JPH023412A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject compsn. providing a cured product having excellent low stress property and impact resistance without lowering the glass transition temp. and mechanical characteristics below those of conventional products by using a block addition product obtd. by combining hydrogenpolysiloxanes having different degrees of polymn. CONSTITUTION:A compsn. wherein a block addition product obtd. by performing an addition reaction of a phenolic novolak epoxy resin partially contg. alkenyl groups with a mixture of an organopolysiloxane having a degree of polymn. of 20-150 and hydrogen atoms on both terminals and another organopolysiloxane having a degree of polymn. of 15-500 and hydrogen atoms on both terminals in the presence of a platinum catalyst, a phenolic novolak curing agent, a curing accelerator and an inorg. filler are incorporated as the essential components is melted and kneaded under heating. By said process, it is possible to obtain a compsn. of an epoxy resin molding material for sealing IC contg. little unreacted siloxane compd., having excellent kneading processability when a molding material is prepd., reduced in the occurrence of flashes and staining of mold and providing a cured sealing material having a high Tg, a high mechanical strength, low stress property and good stamping property.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention provides a cured product that has improved low stress properties and thermal shock resistance without lowering the glass transition temperature and mechanical performance compared to conventional products. The present invention relates to an epoxy resin composition for semiconductor encapsulation that provides the following.

(Prior art) Currently, kneaded compositions containing an epoxidized product of ortho-cresol novolak, a phenol novolak hardener, a hardening accelerator, and an inorganic filler are widely used as epoxy resin compositions for encapsulating semiconductor devices. The production volume is increasing with the growth of the semiconductor industry.

However, as semiconductor elements become more highly integrated, devices become larger and flatter, cured sealants become thinner, and surface mounting is used when mounting on substrates, etc., demands are placed on sealing molding materials. Performance is also changing significantly.

In other words, stress due to the difference in thermal expansion coefficient between the IC substrate, carrier frame, and cured molded product due to temperature changes becomes apparent, causing sliding of IC aluminum wiring, disconnection of bonding gold wire, and damage to the IC interface and sealed cured product. Specific problems such as peeling and cracking of the cured sealant have occurred.

One method to deal with these problems is to reduce the stress of the cured sealing resin, but simply reducing the elastic modulus of the cured product will also lower the glass transition point (Tg). Therefore, the coefficient of thermal expansion at high temperatures increases, resulting in stress, and at the same time, the mechanical strength inevitably decreases. These lower elastic modulus (lower stress) and higher Tg
As a method for reconciling the contradictory demands for properties, so-called resin hybridization, in which rubber-like low-modulus fine particles are uniformly dispersed in a matrix of cured epoxy resin, has been proposed and has been widely adopted.

Specifically, this is a method in which an organopolysiloxane oil having a functional group capable of reacting with silicone rubber powder and an epoxy resin is added at the time of kneading the resin and the filler. However, this method has a problem with uniform dispersion of particles from the viewpoint of compatibility, and there is a natural limit to the amount of particles added, and it is difficult to achieve the desired high T.
g and a low elastic modulus cured product has not yet been obtained. In addition, in this case, the so-called domain particle size formed by the organopolysiloxane also becomes very large, and when it is made into a sealed body, separation etc. occur, resulting in various problems as a sealed IC.

As a method to improve these difficulties, a method is proposed in which a block copolymer formed from an aromatic polymer and an organopolysiloxane is added to a system consisting of an ordinary curable epoxy resin and an inorganic filler (Japanese Patent Publication No. 61-48544). (Japanese Patent Application Laid-open No. 58-21417), an alkenyl base is added to an epoxy resin composition containing a conventional curable epoxy resin, a curing agent, and an inorganic filler by an addition reaction between an epoxy resin and an organopolysiloxane. Methods such as a method of blending a copolymer obtained by (JP-A-62-84147) have been proposed.

However, in the case of such a composition, the degree of polymerization of the organopolysiloxane used must be substantially low.

That is, when a high degree of polymerization polysiloxane is used, (1) its compatibility with aromatic polymers or alkenyl group-containing epoxy resins is extremely poor, and a complete block copolymer reaction between the two cannot be expected; Unreacted organopolysiloxane will be mixed in.

Therefore, these compositions cause a bleed phenomenon during roll kneading and molding, resulting in poor roll kneading workability, mold staining during molding, and poor marking on molded products. 2) The polysiloxane-aromatic polymer block copolymer that makes up the composition has poor compatibility with the curable epoxy resin. The amount generated increases. 3) There are problems such as the formed domain grain size is relatively large, reducing the stress reduction effect, and poor adhesion with the resin layer that is the matrix, resulting in a decrease in mechanical strength. ing.

