U.S. patent application number 14/409974 was filed with the patent office on 2015-05-28 for polyimide metal clad laminate.
The applicant listed for this patent is E. I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to Sidney G. Cox, Christopher Dennis Simone.
Application Number | 20150147567 14/409974 |
Document ID | / |
Family ID | 48746133 |
Filed Date | 2015-05-28 |
United States Patent
Application |
20150147567 |
Kind Code |
A1 |
Simone; Christopher Dennis ;
et al. |
May 28, 2015 |
POLYIMIDE METAL CLAD LAMINATE
Abstract
The present disclosure is directed to a polyimide metal clad
laminate. The metal clad laminate has a metal foil and a polyimide
layer. The polyimide layer having a polyimide derived from 80 to 90
mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20
mole % 4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine. The polyimide metal clad
laminate does not have an adhesive layer between the metal foil and
the polyimide layer.
Inventors: |
Simone; Christopher Dennis;
(Pickerington, OH) ; Cox; Sidney G.; (Durham,
NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E. I. DU PONT DE NEMOURS AND COMPANY |
Wilmington |
DE |
US |
|
|
Family ID: |
48746133 |
Appl. No.: |
14/409974 |
Filed: |
June 21, 2013 |
PCT Filed: |
June 21, 2013 |
PCT NO: |
PCT/US13/46939 |
371 Date: |
December 19, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61663270 |
Jun 22, 2012 |
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61663254 |
Jun 22, 2012 |
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61663258 |
Jun 22, 2012 |
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61663280 |
Jun 22, 2012 |
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61663291 |
Jun 22, 2012 |
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Current U.S.
Class: |
428/335 ;
428/334; 428/458 |
Current CPC
Class: |
H05K 2201/0323 20130101;
H05K 1/036 20130101; B32B 2307/206 20130101; B32B 2457/00 20130101;
C08G 73/105 20130101; Y10T 428/31681 20150401; B32B 15/08 20130101;
B32B 27/281 20130101; H05K 1/0373 20130101; Y10T 428/264 20150115;
B32B 2457/08 20130101; B32B 15/20 20130101; B32B 2307/204 20130101;
H05K 3/022 20130101; Y10T 428/266 20150115; C08G 73/1042 20130101;
C08G 73/1039 20130101; C08G 73/1071 20130101; H05K 2201/0154
20130101; Y10T 428/263 20150115; H05K 1/0271 20130101; B32B
2307/4026 20130101; H05K 1/056 20130101; H05K 3/281 20130101; Y10T
428/24851 20150115; B32B 7/12 20130101; C08G 73/1067 20130101; H05K
1/09 20130101; H05K 1/0298 20130101; B32B 2307/302 20130101; H01B
3/306 20130101; B32B 27/20 20130101; H05K 1/0346 20130101 |
Class at
Publication: |
428/335 ;
428/458; 428/334 |
International
Class: |
B32B 15/08 20060101
B32B015/08 |
Claims
1. A polyimide metal clad laminate comprising: a. a metal foil; b.
a polyimide layer having a first side and a second side, the first
side in direct contact with the metal foil, the polyimide layer
comprising: a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine; wherein the polyimide metal
clad laminate does not have an adhesive layer between the metal
foil and the polyimide layer; and wherein the polyimide metal clad
laminate has a peel strength of at least 1.0 N/mm, as measured in
accordance with IPC-TM-650-2.4.9d, when the metal foil and the
polyimide layer are laminated together at a temperature of
340.degree. C. or greater and a pressure from 150 psi (10.55 Kg/cm)
to 400 psi (28.13 Kg/cm).
2. The polyimide metal clad laminate of claim 1 wherein the metal
foil is copper.
3. The polyimide metal clad laminate of claim 1 wherein the
polyimide layer comprises from 1 to 55 weight percent of a
thermally conductive filler, dielectric fillers or mixtures
thereof.
4. The polyimide metal clad laminate of claim 1 wherein the metal
foil is copper and the polyimide layer comprises from 1 to 55
weight percent of a thermally conductive filler, dielectric fillers
or mixtures thereof.
5. The polyimide metal clad laminate of claim 1 further comprising
a second metal foil in direct contact with the second side of the
polyimide layer and wherein the polyimide metal clad laminate does
not have an adhesive layer between the second metal foil and the
polyimide layer.
6. The polyimide metal clad laminate of claim 5 wherein the second
metal foil is copper.
7. The polyimide metal clad laminate of claim 5 wherein the
polyimide layer comprises from 1 to 55 weight percent of a
thermally conductive filler, dielectric fillers or mixtures
thereof.
8. The polyimide metal clad laminate of claim 5 wherein the metal
foil, the second metal foil or both are copper and the polyimide
layer comprises from 1 to 55 weight percent of a thermally
conductive filler, dielectric fillers or mixtures thereof.
9. The polyimide metal clad laminate of claim 1 wherein the
polyimide layer is from 2 to 26 micron thick.
10. The polyimide metal clad laminate of claim 1 wherein the
polyimide layer is from 27 to 105 micron thick.
Description
FIELD OF DISCLOSURE
[0001] This disclosure relates generally to a polyimide metal clad
laminate.
BACKGROUND OF THE DISCLOSURE
[0002] Metal clad laminates for circuit board construction are
constructed by laminating a polyimide film to a metal foil with an
adhesive layer in between. The adhesive layer may consist of
conventional adhesives (acrylates, epoxides, polyamides, phenolic
resins, etc.) where the adhesive is cured during the metal foil
lamination. However, these conventional adhesives do not usually
possess the high temperature heat stability of the base polyimide
dielectric, and the strength of the adhesive bonds in the
multiplayer laminate structure deteriorates rapidly when subjected
to elevated temperatures. These adhesives also show high electric
loss in high speed circuit layers due to the high loss tangent of
these adhesives.
[0003] As electronic packaging becomes more sophisticated and the
desire for thinner, smaller, light weight, flexible, electronic
components with low CTE, low moisture absorption, high temperature
heat stability and high modulus have necessitated the elimination
of the adhesive layer.
[0004] One means to an adhesiveless laminate is to coat a high
modulus polyimide film core layer with a thin layer of polyamic
acid precursor solution on both sides, dry this layer, and finally
imidize the applied coating to create a thermoplastic polyimide.
Copper foil is then laminated with heat and pressure to create a
double sided copper clad laminate.
[0005] A polyimide precursor can also be coated directly onto
copper foil and then cured to create a polyimide film with copper
foil on one side. This is a common method of making adhesiveless
copper clad films but can create polyimide clads with copper on
just one side. Another method of making adhesiveless polyimide
copper clad laminates is to start with a standard rigid polyimide
base film. A thin metal layer is deposited, typically by sputtering
or vapor deposition to improve adhesion between the metal and the
polyimide. Then the copper is electroplated up to the required
thickness to create a double sided copper clad laminate.
[0006] Each of these suffers from one or more of the following
disadvantages: requisite additional steps as opposed to lamination
of a metal foil(s) to polyimide film, inferior adhesion of the
metal foil to the polyimide when an adhesive is used, multiple
layers of polyimide add to overall the thickness of the
construction.
[0007] For the forgoing reasons, a need exists for polyimide films
that can be directly laminated/adhered to metal foils without using
an adhesive to providing thinner, flexible electronic components
with low CTE, low moisture absorption, high temperature heat
stability while maintaining good mechanical and electrical
properties.
DETAILED DESCRIPTION
Definitions
[0008] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a method, process, article, or apparatus that comprises a
list of elements is not necessarily limited only to those elements
but may include other elements not expressly listed or inherent to
such method, process, article, or apparatus. Further, unless
expressly stated to the contrary, "or" refers to an inclusive or
and not to an exclusive or. For example, a condition A or B is
satisfied by any one of the following: A is true (or present) and B
is false (or not present), A is false (or not present) and B is
true (or present), and both A and B are true (or present).
[0009] Also, use of the "a" or "an" are employed to describe
elements and components of the invention. This is done merely for
convenience and to give a general sense of the invention. This
description should be read to include one or at least one and the
singular also includes the plural unless it is obvious that it is
meant otherwise.
[0010] The term "dianhydride" as used herein is intended to include
precursors, derivatives or analogs thereof, which may not
technically be a dianhydride but would nevertheless react with a
diamine to form a polyamic acid which could in turn be converted
into a polyimide.
[0011] The term "diamine" as used herein is intended to include
precursors, derivatives or analogs thereof, which may not
technically be a diamine but would nevertheless react with a
dianhydride to form a polyamic acid which could in turn be
converted into a polyimide.
[0012] The term "polyamic acid" as used herein is intended to
include any polyimide precursor material derived from a combination
of dianhydride and diamine and capable of conversion to a
polyimide.
[0013] The term "film" as used herein is intended to mean a
free-standing film or a (self-supporting or non-self-supporting)
coating. The term "film" is used interchangeably with the term
"layer".
[0014] The term "chemical conversion" or "chemically converted" as
used herein denotes the use of a catalyst (accelerator) or
dehydrating agent (or both) to convert the polyamic acid to
polyimide and is intended to include a partially chemically
converted polyimide which is then dried at elevated temperatures to
a solids level greater than 98%.
[0015] The term "metal" as used herein is intended to include
elemental metals and metal alloys.
[0016] The term "direct contact" as used herein is intended to mean
that layers are in contact with one another at their interface and
an intervening layer, such as an adhesive layer, is not
present.
[0017] When an amount, concentration, or other value or parameter
is given as either a range, preferred range or a list of upper
preferable values and lower preferable values, this is to be
understood as specifically disclosing all ranges formed from any
pair of any upper range limit or preferred value and any lower
range limit or preferred value, regardless of whether ranges are
separately disclosed. Where a range of numerical values is recited
herein, unless otherwise stated, the range is intended to include
the endpoints thereof, and all integers and fractions within the
range. Numerical values are to be understood to have the precision
of the number of significant figures provided. For example, the
number 1 shall be understood to encompass a range from 0.5 to 1.4,
whereas the number 1.0 shall be understood to encompass a range
from 0.95 to 1.04, including the end points of the stated ranges.
