to choose
such additional recurring units, and for example, they can be
derived from one or more ethylenically unsaturated polymerizable
monomers selected from the group consisting of alkyl acrylates
(including benzyl acrylate), alkyl methacrylates (including benzyl
methacrylate), (meth)acrylamides, styrene and styrene derivatives,
vinyl ethers, vinyl benzoates, vinylidene halides, vinyl halides,
vinyl imides, and other materials that a skilled worker in the art
would understand could provide desirable properties to the reactive
polymer. Such (c) recurring units can be represented as
follows:
##STR00005##
wherein the D groups in the (c) recurring units can be for example,
hydrogen, substituted or unsubstituted alkyl groups (such as
hydroxyalkyl groups), substituted or unsubstituted aryl groups
(such as substituted or unsubstituted phenyl groups including those
found in styrene monomers), alkyl ester groups, aryl ester groups,
halogens, or ether groups. In many useful (c) recurring units, the
D groups are alkyl carboxyl ester groups wherein the alkyl moiety
has 1 to 7 carbon atoms and is linear, branched, or cyclic in form
and can include benzyl ester groups.
[0075] The reactive polymers can comprise multiple different types
of (c) recurring units that are derived from two or more different
ethylenically unsaturated polymerizable monomers.
[0076] In Structure (C), p represents the mol % of such (c)
recurring units and when such recurring units are present, p is at
least 1 mol % or at least 5 mol % or even at least 10 mol %, and up
to and including 25 mol %, or even up to and including 50 mol %,
all based on the total molar amount of recurring units in the
reactive polymer.
[0077] In the (a), (b), and (c) recurring units, R, R', R'' can be
the same or different hydrogen, methyl, ethyl, or chloro groups and
each type of recurring unit can have the same or different R, R',
and R'' groups along the reactive polymer backbone. In most
embodiments, R, R', and R'' are hydrogen or methyl for all
recurring units along the reactive polymer backbone, and R, R', and
R'' can be the same or different for the each type of (a), (b), and
(c) recurring units in a given reactive polymer.
[0078] Some particularly useful reactive polymers comprise R, R',
and R'' that are independently hydrogen or methyl, R.sub.1 is
hydrogen or methyl, L is a carbonyloxyalkylene group having 1 to 10
carbon atoms or a substituted or unsubstituted arylene group, EWG
represents a trichloromethyl or trifluoromethyl group, X is oxygen,
Ar is a substituted or unsubstituted phenylene group, and t-alkyl
represents a tertiary alkyl group having 4 or 5 carbon atoms.
Moreover, EWG can represent trifluoromethyl, Ar is an unsubstituted
phenylene group, and t-alkyl represents a tertiary butyl group.
[0079] In Structures (A), (B), and (C), "m," "n," and "p" are used
to represent the respective molar amounts of the defined types of
recurring units, based on total recurring units, in a given
reactive polymer, so that the sum of m, n, and p equal 100 mol % in
a given reactive polymer. The amounts of m, n, and p are defined
above for each type of recurring unit.
[0080] The mol % amounts of the various recurring units defined
herein for the reactive polymers defined herein are meant to refer
to the actual molar amounts present in the reactive polymers. It is
understood by one skilled in the art that the actual mol % values
may differ from those theoretically possible from the amount of
ethylenically unsaturated polymerizable monomers that are used in
the polymerization procedure to synthesize the reactive polymers
(or reactive polymer precursors). However, under most
polymerization conditions that allow high polymer yield and optimal
reaction of all monomers, the actual mol % of each monomer is
generally within .+-.15 mol % of the theoretical amounts.
[0081] Some representative reactive polymer embodiments include but
are not limited to, the following copolymers and terpolymers
wherein the molar ratios are theoretical (nominal) amounts based on
the molar ratio of ethylenically unsaturated polymerizable monomers
used in the polymerization process. As noted, the actual molar
amounts of recurring units can differ from the theoretical
(nominal) amounts of monomers if the polymerization reactions are
not carried out to completion.
[0082]
Poly(3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
propyl methacrylate-co-glycidyl methacrylate) (85:15 mol %);
[0083]
Poly(3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
propyl methacrylate-co-glycidyl methacrylate) (95:5 mol %);
[0084]
Poly(3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
propyl methacrylate-co-glycidyl methacrylate) (70:30 mol %);
[0085] Poly(3-
[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]propyl
methacrylate-co-glycidyl methacrylate-co-t-butyl methacrylate)
(65:15:20 mol %);
[0086]
Poly(3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
propyl methacrylate-co-glycidyl methacrylate-co-butyl methacrylate)
(55:15:30 mol %);
[0087]
Poly(3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
propyl methacrylate-co-glycidyl methacrylate-co-benzyl
methacrylate) (75:15:10 mol %);
[0088]
Poly(2-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
ethyl acrylate-co-glycidyl methacrylate) (85:15 mol %); and
[0089]
Poly(4-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]-
styrene-co-glycidyl methacrylate) (85:15 mol %).
[0090] The reactive polymers generally have a molecular weight
(M.sub.w) of at least 30,000 and up to and including 1,000,000 as
measured by gel permeation chromatography (GPC) or by size
exclusion chromatography (SEC).
[0091] Examples of reactive polymers can be prepared using known
free radical solution polymerization techniques using known
starting materials, free radical initiators, and reaction
conditions in suitable organic solvents such as dimethyl formamide,
N,N-dimethylacetamide, tetrahydrofuran, methyl ethyl ketone,
isopropyl alcohol, and various Dowanol.RTM. solvents that can be
adapted from known polymer chemistry. Where starting materials
(such as ethylenically unsaturated polymerizable monomers) are not
available commercially, such starting materials can be synthesized
using known chemical starting materials and procedures. It may also
be desirable to prepare reactive polymer precursors that would have
pendant groups that can be modified using one or more reactions to
provide the desired pendant groups for either or both (a) or (b)
recurring units defined above. Such reactive polymer precursors can
be prepared using known starting materials, polymerization
conditions, and post-polymerization reaction conditions and
materials that would be readily apparent to one skilled in polymer
chemistry using the teaching provided herein.
[0092] Representative preparations of particularly useful reactive
polymers are provided below for the Invention Examples. Additional
details of polymerization procedures and starting materials can be
found in Malcolm P. Stevens, Polymer Chemistry: An Introduction,
3.sup.rd Edition, Oxford University Press, 1999.
[0093] In general, the reactive polymers can be stored in solution
in suitable organic solutions or dispersions. Depending upon the
sensitivity of the reactive polymer to light (such as room light),
during and after preparation, the reactive polymers can be kept in
the dark or away from light exposure until they are formulated into
reactive compositions and used for various purposes.
Reactive Compositions
[0094] The reactive polymers described herein can be used in
reactive compositions incorporated into polymeric layers in various
methods for forming conductive patterns, for example using
electroless plating after metal seed catalysts are formed in a
patternwise fashion.
[0095] Each reactive composition has only three essential
components: (1) one or more reactive polymers as described above
that can be de-blocked and crosslinked upon exposure to radiation
having .lamda..sub.max of at least 150 nm and up to and including
450 nm; (2) one or more compounds that provide a cleaving acid upon
exposure to the radiation described above, that can provide a
cleaving acid having a pK.sub.a of 2 or less, or even 0 or less, as
measured in water; and (3) one or more crosslinking agents, each of
which is capable of reacting in the presence of the cleaving acid
by (2), to provide crosslinking in the reactive polymer. While
various other optional components can be included as described
below (such as a photosensitizer), only components (1), (2), and
(3) are essential for providing the desired precursor article,
intermediate articles, product articles, and conductive electroless
metal plated pattern in the reactive composition forming the
polymeric layer as described herein.
[0096] One or more reactive polymers as described above are
generally present in the reactive composition (and in the resulting
dry polymeric layer) in an amount of at least 50 weight % and up to
and including 99.5 weight %, or typically at least 80 weight % and
up to and including 95 weight %, based on the total solids in the
reactive composition (or total dry weight of the polymeric
layer).
[0097] The compounds used in the present invention to provide a
cleaving acid having a pKa of less than 2 or typically a pKa less
than 0, as measured in water, generally absorb radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm,
or typically radiation having a .lamda..sub.max of at least 150 nm
and up to and including 330 nm. Upon such exposure, these compounds
cleave the tertiary alkyl ester groups in the pendant groups of the
(a) recurring units in the reactive polymer and begin a chain of
reactions that will leave pendant sulfonic acid groups (as well as
any sulfonate groups) as metal complexation sites.
[0098] Particularly useful compounds to provide cleaving acids are
onium salts that decompose upon the noted irradiation. An onium
salt (also known as an onium compound) is a compound that is formed
by the attachment of a proton to a mononuclear parent hydride of a
Group 15 element (for example nitrogen and phosphorus), a chalcogen
of Group 16 (for example sulfur and selenium), or a halogen (such
as fluorine, bromine, chlorine, and iodine). Particularly useful
(b) compounds include but are not limited to, onium salts such as
sulfonium salts, phosphonium salts, iodonium salts, aryldiazonium
salts, and other acid-generating compounds such as nitrobenzyl
esters as described for example in U.S. Pat. No. 5,200,544
(Houlihan et al.) and oximes of sulfonates as described in U.S.
Pat. No. 7,749,677 (Ando). The sulfonium salts, phosphonium salts,
and iodonium salts are particularly useful, including but not
limited to the arylsulfonium salts and aryliodonium salts that can
provide an acid having a pKa less than 2, or even less than 0, as
measured in water.
[0099] Useful onium salts have substituted aryl groups and strong
acid anions such as hexafluorophosphate, tetrafluoroborate,
hexofluoroarsenate, hexafluoroantimonate, and
trifluoromethylsulfonate (triflate). Representative examples of
useful onium salts include triarylsulfonium and biaryl iodonium
salts such as triphenylsulfonium triflate,
(4-methylphenyl)diphenylsulfonium triflate,
(4-t-butyphenyl)diphenylsulfonium triflate,
4-methoxyphenyl)diphenylsulfonium triflate, and
bis(4-t-butylphenyl)iodonium triflate.
[0100] One or more compounds to provide the cleaving acids
described herein are generally present in the reactive composition
(and dry polymeric layer) in an amount of at least 0.5 weight % and
up to and including 40 weight %, or more likely at least 2 weight %
and up to and including 20 weight %, based on the total solids in
the reactive composition (or dry polymeric layer weight).
[0101] The reactive composition also includes one or more (3)
crosslinking agents. In many embodiments, such crosslinking agents
can be part of the (a) reactive polymer, for example as part of the
(b) recurring units as described above and in the described molar
amounts. In other embodiments, the (3) crosslinking agent is a
compound (or group of compounds) distinct from the (a) reactive
polymers. In other words, these crosslinking agents are not
attached to or complexed with the (a) reactive polymer. Such
crosslinking agents are capable of reacting with the pendant
sulfonic acid groups generated from the de-blocking in the (a)
reactive polymer in the presence of the cleaving acid provided by
the (2) compound described above, or other reactive groups that are
associated with the (b) or (c) recurring units that can be in the
reactive polymer.
[0102] Some useful (3) crosslinking agents that are not part of the
(a) reactive polymer include but are not limited to, melamine
formaldehyde resins, glycoluril formaldehyde resins, polycarboxylic
acids and anhydrides, polyamines, epihalohydrins, diepoxides,
dialdehydes, diols, carboxylic acid halides, ketenes, aziridines,
carbodiimides, isocyanates, and mixtures thereof. Such (3)
crosslinking agents can be present in the reactive composition in
an amount of at least 1 weight % and up to and including 30 weight
%, or more typically at least 2 weight % and up to and including 15
weight %, based on the total solids in the reactive composition.
