U.S. patent application number 09/866727 was filed with the patent office on 2002-07-04 for photosensitive composition.
Invention is credited to Chen, Man-Lin, Lin, Hsien-Kuang, Liu, Shur-Fen, Pan, Jing-Pin.
Application Number | 20020086239 09/866727 |
Document ID | / |
Family ID | 21661789 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020086239 |
Kind Code |
A1 |
Chen, Man-Lin ; et
al. |
July 4, 2002 |
Photosensitive composition
Abstract
The present invention discloses a photo-sensitive composition,
used as a solder resist or a photosensitive material for insulation
layers in the production of printed circuit boards. The
photo-sensitive composition comprises a prepolymer containing
carboxylic groups and unsaturated vinyl groups; photoinitiator;
unsaturated photo-monomer; and the reaction adduct of bismaleimide
derivative, barbituric acid derivative and epoxy compounds. The
obtained photosensitive composition exhibits high adhesion towards
PI substrates, in addition, it can be developed with alkaline
water. The photosensitive composition obtained in the invention is
very useful in packaging substrates, such as P-BGA, T-BGA and F-CSP
due to its high heat resistance and solder resistance.
Inventors: |
Chen, Man-Lin;
(Miaoli-Hsien, TW) ; Pan, Jing-Pin; (Hsinchu
Hsien, TW) ; Lin, Hsien-Kuang; (Taipei, TW) ;
Liu, Shur-Fen; (Hsinchu, TW) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
21661789 |
Appl. No.: |
09/866727 |
Filed: |
May 30, 2001 |
Current U.S.
Class: |
430/285.1 ;
430/280.1; 430/283.1; 430/286.1; 522/100; 522/103 |
Current CPC
Class: |
G03F 7/038 20130101 |
Class at
Publication: |
430/285.1 ;
430/283.1; 430/280.1; 430/286.1; 522/100; 522/103 |
International
Class: |
G03F 007/038 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 3, 2000 |
TW |
89123177 |
Claims
What is claimed is:
1. A photosensitive composition, comprising: (a). a prepolymer,
containing a carboxyl group and an unsaturated vinyl group; (b). a
photoinitiator; (c). an unsaturated photomonomer; and (d). adduct
of reacting bismaleimide derivative, a barbituric acid derivative,
and an epoxy.
2. The composition as claimed in claim 1, wherein the adduct is
obtained by the reaction of the following: a. dissolving a
bismaleimide in a solvent or a solvent system, then a barbituric
acid or its derivative is added to form a mixture; b. heating the
obtained mixture to 115-145.degree. C. to form a bismaleimide resin
mixture; and c. adding an epoxy resin to the resin mixture to form
a resin system.
3. The composition as claimed in claim 1, wherein the composition
further include organic solvents as diluents.
4. The composition as claimed in claim 1, wherein the formula of
the barbituric acid or its derivative follows: 4wherein R.sub.1 and
R.sub.2 represent hydrogen, alkyl or phenyl.
5. The composition as claimed in claim 2, wherein the formula of
the bismaleimide follows: 5wherein R represent -CH.sub.2 or
-O-.
6. The composition as claimed in claim 2, wherein the epoxy resin
is a finely powdered epoxy compound, and each molecule includes at
least 2 epoxy groups, having minor dissolubity in the diluent
used.
7. The composition as claimed in claim 6, wherein the finely
powdered epoxy compound is at least one compound selected from
compounds that are solid or semi-solid at room temperature, such as
bisphenol S type epoxy resin, diglycidyl phthalate resin,
heterocycloepoxy resin, bixylenol resin, bisphenol epoxy resin and
tetraglycidyl xylenol ethane resin.
8. The composition as claimed in claim 5, wherein part of the
finely powdered epoxy compound with minor dissolubity is
substituted with soluble epoxy compound wherein each molecule
contains at least 2 epoxy groups.
9. The composition as claimed in claim 8, wherein the mixing ratio
of the finely powdered epoxy compound with minor dissolubility and
the soluble epoxy compound is between 1:1.5 and 1:0 (based on
weight).
10. The composition as claimed in claim 2, wherein the weight ratio
of the bismaleimide derivative and the barbituric acid derivative
is between 3:1 and 20:1.
11. The composition as claimed in claim 10, wherein the weight
ratio of the bismaleimide derivative to the barbituric acid
derivative is between 5:1 and 10:1.
12. The composition as claimed in claim 2, wherein the weight ratio
of the bismaleimide derivative and the barbituric acid derivative
to the epoxy resin is between 1:2 and 1:5.
13. The composition as claimed in claim 12, wherein the weight
ratio of the bismaleimide derivative and the barbituric acid
derivative to the epoxy resin is between 1:3 and 1:4.
14. The composition as claimed in claim 13, wherein the weight
ratio of the prepolymer and the bismaleimide derivative to the
barbituric acid derivative and the epoxy resin is between 1:1.4 and
1:0.1.
15. The composition as claimed in claim 1, wherein the prepolymer
is selected from the complete esterification product of a novolak
epoxy compound and an unsaturated monocarboxylic acid, and is the
product of reacting the secondary hydroxyl group of the
esterification product with a saturated or an unsaturated polybasic
anhydride.
16. The composition as claimed in claim 1, wherein the novolak
epoxy compound is cresol novolak epoxy compound.
17. The composition as claimed in claim 15, wherein the
esterification product is the complete esterification product
obtained by reacting the novolak type epoxy compound and the
unsaturated monocarboxylic acid in a relative amount such that the
ratio of the equivalent number of the epoxy group to that of the
carboxyl group is in the range of 0.8 to 3.3.
18. The composition as claimed in claim 2, wherein the
esterification product is the complete esterification product
obtained by reacting the novolak type epoxy compound and the
unsaturated monocarboxylic acid in a relative amount such that the
ratio of the equivalent number of the epoxy group to that of the
carboxyl group is in the range of 0.9 to 1.1.