It is not intended that the scope of the invention be limited to
the specific values recited when defining a range.
[0018] In describing certain polymers it should be understood that
sometimes applicants are referring to the polymers by the monomers
used to make them or the amounts of the monomers used to make them.
While such a description may not include the specific nomenclature
used to describe the final polymer or may not contain
product-by-process terminology, any such reference to monomers and
amounts should be interpreted to mean that the polymer is made from
those monomers, unless the context indicates or implies
otherwise.
[0019] The materials, methods, and examples herein are illustrative
only and, except as specifically stated, are not intended to be
limiting. Although methods and materials similar or equivalent to
those described herein can be used, suitable methods and materials
are described herein.
[0020] The present disclosure is directed to a thermoset polyimide
film that can be directly adhered to metal and have good peel
strength without the need for an additional adhesive layer. Good
peel strength for copper clad laminate, for the purpose of this
disclosure, is at least 1 N/mm. Good peel strength for a coverlay
or a bondply, for the purpose of this disclosure, is 0.7 to 2
N/mm.
[0021] In some embodiments, a polyimide film (polyimide layer or
polyimide coverlay or polyimide bondply or electrically insulating
layer) comprises a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine and is capable of directly
adhering to metal and other polymers at lamination temperatures
from 340 to 400.degree. C.
[0022] In some embodiments, a polyimide film (polyimide layer or
polyimide coverlay or polyimide bondply or electrically insulating
layer) comprises a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine and is capable of directly
adhering to metal and other polymers at lamination temperatures of
at least 340, 350, 380, 395 or 400.degree. C.
[0023] Thus the thermoset polyimides of the present disclosure are
useful for any application where direct adherence of a polyimide to
metal is beneficial and thin, flexible electronic components with
low CTE, low moisture absorption are desired such as, but not
limited to, metal clad laminates, coverlays and bondplys.
Polyimide Metal Clad Laminate
[0024] One embodiment of the present disclosure is a polyimide
metal clad laminate of comprising a metal foil and a polyimide
layer. The polyimide layer having a first side and a second side,
the first side in direct contact with the metal foil, the polyimide
layer comprising: a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine. The polyimide metal clad
laminate does not have an adhesive layer between the metal foil and
the polyimide layer. The polyimide metal clad laminate has a peel
strength of at least 1.0 N/mm and in some embodiments 1 to 3 N/mm,
as measured in accordance with IPC-TM-650-2.4.9d, when the metal
foil and the polyimide layer are laminated together at a
temperature of 340.degree. C. or greater and a pressure from 150
psi (10.55 Kg/cm) to 400 psi (28.13 Kg/cm).
[0025] In some embodiments, the polyimide is derived from between
and including any two of the following: 80, 85 and 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, between and
including any two of the following 10, 15 and 20 mole
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine.
[0026] In some embodiments, the polyimide metal clad laminate
further comprises a second metal foil in direct contact with the
second side of the polyimide layer and wherein the polyimide metal
clad laminate does not have an adhesive layer between the second
metal foil and the polyimide layer.
[0027] In some embodiments, wherein the metal foil, the second
metal foil or both are copper.
[0028] In some embodiments, the polyimide metal clad laminate
comprises: [0029] a. a metal foil; [0030] b. a polyimide layer
having a first side and a second side, the first side in direct
contact with the metal foil, the polyimide layer comprising: a
polyimide derived from 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; and
[0031] c. a second metal foil; wherein the polyimide metal clad
laminate does not have an adhesive layer between the metal foil and
the polyimide layer; and wherein the polyimide metal clad laminate
has a peel strength of at least 1.0 N/mm, as measured in accordance
with IPC-TM-650-2.4.9d, when the metal foil and the polyimide layer
are laminated together at a temperature of 340.degree. C. or
greater and a pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13
Kg/cm). In some embodiments, the polyimide metal clad laminate is
laminated together at a temperature of 340 to 400.degree. C.
[0032] It is surprising the polyimides of the present disclosure
have good peel strength with metals, and with imaged metal having
exposed polymer areas where the metal was removed, without the need
for an adhesive when laminated at temperatures from 340 to
400.degree. C. The polyimide layer maintains a good balance of
mechanical and electrical properties as well as low CTE. Not all
low Tg polyimides have good peel strength, balance of properties
and low CTE.
[0033] Desirable electrical properties and mechanical properties
will depend on the desired end use that the material will be used
for. Ordinary skill and experimentation may be necessary in fine
tuning properties for desired end use. Generally, good machine
direction (MD) tensile modulus is greater than 2.75 GPa, MD tensile
strength is greater than 125 MPa, MD elongation is greater than
25%, water uptake less than 1.5%, dielectric constant at 100 Hz
less than 3.5 and loss tangent below 0.006.
[0034] Another advantage of a single layer of polyimide having the
ability to directly adhere to metal foil is film thickness
uniformity can be more easily controlled for thicknesses less than
25 microns via a single slot casting die than a multilayer casted
film which relies on a sophisticated layer combining system. All
polyimide metal clad laminates can be made with 3 layers; a rigid
thermoset polyimide core and thin thermoplastic polyimide coatings
(adhesive) on both sides of the polyimide core. However, it is
difficult to control the thickness of the thin coatings, plus is
requires much more complicated manufacturing methods to make 3
layer film.
[0035] Another advantage of a single layer of polyimide film of the
present disclosure is that it produces the properties expected of
metal (copper) clad laminate with a rigid polyimide core and also
produces adhesion to metal foil (copper foil) similar to a
thermoplastic polyimide. Good adhesion to metal foil could be
achieved with an all thermoplastic polyimide film. However, the all
thermoplastic films would have large CTE values (>50) that are
unacceptable for metal clad laminates. Also the dimensional
stability is poor.
[0036] Another advantage is that thinner polyimide films can be
made allowing for higher thermal conductivity while maintaining
electrical properties.
[0037] In some embodiments the polyimide layer (of the polyimide
metal clad laminate) is from, between and including any two of the
following: 2, 5, 10, 15, 20, 26, 30, 35, 40, 45, 50, 55, 60, 65,
70, 75, 80, 85, 90, 95, 100 and 105 microns thick. In some
embodiments, the polyimide layer is from 2 to 26 micron thick. In
some embodiments, the polyimide layer is from 27 to 105 micron
thick.
[0038] In some embodiments, the polyimide layer comprises from 1 to
55 weight percent of thermally conductive filler, dielectric
fillers or mixtures thereof. In some embodiments, the metal foil is
copper and the polyimide layer comprises from 1 to 55 weight
percent of a thermally conductive filler, dielectric fillers or
mixtures thereof. In some embodiments, the metal foil, the second
metal foil or both are copper and the polyimide layer comprises
from 1 to 55 weight percent of a thermally conductive filler,
dielectric fillers or mixtures thereof.
[0039] The polyimide of the present disclosure can be made by any
known thermal conversion or chemical conversion method for making
polyimide films or filled polyimide films. In some embodiments, it
is desirable to use chemical conversion due to the advantages
chemical conversion over thermal conversion such as but not limited
to, lower CTE and films are matte on both sides even when cast on
to a smooth surface.
[0040] In some embodiments, the polyimide layer can be a free
standing film that is then directly adhered to metal foil, on one
or both sides, using nip roll lamination or vacuum press to form a
metal clad laminate. The nip roll or vacuum press must be capable
of reaching the required temperature and pressure.
[0041] In some embodiments, a polyamic acid can be cast on to metal
foil and cured. This process can produce very thin electrically
insulating layers (dielectric layers). And optionally another metal
foil can be adhered to the other side of the polyimide layer using
a nip roll process or vacuum press, capable of reaching the
required temperature and pressure.
[0042] In some embodiment, the polyimide film can be a free
standing film that is then directly adhered to metal foil, on one
or both sides, using nip roll lamination or vacuum press to form a
metal clad laminate.
Metal Foil--Polyimide Metal Clad Laminate
[0043] In some embodiments, the metal foil is elemental metal. In
some embodiments, the metal foil is a metal alloy. In some
embodiments, the metal foil is copper. In some embodiments, the
metal alloy comprises 50 to 72 weight % nickel. In another
embodiment, the metal alloy comprises 50 to 72% weight % nickel an
14 to 24 weight % Chromium. In some embodiments, the metal foil is
aluminum.
[0044] In some embodiments, the polyimide metal clad laminate
further comprises a second metal foil in direct contact with the
second side of the polyimide layer and wherein the polyimide metal
clad laminate does not have an adhesive layer between the second
metal foil and the polyimide layer.
[0045] In some embodiments, the second metal foil is elemental
metal. In some embodiments, the second metal foil is a metal alloy.
In some embodiments, the second metal foil is copper. In some
embodiments, the metal alloy comprises 50 to 72 weight % nickel. In
another embodiment, the metal alloy comprises 50 to 72% weight
nickel an 14 to 24 weight % Chromium. In some embodiments, the
metal foil is aluminum.
[0046] In some embodiments, the metal foil is from 5 to 72 microns
thick. In some embodiments, the metal foil is between and including
any two of the following: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50,
55, 60, 65, 70 and 72 microns thick. In some embodiments, the metal
foil is surface treated to improve adhesion to electrically
insulating layers.
[0047] In some embodiments, the second metal foil is from 5 to 72
microns thick. In some embodiments, the second metal foil is
between and including any two of the following: 5, 10, 15, 20, 25,
30, 35, 40, 45, 50, 55, 60, 65, 70 and 72 microns thick. In some
embodiments, the second metal foil is surface treated to improve
adhesion to electrically insulating layers.
