Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2001-04-13
2003-02-25
Sellers, Robert E.L. (Department: 1712)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C523S466000, C523S468000, C525S481000, C528S089000, C528S337000
Reexamination Certificate
active
06524989
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a latent catalyst extremely excellent in moisture resistance reliability, curability and storage stability at ordinary temperature, a thermosetting resin composition comprising the same, an epoxy resin molding material for encapsulating a semi-conductor responding to insertion mounting and surface mounting which molding material comprises the above latent catalyst and is excellent in moisture resistance reliability, storage stability at ordinary temperature and moldability, and a semiconductor device in which the molding material is used.
2. Related Art Statement
Thermosetting resins have been required to have a storage stability at ordinary temperature for the purpose of simplifying the handling thereof, and various latent catalysts have been developed by now. The latent catalyst means a catalyst having excellent curability and excellent storage stability at ordinary temperature for exhibiting its catalytic activity at an appropriate temperature or higher. For example, JP-A-8-295,721 discloses that a tetra-substituted phosphonium tetra-substituted borate in which the substituents on boron have a specific structure has both excellent curability and excellent storage stability at ordinary temperature. The tetra-substituted phosphonium tetra-substituted borate exhibits its catalytic activity upon dissociation of the ionic bond between the anion portion and the cation portion, so that the temperature at which the catalytic activity is exhibited can be varied by changing the temperature at which the bond is dissociated. When the substituents on boron have a specific structure, the ionic bond comes to have an appropriate bond-strength and exhibits no activity at ordinary temperature but is dissociated at the curing temperature to rapidly exhibit activity. Therefore, excellent curability and excellent storage stability, namely latency, is developed. The field in which such a latent catalyst takes an important part includes an epoxy resin molding material for encapsulating a semiconductor such as IC, LSI or the like. As the catalyst which has heretofore been used, there are imidazoles, diazabicyclo-alkenes, triarylphosphines and the like; however, these catalysts act even at relatively low temperatures, so that molding materials in which these catalysts are used are inferior in storage stability at ordinary temperature. Therefore, when these molding materials are stored at ordinary temperature, such troubles arise that incomplete filling results from the lowering of flow property during molding, gold wire in IC chips is broken to cause conduction failure, and the like. Therefore, it has been essential to refrigerate the epoxy resin molding material for encapsulating a semiconductor (referred to hereinafter as the encapsulating material in some cases) when it is transported and stored. Moreover, recently, the performance required for IC as to the moisture resistance reliability has become strict more and more. For example, JP-A-7-242,683 mentions tetra-substituted phosphonium tetra-substituted borates in which phenoxy groups or the like are bonded to the phosphorus atom, namely P—O—C bonds are formed, and it discloses that the borates are effective as a catalyst enabling the encapsulating material to develop the storage stability at ordinary temperature; however, these tetra-substituted phosphonium tetra-substituted borates are easily hydrolyzed to produce phosphoric acid and there is a fear that the moisture resistance reliability may be remarkably deteriorated.
SUMMARY OF THE INVENTION
This invention provides a latent catalyst having extremely excellent moisture resistance reliability, curability and storage stability at ordinary temperature; a thermosetting resin composition comprising the same; an epoxy resin molding material for encapsulating a semiconductor responding to insertion mounting and surface mounting which molding material comprises the above latent catalyst and has excellent moisture resistance reliability, storage stability at ordinary temperature and moldability; and a semiconductor device in which the thermosetting molding material is used.
The present inventors have diligently repeated research for solving the above-mentioned problems, and as a result of their examination of a relation between the moisture resistance reliability of the latent catalyst and the structure of a substituent bonded to the boron atom of the tetra-substituted phosphonium tetra-substituted borate described in JP-A-8-295,721 which is a patent application previously filed by the present inventors, they have found that a certain electric activity exhibited in water by a proton donor from which the substituent bonded to the boron atom results is closely connected with the moisture resistance reliability. That is to say, it has been clarified that when the electrical conductivity of the extraction water of the proton donor which is described in detail hereinafter is low, extremely excellent moisture resistance reliability is developed. Based on the above knowledge, this invention has been completed. That is to say, this invention provides the following:
(1) a latent catalyst composed of a phosphonium borate represented by the general formula (1) and a thermo-setting resin composition comprising the catalyst:
wherein R
1
, R
2
, R
3
and R
4
may be the same as or different from one another and each is a monovalent, organic group having an aromatic ring or a heterocyclic ring or a monovalent, aliphatic group and is bonded to the phosphorus atom to form a P—C bond; X
1
, X
2
, X
3
and X
4
may be the same as or different from one another and at least one of them is a group formed when a proton donor having at least one proton capable of being liberated out of the molecule has liberated one proton and each of the others is a monovalent, organic group having an aromatic ring or a heterocyclic ring or a monovalent, aliphatic group; and each of the above proton donors satisfies the condition that when 1 g of each proton donor is mixed with 50 g of purified water and the resulting mixture is subjected to pressure cooker treatment at 125° C. for 20 hours in a pressure cooker vessel, the electrical conductivity of the extraction water thus obtained becomes not more than 1,000 &mgr;S/cm,
(2) a latent catalyst composed of a phosphonium borate represented by the general formula (2) and a thermosetting resin composition comprising the catalyst:
wherein R
5
, R
6
, R
7
and R
8
may be the same as or different from one another and each is a monovalent, organic group having an aromatic ring or a heterocyclic ring or a monovalent, aliphatic group and is bonded to the phosphorus atom to form a P—C bond; Z
1
is an organic group bonding to Y
1
and Y
2
; Z
2
is an organic group bonding to Y
3
and Y
4
; each of Y
1
and Y
2
is a group formed when a monovalent, proton-donating substituent has liberated a proton and the substituents Y
1
and Y
2
in the same molecule are bonded to the boron atom to form a chelate structure; each of Y
3
and Y
4
is a group formed when a monovalent, proton-donating substituent has liberated a proton and the substituents Y
3
and Y
4
are bonded to the boron atom to form a chelate structure; Z
1
and Z
2
may be the same as or different from each other and also Y
1
, Y
2
, Y
3
and Y
4
may be the same as or different from one another; and HY
1
Z
1
Y
2
H and HY
3
Z
2
Y
4
H which are proton donors before the ligands of boron Y
1
Z
1
Y
2
and Y
3
Z
2
Y
4
are formed by liberation of the respective protons satisfy the condition that when 1 g of each of the proton donors is mixed with 50 g of purified water and the resulting mixture is subjected to pressure cooker treatment at 125° C. for 20 hours in a pressure cooker vessel, the electrical conductivity of the extraction water thus obtained becomes not more than 1,000 &mgr;S/cm,
(3) a latent catalyst composed of a phosphonium borate represented by the general formula (3) and a thermosetting resin composition comprising the catalyst:
wherein R
9
, R
10
Go Yoshiyuki
Honda Hiromi
Kobayashi Minoru
Miyake Sumiya
Nagata Hiroshi
Sellers Robert E.L.
Smith , Gambrell & Russell, LLP
Sumitomo Bakelite Company Limited
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