19. The composition as claimed in claim 15, wherein the prepolymer
is a reaction product of reacting the esterification product and
the saturated or unsaturated polybasic acid anhydride, and the acid
value of the produced resin is in the range of 30 to 160 mg
KOH/g.
20. The composition as claimed in claim 19, wherein the prepolymer
is a reaction product of reacting the esterification product and
the saturated or unsaturated polybasic acid anhydride, and the acid
value of the produced resin is in the range of 45 to 120 mg
KOH/g.
21. The composition as claimed in claim 1, wherein the prepolymer
is synthesized from styrene-maleic anhydride resin, an unsaturated
compound containing an hydroxyl group and at least three acrylic
groups and a saturated alcohol.
22. The composition as claimed in claim 21, wherein the saturated
alcohol is substituted with H.sub.2O.
23. The composition as claimed in claim 21, wherein the saturated
alcohol is an alkyl alcohol.
24. The composition as claimed in claim 21, wherein the the
saturated alcohol is an alcohol containing ether groups.
25. The composition as claimed in claim 23, wherein the alkyl
alcohol is selected from the group consisting of ethanol,
n-propanol, iso-propanol, n-butanol, sec-butanol, iso-butanol,
n-pentanol, 2-methyl-1-butanol, isopentyl alcohol, n-hexyl alcohol,
n-heptyl alcohol, n-octyl alcohol, cyclopentanol and
cyclohexanol.
26. The composition as claimed in claim 24, wherein the saturated
alcohol containing ether groups is selected from the group
consisting of methyl cellosolve, ethyl cellosolve, butyl
cellosolve, carbitol, propyleneglycol monomethylether and
dipropyleneglycol monomethylether.
27. The composition as claimed in claim 21, wherein the equivalent
ratio of the anhydride and the unsaturated compound is between
1:0.05 and 1:0.9.
28. The composition as claimed in claim 21, wherein the equivalent
ratio of the anhydride and the unsaturated compound is between
1:0.2 and 1:0.7.
29. The composition as claimed in claim 21, wherein the equivalent
ratio of the anhydride and the unsaturated compound is between
1:0.1 and 1:0.7.
30. The composition as claimed in claim 21, wherein the the
styrene-maleic anhydride resin is synthesized by reacting styrene
and maleic anhydride in a co-monomer ratio of between 3:1 and
1:3.
31. The composition as claimed in claim 21, wherein the molecular
weight of the styrene-maleic anhydride is between 800 and
100000.
32. The composition as claimed in claim 21, wherein the the
unsaturated compound contains a carboxylic group and three
unsaturated acrylic acid group.
33. The composition as claimed in claim 21, wherein the unsaturated
compound is pentaerythritol triacrylate.
34. The composition as claimed in claim 21, wherein the unsaturated
compound contains a carboxylic group and five unsaturated acrylic
acid group.
35. The composition as claimed in claim 21, wherein the unsaturated
compound is pentaerythritol pentacrylate.
36. The composition as claimed in claim 1, wherein the composition
further comprises a curing agent or curing promoter in an amount of
10 wt % of the composition.
37. The composition as claimed in claim 36, wherein the curing
agent is dicyandiamide.
38. The composition as claimed in claim 36, wherein the curing
agent is an imidazole compound.
39. The composition as claimed in claim 1, wherein the composition
further comprising inorganic filler.
40. The composition as claimed in claim 1, wherein the composition
further comprises an additive selected from the group consisting of
coloring agent, polymerization inhibitor, thickening agent,
anti-foaming agent, leveling agent and adhesion promotor.
41. The composition as claimed in claim 21, wherein the composition
further comprises epoxy acrylate.
42. The composition as claimed in claim 41, wherein the epoxy
acrylate is a reaction adduct of novolak epoxy compound and acrylic
acid.
43. The composition as claimed in claim 42, wherein the novolak
epoxy compound is cresol novolak epoxy compound.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a photosensitive
composition, and more particularly to a photosensitive composition
having a high resistance to heat, mainly for use in packaged
circuit boards, such as P-BGA, T-BGA and F-CSP.
[0003] 2. Description of the Prior Art
[0004] Circuit boards are widely used in electronic industries and
the production of various kinds of electronic products. Current
market trends in the electronics industry focus on decreased size
and weight of circuit boards while increasing speed, capability and
interconnection density. Recently there has been focus on the
techniques used to manufacture high-density integrated circuit
boards, for example: MCM-L, plastic ball grid array
packaging(PBGA), flip-chip, and chip scale packaging.
[0005] With PBGA, for example, after a die is attached to a PBGA
substrate, a series of steps, such as wiring, molding, soldering
and reflowing are carried out. During the above process, local or
external temperatures can reach 200.degree. C., or even 300.degree.
C., thus the substrate material must be a resin having high glass
transition temperature (Tg), a low heat swelling coefficient, low
moisture absorbency, low dielectric properties, and high
reliability. The photosensitive solder resist used in the substrate
material must be highly adhesive, insulating, resistant to solder
temperature, solvent-resistant, corrosion-resistant,
plating-resistant, and singularly resistant to heat, pressure
cooker, and thermal cycle tests.
[0006] Examples of conventional photosensitive solder resist
material are disclosed in U.S. Pat. Nos. 5,100,767 and 4,943,516,
wherein coating polymers containing carboxylic groups and multiple
alkene unsaturated bonds, photosensitive monomers, photoinitiators
and epoxy resins are subsequently photo-cured, developed with
alkali water and heat-cured to be used in conventional printed
circuit boards.
[0007] Moreover, U.S. Pat. No. 5,041,519 discloses that a modified
PI resin has a high workability, a high rigidity, and good
compatibility with epoxy resin. It is also highly resistant to heat
and has a high glass transition temperature. In addition, U.S. Pat.