Circuit Board
[0048] One embodiment of the present disclosure is a circuit board,
comprising: [0049] a. a first electrically insulating layer having
a first side and a second side; [0050] b. a first imaged metal
layer; [0051] c. a first polyimide coverlay comprising a polyimide
derived from 80 to 90 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic anhydride and 100
mole % 2,2'-bis(trifluoromethyl)benzidine. The first polyimide
coverlay is in direct contact with the first imaged metal layer and
exposed areas of the first side of the first electrically
insulating layer. An adhesive layer is not present between the
first imaged metal layer and the first polyimide coverlay. The
first polyimide coverlay has a peel strength from 0.7 to 2 N/mm, as
measured in accordance with IPC-TM-650-2.4.9d, when the first
polyimide coverlay is laminated to the first imaged metal layer and
exposed areas of the first side of the first electrically
insulating layer at a lamination temperature from 340.degree. C. or
greater and a pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13
Kg/cm). The first electrically insulating layer is any electrically
insulating material that can withstand the lamination temperature
of 340.degree. C. or greater.
[0052] The advantages are the same as the polyimide metal clad
laminate. The first polyimide coverlay has good peel strength with
imaged metal having exposed polymer areas where the metal was
removed, without the need for an adhesive when laminated at
temperatures from 340.degree. C. or greater. In some embodiments,
the circuit board is laminated together at a temperature of 340 to
400.degree. C.
[0053] In another embodiment, the circuit board further comprises a
second imaged metal layer on the second side of the first
electrically insulating layer. In another embodiment, the circuit
board further comprises a second polyimide coverlay comprising a
polyimide derived from 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine and is
in direct contact with the second imaged metal layer and exposed
areas of the second side of the first electrically insulating
layer. An adhesive layer is not present between the second imaged
metal layer and the second polyimide coverlay. The second polyimide
coverlay has a peel strength from 0.7 to 2 N/mm, as measured in
accordance with IPC-TM-650-2.4.9d, when the second polyimide
coverlay is laminated to the second imaged metal layer and the
exposed areas of the second side of the first electrically
insulating layer at a lamination temperature from 340.degree. C. or
greater and a pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13
Kg/cm).
[0054] In another embodiment of the present disclosure, the circuit
board comprises in the following order:
[0055] a. a first imaged metal layer;
[0056] b. a first electrically insulating layer having a first side
and a second side; the first side of the first electrically
insulating layer is next to the first imaged metal layer;
[0057] c. a second imaged metal layer; the second side of the first
electrically insulating layer is next to the second imaged metal
layer;
[0058] d. a polyimide bondply comprising a polyimide derived from
80 to 90 mole 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to
20 mole % 4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine;
[0059] e. a third imaged metal layer;
[0060] f. a second electrically insulating layer having a first
side and a second side; the first side of the second electrically
insulating layer is next to the third imaged metal layer;
[0061] g. a fourth imaged metal layer; the second side of the
second electrically insulating layer is next to the fourth imaged
metal layer. The polyimide bondply is in direct contact with the
second imaged metal layer and exposed areas of the second side of
the first electrically insulating layer; and in direct contact with
the third imaged metal layer and exposed areas of the first side of
the second electrically insulating layer. The polyimide bondply has
a peel strength from 0.7 to 2 N/mm as measured in accordance with
IPC-TM-650-2.4.9d, when
[0062] i) the first imaged metal layer, the first electrically
insulating layer and the second image metal layer;
[0063] ii) the polyimide bondply; and
[0064] iii) the third imaged metal layer, the second electrically
insulating layer and the fourth imaged metal layer
are laminated at a lamination temperature of 340.degree. C. or
greater and a pressure from 150 psi (10.55 Kg/cm) to 400 psi (28.13
Kg/cm). The first electrically insulating layer and the second
electrically insulating layer are any electrically insulating
material that can withstand the lamination temperature of
340.degree. C. or greater.
[0065] The advantage of the bondply of the present disclosure is
the bondply has good peel strength with imaged metal having exposed
electrically insulating layers areas where the metal was removed,
without the need for an adhesive when laminated at temperatures
from 340.degree. C. or greater. In some embodiments, the circuit
board is laminated together at a temperature of 340 to 400.degree.
C.
[0066] In some embodiments, the polyimide bondply comprises from 1
to 55 weight percent of a thermally conductive filler, dielectric
fillers or mixtures thereof.
[0067] In some embodiments, the circuit board further comprises an
adhesive and a coverlay wherein the adhesive is between and in
direct contact with the first imaged metal layer and the coverlay.
In such embodiments the circuit board comprises in the following
order: [0068] a. a coverlay; [0069] b. a adhesive; [0070] c. a
first imaged metal layer; [0071] d. a first electrically insulating
layer having a first side and a second side; the first side of the
first electrically insulating layer is next to the first imaged
metal layer; [0072] e. a second imaged metal layer; the second side
of the first electrically insulating layer is next to the second
imaged metal layer; [0073] f. a polyimide bondply comprising a
polyimide derived from 80 to 90 mole 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; [0074]
g. a third imaged metal layer; [0075] h. a second electrically
insulating layer having a first side and a second side; the first
side of the second electrically insulating layer is next to the
third imaged metal layer; [0076] i. a fourth imaged metal layer;
the second side of the second electrically insulating layer is next
to the fourth imaged metal layer. The polyimide bondply is in
direct contact with the second imaged metal layer and exposed areas
of the second side of the first electrically insulating layer; and
in direct contact with the third imaged metal layer and exposed
areas of the first side of the second electrically insulating
layer.
[0077] In another embodiment, the circuit board further
comprises:
[0078] i) a adhesive and a coverlay wherein the adhesive is between
and in direct contact with the first imaged metal layer and the
coverlay; and
[0079] ii) a second adhesive and a second coverlay wherein the
second adhesive is between and in direct contact with the fourth
imaged metal layer and the second coverlay. In such embodiments the
circuit board comprises in the following order: [0080] a. a
coverlay; [0081] b. a adhesive; [0082] c. a first imaged metal
layer; [0083] d. a first electrically insulating layer having a
first side and a second side; the first side of the first
electrically insulating layer is next to the first imaged metal
layer; [0084] e. a second imaged metal layer; the second side of
the first electrically insulating layer is next to the second
imaged metal layer; [0085] f. a polyimide bondply comprising a
polyimide derived from 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; [0086]
g. a third imaged metal layer; [0087] h. a second electrically
insulating layer having a first side and a second side; the first
side of the second electrically insulating layer is next to the
third imaged metal layer; [0088] i. a fourth imaged metal layer;
the second side of the second electrically insulating layer is next
to the fourth imaged metal layer. [0089] j. a second adhesive;
[0090] k. a second coverlay The polyimide bondply is in direct
contact with the second imaged metal layer and exposed areas of the
second side of the first electrically insulating layer; and in
direct contact with the third imaged metal layer and exposed areas
of the first side of the second electrically insulating layer.
[0091] The adhesive and the second adhesive can be any traditional
adhesive used to bond a coverlay to an imaged metal layer when the
coverlay is added after the circuit board is formed. The circuit
board can have any number of imaged metal layers and electrically
insulating layers. In some embodiments, two imaged metal layers
separated by an electrically insulating layer can be called a clad
or metal clad. And number of these clads can be adhered to each
other via the polyimide bondply of the present disclosure.
[0092] The coverlay and the second coverlay can be any traditional
coverlay material. Ordinary skill and experimentation may be
necessary in selecting the combinations of the coverlay material
and the appropriate traditional adhesive.
[0093] In another embodiment of the present disclosure, the circuit
board comprises in the following order:
[0094] a. a first polyimide coverlay comprising a polyimide derived
from [0095] i) 80 to 90 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic anhydride and 100
mole % 2,2'-bis(trifluoromethyl)benzidine; or [0096] ii) 100 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %
2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline;
[0097] b. a first imaged metal layer;
[0098] c. a first electrically insulating layer having a first side
and a second side; the first side of the first electrically
insulating layer is next to the first imaged metal layer;
[0099] d. a second imaged metal layer; the second side of the first
electrically insulating layer is next to the second imaged metal
layer;
[0100] e. a polyimide bondply comprising a polyimide derived from
80 to 90 mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10
to 20 mole % 4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine;
[0101] f. a third imaged metal layer;
[0102] g. a second electrically insulating layer having a first
side and a second side; the first side of the second electrically
insulating layer is next to the third imaged metal layer
[0103] h. a fourth imaged metal layer; the second side of the
second electrically insulating layer is next to the fourth imaged
metal layer; and
[0104] i. a second polyimide coverlay comprising a polyimide
derived from [0105] i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; or
[0106] ii) 100 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 20 to 90 mole 2,2'-bis(trifluoromethyl)benzidine, and
10 to 80 mole % 4,4'-oxydianiline. The polyimide bondply is in
direct contact with the second imaged metal layer and exposed areas
of the second side of the first electrically insulating layer; and
in direct contact with the third imaged metal layer and exposed
areas of the first side of the second electrically insulating
layer. The polyimide bondply has a peel strength from 0.7 to 2 N/mm
as measured in accordance with IPC-TM-650-2.4.9d, when
[0107] i) the first imaged metal layer, the first electrically
insulating layer and the second imaged metal layer;
[0108] ii) the polyimide bondply; and
[0109] iii) the third imaged metal layer, the second electrically
insulating layer and the fourth imaged metal layer
[0110] are laminated at a lamination temperature of 340.degree. C.
or greater and a pressure from 150 psi (10.55 Kg/cm) to 400 psi
(28.13 Kg/cm). The first polyimide coverlay is in direct contact
with the first imaged metal layer and exposed areas of the first
side of the first electrically insulating layer; wherein the second
polyimide coverlay is in direct contact with the fourth imaged
metal layer and exposed areas of the second side of the second
electrically insulating layer; and wherein the first electrically
insulating layer and the second electrically insulating layer are
any electrically insulating material that can withstand the
lamination temperature of 340.degree. C. or greater.