In addition, if a low polymerization degree polysiloxane is used in order to avoid the above-mentioned disadvantages when using a high polymerization degree polysiloxane, l) compatibility is improved and a complete block copolymer can be obtained, but on the contrary, the domains formed are Since it becomes too small, the Tg1 mechanical performance deteriorates. 2) A fatal flaw occurs in achieving the objective, such as a decrease in crack resistance.

(Problems to be Solved by the Invention) The present invention improves the above-mentioned drawbacks of the prior art, has less unreacted siloxane compounds, is excellent in cross-wire workability when used as a molding material, and eliminates the occurrence of flakes and mold stains during molding. Low, high Tg
This invention was made for the purpose of providing a molding material composition for epoxy resin IC encapsulation, which provides a cured sealed IL body with high mechanical strength, low stress, and sealability.

(Means for Solving the Problems) In order to achieve the above object, the present inventors have made intensive studies and found that two or more types of phenolic novolak epoxy resins partially containing an alkenyl group have two or more types with different degrees of polymerization. A resin composition is composed of a block adduct obtained by reacting a mixture of hydrogen-terminated organopolysiloxanes in the presence of a platinum catalyst, a phenolic novolak as a curing agent, a curing accelerator, and an inorganic filler as essential components. The present invention was realized based on the knowledge that the present invention is effective for achieving the objective.

That is, by using polysiloxanes with different degrees of polymerization together, (1) A complete block of low polymerization degree hydrodiene polysiloxane and an epoxy resin containing an alkenyl group is obtained, which acts as a compatibilizer. The reaction between the high polymerization degree hydrogen polysiloxane and the epoxy resin is completed, and unreacted materials are eliminated. The present invention was achieved based on the discovery that the impact resistance effect and stress reduction effect are large.

The details of the present invention will be described below.

The novolak epoxy resin partially containing alkenyl groups used in the present invention is obtained by the reaction of a novolak epoxy resin and allylphenol, and is obtained by the following formula (1
), and tertiary amines, derivatives thereof, cycloamidine derivatives, etc. are used as reaction catalysts.

[However, in the formula, R1 represents a hydrogen atom or an alkyl group, and n and m each represent an integer of 1 or more. ] Note that this reaction is a known reaction, and any method for partially introducing an alkenyl group into an epoxy resin can be used.

Next, the obtained alkenyl group-containing epoxy resin is dissolved in an aromatic solvent such as toluene, benzene, xylene, etc., and an organopolysiloxane having at least two or more hydrogen silyl groups is added and reacted.

At this time, it is important to add organopolysiloxanes of 2PN or more having different degrees of polymerization, preferably hydrogen polysiloxanes at both ends with a degree of polymerization of 20 to 150 and hydrogen polysiloxanes having a degree of polymerization of 150 to 500.
A combination of the two terminals with hydrogen-terminated organopolysiloxane is an effective combination for achieving the objective, and the ratio thereof is appropriately selected.

Further, as a catalyst for this hydrosilylation reaction, a platinum-based catalyst such as platinum chlorate is usually used. After the reaction is completed, the solvent is completely removed and the resin is dried to obtain a solid hydrosilylated epoxy resin.

As the novolac type phenol resin used as a curing agent in the present invention, a novolac type phenol resin obtained by reacting phenol such as phenol or alkylphenol with formaldehyde or paraformaldehyde, and a modified resin such as xylene-modified phenol novolak are used.

Furthermore, as the curing accelerator used in the present invention, all reaction accelerators for epoxy resins and phenol novolacs can be used, such as imidazole or its derivatives, tertiary amine derivatives, phosphine derivatives, cycloamidine derivatives, etc. can be mentioned.

Silica powder is generally used as the inorganic filler used in the present invention, but fillers such as alumina, antimony trioxide, aluminum hydroxide, titanium oxide, and talc can also be used depending on the purpose of use. The amount of inorganic filler blended is 50% to 80% of the entire compound,
If it is less than 50%, the performance will be insufficient when made into a molded product.8
If it is 0% or more, there will be a problem in moldability.

Note that when observing the size of domains formed due to aggregation of polysiloxane units of a block body, which is the gist of the present invention, it is effective to observe a molded body that does not contain a filler.

A general method for obtaining the sealing resin molding material of the present invention is to thoroughly mix the above-mentioned compounded composition using a mixer or the like, then perform a melt-kneading treatment using a heated roll or a niegu, and then cool and solidify. Obtained by grinding.