No. 4,886,842 discloses that by adding bismaleimide in a
photosensitive material containing epoxy resin and acrylic
monomers, significant improvement in the reliability of TCT is
observed. However, it is mainly used as adhesive clay for
electronics devices and is a fully disposed type of resin. Hence,
it cannot be developed to form images.
SUMMARY OF THE INVENTION
[0008] To overcome these problems, the invention provides a
photosensitive composition having enhanced heat resistance that can
be used in manufacturing MCM-L, plastic ball grid array packaging,
flip-chip, and chip scale packaging. The photosensitive composition
comprises:
[0009] (a) a prepolymer, containing a carboxyl group and an
unsaturated vinyl group;
[0010] (b) a photoinitiator;
[0011] (c) an unsaturated photomonomer; and
[0012] (d) adduct of reacting bismaleimide derivative, a barbituric
acid derivative, and an epoxy.
[0013] The above photosensitive composition undergoes processes,
such as coating, drying, disposing, developing etc. to form
patterns of photosensitive material on printed circuit boards.
[0014] The photosensitive composition with high resistance to heat
of the invention has high adhesion with PI substrates. As well, it
can be developed with alkali solutions. Having met the requirements
of a highly heat-resistant solder resist material, the
photosensitive composition of the invention can be used in package
substrates, such as P-BGA, T-BGA, F-CSP. It also can be used as a
photosensitive insulation layer.
DETAILED DESCRIPTION OF THE INVENTION
[0015] The following will further explain the photosensitive
composition of the invention.
[0016] The photosensitive composition of the invention is comprised
of a prepolymer containing a carboxyl group and an unsaturated
vinyl group; photoinitiator; unsaturated photomonomer; and the
reaction adduct of bismaleimide derivative, barbituric derivative
and epoxy compound. Suitable solvents can be added as diluents.
[0017] The above prepolymer is selected from the group consisting
of complete esterification products formed by the esterification of
a novolak type epoxy compound with an unsaturated monocarboxylic
acid; reaction products obtained by causing the secondary hydroxyl
group of the esterification product resulting from said
esterification to react with a saturated or unsaturated polybasic
acid anhydride.
[0018] As the novolak type epoxy compounds described above, those
which are obtained by the reaction of epichlorohydrin and/or methyl
epichlorohydrin with novolaks resulting from the reaction of such
phenols as phenol, cresol, halogenated phenol, and alkylphenol with
formaldehyde in the presence of an acidic catalysts are
particularly suitable. Examples of such suitable novolak type epoxy
compounds are as follows: "Epo Tohto" YDCN-701, YDCN-704, YDPN-638
and YDPN-602 available from Tohto Kasei Company Ltd.; "D.E.N"-431
and -439 available from The Dow Chemical Company; "ARALDITE"
EPN-1138, -1235, and -1299 available from Ciba-Geigy Ltd.;
"EPICLON" N-730, -770, -865, -665, -673 and -695, and "PLYOPHEN"
VH-4150, -4240, and -4440 available from Dainippon Ink and
Chemicals Inc.; "EOCN" -120 and -104 , and "BRRN"-1020 available
from Nippon Kayaku Company Ltd.; and "AER" ECN-265, -293, -285, and
-299 available from Asahi Chemical Industry Company Ltd..
Optionally, the novolak type epoxy compounds may be partially or
completely substituted with bisphenol A type, bisphenol F type,
hydrogenated bisphenol A type, brominated bisphenol A type, amino
group-containing, alicyclic, or polybutadiene modified glycidyl
ether epoxy compounds, such as "EPIKOTE" -828, -1007 and -807
available from Yuka Shell Epoxy Kabushiki Company; "EPICLON" -840,
-860, -3050, and -830 available from Dainippon Ink and Chemicals
Inc; "D.E.R." -330, -337 and -361 available from The Dow Chemical
Company; "Celloxide" 2021 and 3000 available from Daicel Chemical
Industries Ltd.; "TETRAD"-X and -C available from Mitsubishi Gas
Chemical Company Inc.; "NISSO EPOXYN" EPB-13 and -27 available from
Nippon Soda Company Ltd.; "Epo Tohto" YD-116, -128, -013, and -020,
YDG-414, YDF-190, -2004, and -2007 available from Tohto Kasei
Company Ltd.; ST-3000 and -110 available from Sun Tohto; "ARALDITE"
GY-260, -255, XB-2615 available from Ciba Geigy Ltd.; "D.E.R" -332,
-662 and -542 available from Dow Chemical Company. Among these, the
cresol novolak type epoxy compounds are particularly desirable.
[0019] The unsaturated monocarboxylic acids used are, for example,
acrylic acid, methacrylic acid, beta-styryl acrylic acid,
beta-furfuryl acrylic acid, crotonic acid, alpha-cyanocinnamic
acid, cinnamic acid, half esters of saturated or unsaturated
dibasic acid anhydrides with (meth)acrylates possessing one
hydroxyl group in the molecular unit thereof, such as, for example,
half esters obtained by causing such saturated or unsaturated
dibasic acid anhydrides of phthalic acid, tetrahydrophthalic acid,
hexahydrophthalic acid, maleic acid, succinic acid, itaconic acid,
chlorendic acid,methylhexahydrophthalic acid, methylendomethylene
tetrahydrophthalic acid, and methyltetrahydrophthalic acid to react
in equimolar ratio with hydroxyethyl acrylate, hydroxypropyl
acrylate, hydroxybutyl acrylate, polyethylene glycol monoacrylate,
glycerin diacrylate, trimethylol propane diacrylate,
pentaerythritol triacrylate, dipentaerythritol pentacrylate and
diacrylate of triglycidyl isocyanurate or with methacrylates
corresponding to the acrylate enurerated above, and half esters of
saturated or unsaturated dibasic acid anhydrides with unsaturated
monoglycidyl compounds obtained by causing the saturated or
unsaturated dibasic acids mentioned above to react similarly with
glycidyl (meth)acrylate by the conventional method. These are used
either singly or in a mixture of two or more constituents. Among
other unsaturated monocarboxylic acids mentioned above, acrylic
acid is preferable.