The particular useful amount can be determined in view of the
particular (3) crosslinking agent and specific (a) reactive polymer
that is used.
[0103] While not essential, it is sometimes desirable to enhance
the sensitivity of some reactive compositions to longer wavelengths
(for example, at least 300 nm and up to and including 450 nm) by
including one or more (4) photosensitizers in the reactive
composition. A variety of photosensitizers are known in the art
such as aromatic tertiary amines, aromatic tertiary diamines and
certain aromatic polycyclic compounds such as substituted or
unsubstituted anthracene compounds, as described for example in
U.S. Pat. Nos. 4,069,054 (Smith) and 7,537,452 (Dede et al.).
Particularly useful photosensitizers include unsubstituted
anthracene and substituted anthracenes such as
9,10-diethoxyanthracene and 2-t-butyl-9,10-diethoxyanthracene.
[0104] One or more photosensitizers can be present in the reactive
composition (and resulting dry polymeric layer) in an amount of at
least 0.1 weight % and up to and including 30 weight %, or more
likely at least 0.5 weight % and up to and including 15 weight %,
based on the total solids in the reactive composition (or total dry
weight of the polymeric layer).
[0105] The reactive compositions can optionally include one or more
addenda such as film-forming compounds, surfactants, plasticizers,
filter dyes, viscosity modifiers, high boiling solvents that are
compatible with the reactive polymer (such as phthalated esters
including dibutyl phthalate and dioctyl phthalate), and any other
optional components that would be readily apparent to one skilled
in the art, and such addenda can be present in amounts that would
also be readily apparent to one skilled in the art.
[0106] The essential (1) through (3) compounds and any optional
compounds described above are generally dissolved or dispersed in
organic solvent (or mixture of organic solvents) to form a reactive
composition that can be applied to a suitable substrate (described
below). Useful organic solvents include but are not limited to,
ketones such as 2-butanone, cyclopentanone and cyclohexanone,
substituted benzenes such as chlorobenzene and anisole, ethyl
lactate, propylene glycol methyl ether acetate, or
.gamma.-butyrolacthne. Various mixtures of these organic solvents
can be used if desired especially to dilute more toxic organic
solvents with less toxic organic solvents such as blends of
cyclopentanone with any of ethyl lactate, propylene glycol methyl
ether acetate, or .gamma.-butyrolactone. Some water can also be
present if it is miscible with the organic solvents that
predominant the reaction medium.
Articles
[0107] The reactive composition described above can be applied to a
suitable substrate using any suitable method including but not
limited to, spin coating, bead coating, blade coating, curtain
coating, or spray coating, from a suitable reservoir to form a
polymeric layer. Useful substrates can be chosen for particular use
or method as long as the substrate material will not be degraded by
the reactive composition or any treatments to which the resulting
precursor articles are subjected during the methods described
herein. The reactive composition can be applied multiple times if
desired to obtain a thicker coating (reactive polymer layer) of the
reactive composition, and dried between each coating or dried only
after the last application. Solvent(s) can be removed from the
reactive composition using any suitable drying technique.
[0108] In general, the final dry coating of reactive composition
(polymeric layer) can have an average dry thickness of at least 10
nm and up to and including 1 mm, with a dry thickness of at least
0.1 .mu.m and up to and including 100 .mu.m being more useful. The
average dry thickness can be determined by measuring the dry layer
thickness in at least 2 different places within a 10 cm by 10 cm
square of the dry reactive layer using an electron microscope or
other suitable analytical device.
[0109] Thus, useful substrates can be composed of glass, quartz,
and ceramics as well as a wide variety of flexible materials such
as cellulosic papers and polyesters including poly(ethylene
terephthalate) and poly(ethylene naphthalate), polycarbonates,
polyamides, poly(meth)acrylates, and polyolefins. Useful polymeric
substrates can be formed by casting or extrusion methods.
[0110] Laminates of various substrate materials can also be put
together to form a composite substrate. Any of the substrates can
be treated to improve adhesion using for example corona discharge,
oxygen plasma, ozone or chemical treatments using silane compounds
such as aminopropyltriethoxysilane. The substrates can be of any
suitable dry thickness including but not limited to at least 10
.mu.m and up to and including 10 mm, depending upon the intended
use of the resulting articles.
[0111] Particularly useful substrates are composed of poly(ethylene
terephthalate) such as biaxially oriented poly(ethylene
terephthalate) (PET) films that have broad uses in the electronics
market. These PET films, ranging in dry thickness of at least 50
.mu.m and up to and including 200 .mu.m, can also comprise, on at
least one side, a polymeric primer layer (also known as a subbing
layer, adhesive layer, or binder layer) that can be added prior to
or after film stretching. Such polymeric primer layers can comprise
poly(acrylonitrile-co-vinylidene chloride-co-acrylic acid),
poly(methyl acrylate-co-vinylidene chloride-co-itaconic acid),
poly(glycidyl methacrylate-co-butyl acrylate), or various
water-dispersible polyesters, water-dispersible polyurethanes, or
water-dispersible polyacrylics, as well as sub-micrometer silica
particles. The dry thickness of the primer layer can be at least
0.1 .mu.m and up to and including 1 .mu.m.
[0112] Thus, with the application of the described reactive
composition to a suitable substrate, with or without appropriate
drying, the present invention provides a precursor article
comprising a substrate and having disposed thereon a polymeric
layer comprising: (1) the reactive polymer described above; (2) the
compound that provides a cleaving acid having a pK.sub.a or 2 or
less as measured in water, upon suitable exposure as described
above; (3) a crosslinking agent that is capable of reacting in the
presence of the cleaving acid, to provide crosslinking in the
reactive polymer; and (4) optionally, a photosensitizer.
Uses of Reactive Compositions
[0113] The reactive compositions described herein can be used to
form reactive polymer patterns (or patterns of the reactive
compositions) that can be used as described below to form surface
conductive patterns for various purposes as described above. The
following discussion provides some details about representative
electroless plating methods in which the reactive compositions
described herein can be used.
[0114] In these electroless plating methods, each aqueous-based
"processing" solution, dispersion, or bath (for example, solutions
containing electroless seed metal ions, reducing agent solutions,
and solutions for electroless plating, as well as rinsing
solutions) used at various points can be specifically designed with
essential components as well as optional addenda that would be
readily apparent to one skilled in the art. For example, one or
more of those aqueous-based processing solutions can include such
addenda as surfactants, anti-coagulants, anti-corrosion agents,
anti-foamants, buffers, pH modifiers, biocides, fungicides, and
preservatives. The aqueous-based reducing solutions can also
include suitable antioxidants.
Electroless Plating Method 1:
[0115] The method for forming a pattern in a polymeric layer
comprises providing a polymeric layer (as in forming the described
precursor article), the polymeric layer comprising the reactive
composition described above. This polymeric layer can be formed on
a suitable substrate, if desired, as described above by suitable
application of the reactive composition, after which the reactive
composition is typically dried before the resulting precursor
article is used in the method.
[0116] This polymeric layer in the precursor article, usually in
dry form, can be then patternwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm
(or at least 150 nm and up to and including 400 nm), to provide a
polymeric layer comprising non-exposed regions and exposed regions
comprising an at least partially crosslinked polymer having pendant
sulfonic acid groups. This exposure can be provided with any
suitable exposing source or device that provides the desired
radiation including but not limited to, various arc lamps and LED
sources. The particular exposing source can be chosen depending
upon the absorption characteristics of the reactive composition
used. The exposing radiation can be projected through lenses and
mirrors or through a lens or mask element that can be in physical
contact or in proximity with the outer surface of the polymeric
layer. Exposure time can range from a fraction (0.1) of a second
and up to and including 10 minutes depending upon the intensity of
the radiation source and the reactive composition. Suitable masks
can be obtained by known methods including but not limited to
photolithographic methods, flexographic methods, or vacuum
deposition of a chrome mask onto a suitable substrate such as
quartz or high quality optical glass followed by photolithographic
patterning.
[0117] It is optional but desirable to heat or bake the polymeric
layer in the precursor article simultaneously with or after the
patternwise exposure at a temperature sufficient to further
generate sulfonic acid groups in the exposed regions of the
polymeric layer. In most embodiments, this heating is carried out
at least after the patternwise exposure of the polymeric layer, but
it can be carried out both during and after the patternwise
exposure of the polymeric layer. Such heating can be accomplished
on a hot plate with vacuum suction to hold the precursor article in
close contact with the heating surface. Alternatively, the heating
device can be a convection oven. The duration of the heating
procedure is generally less than 10 minutes with heating for least
10 seconds and up to and including 5 minutes being most likely. The
optimal heating time and temperature can be readily determined with
routine experimentation depending upon the particular reactive
composition, for example at a temperature of at least 50.degree. C.
and up to and including 180.degree. C. for a time of up to 10
minutes.
[0118] The polymeric layer is generally hydrophilic in the exposed
regions while still being hydrophobic in the non-exposed regions
such that immersion in aqueous-based solutions (described below)
will allow the aqueous molecules, ions, or reagent molecules to
rapidly diffuse into the exposed regions.
[0119] At any time after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer can be removed using an
organic solvent in which the polymeric layer comprising the
reactive composition is soluble or dispersible. In such procedures
at least 50 weight % and typically at least 80 weight % or even at
least 90 weight % of the reactive composition in the polymeric
layer is removed from the non-exposed regions, based on the total
amount of reactive composition originally present in those
non-exposed regions. Upon this removal of reactive composition from
the non-exposed regions of the polymeric layer, the various
articles described herein will contain de-blocked and crosslinked
polymer in the exposed regions of the polymeric layer, along with
reducing agent molecules, electroless seed metal ions, electroless
seed metal particles, or electroless plated metal, depending upon
the stage at which the non-exposed reactive composition has been
removed.
[0120] The removal procedure can be carried out in any suitable
manner, including immersion of the intermediate or product article
into a suitable organic solvent or mixture of organic solvents or
by spraying the organic solvent or mixture of organic solvents onto
the intermediate article surface. Contact with the organic solvent
(or mixture thereof) can be carried out for a suitable time and
temperature so that reactive composition is desirably removed in
the non-exposed regions but little removal (less than 10 weight %
of the total material) occurs in the exposed regions containing the
de-blocked and crosslinked polymer derived from the reactive
polymer. For example, the contact time can be at least 10 seconds
and up to and including 10 minutes, and the contact temperature can
be at room temperature (about 20.degree. C.) and up to and
including 50.degree. C.
[0121] Organic solvents that can used for this purpose include but
are not limited to, ketones such as 2-butanone, cyclopentanone and
cyclohexanone, substituted benzenes such as chlorobenzene and
anisole, ethyl lactate, propylene glycol methyl ether acetate, or
.gamma.-butyrolactone. Various mixtures of these organic solvents
can be used if desired especially to dilute more toxic organic
solvents with less toxic organic solvents such as blends of
cyclopentanone with any of ethyl lactate, propylene glycol methyl
ether acetate, or .gamma.-butyrolactone.
[0122] In many embodiments, removing the reactive composition in
the non-exposed regions of the polymeric layer is carried out
immediately after the patternwise exposure and any optional heating
procedure.
[0123] This results in an intermediate article comprising a
substrate and having disposed thereon a polymeric layer comprising
exposed regions and non-exposed regions,
[0124] the exposed regions comprising a pattern of polymer
comprising reactive sulfonic acid groups, which polymer has been
derived from the reactive polymer described above in the reactive
composition as described above, and
[0125] the non-exposed regions comprising a reactive composition as
described above, unless the reactive composition has been removed
as noted above.