(Effects of the Invention) The soil composition of the present invention has a block body formed uniformly and completely by combining a low polymer and a high polymer hydrodiene polysiloxane during the hydrosilylation reaction. Since epoxy resin is used, the composition is uniformly kneaded without any phenomenon such as slip during roll kneading.

In addition, for the same reason, there is no unreacted polysiloxane component, so there is no generation of flakes or mold stains during molding.
Furthermore, the printability on the surface of the molded product is also excellent.

Furthermore, the particle size of domains composed of hydrogen polysiloxane units with different degrees of polymerization has a wide distribution, and therefore conflicting properties such as low stress and maintenance of Tg are compatible, and an excellent sealed molded product can be obtained. It was a molding material composition.

(Reference Example) 1.000 parts of an orthocresol novolac epoxy resin having an epoxy equivalent of 200 and a softening point of 65°C was heated at 150°C and stirred in a molten state.

A mixture of 25 parts of orthoallylphenol and 5 parts of 1,8-diazabicyclo(5,4,0)-7-undecene was added dropwise to this over 1 hour, and the reaction was then continued for 2 hours.

The allyl group-containing epoxy resin thus obtained had an epoxy equivalent of 214 and a softening point of 67°C.

(Example) Parts of the allyl group-containing epoxy resin t of the reference example, ooo parts, and 2.000 parts of toluene were heated to 80°C and stirred to form a uniform solution. After adding 6 parts of 1% by weight isopropanol chloroplatinate solution to this, 120 parts of hydrodiene dimethyl polysiloxane (hereinafter referred to as oil A) having an average degree of polymerization of 300 and having hydrogen groups only at both ends was polymerized. A mixture of 180 parts of hydrodiene dimethylpolysiloxane (hereinafter referred to as oil B) having hydrogen groups only at both ends of 40 °C was added dropwise over 1 hour, and then the thread was heated to 100 °C and the reaction was continued for 3 hours. Ta.

After cooling, the toluene is distilled off under reduced pressure to remove 1 epoxy
1278, a block adduct C having a softening point of 71''C was obtained.

Table 1 shows the obtained adduct, a phenol novolak resin with an OH equivalent of 103 as a curing agent, triphenylphosphine, crystalline silica, 3-glycidoxypropyltrimethoxysilane, carnauba wax, and carbon black as a curing accelerator. A molding material was obtained by blending the mixture in the following amounts and kneading it with a heating roll.

Table 2 shows the roll workability during material preparation, the moldability of the obtained molding material in transfer molding, and the properties of the cured product.

Comparative Example 1 A block adduct was obtained in exactly the same manner as in the example except that 300 parts of oil A was used instead of 8180 parts of oil Al2O and oil. This resin had an epoxy equivalent of 278 and a softening point of 09°C.

Table 2 shows the roll workability, moldability, and softened material properties of the materials made from the adducts according to the formulations shown in Table 1.

Comparative Example 2 In the reaction of Example, 120 parts of oil A, 8 parts of oil
Block adduct E was obtained in exactly the same manner as in Example except that 8300 parts of oil was used instead of 180 parts.

This resin had an epoxy equivalent of 278 and a softening point of 70°C.

Table 2 shows the roll workability, moldability, and softened material properties of materials made from Adduct E according to the formulations shown in Table 1.

Comparative Example 3 In the example, epoxy ffi was used instead of adduct C.
Table 2 shows the roll workability, moldability, and properties of the cured product of materials prepared using orthocresol novolak epoxy resin No. 200 and a softening point of 65° C. according to the formulations shown in Table 1.

Table *1 *2 A piezoresistive element was set on an IC frame and transferred molded, and the stress on the element was evaluated by changes in resistance value.

After mounting a 4 x 7.5 mm element on an I6-pin lead frame, the transfer-molded molded body was repeatedly treated in an atmosphere of -196°C and 150°C for 30 seconds each.
The occurrence of cracks on the surface of the molded product after 300 cycles was observed.

Claims (1)

[Claims] (1) A phenol novolac epoxy resin partially containing alkenyl groups, a hydrodiene organopolysiloxane at both ends with a polymerization degree of 20 to 150, and a polymerization degree of 15
The essential components are a block adduct obtained by addition-reacting a mixture of 0 to 500 hydrogen-terminated organopolysiloxanes in the presence of a platinum contact, a phenolic novolak as a curing agent, a curing accelerator, and an inorganic filler. An epoxy resin composition obtained by hot-melting and kneading the composition.