Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Radiation sensitive composition or product or process of making
Reexamination Certificate
1999-12-15
2001-05-08
Hamilton, Cynthia (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Radiation sensitive composition or product or process of making
C430S283100, C522S095000, C522S063000, C522S117000, C522S009000, C522S016000, C522S026000
Reexamination Certificate
active
06228560
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a photosensitive resin composition and a photosensitive element using the same.
In the art of manufacture of printed circuit boards, photosensitive elements made of photosensitive resin compositions with a support and a protective film have been popularly used as resist in such treatments as etching and plating.
A printed circuit board is manufactured by a process comprising the steps of laminating a photosensitive film on a copper substrate, subjecting it to pattern exposure, removing the unexposed portion with a developer, carrying out etching or plating to form a pattern, and then stripping the cured portion from the substrate.
An alkaline developer comprising a sodium bicarbonate solution or the like is popularly used as developer for removing the unexposed portion. Usually developer is used as long as it maintains the ability to dissolve the photosensitive layer to a desired degree, and in use thereof, the photosensitive resin composition is dissolved or dispersed in the developing solution.
With the recent trend toward higher density of printed circuit boards, which entails reduction of contact area between the copper substrate and the pattern-formed photosensitive layer, it is required of the composition used for forming the photosensitive layer to show excellent adhesiveness, mechanical strength, chemical resistance and flexibility in the development, etching or plating step.
For the improvement of chemical resistance, methods using a photopolymerizable compound having isocyanurate rings are disclosed in JP-A-61-77844, JP-A-62-290705, JP-A-61-14212, JP-A-59-222480, JP-A-1-14190, JP-A-57-55914, JP-A-5-216224, JP-A-5-273754, etc., but these methods have the problem that the cured film of said compound is hard and frangible.
On the other hand, from the viewpoint of improvement of processability, a photosensitive resin composition having high sensitivity and little possibility of causing contamination of the plating bath is desired, but these properties are dependent on the type and amount of the photoinitiator used in the composition.
High-sensitivity photoinitiators are disclosed in DE-AS 2027467, EP-A 11786, EP-A 220, EP-A 589, JP-A 6-69631, etc., but these photoinitiators have the disadvantage that they may cause contamination of the plating bath.
Photoinitiators with low possibility of causing plating bath contamination and high sensitivity are proposed in JP-A-60-239744, JP-A-2-226149, etc., but they are at a disadvantage in that their sensitivity is low.
U.S. Pat. No. 3,479,185 discloses a photosensitive resin composition comprising a 2,4,5-triphenylimidazole dimer, which is a photoinitiator with low possibility of causing plating bath contamination, combined with a hydrogen donative compound to elevate sensitivity. This composition, however, has the drawbacks that in case sensitivity of the composition has been adjusted to a desired level, when the amount of said 2,4,5-triphenylimidazole dimer used is increased, the line width of the resist is enlarged, while when the amount of the hydrogen donative compound is increased, adhesiveness to copper and storage stability are deteriorated.
Combination of a 2,4,5-triphenylimidazole dimer and a compound having a highly reactive ethylenically unsaturated group (such as polyethylene glycol dimethacrylate) has also been studied, but this combination is very poor in chemical resistance.
SUMMARY OF THE INVENTION
The present invention proposes to solve the problems of the prior art and, to this end, it provides a photosensitive resin composition which can satisfy various property requirements such as mentioned above by using as an ethylenically unsaturated compound a compound in which an isocyanurate ring and an acrylate (or methacrylate) are bonded by a flexible alkylene oxide group (such as polyethylene oxide group or polypropylene oxide group) and an alkylene group (such as hexamethylene group), and if necessary, to improve plating resistance by adding a dicyanediamide thereto. This resin composition has excellent mechanical strength, chemical resistance and flexibility. Also the present invention provides a photosensitive element using said photosensitive resin composition.
The present invention further provides a photosensitive resin composition improved in adhesiveness, photosensitivity, plating bath anti-contamination property, etc., by use of a specific combination of a photopolymerizable compound containing an ethylenically unsaturated group and a photoinitiator, and a photosensitive element using such a composition.
The present invention further provides a photosensitive resin composition comprising:
(A) a binder polymer having carboxyl groups;
(B) at least one photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule;
(C) a photoinitiator; and if necessary
(D) dicyandiamide,
wherein said component (B) must comprise a compound represented by the formula:
wherein R
1
is a divalent organic group and each R
2
represents independently a group of the formula:
wherein R
3
is a hydrogen atom or a methyl group; X is an alkylene oxide group containing 2-10 carbon atoms; and n is an integer of 1 to 14.
The present invention further provides a photosensitive element comprising a support and a layer of said photosensitive resin composition formed thereon.
The present invention additionally provides a photosensitive resin composition comprising:
(A) a binder polymer having carboxyl groups;
(B′) at least one photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule; and
(C′)
a photoinitiator containing a 2,4,5-triphenylimidazole dimer, wherein one constituent of said component (B′) is a compound represented by the formula (I) or a compound of the formula:
wherein R
4
s represent independently a group of the formula:
wherein Y is —CH
2
CH
2
—O—,
R
3
is a hydrogen atom or a methyl group; and n is an integer of 1 to 14, or of the formula:
wherein R
3
is a hydrogen atom or a methyl group; p is an integer of 1 to 9; and n is an integer of 1 to 14.
The present invention also provides a photosensitive element comprising a support and a layer of said photosensitive resin composition formed thereon.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The photosensitive resin composition according to a first embodiment of the present invention comprises:
(A) a binder polymer having carboxyl groups;
(B) at least one photopolymerizable compound having at least one polymerizable ethylenically unsaturated group in the molecule;
(C) a photoinitiator; and, if necessary,
(D) dicyandiamide,
wherein said component (B) must contain a compound represented by the formula:
wherein R
1
is a divalent organic group; and each R
2
represents independently a group of the formula:
wherein R
3
is a hydrogen atom or a methyl group; X is an alkylene oxide group; and n is an integer of 1 to 14.
The binder polymers having carboxyl groups usable as component (A) in this invention include homopolymers of acrylic and methacrylic acid [when the term “(meth)acrylic acid” is used in the present specification, it means both acrylic acid and methacrylic acid] and copolymers thereof with vinyl monomers copolymerizable therewith.
Examples of said vinyl monomers, which are not specified in this invention, include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, glycidyl methacrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate (and corresponding acrylates), acrylamide, diacetoacrylamide, styrene, vinyltoluene and the like.
The binder polymer (A) used in the present invention is preferably soluble or swellable in alkaline solutions (such as 1-3 wt % sodium carbonate or potassium carbonate solutions) for facilitation of development or for environmental protection.
The acid value of the binder polymer (A
Chiba Tatsuo
Ichikawa Tatsuya
Antonelli Terry Stout & Kraus LLP
Hamilton Cynthia
Hitachi Chemical Company Ltd.
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