[0126] The polymeric layer is generally hydrophilic in the
crosslinked and exposed regions such that immersion in
aqueous-based solutions (described below) will allow the aqueous
molecules, ions, or reagent molecules to rapidly diffuse into the
exposed regions.
[0127] Once patternwise exposure and optional heating have been
carried out, the exposed regions of the polymeric layer can be
contacted with an aqueous-based solution or dispersion of
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer. There are
various ways that this contacting can be carried out. Typically,
the entire intermediate article is immersed within a dilute
aqueous-based solution, bath, or dispersion of the electroless seed
metal ions for a sufficient time to coordinate the optimum number
of electroless seed metal ions within the crosslinked polymer that
has been derived from the reactive polymer described above. For
example, this contact with the electroless seed metal ions can be
carried out for at least 1 second and up to and including 30
minutes, at room temperature (about 20.degree. C.) or at a higher
temperature of up to and including 95.degree. C. The time and
temperature for this contact can be optimized for a given reactive
composition and electroless seed metal ions that are to be
used.
[0128] Representative electroless seed metal ions that can be used
in these procedures are selected from the group consisting of
silver ions, platinum ions, palladium ions, gold ions, tin ions,
rhodium ions, iridium ions, nickel ions, and copper ions. Most
noble metal ions can serve as electroless seed metal ions in the
present invention. These electroless seed metal ions can be
provided in the form of a suitable metal salt or metal-ligand
complex (that can have an overall positive, negative, or neutral
charge). Useful materials of this type include but are not limited
to, metal salts and metal-ligand complexes of nitrates, halides,
acetates, cyanides, thiocyanates, amines, nitriles, and sulfates.
Thus, the electroless seed metal ions can be provided from simple
salts or in the form of metal-ligand complexes. The amount of metal
salts or metal-ligand complexes present in the aqueous-based
solution would be readily apparent to one skilled in the art and
can be optimized for a particular reactive composition and exposure
procedure. For example, the metal salts or metal-ligand complexes
can be present in the aqueous-based solution in an amount
sufficient to provide at least 0.00001 molar and up to and
including 2 molar of the desired electroless metal ions. In one
embodiment, a 0.4 molar silver nitrate solution can be used at room
temperature to provide electroless seed silver ions. In another
embodiment, a 0.001 molar palladium chloride solution is used to
provide electroless metal palladium ions.
[0129] The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0130] the exposed regions comprising a pattern of electroless seed
metal ions complexed within the at least partially crosslinked
polymer derived from a reactive polymer in a reactive composition
as described above, and
[0131] the non-exposed regions comprising a reactive composition as
described above, unless it has been removed as described above.
[0132] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer as
described above, leaving the pattern of electroless seed metal ions
within the de-blocked and crosslinked polymer in the exposed
regions of the polymeric layer.
[0133] If this removal procedure is carried out, an intermediate
article is created, which intermediate article comprises a
substrate and having disposed thereon exposed regions of the
polymeric layer containing at least partially crosslinked polymer
derived from a reactive polymer as described above, and non-exposed
regions of the polymeric layer comprising little or no reactive
composition, wherein the exposed regions further comprise a pattern
of electroless seed metal ions coordinated within the at least
partially crosslinked polymer.
[0134] After forming the pattern of electroless seed metal ions,
the electroless seed metal ions are then reduced to provide a
pattern of the corresponding electroless seed metal particles in
the exposed regions of the polymeric layer. This can be done by
contacting the polymeric layer (or at least the exposed regions)
with a suitable reducing agent for the electroless seed metal ions.
For example, the intermediate article comprising the polymeric
layer can be immersed within an aqueous-based reducing solution
containing one or more reducing agents for a suitable time to cause
sufficient metal ion reduction. Alternatively, an aqueous-based
reducing solution comprising the reducing agent can be sprayed or
rolled uniformly onto the polymeric layer.
[0135] Useful reducing agents include but are not limited to, an
organic borane, an aldehyde such as formaldehyde, aldehyde sugar,
hydroquinone, or sugar (or polysaccharide) such as ascorbic acid,
and metal ions such as tin(II). These reducing agents can be used
individually or in combination, and the total amount in the
aqueous-based reducing solution used for the reducing procedure can
be at least 0.01 weight % and up to and including 20 weight % based
on the total reducing solution weight. The amount of reducing agent
to be used will depend upon the particular electroless seed metal
ions and reducing agent to be used, and this can be readily
optimized using routine experimentation. The time and temperature
for the reduction can also be readily optimized in the same manner.
Generally, the reducing temperature is at least room temperature
(about 20.degree. C.) and up to and including 95.degree. C. and the
reducing time can be for at least 1 second and up to and including
30 minutes.
[0136] For example, some embodiments can be carried out using an
immersion bath comprising 1 reducing solution weight % of an
organic borane such as dimethylamine borane (DMAB) at room
temperature for up to 3 minutes. Longer or shorter times at higher
temperatures are possible if needed.
[0137] After this reducing procedure, the polymeric layer,
especially the exposed regions, can be again washed using distilled
water or deionized water or another aqueous-based solution at a
suitable temperature for a suitable time.
[0138] At this point, the method of this invention has provided yet
another intermediate article, comprising a substrate and having
disposed thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0139] the exposed regions comprising a pattern of corresponding
electroless seed metal particles within the at least partially
crosslinked polymer that has been derived from the reactive polymer
in the reactive composition described above, and
[0140] the non-exposed regions comprising a reactive composition as
described above.
[0141] Optionally, the reactive composition in the non-exposed
regions of the polymeric layer can be removed (as described above)
after this reducing procedure. This would produce yet another
intermediate article that would comprise exposed regions in the
polymeric layer comprising a pattern of corresponding electroless
seed metal particles within the exposed regions, but comprise
little or no reactive composition in the non-exposed regions of the
polymeric layer.
[0142] This intermediate article can be immediately immersed in an
aqueous-based electroless metal plating bath or solution, or the
intermediate article can be stored with just the catalytic pattern
comprising corresponding electroless seed metal particles for use
at a later time.
[0143] The intermediate article can be contacted with an
electroless plating metal that is the same as or different from the
corresponding electroless seed metal particles. In most
embodiments, the electroless plating metal is a different metal
from the corresponding electroless seed metal particles.
[0144] Any metal that will likely electrolessly "plate" on the
corresponding electroless seed metal particles can be used at this
point, but in most embodiments, the electroless plating metal can
be for example copper(II), silver(I), gold(IV), palladium(II),
platinum(II), nickel(II), chromium(II), and combinations thereof.
Copper(II), silver(I), and nickel(II) are particularly useful
electroless plating metals.
[0145] The one or more electroless plating metals can be present in
the aqueous-based electroless plating bath or solution in an amount
of at least 0.01 weight % and up to and including 20 weight % based
on total solution weight.
[0146] Electroless plating can be carried out using known
temperature and time conditions, as such conditions are well known
in various textbooks and scientific literature. It is also known to
include various additives such as metal complexing agents or
stabilizing agents in the aqueous-based electroless plating
solutions. Variations in time and temperature can be used to change
the metal electroless plating thickness or the metal electroless
plating deposition rate.
[0147] A useful aqueous-based electroless plating, solution or bath
is an electroless copper(II) plating bath that contains
formaldehyde as a reducing agent. Ethylenediaminetetraacetic acid
(EDTA) or salts thereof can be present as a copper complexing
agent. For example, copper electroless plating can be carried out
at room temperature for several seconds and up to several hours
depending upon the desired deposition rate and plating rate and
plating metal thickness.
[0148] Other useful aqueous-based electroless plating solutions or
baths comprise silver(I) with EDTA and sodium tartrate, silver(I)
with ammonia and glucose, copper(II) with EDTA and
dimethylamineborane, copper(II) with citrate and hypophosphite,
nickel(II) with lactic acid, acetic acid, and a hypophosphite, and
other industry standard aqueous-based electroless baths or
solutions such as those described by Mallory et al. in Electroless
Plating: Fundamentals and Applications 1990.
[0149] After the electroless plating procedure, the resulting
product article is removed from the aqueous-based electroless
plating bath or solution and can again be washed using distilled
water or deionized water or another aqueous-based solution to
remove any residual electroless plating chemistry. At this point,
the polymeric layer and electrolessly plated metal are generally
stable and can be used for their intended purpose.
[0150] Thus, this method provides a product article comprising a
substrate and having disposed thereon a polymeric layer comprising
exposed regions and non-exposed regions,
[0151] the exposed regions comprising a pattern of electrolessly
plated (for example in a pattern) metal complexed within or
deposited on the surface of the at least partially crosslinked
polymer comprising sulfonic acid groups and derived from the
reactive polymer in a reactive composition as described above,
and
[0152] the non-exposed regions comprising reactive composition as
described above.
[0153] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer after
electrolessly plating the corresponding electroless seed metal
particles so that the resulting product article comprises a pattern
of electrolessly plated metal in the exposed regions of the
polymeric layer comprising the de-blocked and crosslinked polymer,
but the product article comprises little or no reactive composition
in the non-exposed regions of the polymeric layer.
[0154] To change the surface of the electroless plated metal for
visual or durability reasons, it is possible that a variety of
post-treatments can be employed including surface plating of still
at least another (third or more) metal such as nickel or silver on
the electrolessly plated metal (this procedure is sometimes known
as "capping"), or the creation of a metal oxide, metal sulfide, or
a metal selenide layer that is adequate to change the surface color
and scattering properties without reducing the conductivity of the
electrolessly plated (second) metal. Depending upon the metals used
in the various capping procedures of the method, it may be
desirable to treat the electrolessly plated metal with a seed metal
catalyst in an aqueous-based seed metal catalyst solution to
facilitate deposition of additional metals.
[0155] After the electroplating procedure described above, the
product article is removed from the electroless plating bath and
can be further treated to decompose any residual onium salt on the
polymeric layer or to change the visual characteristics and or
durability of the electrolessly plated metal. For example, to
decompose any remaining onium salt or other compound that provides
a cleaving acid, the polymeric film can be uniformly exposed or
blanket flashed with ultraviolet radiation and baked (or heated)
similarly as described above after the initial exposure.
[0156] As one skilled in the art should appreciate, the individual
treatment features or steps described above for this method can be
carried out two or more times before proceeding to the next
procedure or step. For example, the treatment with the
aqueous-based solution containing electroless seed metal ions can
be carried out two or more times in sequence, for example, with a
rinsing step between sequential treatments. The electroless seed
metal ions can be the same or different for the sequential
treatments and the treatment conditions can be the same or
different.
[0157] In addition, multiple treatments with an aqueous-based
reducing solution or aqueous-based electroless metal plating
solution can be carried out in sequence, using the same or
different conditions. Sequential washing or rinsing steps can also
be carried out where appropriate.
[0158] Further, the electroless plating procedures can be carried
out multiple times, in sequence, using the same or different
electroless plating metal and the same or different electroless
plating conditions.
[0159] It is also possible to use the article provided by this
method that comprises the noted pattern of an electrolessly plated
metal, to incorporate a second or more patterns in the non-exposed
regions. This can be accomplished by subjecting this product
article to the same sequence of procedures or steps using the same
or different reagents and aqueous-based solutions to provide at
least a second pattern in what would be considered second exposed
regions since the electrolessly plated metal would be in what is
considered the first exposed regions. The second exposed regions
can comprise all of the original non-exposed regions, or they can
comprise only some of the non-exposed regions. For example, to
create a second pattern in the product article having the
electrolessly plated metal, the article can be treated or processed
as follows, using conditions and aqueous-based solutions similar to
or the same as those described above: [0160] a) patternwise
exposing the previously non-exposed regions comprising reactive
composition to form second exposed regions in the polymeric layer,
[0161] b) optionally heating the polymeric layer, [0162] c)
contacting at least the second exposed regions with an
aqueous-based solution containing electroless seed metal ions, and
optionally rinsing, [0163] d) reducing the coordinated electroless
seed metal ions with an aqueous-based reducing solution, and
optionally rinsing, and [0164] e) electrolessly plating the same or
different metal in the second exposed regions.