Imaged Metal Layers--Circuit Board
[0111] In some embodiments, the first imaged metal layer, the
second imaged metal layer, the third imaged metal layer or the
fourth imaged metal layer is elemental metal. In some embodiments,
the first imaged metal layer, the second imaged metal layer, the
third imaged metal layer or the fourth imaged metal layer is a
metal alloy. In some embodiments, the first imaged metal layer, the
second imaged metal layer, the third imaged metal layer or the
fourth imaged metal layer is copper. In some embodiments, the metal
alloy comprises 50 to 72 weight % nickel. In another embodiment,
the metal alloy comprises 50 to 72% weight % nickel an 14 to 24
weight % Chromium. In some embodiments, the first imaged metal
layer, the second imaged metal layer, the third imaged metal layer
or the fourth imaged metal layer is aluminum.
[0112] In some embodiments, the first imaged metal layer, the
second imaged metal layer, the third imaged metal layer or the
fourth imaged metal layer is from 5 to 72 microns thick. In some
embodiments, the first imaged metal layer, the second imaged metal
layer, the third imaged metal layer or the fourth imaged metal
layer is between and including any two of the following: 5, 10, 15,
20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 and 72 microns thick. In
some embodiments, the first imaged metal layer, the second imaged
metal layer, the third imaged metal layer or the fourth imaged
metal layer is surface treated to improve adhesion to electrically
insulating layers.
[0113] In some embodiments, the first imaged metal layer, the
second imaged metal layer, the third imaged metal layer and the
fourth imaged metal layer are made by imaging a metal foil/metal
layer with a photoresist and copper etching to created imaged metal
layers having lines of different widths using standard procedures
in the flexible printed circuit board industry.
Polyimide Coverlay(s)--Circuit Board
[0114] In some embodiments, the first polyimide coverlay comprises
a polyimide derived from i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; or ii)
100 mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90
mole % 2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline.
[0115] In some embodiments, the second polyimide coverlay comprises
a polyimide derived from i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; or ii)
100 mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90
mole % 2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline.
[0116] The polyimide coverlays of the present disclosure have good
peel strength to imaged metal layers and exposed electrically
insulating layers areas where the metal was removed, without the
need for an adhesive when laminated at temperatures from
340.degree. C. or greater. In some embodiments, the circuit board
is laminated together at a temperature of 340 to 400.degree. C.
[0117] The polyimide coverlays of the present disclosure can be
made by any known thermal conversion or chemical conversion method
for making polyimide films or filled polyimide films. In some
embodiments, it is desirable to use chemical conversion due to the
advantages chemical conversion over thermal conversion such as but
not limited to, lower CTE and films are matte on both sides even
when cast on to a smooth surface.
[0118] In some embodiments, it is desirable for a coverlay to have
optical properties which provide security against unwanted visual
inspection and tampering of the electronic components. In some
embodiments, the optical density (opacity) desirable (e.g., to hide
the conductor traces in the flex circuits from view) is greater
than or equal to 2. An optical density of 2 is intended to mean
1.times.10.sup.-2 or 1% of light is transmitted through the film.
The optical density is measured with a Macbeth TD904 optical
densitometer. The optical density can be increased by making a
thicker coverlay. This is undesirable since the trend is for
coverlays to be increasingly thin. The optical density can be
increased by adding filler. In some embodiments a pigment is added
is increase the optical density. In some embodiments, a matting
agent is added to increase the optical density. In some embodiments
a combination of pigment and matting agents can be added.
[0119] In some embodiments, the pigment is a low conductivity
carbon black. In some embodiments, the pigment is a non-carbon
black pigment.
[0120] Virtually any pigment (or combination of pigments) can be
used. In some embodiments, a low conductivity carbon black is used.
Low conductivity carbon black is intended to mean, channel black or
furnace black. In some embodiments, the low conductivity carbon
black is a surface oxidized carbon black. One method for assessing
the extent of surface oxidation (of the carbon black) is to measure
the carbon black's volatile content. The volatile content can be
measured by calculating weight loss when calcined at 950.degree. C.
for 7 minutes. Generally speaking, a highly surface oxidized carbon
black (high volatile content) can be readily dispersed into a
polyamic acid solution (polyimide precursor), which in turn can be
imidized into a (well dispersed) filled polyimide polymer of the
present disclosure. It is thought that if the carbon black
particles (aggregates) are not in contact with each other, then
electron tunneling, electron hopping or other electron flow
mechanism are generally suppressed, resulting in lower electrical
conductivity. In some embodiments, the low conductivity carbon
black has a volatile content greater than or equal to 1%. In some
embodiments, the low conductivity carbon black has a volatile
content greater than or equal to 5, 9, or 13%. In some embodiments,
furnace black may be surface treated to increase the volatile
content. In some embodiments a bone black is used.
[0121] In some embodiments, the first polyimide coverlay comprises
a pigment. In some embodiments, the second polyimide coverlay
comprises a pigment. In another embodiment, the first polyimide
coverlay and the second polyimide coverlay comprise a pigment. In
another embodiment, the first polyimide coverlay, the second
polyimide coverlay or both comprise a pigment.
[0122] In one embodiment, the pigment is a low conductivity carbon
black present in an amount from 2 to 9 weight percent. In some
embodiment, the pigment is a low conductivity carbon black present
in amount between and optionally including any two of the
following: 2, 3, 4, 5, 6, 7, 8 and 9 weight percent of the first
polyimide coverlay. In some embodiment, the pigment is a low
conductivity carbon black present in amount between and optionally
including any two of the following: 2, 3, 4, 5, 6, 7, 8 and 9
weight percent of the second polyimide coverlay.
[0123] In another embodiment, the pigment is a non-carbon black
pigment present in an amount from 10 to 60 weight percent. In
another embodiment, the pigment is a non-carbon black pigment
present in an amount between and optionally including any two of
the following: 10, 20, 30, 40, 50 and 60 weight percent of the
first polyimide coverlay. In another embodiment, the pigment is a
non-carbon black pigment present in an amount between and
optionally including any two of the following: 10, 20, 30, 40, 50
and 60 weight percent of the second polyimide coverlay.
[0124] In some embodiments, the first polyimide coverlay comprises
a pigment and a matting agent. In some embodiments, the second
polyimide coverlay comprises a pigment and a matting agent. In some
embodiments, the first polyimide coverlay, the second polyimide
coverlay or both comprise a pigment and a matting agent. In some
embodiments, the first polyimide coverlay and the second polyimide
coverlay comprise a pigment and a matting agent. In one embodiment,
the matting agent is polyimide particles. In another embodiment,
the pigment and the matting agent are both a low conductivity
carbon black and the low conductivity carbon black is present in
the first polyimide coverlay in an amount from 2 to 20 weight
percent of the first polyimide coverlay. In another embodiment, the
pigment and the matting agent are both a low conductivity carbon
black and the low conductivity carbon black is present in the
second polyimide coverlay in an amount from 2 to 20 weight percent
of the second polyimide coverlay. In another embodiment, the
pigment and the matting agent are both a low conductivity carbon
black and the low conductivity carbon black is present in the first
polyimide coverlay in an amount from 2 to 20 weight percent of the
first polyimide coverlay and present in the second polyimide
coverlay in an amount from 2 to 20 weight percent the second
polyimide coverlay.
[0125] In some embodiments, useful non-carbon black pigments
include but are not limited to the following: Barium Lemon Yellow,
Cadmium Yellow Lemon, Cadmium Yellow Lemon, Cadmium Yellow Light,
Cadmium Yellow Middle, Cadmium Yellow Orange, Scarlet Lake, Cadmium
Red, Cadmium Vermilion, Alizarin Crimson, Permanent Magenta, Van
Dyke brown, Raw Umber Greenish, or Burnt Umber. In some
embodiments, useful black pigments include: cobalt oxide,
Fe--Mn--Bi black, Fe--Mn oxide spinel black, (Fe,Mn)2O3 black,
copper chromite black spinel, lampblack, bone black, bone ash, bone
char, hematite, black iron oxide, micaceous iron oxide, black
complex inorganic color pigments (CICP), CuCr2O4 black,
(Ni,Mn,Co)(Cr,Fe)2O4 black, Aniline black, Perylene black,
Anthraquinone black, Chromium Green-Black Hematite, Chrome Iron
Oxide, Pigment Green 17, Pigment Black 26, Pigment Black 27,
Pigment Black 28, Pigment Brown 29, Pigment Black 30, Pigment Black
32, Pigment Black 33 or mixtures thereof.
Electrically Insulating Layer(s)--Circuit Board
[0126] In some embodiments, the first electrically insulating layer
comprises a polyimide derived from [0127] i) 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine; [0128] ii) 100 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90 mole
2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline; or [0129] iii) 100 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 100 mole %
2,2'-bis(trifluoromethyl)benzidine when laminated at a temperature
of 380 or greater.
[0130] In some embodiments, the second electrically insulating
layer comprises a polyimide derived from [0131] i) 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine; [0132] ii) 100 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90 mole
2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline; or [0133] iii) 100 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 100 mole %
2,2'-bis(trifluoromethyl)benzidine when laminated at a temperature
of 380 or greater.
[0134] The electrically insulating layers derived from 80 to 90
mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20
mole % 4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine or 100 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 20 to 90 mole %
2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline or 100 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 100 mole % 2,2'-bis(trifluoromethyl)benzidine have
good peel strength to imaged metal layers and exposed areas of the
underlying layers where the metal was removed, without the need for
an adhesive when laminated at temperatures from 340.degree. C. or
greater. In some embodiments, the circuit board is laminated
together at a temperature of 340 to 400.degree. C.
[0135] The above disclosed polyimide electrically insulating layers
can be made by any known thermal conversion or chemical conversion
method for making polyimide films or filled polyimide films. In
some embodiments, it is desirable to use chemical conversion due to
the advantage of lower CTE films.