[0020] The saturated or unsaturated polybasic acid anhydrides
described above may be, for example, the anhydrides of phthalic
acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid,
succinic acid, itaconic acid, chlorendic acid,
methylhexahydrophthalic acid,
methylendomethylenete-tetrahydrophthalic acid,
methyltetrahydrohthalic acid, trimellitic acid, pyromellitic acid,
or benzophenone tetracarboxylic acid. Among other anhydrides listed
above, tetrahydrophthalic acid anhydride or hexahydrophthalic acid
anhydride are preferable.
[0021] The prepolymer used in the invention can also be obtained
from the reaction of styrene-maleic anhydride resin with the
following two compounds:
[0022] i. unsaturated alcohols containing at least three acrylic
groups in each molecule; and
[0023] ii. saturated alcohols.
[0024] The styrene-maleic anhydride is obtained by the
copolymerization reaction of styrene and maleic anhydride. Because
there is still anhydride group present in the resin, it is able to
undergo a ring-opening, or esterification reaction with alcohols,
introducing an hydroxyl group to the side chain.
[0025] The amount of styrene-maleic anhydride can be adjusted by
the ratio of styrene to maleic anhydride. The number of the
repeating unit is from about 1:1 to 3:1. The higher the relative
amount of styrene, the harder the modified resin will be, however,
the amount of substitution group elements is reduced. When the
ratio of repeating units is greater than 1:1, the more the
unsaturated double bond is introduced, which in turn, increases the
degree of crosslinking and photosensitivity. Moreover, the more of
the hydroxyl group that is introduced, the easier the development
of the photosensitive layer will be. But more hydroxyl groups do
not guarantee the improvement of resolution or adhesion. A suitable
ratio of amount and other additives used must be employed. The
preferable molecular weight of styrene-maleic anhydride is between
800 and 100000. When the molecular weight is lower than 800, film
formation is poor, and there will be problems of absorption and
pollution of the disposure film after drying and exposure. On the
other hand, when the molecular weight is greater than 100000,
problems such as unclean development will occur. Suitable
styrene-maleic anhydride is selected from SMA1000, SMA2000 and
SMA3000 (the repeating unit of styrene and maleic anhydride is 1:1,
2:1 and 3:1 respectively; available from ATO company).
[0026] The main function of the unsaturated alcohols is to provide
an unsaturated double bond for the film-forming polymer. Also, by
having at least three acrylic groups in each molecule, after it is
reacted with the anhydride group, enough unsaturated vinyl groups
are introduced in the side chain of the styrene-maleic anhydride.
This will enhance the degree of crosslinking and photosensitivity
of the photosensitive composition. Suitable unsaturated alcohol is
selected from low volatile alcoholes, such as pentaerylthritol
triacrylate (PETA) and dipentaerylthritol pentacrylate (DPPA).
Between them, DPPA is able to introduce more double bonds.
Therefore, it has higher photosensitivity, but the film formed is
softer. PETA, however is able to form harder polymer, because it
has a lower molecular weight. After grafting, the side chain is
shorter, which increases the hardness of the polymer. Due to the
high demand of hard solder resist material, PETA is preferable. In
styrene-maleic anhydride, the ratio of the anhydride group and the
hydroxyl group of unsaturated alcohol is preferably between 1:0.05
and 1:0.9, most preferably between 1:0.2 and 1:0.7. When
unsaturated alcohol is used excessively, the hardness of the
coating tends to be insufficient. If the amount of the unsaturated
alcohol is deficient, the double bond is inadequate, lowering
photosensitivity.
[0027] The main function of the saturated alcohol is to participate
in the ring-opening reaction, and introduce a sufficient number of
hydroxyl groups in the side chain of the film-forming polymer. The
structure of general saturated alcohol is not limited, as long as
it is not an irritant. Examples are alkyl alcohol, such as ethanol,
n-propanol, iso-propanol, n-butanol, sec-butanol, iso-butanol,
n-pentanol, 2-methyl-1-butanol, isopentyl alcohol, n-hexyl alcohol,
n-heptyl alcohol, n-octyl alcohol, cyclopentanol and cyclohexanol,
and ether alcohols such as ethylene glycol monomethyl ether,
ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
carbitol, propyleneglycol monomethyl ether and dipropyl diol methyl
ether. The amount and the size of molecules of the above saturated
alcohols will affect the number of hydroxyl groups and hardness of
the film-forming polymer. Generally, the more saturated alcohol
that is used, the higher the ratio of the anhydride ring-opening
will be, which results in easier development of the photosensitive
material. Preferably, the equivalent amount of the anhydride and
the saturated alcohol is between 1:0.2 and 1:10. The size of the
molecules of the saturated alcohol will affect the distance between
the chains of the molecules. Usually, the less saturated alcohol is
used, the harder the film gets. Before exposure, if the film is too
hard, it is unfavorable to photosensitivity. The amount and size of
the saturated alcohol molecules used relates to acid value and
degree of hardness. In addition, the two properties also relate to
other additives.
[0028] The photoinitiator used in the photosensitive composition of
the invention is not limited. For use with liquid photosensitive
material, however, preferably with high light-absorbing
decomposition, reducing the crosslinking problem on surfaces caused
by the suppression of oxygen. Suitable photoinitiators are selected
from 2-dimethoxy-2-benzil dimethyl ketal, 2,4-diethylthioxanthone,
isopropylthioxanthone,
2-methyl-1-(4-(methyl-thio)phenol)-2-morpholinopropanone-1),
benzophenone etc. To enhance photosensitivity, 2-dimethylaminoethyl
benzoate, ethyl(p-dimethylaminio)benzoate or Michler's ketone can
be added.