[0165] The reactive polymers and reactive compositions described
above can also be used in additional patterning methods described
as follows:
Electraless Plating Method 2:
[0166] This method can be used to form a pattern in a polymeric
layer, the method comprising:
[0167] providing a polymeric layer comprising a reactive
composition that comprises: (1) a reactive polymer according to the
present invention; (2) a compound that provides a cleaving acid as
described above; (3) a crosslinking agent that is capable of
reacting in the presence of the cleaving acid, to provide
crosslinking in the reactive polymer; and (4) optionally, a
photosensitizer, all as described above,
[0168] patternwise exposing the polymeric layer to radiation having
a .lamda..sub.max of at least 150 nm and up to and including 450 nm
that is sufficient to induce generate pendant sulfonic acids within
the reactive polymer, to provide a polymeric layer comprising
non-exposed regions and exposed regions comprising an at least
partially crosslinked polymer derived from the reactive
polymer,
[0169] optionally heating the polymeric layer simultaneously with
or after patternwise exposing the polymeric layer but before
removing the reactive composition comprising the reactive polymer
in the non-exposed regions, at a temperature sufficient to further
generate sulfonic acid groups in the at least partially crosslinked
polymer in the exposed regions of the polymeric layer,
[0170] incorporating a reducing agent into the exposed regions of
the polymeric layer,
[0171] contacting the exposed regions of the polymeric layer with
electroless seed metal ions to oxidize the reducing agent in the
exposed regions of the polymeric layer and to form a pattern of
electroless seed metal particles in the exposed regions of the
polymeric layer, and
[0172] electrolessly plating the corresponding electroless seed
metal particles in the exposed regions of the polymeric layer with
a metal that is the same as or different from the corresponding
electroless seed metal particles. The polymeric layer in a
precursor article, usually in dry form, can be then patternwise
exposed to radiation having a .lamda..sub.max of at least 150 nm
and up to and including 450 nm or to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 400 nm,
as described above.
[0173] It is optional but desirable to heat or bake the reactive
composition in the precursor article simultaneously with or after
the patternwise exposure but generally before contacting the
exposed polymeric layer with the aqueous-based reducing solution
(described below) and conditions as described above for the
Electroless Plating Method 1.
[0174] The polymeric layer is generally hydrophilic in the exposed
regions while still being hydrophobic in the non-exposed regions
such that immersion in aqueous-based solutions (described below)
will allow the aqueous molecules, ions, or reagents to rapidly
diffuse into the exposed regions.
[0175] At any time after the patternwise exposing or optional
heating procedures, the reactive composition in the non-exposed
regions of the polymeric layer can be removed using an organic
solvent in which the polymeric layer comprising the reactive
composition is soluble or dispersible as described for the
Electroless Plating Method 1.
[0176] In many embodiments, removing the reactive composition in
the non-exposed regions of the polymeric layer is carried out
immediately after the pattemwise exposure and any optional heating
procedure.
[0177] At this point, an intermediate article has been created in
which the exposed regions of the polymeric layer on the substrate
comprise de-blocked and crosslinked polymer derived from the
reactive polymer in the reactive composition as described herein,
and the non-exposed regions of the polymeric layer comprise little
or no reactive composition.
[0178] After the exposure and optional heating, the exposed regions
of the polymeric layer are contacted with an aqueous-based reducing
solution containing one or more reducing agents and conditions, as
described above for the Electroless Plating Method 1. In the
exposed regions, the reducing agent can diffuse into the
crosslinked polymer provided during irradiation or the reactive
composition described herein. In the non-exposed regions, the
reducing agent does not readily diffuse into or attach to the
substrate where the non-crosslinked reactive polymer had been
removed, or to the reactive composition (if present).
[0179] After this reducing procedure, the polymeric layer,
especially the exposed regions, can be again washed using distilled
water or deionized water or another aqueous-based solution at a
suitable temperature for a suitable time.
[0180] At this point, an intermediate article is provided, which
intermediate article comprises a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0181] the exposed regions comprising a pattern of a crosslinked
polymer derived from the reactive polymer in the reactive
composition described herein, and comprising reducing agent
dispersed within the crosslinked polymer, and
[0182] the non-exposed regions comprising a reactive composition as
described above.
[0183] Optionally at this point, the reactive composition in the
non-exposed regions of the polymeric layer can be removed from the
substrate as described above, leaving the reducing agent diffused
into the de-blocked and crosslinked polymer in the exposed regions
of the polymeric layer.
[0184] If this procedure is carried out, an intermediate article is
created, which intermediate article comprises a substrate and
having disposed thereon exposed regions of the polymeric layer
containing crosslinked polymer, and non-exposed regions of the
polymeric layer comprising little or no reactive composition,
wherein the exposed regions further comprise a reducing agent
diffused within the de-blocked and crosslinked polymer.
[0185] Once the pattemwise exposure, optional heating, and
contacting with the reducing agent have been carried out, the
exposed regions of the polymeric layer can be contacted with an
aqueous-based solution or dispersion of electroless seed metal ions
to form electroless seed metal particles in the exposed regions of
the polymeric layer using aqueous-based solutions and conditions as
described above. These electroless seed metal particles form
catalytic sites for electroless metal plating (deposition of metal)
described below.
[0186] The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0187] the exposed regions comprising a pattern of electroless seed
metal particles within the crosslinked polymer resulting from the
irradiation of the reactive polymer in the reactive composition
described herein, and
[0188] the non-exposed regions comprising reactive composition (if
not removed).
[0189] After the requisite time to react within the resulting
crosslinked polymer in the exposed regions, the polymeric layer can
be rinsed with distilled or deionized water or other aqueous-based
solution for a suitable time and at a suitable temperature, usually
room temperature or slightly higher.
[0190] Optionally at this point, the reactive composition can be
removed from the substrate in the non-exposed regions of the
polymeric layer as described above for Electroless Plating Method
1, leaving the pattern of electroless seed metal particles in the
exposed regions of the polymeric layer.
[0191] If this procedure is carried out, an intermediate article is
created, which intermediate article comprises a substrate and
having disposed thereon exposed regions of the polymeric layer
containing de-blocked and crosslinked polymer, non-exposed regions
of the polymeric layer comprising little or no reactive
composition, wherein the exposed regions further comprise a pattern
of electroless seed metal particles.
[0192] The resulting intermediate article can be immediately
immersed in an aqueous-based electroless plating bath or solution
or the immediate article can be stored with the catalytic pattern
comprising corresponding electroless seed metal particles for use
at a later time. The intermediate article can be contacted with an
electroless plating metal that is the same as or different from the
corresponding electroless seed metal particles, using aqueous-based
solutions and conditions as described above.
[0193] After the electroless plating procedure, a product article
is removed from the aqueous-based electroless plating bath and can
again be washed using distilled water or deionized water or another
aqueous-based solution to remove any residual electroless plating
chemistry. At this point, the polymeric layer and electrolessly
plated metal are generally stable and can be used for their
intended purpose.
[0194] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer after
electrolessly plating the corresponding electroless seed metal
particles so that the resulting product article comprises a pattern
of electrolessly plated metal in the exposed regions of the
polymeric layer containing the de-blocked and crosslinked polymer,
but the resulting product article comprises little or no reactive
composition in the non-exposed regions of the polymeric layer.
[0195] Thus, this method provides a product article comprising a
substrate and having disposed thereon a polymeric layer comprising
exposed regions and non-exposed regions,
[0196] the exposed regions comprising a pattern of an electroless
seed metal particles (for example, in a pattern) that have been
electrolessly plated with the same or different metal, and
crosslinked polymer resulting from irradiation of the reactive
polymer in the reactive composition described above, and the
non-exposed regions comprising reactive composition (unless it has
been previously removed using a suitable organic solvent as
described for Electroless Plating Method 1).
Electroless Plating Method 3:
[0197] This method can be used to form a pattern in a polymeric
layer, the method comprising:
[0198] providing a polymeric layer comprising a reactive
composition that comprises: (1) a reactive polymer; (2) a compound
that provides a cleaving acid; (3) a crosslinking agent that is
capable of reacting in the presence of the cleaving acid, to
provide crosslinking in the reactive polymer, and (4) optionally, a
photosensitizer, all as described above,
[0199] patternwise exposing the polymeric layer to radiation having
a .lamda..sub.max of at least 150 nm that is sufficient to generate
sulfonic acid groups and to induce crosslinking within the reactive
polymer, to provide a polymeric layer comprising non-exposed
regions and exposed regions comprising an at least partially
crosslinked polymer derived from the reactive polymer,
[0200] optionally heating the polymeric layer simultaneously with
or after patternwise exposing the polymeric layer at a temperature
sufficient to further generate sulfonic acid groups in the at least
partially crosslinked polymer in the exposed regions of the
polymeric layer,
[0201] contacting both the non-exposed regions and the exposed
regions of the polymeric layer with a reducing agent,
[0202] bleaching the polymeric layer to remove surface amounts of
the reducing agent in both non-exposed regions and exposed regions
comprising crosslinked polymer,
[0203] contacting the exposed regions of the polymeric layer with
electroless seed metal ions to oxidize the reducing agent and to
form a pattern of electroless seed metal particles in the exposed
regions of the polymeric layer, and
[0204] electrolessly plating the corresponding electroless seed
metal particles in the exposed regions of the polymeric layer with
a metal that is the same as or different from the corresponding
electroless seed metal particles.
[0205] Thus, in this method that includes providing a polymeric
layer (as in forming the described precursor article), the
polymeric layer comprises a reactive composition as described
above. This polymeric layer can be formed on a suitable substrate,
if desired, as described above by suitable application of the
reactive composition, after which the reactive composition is
typically dried before the resulting precursor article is used in
the method.
[0206] This polymeric layer in the precursor article, usually in
dry form, can be then patternwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm
or to radiation having a .lamda..sub.max of at least 150 nm and up
to and including 400 nm, as described above to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
the pendant sulfonic acid groups. This exposure can be provided
using any suitable exposing source or device for suitable times as
described above.
[0207] At any time after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer can be removed using an
organic solvent in which the polymeric layer comprising the
reactive composition is soluble or dispersible, as described above
in Electroless Plating Method 1.
[0208] In many embodiments, removing the reactive composition from
the non-exposed regions of the polymeric layer is carried out
immediately after the pattemwise exposure and any optional heating
procedure.
[0209] At this point, an intermediate article has been created in
which the exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and the non-exposed
regions of the polymeric layer comprise little or no reactive
composition.
[0210] After the exposure and optional heating, the exposed regions
of the polymeric layer are contacted with an aqueous-based reducing
solution containing one or more suitable reducing agents using
aqueous-based solutions and conditions as described above. In the
exposed regions, the reducing agent can diffuse into the
crosslinked polymer. In the non-exposed regions, the reducing agent
does not readily diffuse into the substrate wherein the non-exposed
reactive composition has been removed but will become attached to
the surface of the substrate.
[0211] After this reducing procedure, the polymeric layer,
especially the exposed regions, can be again washed using distilled
water or deionized water or another aqueous-based solution at a
suitable temperature for a suitable time.
[0212] At this point, an intermediate article is provided, which
intermediate article comprises a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0213] the exposed regions comprising an at least partially
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, into which a reducing agent
has diffused, and
[0214] the non-exposed regions comprising reducing agent attached
to the reactive polymer in the reactive composition described
above.