[0136] In one embodiment, the first electrically insulating layer
is in direct contact with the first imaged layer and the exposed
areas of the first polyimide coverlay.
[0137] In another embodiment, the first electrically insulating
layer is in direct contact with the first imaged layer and the
exposed areas of the first polyimide coverlay and in direct contact
with the second imaged layer and the exposed areas of the second
polyimide coverlay. In such embodiments the circuit board comprises
in the following order: [0138] a. a second polyimide coverlay
comprising a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine; [0139] b. a second imaged metal
layer; [0140] c. a first electrically insulating layer comprising a
polyimide derived from 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine [0141]
d. a first imaged metal layer; and [0142] e. a first polyimide
coverlay comprising a polyimide derived from 80 to 90 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to 20 mole %
4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine.
[0143] In another embodiment, the first electrically insulating
layer is direct contact with the first imaged metal layer, the
second imaged metal layer and exposed areas of the polyimide
bondply. In another embodiment, the second electrically insulating
layer is direct contact with the fourth imaged metal layer, the
third imaged metal layer and exposed areas of the polyimide
bondply.
[0144] In one embodiment the circuit board comprises in the
following order:
[0145] a. a first polyimide coverlay comprising a polyimide derived
from [0146] i) 80 to 90 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic anhydride and 100
mole % 2,2'-bis(trifluoromethyl)benzidine; or [0147] ii) 100 mole %
3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20 to 90 mole %
2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole %
4,4'-oxydianiline;
[0148] b. a first imaged metal layer;
[0149] c. a first electrically insulating layer comprising a
polyimide derived from [0150] i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; [0151]
ii) 100 mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20
to 90 mole % 2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole
% 4,4'-oxydianiline; or [0152] iii) 100 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 100 mole %
2,2'-bis(trifluoromethyl)benzidine when laminated at a temperature
of 380 or greater;
[0153] d. a second imaged metal layer; the second side of the first
electrically insulating layer is next to the second imaged metal
layer;
[0154] e. a polyimide bondply comprising a polyimide derived from
80 to 90 mole 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 10 to
20 mole % 4,4'-oxydiphthalic anhydride and 100 mole %
2,2'-bis(trifluoromethyl)benzidine;
[0155] f. a third imaged metal layer;
[0156] g. a second electrically insulating layer comprising a
polyimide derived from [0157] i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; [0158]
ii) 100 mole % 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 20
to 90 mole % 2,2'-bis(trifluoromethyl)benzidine, and 10 to 80 mole
% 4,4'-oxydianiline; or [0159] iii) 100 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 100 mole %
2,2'-bis(trifluoromethyl)benzidine when laminated at a temperature
of 380 or greater;
[0160] h. a fourth imaged metal layer; the second side of the
second electrically insulating layer is next to the fourth imaged
metal layer; and
[0161] i. a second polyimide coverlay comprising a polyimide
derived from [0162] i) 80 to 90 mole % 3,3',4,4'-biphenyl
tetracarboxylic dianhydride, 10 to 20 mole % 4,4'-oxydiphthalic
anhydride and 100 mole % 2,2'-bis(trifluoromethyl)benzidine; or
[0163] ii) 100 mole % 3,3',4,4'-biphenyl tetracarboxylic
dianhydride, 20 to 90 mole 2,2'-bis(trifluoromethyl)benzidine, and
10 to 80 mole % 4,4'-oxydianiline; wherein the polyimide bondply is
in direct contact with the second imaged metal layer and exposed
areas of the second side of the first electrically insulating
layer; and in direct contact with the third imaged metal layer and
exposed areas of the first side of the second electrically
insulating layer;
[0164] In some embodiments, the first electrically insulating layer
comprises from 1 to 55 weight percent of a thermally conductive
filler, a dielectric filler or mixtures thereof. In some
embodiments, the second electrically insulating layer comprises
from 1 to 55 weight percent of a thermally conductive filler, a
dielectric filler or mixtures thereof. In some embodiments, the
first electrically insulating layer and the second electrically
insulating layer comprise from 1 to 55 weight percent of a
thermally conductive filler, a dielectric filler or mixtures
thereof.
[0165] In some embodiments, the polyimide bondply, the first
polyimide coverlay, the second polyimide coverlay, the first
electrically insulating layer, the second electrically insulating
layer or any combination thereof comprises from 1 to 55 weight
percent of a thermally conductive filler, dielectric fillers or
mixtures thereof.
[0166] In some embodiments, the circuit board is made by taking a
first polyimide coverlay (if present), a double-sided clad (first
imaged metal layer, first electrically insulating layer and a
second imaged metal layer), bondply, a second double-sided clad
(third imaged metal layer, second electrically insulating layer and
a fourth imaged metal layer) and a second polyimide coverlay (if
present) and laminating at lamination temperature of 340 to
400.degree. C. and a pressure from 150 psi (10.55 Kg/cm) to 400 psi
(28.13 Kg/cm) using a vacuum platen press.
EXAMPLES
[0167] The materials, methods, and examples herein are illustrative
only and, except as specifically stated, are not intended to be
limiting.
[0168] The glass transition temperatures of the polyimide films of
the present invention were determined using a TA Instruments 2980
dynamic mechanical analyzer. The Tg measurement method used a
sampling frequency of about 1.0 Hz (an amplitude of about 10.0
.mu.m) and a pre-load force of about 0.01 N. A temperature ramp
rate of about 5.degree. C. min-1 was used.
[0169] The Tg was measured at the peak of the tan .delta.
[0170] Tensile Modulus was determined by ASTM D-882.
[0171] Tensile strength was determined by ASTM D-882
[0172] Elongation was determined by ASTM D-882 Dielectric Constant
was measured as described in ASTM D150, "Standard Test Methods for
AC Loss Characteristics and Permittivity (Dielectric Constant) of
Solid Electrical Insulation". The composite film dielectric
constant was calculated based on the measured capacitance of the
2.5 cm diameter capacitors.
[0173] In-plane CTE of a polyimide films of the present invention
were measured using a TA Instruments TMA 2940 thermal mechanical
analyzer. The expansion of a film was measured between about
50.degree. C. and about 250.degree. C. on a second pass. The
expansion was then divided by the temperature difference (and
sample length) to obtain the CTE in ppm .degree. C.-1. The first
pass was used to remove shrinkage from the sample over the same
temperature range as well as to dry out the sample. As such, the
second pass then provided a CTE value characteristic of the film's
inherent properties (e.g. minus water absorption and the effect
water would have on a film's CTE). This method employed a 0.05 N
load force and operated within the above mentioned temperature
range ramping temperature at a rate of about 10.degree. C. per
minute
[0174] Moisture absorption was determined by IPC-TM-650, Method
2.6.2.
[0175] Peel strength data reported in this application are the
average of 8 to 12 measurements, consistent with requirement for
statistically valid data per IPC-TM650 2.4.8d test method. The
copper foil for the peel strength testing was 35 um thick roll
annealed (RA) copper foil with pink treatment available from Somers
Corporation.
Example 1
BPDA//TFMB
[0176] Example 1 shows that a polyimide derived from 100 mole %
BPDA and 100 mole % TFMB has a peel strength of at least 1 N/mm
when laminated at a temperature of 380.degree. C. or greater.
[0177] Within a nitrogen inerted glovebox, 21.472 g (0.067 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 159 grams of
N,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliter
jacketed beaker equipped with mechanical stirrer. The mixture was
heated using recirculating 45.degree. C. glycol-water for several
minutes until the diamine had completely dissolved resulting in a
near colorless solution. Next, 19.528 g (0.066 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0178] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0179] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The polyimide film was removed from the pin
frame and analyzed. The data is shown in Table 1.
[0180] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Examples 2-12 show that a polyimide derived from 100 mole % BPDA,
20 to 90 mole % TFMB and 10 to 80 mole % 4,4'-ODA has a peel
strength of at least 1 N/mm when laminated at a temperature of
330.degree. C. or greater
Example 2
BPDA//90 TFMB/10 ODA
[0181] Within a nitrogen inerted glovebox, 19.711 g (0.0615 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 1.369 g (0.006 moles)
4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc)
were charged to a dried 250 milliliter jacketed beaker equipped
with mechanical stirrer. The mixture was heated using recirculating
45.degree. C. glycol-water for several minutes until the diamine
had completely dissolved resulting in a near colorless solution.
Next, 19.919 g (0.0677 moles) of 3,3',4,4'-biphenyltetracarboxylic
dianhydride (BPDA) was added to the diamine solution contained
within the reaction vessel. Stirring was continued until all of the
solids dissolved and the reaction formed a polyamic acid solution.
The polyamic acid solution was decanted and stored at 0.degree. C.
until used for film casting.
[0182] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0183] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The polyimide film was removed from the pin
frame and analyzed. The data is shown in Table 1.
[0184] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 3
BPDA//80 TFMB/20 ODA
[0185] Within a nitrogen inerted glovebox, 17.879 g (0.0558 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2.794 g (0.0139
moles) 4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 20.326 g (0.069 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0186] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0187] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The film was removed from the pin frame and
analyzed. The data is shown in Table 1.
[0188] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 4
BPDA//70 TFMB/30 ODA
[0189] Within a nitrogen inerted glovebox, 15.971 g (0.0498 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4.279 g (0.0213
moles) 4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 20.75 g (0.0705 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0190] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0191] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C.
[0192] The polyimide film was removed from the pin frame and
analyzed. The data is shown in Table 1.
[0193] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 5
BPDA//60 TFMB/40 ODA
[0194] Within a nitrogen inerted glovebox, 13.981 g (0.0436 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 5.827 g (0.0291
moles) 4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 21.192 g (0.0720 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0195] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0196] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The resulting polyimide film was removed from
the pin frame and analyzed. The data is shown in Table 1.