[0029] Unsaturated photo-chained monomers are able to provide a
double bond for polymerization when the photosensitive composition
is under UV exposure. The more unsaturated double bonds in a
molecule, the more chains are formed. Suitable photo-chained
monomers are selected from trimethylolpropane triacrylate,
pentaerythritol triacrylate, pentaerythritol tetracrylate,
dipentaerythritol pentacrylate, dipentaerythritol hexacrylate,
bis-phenol A type epoxy acrylate and urethane acrylate. The above
compounds are used alone or in a mixture of more than two. The
variety and the amount added depend on the softness of the
coating.
[0030] The component d of the photosensitive composition of the
invention is an adduct which is the reaction product of
bismaleimide derivative, barbituric acid derivative and an epoxy.
The formula of bismaleimide is shown as below: 1
[0031] wherein R represents an aromatic group, aliphatic group or
alicyclic group. The barbituric acid or its derivatives of the
invention have the formula: 2
[0032] wherein R.sub.1 and R.sub.2 are hydrogen or alkyl groups,
such as -H, -CH.sub.3, -C.sub.6H.sub.5, CH(CH.sub.3).sub.2-,
CH.sub.2CH.sub.2CH(CH.sub.3).sub.2, and 3
[0033] The finely powdered epoxy compound possessing at least two
epoxy groups in each molecule used in the invention is any epoxy
compound conventionally used. However, the epoxy compound must be
capable of being dispersed in a finely powdered form in the
photosensitive polymer (a) possessing at least two ethylenically
unsaturated bonds in each molecule and is further required to
assume a solid or semisolid state at ambient temperature. In
addition, it is required to be insoluble in the photosensitive
polymer (a) and the diluent (c) used must have no adverse effects
upon photosensitivity and developing properties. The epoxy
compounds satisfying these requirements are bisphenol S type epoxy
resins represented by the products of: Nippon Kayaku Co., Ltd.
under registered trademark designation of EBPS"-200, that of Asahi
Denka Kogyo Co., Ltd. under the trademark of "EPX"-30, and that of
Dainippon Ink and Chemicals, Inc under trademark of "EPOCLON"
EXA-1514; diglycidyl phthalates represented by the product of
Nippon Oil and Fats Co., Ltd. under the trademark of "BLEMMER"-DGT;
heterocyclic epoxy resins represented by the product of Nissan
Chemical Industries, Ltd. under the product code of TEPIC and that
of Ciba-Geigy Ltd, under trademark of "ARALDITE" PT 810; bixylenol
type epoxy resins represented by the product of Yuka Shell Epoxy
Kabushiki Kaisha under trademark of "EPIKOTE" YX04000; biphenol
type epoxy resins represented by the product of Yuka Shell Epoxy
Kabushiki Kaisha under trademark of "EPIKOTE" YL-6056; and
tetraglycidyl xylenoyl ethane resins represented by the product of
Tohto Kasei Co., Ltd. under product code of "ZX-1063".
[0034] In addition, an epoxy compound such as a bisphenol A type
epoxy resin or bisphenol F type epoxy resin which exhibits
solubility to said diluent and possesses at least two epoxy groups
in the molecular unit thereof may be used in place of part of the
sparingly soluble epoxy compound (D) to such an extent that the
substitution brings about practically no problem in terms of
photosensitivity and solubility of the unexposed part in the
developing solution. Desirably, the amount of the soluble epoxy
compound (S) to be used for substitution is such that the ratio of
the soluble epoxy compound (S) to the sparingly soluble epoxy
compound (D), S:D is in the range of 0-60:100-40, preferably
0-40:100-60, and more preferably 0-30:100-70 and the ratio of the
soluble epoxy compound (S) to the photosensitive polymer (a) is not
higher than 25:75, preferably lower than 20:80. If the latter ratio
is higher than 25:75, the unexposed part of the composition
exhibits unduly low solubility in the developing solution and
suffers part thereof to survive the development where the
development is affected with an alkalined developing solution and
the composition is corroded with the developing solution and the
coating tends to suffer from separation or blistering and becomes
nearly unusable where the development is influenced by a
solvent-type developer. The additional use of the soluble epoxy
compound produces the effect of enhancing part of the
characteristic properties of solder resist such as resistance to
plating.
[0035] Examples of the soluble epoxy compound (S) are bisphenol A
type epoxy resins represented by the products of Yuka Shell Epoxy
Kabushiki Kaisha under trademark of "EPIKOTE" 1009 and 1031, those
of Dainippon Ink and Chemicals Inc. under trademark of "EPICLON"
N-3050, -7050, and -9050, those of Asahi Chemical Industry Co.,
Ltd, under trademark of "AER" -664, -667, and -669, those of Tohto
Kasei CO., Ltd. under trademark of "Epo Tohto" YD-012, -017, -014,
-020, and -002, those of Ciba-Geigy Ltd. under trademark of
"ARALDITE" XAC-5005, GT-7004, -6484T, and -6099; those of the Dow
Chemical Company under trademark kof "DER" -642U and -673MF, those
of Asahi Denka Kogyo Co., Ltd. under trademark of "EP" -5400 and
-5900; hydrogenated bisphenol A type epoxy resins represented by
the products of Tohto Kasei Co., Ltd. under trademark of "Sun
Tohto" ST-2004 and -2007; bisphenol F type epoxy resins represented
by the products of Tohto Kasei Co., Ltd. under trademark of "Epo
Tohto" YDF-2004 and -2007; brominated bisphenol A type epoxy resins
represented by the products of Sakamoto Yakuhin Kogyl CO., Ltd
under product code of SR-BBS and SR-TBA-400, those of Asahi Denka
Kogyl Co., Ltd. under product codes of EP-62 and -66, those of
Asahi Chemical Industry Co., Ltd. under trademark of "AER"-755 and
-765, and Tohto Kassei Co., Ltd. under trademark of "Epo-Tohto"
YDB-600 and -715; novolak type epoxy resins such as the products of
Nippon Kayaku Co., Ltd. under trademark of "EPPN"-201, "EOCN"-103,