[0215] Optionally at this point, the reactive composition in the
non-exposed regions of the polymeric layer can be removed (as
described above) after this reducing procedure and before the
oxidizing procedure described below. This would produce yet another
intermediate article that would comprise exposed regions in the
polymeric layer comprising diffused reducing agent within the
de-blocked and crosslinked polymer resulting from irradiation, but
the non-exposed regions of the polymeric layer would comprise
little or no reactive composition.
[0216] Once patternwise exposure, optional heating, and the
reducing procedure have been carried out, the polymeric layer can
be contacted with an aqueous-based bleaching (or oxidizing)
solution comprising one or more bleaching agents, thereby removing
surface amounts of the reducing agent in both non-exposed regions
comprising primarily the substrate after removal of the
non-crosslinked reactive polymer, and exposed regions of the
polymeric layer. The term "bleaching" refers to oxidizing the
reducing agent molecules to make them inactive for further reaction
(thus, they cannot reduce the seedless metal ions when
bleached).
[0217] Useful bleaching agents for this bleaching procedure can be
chosen depending upon the reducing agent that is used in the
previous operation. Representative bleaching agents include but are
not limited to, peroxides such as hydrogen peroxide, persulfates,
iron(III) complexes, and combinations thereof. Hydrogen peroxide is
particularly useful. In general, the one or more bleaching agents
are present in the aqueous-based bleaching solution in an amount of
at least 0.01 weight % and up to and including 20 weight %, based
on total aqueous-based bleaching solution weight.
[0218] In general, bleaching the polymeric layer is carried out in
sufficient time and temperature so that the aqueous-based bleaching
solution reacts with (deactivates) or removes at least 90 mol % (or
typically at least 95 mol %) of the reducing agent in the
non-exposed regions and less than 40 mol % (or typically less than
25 mol %) in the exposed regions of the polymeric layer. The useful
time and temperature conditions needed to achieve these results
would be readily determined with routine experimentation in view of
the teaching provided herein.
[0219] At this point, the present invention provides an
intermediate article, comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0220] the exposed regions comprising a pattern of non-oxidized
reducing agent molecules within the crosslinked polymer resulting
from the irradiation of the reactive polymer in the reactive
composition described herein, and
[0221] the non-exposed regions comprising reactive composition as
described herein.
[0222] Optionally, the reactive composition can be removed from the
non-exposed regions of the polymeric layer as described above for
Electroless Plating Method 1, leaving the partially oxidized
reducing agent molecules in the exposed regions of the polymeric
layer containing the de-blocked and crosslinked polymer derived
from the reactive polymer in the reactive composition described
above.
[0223] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
exposed regions of the polymeric layer containing de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition described herein, and non-exposed regions of
the polymeric layer comprising little or no reactive composition,
wherein the exposed regions further comprise partially oxidized
reducing agent molecules within the de-blocked and crosslinked
polymer.
[0224] Once the previous operations have been carried out, the
exposed regions of the polymeric layer can be contacted with an
aqueous-based solution or dispersion containing electroless seed
metal ions to oxidize the reducing agent and to form corresponding
electroless seed metal particles (for example in a pattern) in the
exposed regions of the polymeric layer using aqueous-based
solutions and conditions as described above. These corresponding
electroless seed metal particles form catalytic sites for
electroless metal plating (deposition of metal) described
below.
[0225] The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions,
[0226] the exposed regions comprising a pattern of corresponding
electroless seed metal particles within the crosslinked polymer
resulting from irradiation of the reactive polymer in the reactive
composition described herein, and
[0227] the non-exposed regions comprising reactive composition as
described above.
[0228] After the requisite time to react the electroless seed metal
ions within the resulting crosslinked polymer in the exposed
regions, the polymeric layer can be rinsed with distilled or
deionized water or another aqueous-based solution for a suitable
time and at a suitable temperature, usually room temperature or
slightly higher.
[0229] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer as
described above for Electroless Plating Method 1, leaving the
pattern of electroless seed metal in the exposed regions of the
polymeric layer.
[0230] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
exposed regions of the polymeric layer containing a de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition, and non-exposed regions of the polymeric
layer comprising little or no reactive composition, wherein the
exposed regions further comprise a pattern of electroless seed
metal coordinated within the de-blocked and crosslinked
polymer.
[0231] The resulting intermediate article can be immediately
immersed in an aqueous-based electroless plating bath or solution
or it can be stored with just the catalytic pattern comprising
electroless seed metal for use at a later time.
[0232] The article can be contacted with an electroless plating
metal that is the same as or different from the electroless seed
metal using aqueous-based solutions and conditions as described
above for Electroless Plating Method 1. In most embodiments, the
electroless plating metal is a metal different from the
corresponding electroless seed metal particles.
[0233] After the electroless plating procedure, the product article
is removed from the aqueous-based electroless plating bath and can
again be washed using distilled water or deionized water or another
aqueous-based solution to remove any residual electroless plating
chemistry. At this point, the polymeric layer and electrolessly
plated metal are generally stable and can be used for their
intended purpose.
[0234] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer after
electrolessly plating the corresponding electroless seed metal
paraticles so that the resulting product article comprises a
pattern of electrolessly plated metal in the exposed regions of the
polymeric layer but the product article comprises little or no
reactive composition in the non-exposed regions of the polymeric
layer.
[0235] Thus, this method provides a product article comprising a
substrate and having disposed thereon a polymeric layer comprising
exposed regions and non-exposed regions,
[0236] the exposed regions comprising a pattern of a corresponding
electroless seed metal particles within the crosslinked polymer
derived from the reactive polymer in the reactive composition
described herein, which has been electrolessly plated with the same
or different metal, and
[0237] the non-exposed regions comprising reactive composition.
Electroless Plating Method 4:
[0238] This method can be used to form a pattern in a polymeric
layer, the method comprising:
[0239] providing a polymeric layer comprising a reactive
composition that comprises: (1) a reactive polymer according to
this invention; (2) a compound that provides a cleaving acid; (3) a
crosslinking agent that is capable of reacting in the presence of
the cleaving acid, to provide crosslinking in the reactive polymer;
and (4) optionally, a photosensitizer, all as described above,
[0240] patternwise exposing the polymeric layer to radiation having
a .lamda..sub.max of at least 150 nm that is sufficient to induce
generate pendant sulfonic acid groups within the reactive polymer,
to provide a polymeric layer comprising non-exposed regions and
first exposed regions comprising an at least partially crosslinked
polymer derived from the reactive polymer,
[0241] optionally heating the polymeric layer simultaneously with
or after patternwise exposing the polymeric layer at a temperature
sufficient to further generate sulfonic acid groups in the at least
partially crosslinked polymer in the first exposed regions of the
polymeric layer,
[0242] contacting the first exposed regions of the polymeric layer
with electroless seed metal ions to form electroless seed metal
ions in the first exposed regions of the polymeric layer,
[0243] contacting the first exposed regions of the polymeric layer
with a halide to react with the electroless seed metal ions and to
form corresponding electroless seed metal halide in the first
exposed regions of the polymeric layer,
[0244] optionally exposing the polymeric layer to convert at least
some of the corresponding electroless seed metal halide in the
first exposed regions to corresponding electroless seed metal
particles and to form second exposed regions in the polymeric
layer,
[0245] optionally contacting the polymeric layer with a reducing
agent either: (i) to develop the corresponding electroless seed
metal image in the second exposed regions of the polymeric layer,
or (ii) to develop all of the corresponding electroless seed metal
halide in the first exposed regions,
[0246] optionally contacting the polymeric layer with a fixing
agent to remove any remaining corresponding electroless seed metal
halide in either the first exposed regions, the second exposed
regions, or both of the first exposed regions and the second
exposed regions, and
[0247] electrolessly plating the corresponding electroless seed
metal particles in the first exposed regions, the second exposed
regions, or both the first exposed regions and the second exposed
regions, of the polymeric layer with a metal that is the same as or
different from the corresponding electroless seed metal
particles.
[0248] Such method is carried out by providing a polymeric layer
(as in forming the described precursor article), the polymeric
layer comprising the reactive composition described above and
formed on a suitable substrate as described above by suitable
application of the reactive composition, after which the reactive
composition is typically dried before the resulting precursor
article is used in the method described herein.
[0249] This polymeric layer in the precursor article, usually in
dry form, can be then pattemwise exposed to radiation having a
.lamda..sub.max of at least 150 nm and up to and including 450 nm
or to radiation having a .lamda..sub.max of at least 150 nm and up
to and including 400 nm, as described above to provide a polymeric
layer comprising non-exposed regions and first exposed regions
comprising a crosslinked polymer.
[0250] It is optional but desirable to heat or bake the reactive
composition in the precursor article simultaneously with or after
the patternwise exposure but generally before contacting the
exposed polymeric layer with electroless seed metal ions (described
below). Conditions and means for this heating or baking are
described above for the Electroless Plating Method 1.
[0251] At any time after the patternwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer can be removed using an
organic solvent in which the polymeric layer comprising the
reactive composition is soluble or dispersible, as described above
for the Electroless Plating Method 1.
[0252] In many embodiments, removing the reactive composition in
the non-exposed regions of the polymeric layer is carried out
immediately after the patternwise exposure and any optional heating
procedure.
[0253] At this point, an intermediate article has been created in
which the exposed regions of the polymeric layer on the substrate
comprise de-blocked and crosslinked polymer derived from the
reactive polymer in the reactive composition described above, and
the non-exposed regions of the polymeric layer comprise the
reactive composition.
[0254] Generally immediately after the pattemwise exposing or
optional heating procedures, the reactive composition remaining in
the non-exposed regions of the polymeric layer is removed as
described above for other methods (at least 90 weight % of the
original amount). Upon this removal of reactive composition from
the non-exposed regions of the polymeric layer, the various
articles described herein will contain crosslinked polymer in the
exposed regions of the polymeric layer.
[0255] At this point, an intermediate article has been created in
which the first exposed regions of the polymeric layer on the
substrate comprise crosslinked polymer derived from the reactive
polymer in the reactive composition as described above, and the
non-exposed regions of the polymeric layer comprise substantially
no reactive composition.
[0256] Once pattemwise exposure and optional heating have been
carried out, the first exposed regions of the polymeric layer are
contacted with electroless seed metal ions to form coordinated
electroless seed metal ions in the first exposed regions of the
polymeric layer using aqueous-based solutions and conditions
described above for the Electroless Plating Method 1.
[0257] The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising first exposed regions and
non-exposed regions, [0258] the first exposed regions comprising a
pattern of electroless seed metal ions within the crosslinked
polymer resulting from irradiation of the reactive polymer in the
reactive composition described above, and [0259] the non-exposed
regions comprising the reactive composition.
[0260] After the requisite time to react the electroless seed metal
ions within the crosslinked polymer in the first exposed regions,
the polymeric layer can be rinsed with distilled or deionized water
or another aqueous-based solution for a suitable time and at a
suitable temperature, usually room temperature or slightly
higher.
[0261] Optionally at this point, the reactive composition can be
removed in the non-exposed regions as described above, leaving the
pattern of electroless seed metal ions in the exposed regions of
the polymeric layer containing the de-blocked and crosslinked
polymer derived from the reactive polymer in the reactive
composition described above.
[0262] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
exposed regions of a de-blocked and crosslinked polymeric layer and
non-exposed regions of the polymeric layer comprising little or no
reactive composition, wherein the exposed regions further comprise
a pattern of electroless seed metal ions coordinated within the
de-blocked and crosslinked polymer derived from the reactive
polymer within the reactive composition described above.