[0197] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 6
BPDA//50 TFMB/50 ODA
[0198] Within a nitrogen inerted glovebox, 11.904 g (0.03717 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 7.442 g (0.0371
moles) 4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 21.654 g (0.0736 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0199] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0200] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The film was removed from the pin frame and
analyzed. The data is shown in Table 1.
[0201] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 7
BPDA//43 TFMB/57 ODA
[0202] Into a dried 50 gallon tank, equipped with nitrogen inlet,
three independently controlled agitator shafts; a low speed anchor
mixer, a high speed disk disperser, and a high shear rotor-stator
emulsifier, and thermocouple, was placed 10.10 kg (31.54 moles) of
2,2'-bis(trifluoromethyl)benzidine (TFMB), 8.37 kg (41.81 moles)
4,4'-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide
(DMAc).
[0203] The mixture was heated and stirred at 35.degree. C. for
several minutes until the diamines had completely dissolved
resulting in a straw colored solution. The speeds of the anchor,
disperser, and emulsifier are adjusted as needed to ensure
efficient mixing and dissolution, without excessively heating the
mixture. Next, 21.4 kg (72.84 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution within the reaction vessel. Stirring was
continued until all of the solids dissolved and the reaction formed
a polyamic acid solution. The viscosity of the resulting polyamic
acid solution was adjusted by chain extension through an addition
of a stoichiometric amount of 6 wt % PMDA solution in DMAc or
alternatively an equivalent stoichiometric amount of BPDA solids so
that the resulting solution had a viscosity of about 2000 poise.
The finished solution is filtered through a 20 micron bag filter
and vacuum degassed to remove entrained air. The polyamic acid
solution was cooled to approximately -6.degree. C., acetic
anhydride dehydrating agent (0.14 cm.sup.3/cm.sup.3 polymer
solution), the imidization catalyst 3-picoline (0.15
cm.sup.3/cm.sup.3 polymer solution) were metered in and mixed, and
a film was cast using a slot die, onto a 90.degree. C. hot,
rotating drum. The resulting gel film was stripped off the drum and
fed into a tenter oven, where it was dried and cured to a solids
level greater than 98%, using convective and radiant heating.
[0204] Two sheets of the film were laminated between two sheets of
35 micron thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
[0205] Two more sheets of film were laminated between two sheets of
35 micron thick treated copper foil in a vacuum platen press at 350
psi. The dimensional stability of these clads were measured per
IPC-TM650 2.2.4c. The results are summarized in Table 2.
Example 8
BPDA//50 TFMB/50 ODA
[0206] Into a dried 50 gallon tank, equipped with nitrogen inlet,
three independently controlled agitator shafts; a low speed anchor
mixer, a high speed disk disperser, and a high shear rotor-stator
emulsifier, and thermocouple was placed 11.56 kg (36.12 moles) of
2,2'-bis(trifluoromethyl)benzidine (TFMB), 7.23 kg (36.12 moles)
4,4'-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide
(DMAc).
The mixture was heated and stirred at 35.degree. C. for several
minutes until the diamines had completely dissolved resulting in a
straw colored solution. The speeds of the anchor, disperser, and
emulsifier are adjusted as needed to ensure efficient mixing and
dissolution, without excessively heating the mixture. Next, 21.1 kg
(71.73 moles) of 3,3',4,4'-biphenyltetracarboxylic dianhydride
(BPDA) was added to the diamine solution within the reaction
vessel. Stirring was continued until all of the solids dissolved
and the reaction formed a polyamic acid solution. The viscosity of
the resulting polyamic acid solution was adjusted by chain
extension through an addition of a stoichiometric amount of 6 wt %
PMDA solution in DMAc or alternatively an equivalent stoichiometric
amount of BPDA solids so that the resulting solution had a
viscosity of about 1500 poise. Finally, a small amount of belt
release agent was added to the polyamic acid solution (which
enables the cast green film to be readily stripped from the casting
belt) A thin polymer film was produced by extruding the film
through a slot die onto a moving stainless steel belt. The belt
passes into a convective oven, to evaporate solvent and partially
imidizing the polymer, to produce a "green" film. Green film solids
(as measured by weight loss upon heating to 300.degree. C.) was
.about.70%. The green film was then stripped off the casting belt
and wound up. The green film was then fed into a tenter oven where
it was dried and cured to a solids level greater than 98%, using
convective and radiant heating to produce a fully cured polyimide
film. During tentering, shrinkage was controlled by constraining
the film along the edges.
[0207] Two sheets of the polyimide film were laminated between two
sheets of 35 um thick treated copper foil in a vacuum platen press
at 200 and 350 psi. The peel strength data was measured per
IPC-TM650 2.4.9d test method. The data at different lamination peak
temperatures are shown in Table 1.
Example 9
BPDA//43 TFMB/57 ODA
[0208] With the polyamic acid polymer solution prepared as
described in example 7, a thin film was prepared by casting a
portion of the solution onto a copper foil (12 um Mitsui
3EC-M35-HTE ED copper) using a doctor blade. The coated copper foil
was then restrained within a clip frame film and heated using a
forced air oven to remove the solvent and imidize the polymer. The
film was exposed to the following oven temperatures for about 1/2
hour, 150.degree. C., 250.degree. C., and 330.degree. C. The
resulting single sided copper coated polyimide was then removed
from the clip frame and then laminated to another sheet of copper
foil of the same specification as described above in a vacuum
platen press at 350 psi pressure and a temperature of 350.degree.
C. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data is shown in Table 1.
Example 10
Prophetic
BPDA//50 TFMB/50 ODA
[0209] Into a dried 50 gallon tank, equipped with nitrogen inlet,
three independently controlled agitator shafts; a low speed anchor
mixer, a high speed disk disperser, and a high shear rotor-stator
emulsifier, and thermocouple is placed 11.56 kg (36.12 moles) of
2,2'-bis(trifluoromethyl)benzidine (TFMB), 7.23 kg (36.12 moles)
4,4'-oxydianiline (ODA), and 159.6 kg of N,N-dimethylacetamide
(DMAc).
[0210] The mixture is heated and stirred at 35.degree. C. for
several minutes until the diamines are completely dissolved
resulting in a straw colored solution. The speeds of the anchor,
disperser, and emulsifier can be adjusted as needed to ensure
efficient mixing and dissolution, without excessively heating the
mixture. Next, 21.1 kg (71.73 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) is added to
the diamine solution within the reaction vessel. Stirring is
continued until all of the solids dissolved and the reaction forms
a polyamic acid solution. The viscosity of the resulting polyamic
acid solution is adjusted by chain extension through an addition of
a stoichiometric amount of 6 wt % PMDA solution in DMAc or
alternatively an equivalent stoichiometric amount of BPDA solids so
that the resulting solution has a viscosity of about 2000 poise.
The finished solution can be filtered through a 20 micron bag
filter and vacuum degassed to remove entrained air. The polyamic
acid solution is cooled to approximately -6.degree. C., acetic
anhydride dehydrating agent (0.14 cm.sup.3/cm.sup.3 polymer
solution), the imidization catalyst 3-picoline (0.15
cm.sup.3/cm.sup.3 polymer solution) is metered in and mixed, and a
film is cast using a slot die, onto a 90.degree. C. hot, rotating
drum. The resulting gel film is stripped off the drum and fed into
a tenter oven, where it is dried and cured to a solids level
greater than 98%, using convective and radiant heating.
[0211] Two sheets of the film are laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. It is expected that the laminate would have good peel strength
measured per IPC-TM650 2.4.9d test method.
Example 11
BPDA//30 TFMB/70 ODA
[0212] Within a nitrogen inerted glovebox, 7.265 g (0.02268 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 10.598 g (0.0529
moles) 4,4'-oxydianiline, and 160 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 22.137 g (0.0752 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0213] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0214] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The polyimide film was removed from the pin
frame and analyzed. The data is shown in Table 1.
[0215] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 12
BPDA//20 TFMB/80 ODA
[0216] Within a nitrogen inerted glovebox, 5.358 g (0.0167 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 13.399 g (0.0669
moles) 4,4'-oxydianiline, and 172 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 24.243 g (0.0824 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0217] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0218] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The polyimide film was removed from the pin
frame and analyzed. The data is shown in Table 1.
[0219] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 13
[0220] Example 13 shows polyimides of the present disclosure have
good conformation over circuitry and are useful as a coverlay.
[0221] A sheet of Pyralux.RTM. AP flexible copper clad laminate
with 18 micron thick copper foil (available from DuPont) was imaged
with photoresist and copper etching to created imaged copper foil
lines of different widths using standard procedures in the flexible
printed circuit board industry. The polymer created in example 7
(film thickness 32 microns) was laminated over the imaged circuit
lines to form a coverlay over the imaged flexible circuit. The
polyimide coverlay was laminated in a vacuum platen press at 350
psi and 320 C peak lamination temperature. The polyimide coverlay
showed very good conformation over the circuitry with no air voids
observed. The polyimide coverlay was able to cover the top of the
circuitry with very little thinning.
Example 14
[0222] Example 14 shows polyimides of the present disclosure are
have good peel strength when laminated at a temperature of
320.degree. C.
[0223] Two sheets of Pyralux.RTM. AP flexible copper clad laminate
(available from DuPont) was imaged with photoresist and copper
etching to remove all of the copper foil from one side of the
Pyralux.RTM. AP using processing common in the flexible printed
circuit board industry. The polymer created in example 7 (50 um
thick) was laminated between the between the two imaged
Pyralux.RTM. AP clads where the dielectric surface of the AP clad
was laminated to the polymer film of example 7. The polyimide film
was laminated in a vacuum platen press at 350 psi and 320.degree.
C. peak lamination temperature. The peel strength between the AP
dielectric surface and the polyimide film of example 7 was measured
per IPC-TM650-2.4.9d. Peels strength of 1.4 N/mm between the AP
dielectric and the polyimide film of example 7
Example 15
[0224] Example 15 shows polyimides of the present disclosure have
good conformation over circuitry and are useful as a bondply.