-1020, and -1025, and "BREN", those of Asahi Chemical Industry Co.,
Ltd. under trademark okf "AER" ECN-278, -292, and -299, those of
Ciba-geigy Ltd. under trademark of "ARALDITE" ECN-1273 and -1299,
those of Tohto Kasei Co,. Ltd. under trademark of "Epo Tohto"
YDCN-220L, -220HH, -702, and -704, and YDPN-601 and -602, and those
of Dainippon Ink and Chemicals Inc. under trademark of "EPICLON"
N-673, -680, -695, -770, and -775; novolak type epoxy resins of
bisphenol A represented by the product of Asahi Denka Kogyo CO.,
Ltd. under trademark of "EPX"-8001 and -8002 and "EPPX"-8060 and
-8061 and the product of Dainippon Ink and Chemicals, Inc. under
trademark okf "EPICLON" N-880; chelate type epoxy resins
represented by the products of Asahi Denka Kogyl Co., Ltd. under
trademark of "EPX"-49-60 and -49-30; glyxal type epoxy resins
represented by the product of Tohto Kasei Co., Ltd. under trademark
of "Epo Tohto" YDG-414; amino group-containing epoxy resins
represented by the products of Tohto Kassei Co., Ltd. under
trademark of "Epo Tohto" YH-1402 and "Sun Tohto" ST-110 and Yuka
Shell Epoxy Kabushiki Kaisha under trademark of "EPIKOTE" YL-931
and -933; rubber-modified epoxy resins represented by the product
of Dainippon Ink and Chemicals, Inc. under trademark of "EPICLON"
TSR-601 and the products of Asahi Denka Kogyo Co., Ltd. under
trademark of "EPX"-84-2 and -4061; dicyclopentadiene phenolic type
epoxy resins represented by the product of Sanyo-Kokusaku Pulp Co.,
Ltd. under trademark of "SK RESIN" DCE-400; silicone-modified epoxy
resins represented by the product of ACR Company Ltd. under product
code of X-1359; and xi-caprolactone-modified epoxy resins
represented by the products of Daicel Chemical Industries Ltd.
under product code of Placel G-402 and G-710. Further, partial
esterification products of the aformentioned epoxy compounds (D)
and (S) with (meth)acrylic acid are also suitable for the
substitution.
[0036] The manufacturing procedure of this resin may be divided
into two steps:
[0037] Step I: Add a suitable amount of barbituric acid or its
derivative to bismaleimide resin. The weight ratio of bismaleimide
and barbituric acid or its derivative is in the range of 3:1 to
20:1, preferably 5:1 to 10:1. After adding suitable solvent or
solvent system and mixing completely, the mixture should be heated
and kept at 120-145.degree. C. for 0.5 to 1.5 hours.
[0038] Step II: Add epoxy resin to the bismaleimide resin mixture
and mix it completely. The weight ratio of bismaleimide derivative
and barbituric acid derivative to epoxy is in the range of 1:2 to
1:5 and preferably 1:3 to 1:4. The mixture is then agitated at
70-125.degree. C. for 0.5-1.5 hours. Then cooling and stirred to
room temperature.
[0039] In addition, the photosensitive polymer (a) to the reaction
product of a bismaleimide derivative, a barbituric acid derivative
and an epoxy is in the range of 1:1.4 to 1:0.1.
[0040] In order to promote the thermal hardening characteristics of
the epoxy resin, curing agents are added. Suitable curing agents
preferably do not cause thermal polymerization of the epoxy resin
when baked to 80.degree. C. However, the reaction of epoxy resin
should be induced when baked at post bake temperature. Curing
agents that meet the above requirements are, for example,
imidazole, 2M4FZ, 2P4M5FZ, 2PHZ, 2PZ, 2P4MZ, 2PZL from Shikku
Chemical Co.; and dicyandiamide.
[0041] Apart from the above components, other additives can be
added to the photosensitive composition, such as fillers, solvents,
dispersion agents, anti-sagging agents, defoamer, leveling agent,
dyes or pigments, thermal inhibitor and flame retardant etc.
[0042] When additives, curing agents or pigments are added to the
photosensitive composition, the mixture must be ground into fine
powder to increase the flatness and burnish of the coating. The
mostly commonly used grinder is a triple-roll mill. When
manufacturing thermosetting liquid solder resist, the epoxy resin
and coat-forming polymer are separately mixed with respective
curing agents. The main agent and curing agent are also separately
ground and stored, and are combined immediately prior to
mixing.
[0043] The application of the liquid photosensitive composition
onto the printed circuit board is usually performed by screen
printing or curtain coating. After being prebaked at around
75-80.degree. C., it is UV exposed at 500.about.600 mJ/cm.sup.2.
Sodium carbonate solution is then used to develop the
photosensitive layer. For the manufacturing of the solder resist,
the exposed photosensitive layer must be post baked at about
180.degree. C. for 40.about.60 minutes to completely cure the
photosensitive layer. The post baked solder resist exhibits
excellent curing and hardness enough to stand the etching of the
follow-up soldering and electroplating. For the manufacture of a
photosensitive insulation layer with small diameter windows, the
exposed photosensitive layer must be post baked at 180.degree. C.
for 60.about.90 minutes to completely cure the photosensitive
layer, followed by non-electrical plating and electroplating
etc.
[0044] Embodiments
[0045] Synthesis of prepolymer
[0046] Binder (I)
[0047] 1000.0 g of diethyleneglycol monoethylether acetate was
added to a vessel with four holes. The temperature was raised to
105, and 1150 g of ECN1299 (available from Ciba-Geigy Ltd.) was
then added slowly to the vessel. The reactant was stirred until the
powder was completely dissolved. 0.5g of hydroquinone, 8.5 g of N,
N-dimethylaminopyridine and 420.0 g of acrylic acid were added. The
reaction continued for 12 hours, followed by the addition of 494 g
of tetrahydrophthalic acid anhydride. After a further eight hours
of reaction, 114.0 g of Naphtha 150 was added to dilute the
reaction product and a resin solution binder (I) was obtained.