[0263] At least the first exposed regions of the polymeric layer
are then contacted with a halide that reacts with the seed metal
ions to form corresponding electroless seed metal halide in the
first exposed regions of the polymeric layer. Halides can be
provided as suitable halide salts to provide iodide ions, chloride
ions, or bromide ions or a combination of two or more of these
halides to form electroless seed metal halide in the first exposed
regions of the polymeric layer. Chloride ions, iodide ions, or
bromide ions or mixtures thereof are particularly useful.
[0264] This contacting with a halide can be carried out by
immersing the intermediate article described above within an
aqueous-based halide bath or halide solution of a suitable halide
salt, or the aqueous-based halide solution can be sprayed or coated
onto the polymeric layer in a uniform or patternwise manner. The
time for this halide treatment can be at least 1 second and up to
and including 30 minutes, and the temperature for the halide
treatment can be room temperature (about 20.degree. C.) and up to
and including 95.degree. C. The time and temperature and the type
and amount of halide in a treatment bath can be optimized in order
to provide the sufficient amount of corresponding electroless seed
metal halide in the first exposed regions of the polymeric
layer.
[0265] At this point, an intermediate article has been created,
which intermediate article comprises a substrate and having thereon
a polymeric layer comprising first exposed regions and non-exposed
regions,
[0266] the first exposed regions of the polymeric layer comprising
a pattern of corresponding electroless seed metal halide in the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and
[0267] the non-exposed regions comprising the reactive
composition.
[0268] Optionally at this point, the reactive composition can be
removed from the non-exposed regions as described above, leaving
the pattern of electroless seed metal halide in the first exposed
regions of the polymeric layer containing the de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition described herein.
[0269] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
first exposed regions of the polymeric layer containing a
de-blocked and crosslinked polymer derived from the reactive
polymer in the reactive composition described above, and
non-exposed regions of the polymeric layer comprising little or no
reactive composition, wherein the first exposed regions further
comprise a pattern of electroless seed metal halide.
[0270] After this halide treatment, the polymeric layer can be
optionally exposed again to convert at least some, or typically at
least 20% (or more typically at least 50%), of the corresponding
electroless seed metal halide in first exposed regions of the
polymeric layer to corresponding electroless seed metal particles
using radiation having a .lamda..sub.max of at least 150 nm and up
to and including 450 nm, or more likely having a .lamda..sub.max of
at least 150 nm and up to and including 330 nm. The second exposed
regions can be the same as or different from the first exposed
regions, or the first and second exposed regions can partially
overlap.
[0271] After this second exposure, the method can provide yet
another intermediate article comprising a substrate and having
disposed thereon a polymeric layer comprising first exposed
regions, second exposed regions, and non-exposed regions,
[0272] the first exposed regions comprising corresponding
electroless seed metal halide in the crosslinked polymer derived
from the reactive polymer in the reactive composition described
above,
[0273] the second exposed regions comprising a pattern of
corresponding electroless seed metal with a latent image in the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and
[0274] the non-exposed regions comprising a reactive composition as
described above.
[0275] Optionally at this point, the reactive composition can be
removed from the non-exposed regions as described above, leaving
the pattern of electroless seed metal halide in the first exposed
regions of the polymeric layer and a pattern of corresponding
electroless seed metal halide with a latent image in the second
exposed regions of the polymeric layer.
[0276] If this procedure is carried out, an intermediate article is
created that comprises a substrate and has disposed thereon first
exposed regions and second exposed regions of the polymeric layer
containing a de-blocked and crosslinked polymer derived from the
reactive polymer in the reactive composition described above, and
non-exposed regions of the polymeric layer comprising little or no
reactive composition, wherein the first exposed regions further
comprise a pattern of electroless seed metal halide and the second
exposed regions further comprise a pattern of electroless seed
metal halide with a latent image.
[0277] The polymeric layer comprising corresponding electroless
seed metal halide in the first exposed regions, or corresponding
electroless seed metal latent image in the second exposed regions,
or both corresponding electroless seed metal halide in the first
exposed regions and corresponding electroless seed metal latent
image in the second exposed regions are then optionally contacted
with a suitable aqueous-based reducing solution comprising one or
more reducing agents using aqueous-based solutions and conditions
as described above.
[0278] After this reducing procedure, the polymeric layer,
especially the first exposed regions or the second exposed regions,
can be again washed using distilled water or deionized water or
another aqueous-based solution for a suitable time to remove excess
reducing agent.
[0279] The reducing procedure can provide another intermediate
article that comprises a substrate and having thereon a polymeric
layer comprising first exposed regions, second exposed regions, and
non-exposed regions,
[0280] the first exposed regions of the polymeric layer comprising
a pattern of corresponding electroless seed metal halide in a
crosslinked polymer derived from the reactive polymer in the
reactive composition described above,
[0281] the second exposed regions of the polymeric layer comprising
a pattern of corresponding electroless seed metal particles in the
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and
[0282] the non-exposed regions of the polymeric layer comprising
the reactive composition.
[0283] Optionally at this point, the reactive composition can be
removed from the non-exposed regions as described above, leaving a
pattern of corresponding electroless seed metal halide in the first
exposed regions of the polymeric layer and a pattern of
corresponding electroless seed metal particles in the second
exposed regions of the polymeric layer.
[0284] If this procedure is carried out, an intermediate article is
created that comprises a substrate and has disposed thereon first
exposed regions and second exposed regions of the polymeric layer
containing a de-blocked and crosslinked polymer derived from the
reactive polymer in the reactive composition, and non-exposed
regions of the polymeric layer comprising little or no reactive
composition, wherein the first exposed regions further comprise a
pattern of corresponding electroless seed metal halide and the
second exposed regions further comprise a pattern of electroless
seed metal particles.
[0285] The polymeric layer comprising corresponding electroless
seed metal halide in the first exposed regions, or corresponding
electroless seed metal particles in the second exposed regions, or
both corresponding electroless seed metal halide in the first
exposed regions and corresponding electroless seed metal particles
in the second exposed regions, are then optionally contacted with a
suitable fixing agent. This contact removes any remaining
corresponding electroless seed metal halide from both the first
exposed regions and the second exposed regions of the polymeric
layer, while leaving behind any corresponding electroless seed
metal particles in the second exposed regions.
[0286] This contact with a fixing agent can be done by immersing
the polymeric layer (or at least the first and second exposed
regions) within an aqueous-based fixing solution containing one or
more fixing agents for a suitable time to cause the desired change
(removal of the corresponding electroless metal halide) in the
first exposed regions and the second exposed regions.
Alternatively, an aqueous-based fixing solution can be sprayed or
rolled uniformly onto the polymeric layer to accomplish the same
results.
[0287] Useful fixing agents include but are not limited to,
sulfites, thiocyanates, thiosulfates, thioureas, halides, ammonia,
chelates such as ethylenediaminetetracetic acid, and mixtures
thereof. Fixing accelerators can also be included in the
aqueous-based fixing solutions, which compounds include, but are
not limited to, thioethers and mercaptotriazoles. The fixing agents
can be present as salts (that is alkali metal or ammonium salts) as
is well known in the art, for instance as described in Research
Disclosure December 1978 publication 38957. The total amount of
fixing agents in the aqueous-based fixing solution can be at least
0.01 weight % and up to and including 50 weight % based on total
fixing solution weight. The fixing agent amount can be readily
optimized using routine experimentation. The fixing time and
temperature can also be readily optimized in the same manner.
Generally, the fixing temperature is at least room temperature
(about 20.degree. C.) and up to and including 95.degree. C. and the
reducing time can be for at least 1 second and up to and including
30 minutes.
[0288] For example, some embodiments can be carried out using an
aqueous-based fixing solution comprising 20 solution weight % of
sodium thiosulfate in combination with 1.5 solution weight % of
sodium sulfite at room temperature for 3 minutes. Longer or shorter
times at higher temperatures are possible.
[0289] After this fixing procedure, the polymeric layer, especially
the first exposed regions or the second exposed regions, can be
again washed using distilled water or deionized water or another
aqueous-based solution for a suitable time to remove excess fixing
agent.
[0290] The fixing procedure can provide another intermediate
article that comprises a substrate and has thereon a polymeric
layer comprising first exposed regions, second exposed regions, and
non-exposed regions,
[0291] the first exposed regions of the polymeric layer from which
the pattern of corresponding electroless seed metal halide has been
removed, the first exposed regions comprising the crosslinked
polymer being derived from a reactive polymer in a reactive
composition as described above,
[0292] the second exposed regions of the polymeric layer comprising
a pattern of corresponding electroless seed metal particles in the
crosslinked polymer being derived from a reactive polymer in a
reactive composition as described above, and
[0293] the non-exposed regions of the polymeric layer comprising
the reactive composition.
[0294] Optionally at this point, the reactive composition can be
removed in the non-exposed regions as described above, leaving
corresponding electroless seed metal particles in the second
exposed regions of the polymeric layer containing a de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition described above.
[0295] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
first exposed regions and second exposed regions of the polymeric
layer containing a de-blocked and crosslinked polymer derived from
the reactive polymer in the reactive composition as described
above, and non-exposed regions of the polymeric layer comprising
little or no reactive composition, the first exposed regions
comprising little or no corresponding electroless seed metal
halide, and the second exposed regions comprising corresponding
electroless seed metal particles in the de-blocked and crosslinked
polymer derived from the reactive polymer in the reactive
composition described above.
[0296] The intermediate article that has been treated as described
above can be immediately immersed in an aqueous-based electroless
metal plating bath or solution using conditions and aqueous-based
solutions described above for the Electraless Plating Method 1, or
the treated article can be stored with just the catalytic pattern
comprising corresponding electroless seed metal particles for use
at a later time.
[0297] The intermediate article can be contacted with an
electroless plating metal that is the same as or different from the
corresponding electroless seed metal particles. In most
embodiments, the electroless plating metal is a metal different
from the corresponding electroless seed metal particles.
[0298] After the electroless plating procedure, the resulting
product article is removed from the aqueous-based electroless
plating bath or solution and can again be washed using distilled
water or deionized water or another aqueous-based solution to
remove any residual electroless plating chemistry. At this point,
the polymeric layer and electrolessly plated metal are generally
stable and can be used for their intended purpose.
[0299] Thus, this method provides a product article comprising a
substrate and having disposed thereon a polymeric layer comprising
first exposed regions (and optional second exposed regions) and
non-exposed regions,
[0300] the first exposed regions comprising a pattern of
corresponding electroless seed metal particles that have been
electrolessly plated with the same or different metal in a
crosslinked polymer derived from the reactive polymer in the
reactive composition described herein, and
[0301] the non-exposed regions comprising the reactive
composition.
[0302] Optionally, the reactive composition can be removed from the
non-exposed regions of the polymeric layer after electrolessly
plating the corresponding electroless seed metal particles so that
the resulting product article comprises a pattern of electrolessly
plated metal in the first exposed regions of the polymeric layer
containing a de-blocked and crosslinked polymer derived from the
reactive polymer in the reactive composition described above, but
the product article comprises little or no reactive composition in
the non-exposed regions of the polymeric layer.
[0303] To change the surface of the electrolessly plated metal for
visual or durability reasons, it is possible that a variety of
post-treatments can be employed including surface plating of still
another (third) metal such as nickel or silver on the "second"
electrolessly plated metal (this procedure is sometimes known as
"capping"), or the creation of a metal oxide, metal sulfide, or a
metal selenide layer that is adequate to change the surface color
and scattering properties without reducing the conductivity of the
electroless plated (second) metal. Depending upon the metals used
in the various capping procedures of the method, it may be
desirable to treat the electrolessly plated metal with a seed metal
catalyst in an aqueous-based seed metal catalyst solution to
facilitate deposition of additional metals. Details for such
procedures are provided above for the Electroless Plating Method
1.
