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
2000-08-04
2003-02-25
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
C522S100000, C528S100000, C528S112000, C525S531000, C525S536000
Reexamination Certificate
active
06524769
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a photosensitive resin composition for use as a material for a printed wiring board. More specifically, it relates to a photosensitive resin composition which has excellent resolution and high heat resistance and which gives, as a material, a printed wiring board excellent in heat resistance and electric insulation under moisture absorption taking place for a long period of time.
2. Prior Art of the Invention
In recent years, electronic machines and equipment are desired to have a decreased size and an increased density, and printed wiring boards are also essentially required to have a smaller size, a higher density, a lighter weight and a smaller thickness. For applying a solder resist material onto a substrate, it is so far general practice to use solder resist material which is curable with ultraviolet light, developable with a diluted alkali and excellent in durability against plating and a solvent. However, in build-up boards having fine wirings inside, and the like, solder resists recently cause a popcorn phenomenon in a solder resist/sealing resin interface, or some other problems. That is, the solder resists cause problems with regard to heat resistance. Further, solder resists are also required to have reliability on insulation between fine wiring lines.
For improving electric insulation and heat resistance, there has been developed a resist utilizing a cyanate ester compound such as a BT resin (Japanese Patent Application No. 8-298641). In development with an alkali, the cyanate ester compound causes a remaining resin after the development, which causes a problem in the steps of electroless plating with nickel and electroless plating with gold. With regard to this problem, it is already known that when a cyanate ester compound such as a BT resin, etc., and an epoxy acrylate are allowed to react with each other in advance for improving developability, electric properties and the developability are improved at the same time (Japanese patent Application No. 11-61075).
The above resist is excellent in resist properties. However, it has been found that the above resist has a problem on durability against heat under long-lasting moisture absorption. When a resist is used for the production of semiconductor packages, the resist is required to have durability against heat under long-lasting moisture absorption, and such durability against heat comes to be of great interest.
SUMMARY OF THE INVENTION
Under the circumstances, it is an object of the present invention to provide a photosensitive resin composition which is highly heat-resistant, which is excellent in durability against heat and electric insulation reliability under long-lasting moisture absorption, and which is developable with an alkali.
According to the present invention, there is provided a photosensitive resin (II) which is a reaction product formed by reacting a reaction product (I) prepared from a biphenyl epoxy acrylate (a) of the formula (1) and a cyanate ester compound (b) with a polybasic acid anhydride
wherein each of R
1
and R
9
is a hydrogen atom or methyl, and n is an integer of 1 or more.
According to the present invention, there is provided a photosensitive resin composition comprising the above photosensitive resin (II) and an epoxy resin (d).
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have made diligent studies for achieving the above objects. As a result, it has been found that the above objects can be achieved by using a resin obtained by reacting a difunctional epoxy acrylate having a biphenyl skeleton with a cyanate ester compound and reacting the resultant reaction product with a polybasic acid anhydride, and the present invention has been accordingly completed.
That is, the present invention provides a photosensitive resin (II) obtained by reacting a reaction product (I) prepared from a biphenyl epoxy acrylate (a) of the above formula (1) and a cyanate ester compound (b) with a polybasic acid anhydride (c). It is preferred to use an epoxy acrylate (a) of the formula (1) in which, of R
1
to R
8
, each of R
2
, R
3
, R
6
and R
7
is a hydrogen atom and the others are methyl or an epoxy acrylate (a) of the formula (1) in which, of R
1
to R
8
, each of R
3
and R
7
is a hydrogen atom and the others are methyl.
The present invention also provides a photosensitive resin composition (III) comprising the above photosensitive resin (II) and an epoxy resin (d).
The cyanate ester compound (b) used in the present invention refers to an aromatic organic compound generally having at least 2 but not more than 5 cyanato groups (—O—C≡N) per molecule, and the cyanate groups bond directly to an aromatic ring of the aromatic group R.
Specific examples of the cyanate ester compound (b) include 1,3- or 1,4-cyanatebenzene, 1,3,5-tricyanatebenzene, 1,3-, 1,4-, 1,6-, 1,8-, 2,6- or 2,7-cyanatenaphthalene, 1,3,6-tricyanatenaphthalene, 4,4′-dicyanatebiphenyl, bis(4-cyanatephenyl)methane, 2,2-bsi(4-cyanatephenyl)propane, 2,2-bsi(3,5-dibromo-4-cyanatephenyl)propane, bis(4-cycanatephenyl)ether, bis(4-cyanatephenyl)thioether, bis(4-cyanatephenyl)sulfone, tris(4-cyanatephenyl)phosphite, tris(4-cyanatephenyl)phosphate and cyanates obtained by reactions of novolak and cyan halides.
In addition to these, the cyanate ester compound (b) can be also selected from polyfunctional cyanate ester compounds described in Japanese Patent Publications Nos. 41-1928, 43-18468, 44-4791, 45-11712, 46-1112, 47-26853 and 51-63149. These cyanate ester compounds may be used alone or in combination. The content of impurities such as hydrolyzing Cl and Na in these compounds is very small, and when any one of these is incorporated as one component in the present invention, the overall content of impurities decreases, so that the photosensitive resin (II) is suitable as a peripheral material for semiconductors.
Further, there may be used triazine-ring-possessing prepolymers having a molecular weight of 200 to 6,000 formed by trimerization of cyanate groups of the above polyfunctional cyanate ester compounds. The prepolymers can be obtained by polymerizing the above polyfunctional cyanate ester compound monomers in the presence of a catalyst selected from acids such as mineral acids and Lewis acids, bases such as sodium alcoholate and tertiary amines or salts such as sodium carbonate. The prepolymers partially contain monomers and have the form of a mixture of a monomer and a polymer, and these materials are preferably used in the present invention.
The polybasic acid anhydride (c) for use in the present invention refers to an acid anhydride having at least 2 carboxylic acids per molecule. Examples of the polybasic acid anhydride (c) include phthalic acid anhydride, trimellitic acid anhydride, pyromellitic acid anhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, benzophenonetetracarboxylic acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, 4-methylhexahydrophthalic acid anhydride, 3-methylhexahydrophthalic acid anhydride, succinic acid anhydride, dodecenylsuccinic acid anhydride, ethylene glycol bias(anhydrotrimellitate), 3,3′,4,4′-diphenylsulfonetetracarboxylic acid dianhydride, 4,4′-oxydiphthalic acid anhydride, 4,4′-diphthalic acid anhydride, and others having molecules containing acid anhydrides. These may be used alone or in combination. A mixture containing pyromellitic acid anhydride is preferred.
The method of practicing the present invention will be explained below.
First, when the epoxy acrylate (a) having a biphenyl skeleton is reacted with the cayante ester compound (b), generally, 5 to 40 part o the cyanate ester compound (b) can be modified per 100 parts of the epoxy acrylate (a), although the amount ratio is not specially limited. When the amount of the cyanate ester compound (b) is small, the heat resistance, the moisture absorption and the electric insulation after a pressure cooker test are insufficient. When the amount of the cyanate ester
Hagiwara Isao
Harada Toru
Ishii Kenji
Miyamoto Makoto
Hamilton Cynthia
Mitsubishi Gas Chemical Company Inc.
Wenderoth , Lind & Ponack, L.L.P.
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