[0048] Binder (II)
[0049] 820.0 g of diethyleneglycol monoethylether acetate was added
to a vessel with four holes. The temperature was raised to 105, and
1165 g of SMA1000 (available from Ato Co. styrene:maleic
anhydride=1:1) was then added slowly in the vessel. The reactant
was continually stirred until the powder was completely dissolved.
0.5g of hydroquinone, 8.5 g of N,N-dimethylaminopyridine and 596.0
g of pentaerythritol triacrylate were added. The reaction continued
for 6 hours followed by the addition of 136 g of ethanol. After 8
hours further reaction, 202.0 g of Naphtha 150 was added to dilute
the reaction product and a resin solution binder (II) was
obtained.
[0050] Resin 1
[0051] 10.2g of N,N'-4,4'-diphenylmethane-bismaleimide was
dissolved in 30 g of N-methyl-2-pyrrolidone, and then 1.79 g of
barbituric acid was added. The mixture was heated and stirred at
130.degree. C. for 1 hour. Subsequently, 25 g of epoxy resin (5 g
of YDCN-704 from South Asia, 15 g of PT-810 from Ciba-Geigy Co. and
5 g of brominated bis-phenol A epoxy) was heated to 130.degree. C.
and added to the mixture. After continuous mixing and heating at
130.degree. C. for 1 hour, the temperature was reduced to
60.degree. C. Finally 5 g of acetone and 5 g of methyl ethyl ketone
were added to the resin mixture. After stirring at 60.degree. C.
for 30 minutes, the mixture was cooled and stirred to room
temperature. A high performance resin composition was obtained.
[0052] Resin 2
[0053] 10.2 g of N,N'-4,4'-diphenylmethane-bismaleimide was
dissolved in 30 g of N-methyl-2-pyrrolidone, and then 1.79 g of
barbituric acid was added. The mixture was heated and stirred at
130.degree. C. for 1 hour. Subsequently, 35 g of epoxy resin (log
of EPON1001 from Shell Co., 20 g of YX4000 from Shell Co. and 5 g
of brominated bis-phenol A epoxy) was heated to 130.degree. C. and
was added to the mixture. After continuous mixing and heating at
130.degree. C. for 1 hour, the temperature was reduced to 60.
Finally 5 g of acetone and 5 g of methyl ethyl ketone was added to
the above resin mixture. After stirring at 60.degree. C. for 30
minutes, the mixture was cooled and stirred to room temperature. A
high performance resin composition was obtained.
[0054] Resin 3
[0055] 10.2 g of N,N'-4,4'-diphenylmethane-bismaleimide was
dissolved in 30 g of N-methyl-2-pyrrolidone, and then 1.79 g of
barbituric acid was added. The mixture was heated and stirred at
130.degree. C. for 1 hour. Subsequently, 20 g of epoxy resin (5 g
of YDCN-704 from South Asia Co., 10 g of EPON 1001 from Shell Co.
and 5 g of brominated bis-phenol A epoxy) was heated to 130 and
added to the mixture. After continuous mixing and heating at
130.degree. C. for 1 hour, the temperature was reduced to
60.degree. C. Finally 5 g of acetone and 5 g of methyl ethyl ketone
were added to the resin mixture. After stirring at 60.degree. C.
for 30 minutes, the mixture was cooled and stirred to room
temperature. A high performance resin composition was obtained.
[0056] 1st Embodiment
[0057] The following main agent and curing agent were prepared and
mixed, followed by grinding by a triple-roll mill.
1 (g) Main agent Binder I 153.0
2-methyl-1-(4-(methylthio)phenyl)-2- 6.0 morpholinopropanone-1
dimethylbenzyl ketal 2.0 2-dimethylaminoethyl benzoate 1.5
Dipentaerythritol hexacrylate 15.0 BaSO.sub.4 50.0 SiO.sub.2 20.0
Aerosil-200 2.0 Modaflow 2100 1.0 Defoamer DC-1000 (Deuchem Trading
Co.) 1.5 Dicyandiamid 2.0 Pigment green-36 1.2 Pigment green-7 1.0
Hydroquinone 0.2 Curing agent Resin I 77 dipentaerythritol 5.0
hexacrylate aerosil-200 1.0 BaSO.sub.4 10.0 Napha-150 (From China
5.0 Petroleum Co.)
[0058] The main agent and the curing agent were mixed and stirred
completely. The photosensitive composition was then applied to a
printed circuit board with metal wires by screen coating. The
printed circuit was then placed in an oven and baked at 80.degree.
C. for 30 minutes. After cooling, a film was applied to the printed
circuit board, followed by UV exposure at 500 mJ/cm.sup.2. 1.0%
Na.sub.2CO.sub.3(aq) was then used to develop and expose the area
to be coated with solder. The circuit board was then placed in a
180.degree. C. oven to cure for 60 minutes. The cured solder resist
was then tested with CH.sub.2Cl.sub.2, 10% NaOH(aq) and 10% HCl(aq)
for chemical resistance, hardness and adhesion tests. The result is
shown in Table 1.
[0059] 2nd Embodiment
[0060] The following main agent and curing agent were prepared and
mixed, followed by grinding by a triple-roll mill.
2 (g) Main agent Binder I 153.0
2-methyl-1-(4-(methylthio)phenyl)-2- 5.0 morpholinopropanone-1
2-dimethylaminoethyl benzoate 1.5 Dipentaerythritol hexacrylate
25.0 BaSO.sub.4 25.0 Talc 10.0 Aerosil-200 1.5 Modaflow 2100 1.0
Defoamer DC-1000 (Deuchem Trading Co.) 1.0 Dicyandiamide 1.0
2-phenyl-4,5-dihydroxy- 1.3 methyl imidazole (2PHZ) Pigment
green-36 1.2 Pigment green-7 1.0 hydroquinone 0.2 curing agent
Resin 2 87 Dipentaerythritol 5.0 pentacrylate aerosil-200 1.0
BaSO.sub.4 20.0 Napha-150 (from China 5.0 Petroleum Co.)