Electroless Plating Method 5:
[0304] This method can be used to form a pattern in a polymeric
layer, the method comprising:
[0305] providing a polymeric layer comprising a reactive
composition that comprises: (1) a reactive polymer according to the
present invention; (2) a compound that provides a cleaving acid;
(3) a crosslinking agent that is capable of reacting in the
presence of the cleaving acid, to provide crosslinking in the
reactive polymer, and (4) optionally, a photosensitizer, as
described above, patternwise exposing the polymeric layer to
radiation having a .lamda..sub.max of at least 150 nm that is
sufficient to induce generate pendant sulfonic acid groups and
cause crosslinking within the reactive polymer, to provide a
polymeric layer comprising non-exposed regions and exposed regions
comprising an at least partially crosslinked polymer derived from
the reactive polymer,
[0306] optionally heating the polymeric layer simultaneously with
or after patternwise exposing the polymeric layer but before
removing the reactive composition comprising the reactive polymer
in the non-exposed regions, at a temperature sufficient to further
generate sulfonic acid groups and to further crosslink the at least
partially crosslinked polymer in the exposed regions of the
polymeric layer,
[0307] contacting the exposed regions of the polymeric layer with
electroless seed metal ions to form a pattern of electroless seed
metal ions in the exposed regions of the polymeric layer,
[0308] optionally contacting the pattern of electroless seed metal
ions in the exposed regions of the polymeric layer with a
non-reducing reagent that reacts with the electroless seed metal
ions to form an electroless seed metal compound that has a
pK.sub.sp of less than 40, and
[0309] electrolessly plating the electroless seed metal compound
within the exposed regions of the polymeric layer with a metal that
is the same as or different from the corresponding electroless seed
metal compound.
[0310] Such method thus comprises providing a polymeric layer (as
in forming the described precursor article), the polymeric layer
comprising a reactive composition as described above. This
polymeric layer can be formed on a suitable substrate, if desired
as described above by suitable application of the reactive
composition, after which the reactive composition is typically
dried before the resulting precursor article is used in the method
of the invention.
[0311] This polymeric layer in the precursor article, usually in
dry form, can be then pattemwise exposed as described above to
radiation having a .lamda..sub.max of at least 150 nm and up to and
including 450 nm or to radiation having a .lamda..sub.max of at
least 150 nm and up to and including 400 nm, to provide a polymeric
layer comprising non-exposed regions and exposed regions comprising
pendant sulfonic acid groups in a crosslinked polymer.
[0312] It is optional but desirable to heat or bake the polymeric
layer in the precursor article simultaneously with or after the
pattemwise exposure but generally before contacting the exposed
polymeric layer with electroless seed metal ions (described below)
using conditions described above.
[0313] At any time after the pattemwise exposing or optional
heating procedures, the reactive composition remaining in the
non-exposed regions of the polymeric layer can be removed using an
organic solvent in which the polymeric layer comprising the
reactive composition is soluble or dispersible as described above
for the Electroless Plating Method 1.
[0314] In many embodiments, removing the reactive composition in
the non-exposed regions of the polymeric layer is carried out
immediately after the patternwise exposure and any optional heating
procedure.
[0315] At this point, an intermediate article has been created in
which the exposed regions of the polymeric layer on the substrate
comprise crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and the non-exposed
regions of the polymeric layer comprise substantially no reactive
composition.
[0316] Then, the exposed regions of the polymeric layer are
contacted with electroless seed metal ions to form coordinated
electroless seed metal ions in the exposed regions of the polymeric
layer using aqueous-based solutions and conditions as described
above.
[0317] The contact with the electroless seed metal ions produces an
intermediate article comprising a substrate and having disposed
thereon a polymeric layer comprising exposed regions and
non-exposed regions, the exposed regions comprising a pattern of
electroless seed metal ions within the crosslinked polymer
resulting from the irradiation of the reactive polymer in the
reactive composition described herein, and the non-exposed regions
comprise the reactive composition as described above.
[0318] After the requisite time to react the electroless seed metal
ions within the crosslinked polymer in the exposed regions, the
polymeric layer can be rinsed with distilled or deionized water or
another aqueous-based solution for a suitable time and at a
suitable temperature, for example usually room temperature or
slightly higher.
[0319] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer as
described above, leaving the pattern of electroless seed metal ions
in the exposed regions of the polymeric layer containing the
de-blocked and crosslinked polymer derived from the reactive
polymer in the reactive composition as described above.
[0320] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
exposed regions of the polymeric layer containing a de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and non-exposed regions of
the polymeric layer comprising little or no reactive composition,
wherein the exposed regions further comprise a pattern of
electroless seed metal ions coordinated within the de-blocked and
crosslinked polymer.
[0321] The electroless seed metal ions in the exposed regions of
the polymeric layer are then contacted with a non-reducing reagent
that reacts with the electroless seed metal ions to form an
electroless seed metal compound (containing the non-reducing
reagent) deposited within the exposed regions of the polymeric
layer containing the crosslinked polymer derived from the reactive
polymer in the reactive composition described above.
[0322] Useful non-reducing reagents include any compound that will
covalently, conically, or otherwise bond to or react with the
electroless seed metal ions to form the electroless seed metal
compound. Useful non-reducing reagents include those that provide
electroless seed metal compounds having a pK.sub.sp value of less
than 40, and for example, a pK.sub.sp that is greater than 4 and
less than 40. For example, such useful non-reducing reagents
include but are not limited to, alkali metal and ammonium
hydroxides, thiosulfates, thiocyanates, sulfites, small organic
acids, and combinations thereof. Halides are also useful
non-reducing reagents for this invention. Alkali metal hydroxides
are particularly useful including mixtures thereof.
[0323] This contacting procedure can be carried out in various ways
including immersing the intermediate article in an aqueous-based
non-reducing solution comprising one or more non-reducing reagents
at a concentration of at least 1 weight % based on total
aqueous-based non-reducing solution weight. Alternatively, an
aqueous-based non-reducing solution can be sprayed or coated onto
the polymeric layer in the intermediate article. The time and
temperature for this contacting would be readily apparent to one
skilled in the art in order to best achieve the desired bonding.
For example, the contacting can be carried out at room temperature
(about 20.degree. C.) and up to and including 95.degree. C. and the
time can be for at least 1 second and up to and including 30
minutes.
[0324] After this contact with the non-reducing reagent, the
polymeric layer, especially the exposed regions, can be again
washed using distilled water or deionized water or another
aqueous-based solution under suitable conditions of time and
temperature.
[0325] At this stage, another intermediate article has been
created, which intermediate article comprises a substrate and
having disposed thereon a polymeric layer comprising exposed
regions and non-exposed regions,
[0326] the exposed regions of the polymeric layer comprising a
pattern of an electroless seed metal compound (comprising a
non-reducing reagent as described above) and a crosslinked polymer
derived from the reactive polymer in the reactive composition
described above, wherein the electroless seed metal compound has a
pK.sub.sp of less than 40, and
[0327] the non-exposed regions comprise the reactive composition as
described above.
[0328] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer as
described above, leaving the pattern of electroless seed metal
compound in the exposed regions of the polymeric layer containing
the de-blocked and crosslinked polymer derived from the reactive
polymer in the reactive composition described above.
[0329] If this procedure is carried out, an intermediate article is
created that comprises a substrate and having disposed thereon
exposed regions of the polymeric layer containing a de-blocked and
crosslinked polymer derived from the reactive polymer in the
reactive composition described above, and non-exposed regions of
the polymeric layer comprising little or no reactive composition,
wherein the exposed regions further comprise a pattern of
electroless seed metal compound (comprising the non-reducing
compound as described above).
[0330] This intermediate article can be immediately immersed in an
aqueous-based electroless metal plating bath or solution, or the
intermediate article can be stored with just the catalytic pattern
comprising electroless seed metal compound for use at a later
time.
[0331] The intermediate article can be contacted with an
electroless plating metal that is the same as or different from the
metal within the electroless seed metal compound using the
aqueous-based solutions and conditions described above for the
Electroless Plating Method 1. In most embodiments, the electroless
plating metal is a different metal from the metal within the
electroless seed metal compound.
[0332] After the electroless plating procedure, the product article
is removed from the aqueous-based electroless plating bath or
solution and can again be washed using distilled water or deionized
water or another aqueous-based solution to remove any residual
electroless plating chemistry. At this point, the polymeric layer
and electrolessly plated metal are generally stable and can be used
for their intended purpose.
[0333] This method provides a product article comprising a
substrate and having disposed thereon a polymeric layer comprising
exposed regions and non-exposed regions,
[0334] the exposed regions comprising a pattern of an electroless
seed metal compound (comprising a non-reducing reagent as described
above) which has been electrolessly plated with the same or
different metal that is part of the electroless seed metal compound
within a crosslinked polymer derived from the reactive polymer in
the reactive composition described above, and
[0335] the non-exposed regions comprising the reactive composition
as described above.
[0336] Optionally at this point, the reactive composition can be
removed from the non-exposed regions of the polymeric layer after
electrolessly plating the corresponding electroless seed metal
compound so that the resulting article comprises a pattern of an
electroless seed metal compound (comprising a non-reducing reagent
as described above) that has been electrolessly plated with the
same or different metal that is part of the electroless seed metal
compound, within the de-blocked and crosslinked polymer derived
from the reactive polymer in the reactive composition described
above, but the product article comprises little or no reactive
composition in the non-exposed regions of the polymeric layer.
[0337] To change the surface of the electroless plated metal for
visual or durability reasons, it is possible that a variety of
post-treatments can be employed including surface plating of still
another (third) metal such as nickel or silver on the "second"
electrolessly plated metal (this procedure is sometimes known as
"capping"), or the creation of a metal oxide, metal sulfide, or a
metal selenide layer that is adequate to change the surface color
and scattering properties without reducing the conductivity of the
electrolessly plated (second) metal. Depending upon the metals used
in the various capping procedures of the method, is may be
desirable to treat the electrolessly plated metal with a seed metal
catalyst in an aqueous-based seed metal catalyst solution to
facilitate deposition of additional metals.
[0338] Alternatively, the resulting product article can undergo
further treatment to decompose any residual onium salt on the
polymeric layer or to change the visual characteristics and or
durability of the electrolessly plated metal. For example, to
decompose any remaining onium salt or other cleaving
acid-generating compound, the polymeric film can be uniformly
exposed or blanket flashed with ultraviolet radiation and baked (or
heated) similarly as described above after the initial exposure.
Details of these procedures are provided above for the Electroless
Plating Method 1.
[0339] The following Examples are provided to illustrate the
practice of this invention and are not meant to be limiting in any
manner. Several compounds including novel monomer and copolymer
were synthesized for use in the method of this invention.
Synthesis of 4-t-butoxycarbonyloxybenzaldehyde:
[0340] 4-Hydroxybenzaldehyde (15.0 g) was dissolved in about 250 ml
of acetonitrile in a 500 ml single-neck flask followed by addition
of 25.5 g of di-t-butyldicarbonate. Following this, 32.3 g of
potassium carbonate were then added to the solution that was
stirred under nitrogen at room temperature. After about 15 minutes,
the solvent started to bubble and react vigorously. After the
reaction subsided, the solid was filtered and the filtrate
evaporated to dryness. Heptane was added to the oil that remained
and crystallization was started by placing the flask on dry
ice/acetone. It was then set in the freezer overnight to complete
crystallization and 25.93 g of white crystals were collected and
verified by NMR to be the desired reaction product.