[0225] Two sheets of Pyralux.RTM. AP flexible copper clad laminate
with 18 micron thick copper foil (available from DuPont) were
imaged with photoresist and copper etching to created imaged copper
foil lines of different widths using standard procedures in the
flexible printed circuit board industry. The polymer created in
example 7 (film thickness of 100 microns) was laminated over the
imaged circuit lines of the two imaged AP clads to form a bondply
between the two imaged flexible circuits. The polyimide bondply was
laminated in a vacuum platen press at 350 psi and 320 C peak
lamination temperature. The polymer bondply showed very good
conformation over the circuitry with no air voids observed. The
polyimide bondply, was able to separate the circuitry on the two AP
imaged laminates with very little thinning between the two imaged
circuits.
Example 16
[0226] Example 16 shows that good peel strength is achieved with
metal alloys.
[0227] Two sheets the film made in example 7 above were laminated
between two sheets of Inconel.RTM. 600 metal alloy foil (25 microns
thick), available from Ulrich. The peel strength data was measured
per IPC-TM650 2.4.9d test method. An average peel strength of 1.8
N/mm was measured.
Comparative Example 1
BPDA//ODA
[0228] Comparative example 1 shows eliminating TFMB compromises
properties, including peel strength.
[0229] Within a nitrogen inerted glovebox, 16.702 g (0.0834 moles)
4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc)
were charged to a dried 250 milliliter jacketed beaker equipped
with mechanical stirrer. The mixture was heated using recirculating
45.degree. C. glycol-water for several minutes until the diamine
had completely dissolved resulting in a near colorless solution.
Next, 24.298 g (0.08266 moles) of 3,3',4,4'-biphenyltetracarboxylic
dianhydride (BPDA) was added to the diamine solution contained
within the reaction vessel. Stirring was continued until all of the
solids dissolved and the reaction formed a polyamic acid solution.
The polyamic acid solution was decanted and stored at 0.degree. C.
until used for film casting.
[0230] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0231] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The resulting polyimide film was removed from
the pin frame and analyzed. The data is shown in Table 1.
[0232] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Comparative Example 2
54BPDA/46PMDA//ODA
[0233] Comparative example 2 shows that even though the film can be
thermoformed, it has poor adhesion to copper.
[0234] Within a nitrogen inerted glovebox, 18.225 g (0.0910 moles)
4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc)
were charged to a dried 250 milliliter jacketed beaker equipped
with mechanical stirrer. The mixture was heated using recirculating
45.degree. C. glycol-water for several minutes until the diamine
had completely dissolved resulting in a near colorless solution.
Next, an admixture of 12.052 g (0.0409 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 10.723 g
(0.0492) pyromellitic dianhydride (PMDA) was added to the diamine
solution contained within the reaction vessel. Stirring was
continued until all of the solids dissolved and the reaction formed
a polyamic acid solution. The polyamic acid solution was decanted
and stored at 0.degree. C. until used for film casting.
[0235] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0236] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The resulting polyimide film was removed from
the pin frame and analyzed. The data is shown in Table 1.
[0237] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Comparative Example 3
PMDA//TFMB
[0238] Comparative example 3 shows when BPDA is replaced with PMDA
the polyimide is brittle and has poor peel strength.
[0239] Within a nitrogen inerted glovebox, 24.552 g (0.0767 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 159 grams of
N,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliter
jacketed beaker equipped with mechanical stirrer. The mixture was
heated using recirculating 45.degree. C. glycol-water for several
minutes until the diamine had completely dissolved resulting in a
near colorless solution. Next, 16.55 g (0.0759 moles) of
pyromellitic dianhydride (PMDA) was added to the diamine solution
contained within the reaction vessel. Stirring was continued until
all of the solids dissolved and the reaction formed a polyamic acid
solution. The polyamic acis solution was decanted and stored at
0.degree. C. until used for film casting.
[0240] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0241] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour,
150.degree. C., 250.degree. C., 300.degree. C. and 325.degree. C.
The resulting polyimide film was removed from the pin frame and
analyzed. The data is shown in Table 1.
[0242] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Comparative Example 4
BPDA//50mTOL/50ODA
[0243] Comparative example 4 shows that replacing TFMB with a
chemically similar diamine but with 2,2'-methyl benzidine
functionality does not yield equivalent peel strength.
[0244] Within a nitrogen inerted glovebox, 8.77 g (0.0413 moles) of
2,2'-dimethyl-4,4'-diaminobiphenyl, 8.271 g (0.0413 moles)
4,4'-oxydianiline, and 159 grams of N,N-dimethylacetamide (DMAc)
were charged to a dried 250 milliliter jacketed beaker equipped
with mechanical stirrer. The mixture was heated using recirculating
45.degree. C. glycol-water for several minutes until the diamine
had completely dissolved resulting in a near colorless solution.
Next, 24.065 g (0.0818 moles) of 3,3',4,4'-biphenyltetracarboxylic
dianhydride (BPDA) was added to the diamine solution contained
within the reaction vessel. Stirring was continued until all of the
solids dissolved and the reaction formed a polyamic acid solution.
The polyamic acid solution was decanted and stored at 0.degree. C.
until used for film casting.
[0245] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0246] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The resulting polyimide film was removed from
the pin frame and analyzed. The data is shown in Table 1.
[0247] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Comparative Example 5
20PMDA/80ODPA//RODA
[0248] Comparative example 5 has poor mechanical properties.
[0249] Into a dried 50 gallon tank, equipped with nitrogen inlet,
three independently controlled agitator shafts; a low speed anchor
mixer, a high speed disk disperser, and a high shear rotor-stator
emulsifier, and thermocouple was placed 20.02 kg (68.49 moles) of
1,3-bis(4-aminophenoxy)benzene (RODA) and 159.6 kg of
N,N-dimethylacetamide (DMAc).
[0250] The mixture was heated and stirred at 35.degree. C. for
several minutes until the diamines had completely dissolved
resulting in a straw colored solution. The speeds of the anchor,
disperser, and emulsifier are adjusted as needed to ensure
efficient mixing and dissolution, without excessively heating the
mixture. Next, 16.99 kg (54.79 moles) of 4,4'-oxydiphthalic
anhydride (ODPA) and 2.88 kg (13.21 moles) pyromellitic dianhydride
(PMDA) was added to the diamine solution within the reaction
vessel. Stirring was continued until all of the solids dissolved
and the reaction formed a polyamic acid solution. The viscosity of
the resulting polyamic acid solution was adjusted by chain
extension through an addition of a stoichiometric amount of 6 wt
PMDA solution in DMAc or alternatively an equivalent stoichiometric
amount of BPDA solids so that the resulting solution had a
viscosity of about 2000 poise. The finished solution is filtered
through a 20 micron bag filter and vacuum degassed to remove
entrained air. The polyamic acid solution was cooled to
approximately -6.degree. C., acetic anhydride dehydrating agent
(0.14 cm.sup.3/cm.sup.3 polymer solution), the imidization catalyst
3-picoline (0.15 cm.sup.3/cm.sup.3 polymer solution) were metered
in and mixed, and a film was cast using a slot die, onto a
90.degree. C. hot, rotating drum. The resulting gel film was
stripped off the drum and fed into a tenter oven, where it was
dried and cured to a solids level greater than 98%, using
convective and radiant heating.
[0251] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
[0252] Two more sheets of film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The dimensional stability of these clads were measured per
IPC-TM650 2.2.4c. The results are summarized in Table 2.
Comparative Example 6
PMDA//ODA
[0253] Comparative example 6 has poor peel strength.
[0254] Two sheets of Kapton.RTM. H film (type 100PFC available from
DuPont), a polyimide comprised of pyromellitic dianyhdride (PMDA)
and 4,4'-oxydianiline (ODA), was obtained from E. I. du Pont de
Nemours and Company were laminated between two sheets of 35 um
thick treated copper foil in a vacuum platen press at 350 psi. The
peel strength data was measured per IPC-TM650 2.4.9d test method.
The data at different lamination peak temperatures are shown in
Table 1.
Comparative Example 7
60PMDA/40BPDA//40ODA/60PPD
[0255] Comparative example 7 has poor peel strength.
[0256] Two sheets of Kapton.RTM. E film (available from DuPont), a
copolyimide comprised of pyromellitic dianhydride (PMDA),
3',4,4'-biphenyltetracarboxylic dianhydride (BPDA),
4,4'-oxydianiline (ODA), and 1,4-phenylene diamine (PPD), was
obtained from E. I. du Pont de Nemours and Company. were laminated
between two sheets of 35 um thick treated copper foil in a vacuum
platen press at 350 psi. The peel strength data was measured per
IPC-TM650 2.4.9d test method. The data at different lamination peak
temperatures are shown in Table 1.
[0257] Examples 17 and 18 show that a polyimide derived from 80-90
mole % BPDA, 10 to 20 mole % ODPA and 100 mole % TFMB has a peel of
at least 1.3 N/mm when laminated at a temperature of 350.degree. C.
or greater.
Example 17
90 BPDA/10 ODPA//TFMB
[0258] Into a dried 250 mL jacketed beaker equipped with mechanical
stirrer within an inerted nitrogen glovebox was placed 20.68 g
(0.064 moles) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 156
g of N,N-dimethylacetamide (DMAc).
[0259] The mixture was heated and stirred at 40.degree. C. for
several minutes until the diamine had completely dissolved
resulting in a straw colored solution. Next, 16.91 g (0.057 moles)
of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 1.41 g
(0.006 moles) of 4,4'-oxydiphthalic anhydride (ODPA) were added to
the diamine solution within the reaction vessel.
[0260] Stirring was continued until all of the solids dissolved and
the reaction formed a polyamic acid solution. The viscosity of the
resulting polyamic acid solution was adjusted by chain extension
through an addition of a stoichiometric amount of 6 wt PMDA
solution in DMAc or alternatively an equivalent stoichiometric
amount of BPDA solids so that the resulting solution had a
viscosity of about 2000 poise. The solution was decanted and stored
at 0.degree. C. until used for film casting.
[0261] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a sheet of DuPont MYLAR.RTM. film. The polymer (and
support sheet) was immersed into a catalytic solution comprising a
1:1 ratio of acetic anhydride and .beta.-picoline. Within minutes
(upon partial imidization), a gel film was formed. The gel film was
peeled from the support sheet and transferred to a restraining
frame (pin frame).
[0262] The film was then heated using a forced air oven to further
imidize the polymer and remove solvent. The film was exposed to the
following oven temperatures for about 1/2 hour, 150.degree. C.,
250.degree. C., and 330.degree. C. The film was removed from the
pin frame and analyzed.
[0263] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Example 18
80 BPDA/20 ODPA//TFMB
[0264] Into a dried 200 mL jacketed beaker equipped with mechanical
stirrer within an inerted nitrogen glovebox was placed 20.94 g
(0.065 moles) of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 156
g of N,N-dimethylacetamide (DMAc).
[0265] The mixture was heated and stirred at 40.degree. C. for
several minutes until the diamine had completely dissolved
resulting in a straw colored solution. Next, 15.20 g (0.051 moles)
of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2.85 g
(0.013 moles) of 4,4'-oxydiphthalic anhydride (ODPA) were added to
the diamine solution within the reaction vessel.
[0266] Stirring was continued until all of the solids dissolved and
the reaction formed a polyamic acid solution. The viscosity of the
resulting polyamic acid solution was adjusted by chain extension
through an addition of a stoichiometric amount of 6 wt % PMDA
solution in DMAc or alternatively an equivalent stoichiometric
amount of BPDA solids so that the resulting solution had a
viscosity of about 2000 poise. The solution was decanted and stored
at 0.degree. C. until used for film casting.
[0267] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a sheet of DuPont MYLAR.RTM. film. The polymer (and
support sheet) was immersed into a catalytic solution comprising a
1:1 ratio of acetic anhydride and .beta.-picoline. Within minutes
(upon partial imidization), a gel film was formed. The gel film was
peeled from the support sheet and transferred to a restraining
frame (pin frame).
[0268] The film was then heated using a forced air oven to further
imidize the polymer and remove solvent. The film was exposed to the
following oven temperatures for about 1/2 hour, 150.degree. C.,
250.degree. C., and 330.degree. C. The film was removed from the
pin frame and analyzed.
[0269] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
Comparative Example 8
60 BPDA/40 ODPA//TFMB
[0270] Comparative example 8 shows a film could not me made for
testing when 40 mole percent of ODPA is used.
[0271] Within a nitrogen inerted glovebox, 23.912 g (0.0746 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB) and 179 grams of
N,N-dimethylacetamide (DMAc) were charged to a dried 250 milliliter
jacketed beaker equipped with mechanical stirrer. The mixture was
heated using recirculating 45.degree. C. glycol-water for several
minutes until the diamine had completely dissolved resulting in a
near colorless solution. Next, 13.18 g (0.045 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 9.03 g
(0.029 moles) 4,4'-oxydiphthalic anhydride (ODPA) was added to the
diamine solution as an admixture contained within the reaction
vessel. Stirring was continued until all of the solids dissolved
and the reaction formed a polyamic acid solution. The polyamic acid
solution was decanted and stored at 0.degree. C. until used for
film casting.
[0272] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0273] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. A viable polyimide film to conduct testing on
could not be obtained using this procedure due extreme wrinkling,
curl, and tear-out from the restraining frame after cure.
Comparative Example 9
BPDA//10 TFMB/90 ODA
[0274] Comparative example 9 shows when 10 mole percent of TFMB is
used the peel strength is low when laminated at 350 degrees C.
[0275] Within a nitrogen inerted glovebox, 2.675 g (0.00835 moles)
of 2,2'-bis(trifluoromethyl)benzidine (TFMB), 15.049 g (0.071
moles) 4,4'-oxydianiline, and 168 grams of N,N-dimethylacetamide
(DMAc) were charged to a dried 250 milliliter jacketed beaker
equipped with mechanical stirrer. The mixture was heated using
recirculating 45.degree. C. glycol-water for several minutes until
the diamine had completely dissolved resulting in a near colorless
solution. Next, 24.27 g (0.083 moles) of
3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) was added to
the diamine solution contained within the reaction vessel. Stirring
was continued until all of the solids dissolved and the reaction
formed a polyamic acid solution. The polyamic acid solution was
decanted and stored at 0.degree. C. until used for film
casting.
[0276] A polyimide film derived from the above polyamic acid was
chemically imidized through the use of a catalytic solution. The
chemically imidized film was prepared by casting the polyamic acid
solution onto a support sheet of DuPont MYLAR.RTM. film. The cast
polyamic acid solution (and support sheet) was immersed into a
catalytic solution comprising a 1:1 ratio of acetic anhydride and
.beta.-picoline. A gel film was formed. The gel film was peeled
from the support sheet and transferred to a restraining frame (pin
frame).
[0277] The gel film was then heated using a forced air oven to
further imidize the polymer and remove solvent. The gel film was
exposed to the following oven temperatures for about 1/2 hour at
each temperature, 150.degree. C., 250.degree. C., 300.degree. C.
and 325.degree. C. The polyimide film was removed from the pin
frame and analyzed. The data is shown in Table 1.
[0278] Two sheets of the film were laminated between two sheets of
35 um thick treated copper foil in a vacuum platen press at 350
psi. The peel strength data was measured per IPC-TM650 2.4.9d test
method. The data at different lamination peak temperatures are
shown in Table 1.
[0279] Note that not all of the activities described above in the
general description or the examples are required, that a portion of
a specific activity may not be required, and that further
activities may be performed in addition to those described. Still
further, the order in which each of the activities are listed are
not necessarily the order in which they are performed. After
reading this specification, skilled artisans will be capable of
determining what activities can be used for their specific needs or
desires.
[0280] In the foregoing specification, the invention has been
described with reference to specific embodiments. However, one of
ordinary skill in the art appreciates that various modifications
and changes can be made without departing from the scope of the
invention as set forth in the claims below. All features disclosed
in this specification may be replaced by alternative features
serving the same, equivalent or similar purpose. Accordingly, the
specification is to be regarded in an illustrative rather than a
restrictive sense and all such modifications are intended to be
included within the scope of the invention.
[0281] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any element(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature or element of any or all the
claims.
TABLE-US-00001 TABLE 1 MD MD Tg [tan MD CTE Tensile Tensile MD
EXAMPLE # delta] [50-250.degree. C.] Modulus Strength Elongation 1
BPDA//TFMB 347 11 1289 47 30 2 BPDA//90 TFMB/10 ODA 308.6 9.1 724
32.4 52.2 3 BPDA//80 TFMB/20 ODA 323 15.3 716 37.8 72.7 4 BPDA//70
TFMB/30 ODA 314 15 728 42.73 110.5 5 BPDA//60 TFMB/40 ODA 295.6
15.9 665 38 106 6 BPDA//50 TFMB/50 ODA 288.1 12.6 663 35.5 105 7
BPDA//43 TFMB/57 ODA 8 BPDA//50 TFMB/50 ODA 350 psi 200 psi 9
BPDA//43 TFMB/57 ODA 10 BPDA//50 TFMB/50 ODA 11 BPDA//30 TFMB/70
ODA 12 BPDA//20 TFMB/80 ODA Comp 1 BPDA//ODA 292 31 377 24.9 80
Comp 2 54BPDA/46PMDA//ODA 314 41 425 29 120 Comp 3 PMDA//TFMB 400
-14 1600 72 25 Comp 4 BPDA//50mTOL/50ODA 313 26 687 39 66 Comp 5
20PMDA/80ODPA//RODA 236 >100 516 16.8 71.8 Comp 6 PMDA//ODA Comp
7 60PMDA/40BPDA// 40ODA/60PPD 17 90BPDA/10ODPA//TFMB 332.2 10.14
780 39.7 65.1 18 80BPDA/20ODPA//TFMB 321 3.14 720 38.7 60.9 Comp 8
60BPDA/40ODPA//TFMB Could not be made in to a film for testing Comp
9 BPDA//10 TFMB/90 ODA Average Average Average peel peel Average
peel Dielectric strength at strength at peel strength strength at
Water Constant 330.degree. C. 350.degree. C. at 380.degree. C.
395.degree. C. EXAMPLE # uptake @ 1 kHz (N/mm) (N/mm) (N/mm) (N/mm)
1 0.38 2.77 0.1 1.1 1.4 2 0.42 3.14 1.1 1.6 3 0.73 3.1 1.6 1.9 4
0.844 2.1 2.0 5 0.92 2.0 2.2 6 1 3.28 2.0 7 1.9 at 2.7 2.1
320.degree. C. 8 3.3 3.3 9 2.5 10 11 2.5 3.2 12 1.1 3.2 Comp 1 1.4
3.45 0.2 0.7 Comp 2 1.5 3.3 0.2 0.6 Comp 3 1.59 3.37 0 <0.1 Comp
4 3.2 3.24 0.2 0.7 Comp 5 0.62 3.43 1.6 Comp 6 <0.1 Comp 7
<0.1 17 0.74 3.04 0.5 1.4 18 0.74 2.98 0.9 1.3 Comp 8 Comp 9 0.7
1.6
TABLE-US-00002 TABLE 2 MD TD MD TD EXAMPLE Etched Etched Thermal
Thermal 7 BPDA//43 -0.125 -0.081 -0.208 -0.183 TFMB/57 ODA Comp 5
20PMDA/ -0.505 -0.506 -0.588 -0.583 80ODPA//RODA
* * * * *