[0061] The main agent and the curing agent were mixed and stirred
completely. The photosensitive composition was then applied to a
printed circuit board with metal wires by screen coating. The
printed circuit was then placed in an oven and baked at 80.degree.
C. for 30 minutes. After cooling, a film was applied to the printed
circuit board, followed by UV exposure at 500 mJ/cm.sup.2. 1.0%
Na.sub.2CO.sub.3(aq) was then used to develop and expose the area
to be coated with solder. The circuit board was then placed in a
180.degree. C. oven to cure for 60 minutes. The cured solder resist
was then tested with CH.sub.2Cl.sub.2, 10% NaOH(aq) and 10% HCl(aq)
for chemical resistance, hardness and adhesion tests. The result is
shown in Table 1.
[0062] 3rd Embodiment
[0063] The following main agent and curing agent were prepared and
mixed, followed by grinding by a triple-roll mill.
3 (g) Main agent Binder II 153.0
2-methyl-1-(4-(methylthio)phenyl)-2- 60 morpholinopropanone-1
2-dimethylaminoethyl benzoate 1.0 Dipentaerythritol pentacrylate
20.0 BaSO.sub.4 30.0 SiO.sub.2 5.0 Aerosil-200 3.0 Modaflow 2100
1.0 Defoamer DC-1000 (Deuchem Trading Co.) 1.0 dicyandiamide 0.5
2-phenyl-4,5-dihydroxy-methylimidazole 2.0 (2PHz) Pigment green-36
0.1 Pigment green-7 0.6 hydroguinone 0.2 Curing agent Resin 3 72
pentaerythritol 5.0 triacrylate aerosil-200 0.5 BaSO.sub.4 10.0
Napha-150 (from China 10.0 Petroleum Co.)
[0064] The main agent and the curing agent were mixed and stirred
completely. The photosensitive composition was then applied to a
printed circuit board with metal wires by screen coating. The
printed circuit was then placed in an oven and baked at 80.degree.
C. for 30 minutes. After cooling, a film was applied to the printed
circuit board, followed by UV exposure at 500 mJ/cm.sup.2. 1.0%
Na.sub.2CO.sub.3(aq) was then used to develop and expose the area
to be coated with solder. The circuit board was then placed in a
180.degree. C. oven to cure for 60 minutes. The cured solder resist
was then tested with CH.sub.2Cl.sub.2, 10% NaOH(aq) and 10% HCl(aq)
for chemical resistance, hardness and adhesion tests. The result is
shown in Table 1.
[0065] 1st Comparative Embodiment
4 (g) Main agent Binder I 153.0
2-methyl-1-(4-(methylthio)phenyl)-2- 6.0 morpholinopropanone-1
Dimethylbenzyl ketal 2.0 2-dimethylaminoethyl benzoate 1.5
Dipentaerythritol hexacrylate 15.0 BaSO.sub.4 50.0 SiO.sub.2 20.0
Aeorsil-200 2.0 Modaflow 2100 1.0 Defoamer DC-1000 (Deuchem Trading
Co.) 1.5 Dicyandiamide 2.0 Pigment green-36 1.2 Pigment green-7 1.0
hydroquinone 0.2 Carbitol acetate 10.0 Curing agent YDCN-7-4 (South
Asia) 5.0 PT-810 (Ciba-Geigy Co.) 15.0 Brominated bisphenol A 5.0
epoxy Dipentaerythritol 5.0 hexacrylate aerosil-200 1.0 BaSO.sub.4
10.0 Napha-150 (from China 5.0 Petroleum Co.)
[0066] The main agent and the curing agent were mixed and stirred
completely. The photosensitive composition was then applied to a
printed circuit board with metal wires by screen coating. The
printed circuit was then placed in an oven and baked at 80.degree.
C. for 30 minutes. After cooling, a film was applied to the printed
circuit board, followed by UV exposure at 500 mJ/cm.sup.2. 1.0%
Na.sub.2CO.sub.3(aq) was then used to develop and expose the area
to be coated with solder. The circuit board was then placed in a
180.degree. C. oven to cure for 60 minutes. The cured solder resist
was then tested with CH.sub.2Cl.sub.2, 10% NaOH(aq) and 10% HCl(aq)
for chemical resistance, hardness and adhesion tests. The result is
shown in Table 1.
5TABLE 1 comparative Embodiment 1 2 3 1 Resolution 50 50 50 50
(.mu.m) Solvent .gtoreq.10 min .gtoreq.10 min .gtoreq.10 min
.gtoreq.10 min resistance (CH.sub.2Cl.sub.2) Chemical .gtoreq.10
min .gtoreq.10 min .gtoreq.10 min .gtoreq.10 min resistance (10%
NaOH) Chemical .gtoreq.10 min .gtoreq.10 min .gtoreq.10 min
.gtoreq.10 min resistance (10% HC1) Hardness 6 H 6 H 6 H 6 H Solder
>400 >450 >300 100 resistance @ 260.degree. C. (sec)
[0067] From Table 1, it is shown that the photosensitive
composition of the invention exhibits excellent solder resistance
compared to the comparative embodiment. As a result, the
photosensitive composition of the invention exhibits excellent heat
resistance in comparison to the prior art.
[0068] The foregoing description of the preferred embodiments of
this invention has been presented for purposes of illustration and
description. Obvious modifications or variations are possible in
light of the above teaching. The embodiments were chosen and
described to provide the best illustration of the principles of
this invention and its practical application to thereby enable
those skilled in the art to utilize the invention in various
embodiments and with various modifications as are suited to the
particular use contemplated. All such modifications and variations
are within the scope of the present invention as determined by the
appended claims when interpreted in accordance with the breadth to
which they are fairly, legally, and equitably entitled.
* * * * *