Synthesis of (4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzyl
alcohol:
[0341] The 4-t-butoxycarbonyloxybenzaldehyde prepared above (5 g)
was dissolved in about 50 ml of tetrahydrofuran (THF) followed by
the addition of 4.25 g of trimethyl(trifluoromethyl)silane. The
reaction mixture was cooled with ice-acetone and then a catalytic
amount of tetrabutylammonium fluoride (TBAF) (-1 drop/mmol) was
added dropwise. The reaction mixture was stirred at 0.degree. C.
for about 15 minutes and then allowed to warm to room temperature
over about an hour. The solvent was evaporated and dried under high
vacuum to yield a yellow viscous oil that was purified by
chromatography (silica gel: 90/10 heptane/ethyl acetate), and dried
under high vacuum to obtain a clear colorless oil. The
trimethylsilyl protecting group of the reaction product was cleaved
by dissolving the oil in 100 ml of a 1:1 mixture of THF and 1 molar
aqueous hydrochloric acid while being stirred at room temperature
for 2 hours. The mixture was poured into about 300 ml of water and
then ethyl acetate was added, followed by stirring for about one
hour. The mixture was transferred to a separatory funnel and
extracted 2 more times with ethyl acetate. The organic compounds
were combined and washed with a 0.1 molar HCl solution, water,
brine, and then dried over magnesium sulfate. Evaporation of the
solvent produced a white solid. Hexane was added to the white solid
that was then set in the freezer overnight to finish crystallizing
to collect 3.43 g (78%; 56% overall yield) of white crystals of the
desired compound.
Preparation of
3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]
propyl methacrylate monomer:
[0342] (4-t-Butoxycarbonyloxy)-.alpha.-trifluoromethylbenzyl
alcohol (3.0 g) prepared as described above was dissolved in about
50 ml of methylene chloride in a 250 ml single-neck round bottom
flask followed by addition of 2.86 ml of triethylamine. The
reaction solution was cooled in an ice-acetone bath and 2.56 g of
3-chlorosulfopropyl methacrylate (prepared from 3-sulfopropyl
methacrylate by standard methods) dissolved in about 15 ml of
methylene chloride were added dropwise. The reaction solution was
stirred at 0.degree. C. for about an hour and then allowed to warm
to room temperature over about 3 hours. Water was added with
stirring for about 20 minutes. The reaction solution was
transferred to a separatory funnel and extracted. The organic
compounds were combined, washed with water, and dried over
magnesium sulfate. The solution was evaporated to dryness leaving
an oil that started to crystallize. Heptane and a small amount of
ethyl acetate were added and swirled until a white solid was
precipitated, which white solid was set in the freezer overnight to
collect 4.85 g of white crystals of the desired ethylenically
unsaturated polymerizable monomer.
Preparation of Electroless Copper Plating Bath:
[0343] The following components were dissolved in a glass container
that was cleaned with concentrated nitric acid followed by a
thorough rinse with distilled water to eliminate any trace of metal
on the glass: 1.8 g of copper (II) sulfate pentahydrate, 6.25 g of
tetrasodium EDTA(ethylenediaminetetraacetic acid) tetrahydrate,
0.005 g of potassium ferrocyanide trihydrate, 2.25 g of a 37 weight
% formaldehyde solution, 80 g of distilled water, and about 2 to 3
g of 45 weight % of a sodium hydroxide solution to adjust the pH to
12.8.
Preparation of the Electroless Nickel Plating Bath:
[0344] The following components were dissolved in a glass container
that was pre-cleaned with concentrated nitric acid followed by a
thorough rinse with distilled water to eliminate any trace of metal
on the glass: 0.36 g of nickel (II) sulfate hexahydrate, 3.37 g of
85 weight % lactic acid solution, 1.42 g of glacial acetic acid,
0.26 g of propionic acid, 0.25 ppm of thiourea, 100 ppm of methanol
solution, 2.835 g of 14 molar ammonium hydroxide, 78.24 g of
distilled water, and about 1.8 g of sodium hypophosphite partial
hydrate (assume 95% anhydrous) added immediately before use.
Invention Example 1: Preparation of a Reactive Polymer A from
3-f(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfolpropyl
methacrylate and glycidyl methacrylate in an 85:15 mol ratio
[0345] 3
-[(4-t-Butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]prop-
yl methacrylate monomer prepared above (2.05 g) and 0.11 g of
glycidyl methacrylate were weighed out in a 100 ml single-neck
round bottom flask and then dissolved in THF and chloroform to
obtain a 20 weight % solids solution. With solution still cloudy,
0.03 g of 2,2'-azodi(2-methylbutyronitrile) (AMBN) initiator was
added and the reaction solution was purged with nitrogen for about
30 minutes, capped with a septum, and placed in a preheated oil
bath at 65.degree. C. overnight. The reaction solution cleared
during heating and was cooled and precipitated into ethanol,
filtered, and dried. The resulting white solid was then dissolved
in THF, precipitated into ethanol, filtered, and dried in a high
vacuum oven at room temperature overnight. The resulting Reactive
Polymer A had a weight average molecular weight of 51,600 as
determined by size exclusion chromatography, and readily dissolved
in MEK to form a clear solution suitable for coating. A follow-up
preparation carried out at 25% solids and 70.degree. C. provided a
Reactive Polymer A with a weight average molecular weight of 85,600
and that readily dissolved in MEK at 35 weight % to form a clear
solution suitable for coating or further dilution with MEK to the
desired coating viscosity.
Comparative Example 1: Showing Criticality of Strong Electron
Withdrawing Group at the Benzyl Carbon
[0346] Attempted Synthesis of
3-[(4-t-butoxycarbonyloxy)-.alpha.-methylbenzylsulfo] propyl
methacrylate Monomer:
[0347] 4-Hydroxy-.alpha.-methylbenzyl alcohol (5.0 g) and 7.5 g of
di-t-butyldicarbonate were dissolved in 120 ml of acetonitrile
followed by the addition of 9.5 g of potassium carbonate. After 2
days of reaction, the resulting precipitate was filtered, the
filtrate was evaporated and the product was recrystallized from
hexane to obtain 5.87 g (72% theoretical yield) of a white solid
that was verified by NMR as the desired
(4-t-butoxycarbonyloxy)-.alpha.-methylbenzyl alcohol product. Five
grams of this (4-t-butoxycarbonyloxy)-.alpha.-methylbenzyl alcohol
was dissolved in about 100 ml of methylene chloride in a 250 ml
single-neck round bottom flask followed by addition of 5.85 ml of
triethylamine. The reaction mixture was cooled in an ice-acetone
bath and to it were added dropwise 5.23 g of 3-chlorosulfopropyl
methacrylate (prepared from 3-sulfopropyl methacrylate by standard
methods) dissolved in about 50 ml of methylene chloride. The
reaction solution was stirred at 0.degree. C. for about an hour and
then allowed to warm to room temperature over about 4 hours. Water
was added and the solution was stirred for about 18 hours, and then
transferred to a separatory funnel and extracted. The organics were
combined and washed with water and dried over magnesium sulfate.
The organic phase was evaporated to dryness leaving an oil, heptane
was added, and the solution was set in the freezer overnight.
Evaporated solvent and NMR showed the desired product was never
formed or it had formed and then decomposed.
[0348] These synthetic results indicate that the strong electron
withdrawing character of the a-trifluoromethyl group is critical to
the stability of the ethylenically unsaturated polymerizable
monomer and any subsequent polymer formed therefrom.
Invention Example 2: Preparation of Reaction Polymer B from
3-[(4-t-butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]propyl
methacrylate, glycidyl methacrylate, and t-butyl methacrylate
(64:15:21 mol ratio)
[0349] 3-
[(4-t-Butoxycarbonyloxy)-.alpha.-trifluoromethylbenzylsulfo]prop-
yl methacrylate monomer prepared above (3.85 g), 0.37 g of (-butyl
methacrylate, and 0.27 g of glycidyl methacrylate were weighed out
in a 100 ml single-neck round bottom flask and then dissolved in
THF to obtain a 25 weight % solids solution. Then, 0.061 g of
2,2'-azodi(2-methylbutyronitrile) (AMBN) initiator was added and
the reaction solution was purged with nitrogen for about 30
minutes, capped with a septum, and placed in a preheated oil bath
at 65.degree. C. overnight. The reaction solution cleared during
heating and was cooled and precipitated into ethanol, filtered, and
dried. The resulting white solid was then dissolved in THF,
precipitated into ethanol, filtered, and dried in a high vacuum
oven at room temperature overnight. The resulting Reactive Polymer
B had a weight average molecular weight of 68,500 as determined by
size exclusion chromatography, and readily dissolved in MEK to form
a clear 35 weight % solids solution.
Use Examples 1 and 2: Preparation of Reactive Composition Films and
Electrically-Conductive Copper Patterns
[0350] Reactive Polymers A (for Invention Example 3) and B (for
Invention Example 4) described above were dissolved in MEK to form
5 weight % reactive compositions along with 0.2 weight % of
(methylphenyl)-diphenylsulfonium triflate salt (a monomer unit to
onium salt molar ratio of 25:1). Each of the resulting reactive
compositions was filtered and spin coated at 1200 RPM onto a
substrate formed from poly(ethylene terephthalate) film with a
polymeric adhesion layer of a polymer derived from glycidyl
methacrylate and butyl acrylate that was applied before stretching
as previously described, to form polymeric films on the
substrate.
[0351] Each of the resulting precursor articles was exposed to
short ultraviolet light through a chrome-on-quartz contact mask for
30 seconds, followed by contact with a vacuum hotplate at
110.degree. C. for 1 to 2 minutes. Each resulting intermediate
article was then immersed in a 0.4 molar silver nitrate solution
for 5 minutes, rinsed in distilled water, immersed in a 1 weight %
dimethylamine borane(DMAB) bath for 1 minute, and followed by a
distilled water rinse. The resulting intermediate articles were
then individually immersed in the electroless copper plating bath
described above for 4 minutes. Brilliant continuous copper was
formed in all exposed regions of each of the resulting product
articles with line widths of 5 to 6 .mu.m diameter were faithfully
reproduced and showed high electrical conductivity.
[0352] This procedure was repeated three times over the course of 6
weeks using the same batch of 35 weight % Reactive Polymer A
dissolved in MEK. The results were not statistically different over
the 6 week period indicating that the reactive composition was
stable when held at room temperature for at least 6 weeks.
Use Example 3: Preparation of Polymer Films and
Electrically-Conductive Nickel Patterns
[0353] Reactive Polymer A (described above) was dissolved in MEK to
form a 5 weight % solution along with 0.2 weight % of
(methylphenyl)diphenylsulfonium triflate salt (to provide a monomer
unit to onium salt molar ratio of 25:1). The resulting reactive
composition was filtered and spin coated at 1200 RPM onto a PET
(polyethylene terephthalate) film with a polymeric adhesion layer
comprised of a copolymer derived from glycidyl methacrylate and
butyl acrylate that had been applied to the PET film before
stretching as previously described, to provide a polymeric layer on
the substrate.
[0354] The resulting precursor article was exposed to short
ultraviolet light through a chrome-on-quartz contact mask for 8
seconds, followed by contact with a vacuum hotplate at 110.degree.
C. for 90 seconds. The resulting intermediate article was then
immersed in a 0.001 M palladium chloride solution in 50:50
acetonitrile and water for 2 minutes, rinsed in distilled water,
immersed in a 1 weight % dimethylamine borane(DMAB) bath for 1
minute, and rinsed with distilled water. This intermediate article
was then immersed in the electroless nickel plating bath described
above at 55.degree. C. for 10 minutes. An electrically-conductive
black nickel pattern was formed in all areas of the precursor
article that has been exposed to the UV radiation. Line widths of 5
to 6 .mu.m diameter were successfully reproduced.
[0355] The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *