JPH10287792A - Epoxy resin composition for sealing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition which can give a seal having excellent soldering resistance, high reliability, low modulus and high strengths by mixing an epoxy resin with a particulate rubbery polymer having an epoxy equivalent in a specified range in a specified ratio. SOLUTION: This composition contains 0.1-30 wt.% particulate rubbery polymer having an epoxy equivalent of 1,000-40,000. Usually, the rubbery polymer is one having a glass transition temperature of 0 deg.C or below. This polymer is obtained by copolymerizing an epoxy unsaturated polymerizable monomer with a crosslinking monomer having at least two unsaturated polymerizable groups and other monomers selected so as to give a polymer being rubbery at ordinary temperature or by copolymerizing an unsaturated polymerizable monomer having a functional group other than an epoxy group with a crosslinking monomer having at least two unsaturated polymerizable groups and other monomers and introducing epoxy groups into the copolymer by the modification of the functional groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for a sealing material for electronic parts and the like, which has a low modulus of elasticity, a high strength, an excellent solder heat resistance and an excellent thermal shock resistance.

[0002]

2. Description of the Related Art Epoxy resin has heat resistance, mechanical strength,
It has excellent electrical insulation and adhesive properties, and is used as a sealing material for electronic components such as semiconductors. In the manufacture of semiconductors, a resin encapsulation method using an epoxy resin is widely used because it is more economically advantageous than an encapsulation method using ceramics or the like. However, there are problems such as peeling off at the interface between the chip and the sealing resin due to the internal stress generated when the sealing material is cured. In order to alleviate internal stress, attempts have been made to lower the elasticity of the sealing resin, and a certain effect has been achieved by using silicone or the like as a stress reducing material.
In recent years, with the increasing integration of semiconductor devices, the mounting method for printed circuit boards has been shifting from the insertion mounting method to the surface mounting method. It is being used. Since the entire package is heated by the solder reflow method or solder bath immersion that heats the entire package, cracks occur in the conventional resin-based sealing material,
There is a problem of solder heat resistance such as peeling off at the interface between the chip and the sealing resin. Cracking and peeling during the soldering process are caused by the difference in linear expansion coefficient between the chip and the sealing resin, and by the explosion of water vapor in the sealing resin. It became clear that there was no. On the other hand, improvement is also attempted by high filling of an inorganic filler into a sealing resin, blending of a low hygroscopic resin, and the like. For example, a method of using an epoxy resin having a biphenyl skeleton and combining inorganic fillers having different particle sizes (Japanese Patent Application Laid-Open No. 2-99514) has been proposed. Is desired. Also, PGA (Pin Grid Ar)
ray), BGA (Ball Grid Arra)
y), CSP (Chip Scale Package)
New semiconductor mounting methods such as e) are also being studied, and in order to cope with these mounting methods, a sealing material with higher reliability is required.

[0003]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention prevents cracks and peeling during the soldering process, that is, has excellent solder heat resistance and high reliability.
An object of the present invention is to provide an epoxy resin composition for a sealing material having a low elastic modulus and a high strength.

[0004]

Means for Solving the Problems The present inventors have solved the above-mentioned problems by blending a specific epoxy-containing particulate rubber-like polymer, and have found it suitable for sealing electronic parts such as semiconductors. The present inventors have found that an epoxy resin composition can be obtained, and have reached the present invention. That is, the present invention provides (A) an epoxy resin,
(B) A resin composition containing a particulate rubbery polymer having an epoxy equivalent of 1,000 to 40,000, wherein the content of (B) is 0.1 to 30% by weight. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the epoxy resin (A) of the present invention, any epoxy resin that is usually used as a sealing material may be used, for example, diglycidyl ether type epoxy resin, epichlorohydrin and phenol novolak, Novolak type epoxy resins obtained by reaction with cresol novolak, furthermore, glycidyl ester type, glycidylamine type, alicyclic epoxy resin, halogenated epoxy resin and the like can be used. Preferably, a novolak type epoxy resin is used in terms of electrical characteristics, heat resistance and the like. The epoxy resin may be used alone, or a plurality of epoxy resins may be used in combination.

In the present invention, (B) the epoxy equivalent is 10
When the epoxy equivalent is less than 1000, the elasticity of the rubber component is reduced, the modifying effect becomes insufficient, and the epoxy equivalent becomes less than 100 to 40,000 as the particulate rubbery polymer (hereinafter referred to as rubber component (B)). If it is larger than 40,000, the dispersibility with the epoxy resin serving as the matrix becomes insufficient, and the adhesiveness at the interface with the epoxy resin is small, so that the modifying effect is reduced.
Although those having a size of from 00 to 40000 are used, preferably,
Those having an epoxy equivalent of 1200 to 20,000, more preferably 1400 to 15000 are used. The rubber component (B) in the present invention is not particularly limited as long as it is rubbery at normal temperature.
Those having a glass transition temperature (Tg) of 0 ° C. or less are used. Preferably, those having a Tg of -10 ° C or lower, more preferably those having a Tg of -20 ° C or lower are used. In the epoxy resin composition of the present invention, the content of the rubber component (B) is usually used in the range of 0.1 to 30% by weight, and when the content of the rubber component (B) is less than 0.1% by weight, If the modifying effect becomes insufficient, and if it exceeds 30% by weight, the viscosity of the composition becomes too high, and when used as a sealing material, the moldability deteriorates, which is not preferable.

The method for producing the rubber component (B) includes an unsaturated polymerizable monomer having an epoxy group (hereinafter referred to as an epoxy monomer) and a crosslinkable monomer having two or more unsaturated polymerizable groups (hereinafter referred to as a crosslinkable monomer). And a method of copolymerizing one or more other monomers (hereinafter, referred to as other monomers) selected so that the rubber component (B) becomes rubbery at room temperature (hereinafter referred to as Production Method I). After copolymerizing an unsaturated polymerizable monomer having a functional group other than an epoxy group (hereinafter referred to as a functional monomer), a crosslinkable monomer having two or more unsaturated polymerizable groups, and other monomers. And a method of introducing an epoxy group by modifying such a functional group (hereinafter referred to as Production Method II).

When the production method I is adopted as the production method of the rubber component (B), the constitution of each monomer can be exemplified as follows. Examples of the epoxy monomer include glycidyl (meth) acrylate and (meth) allyl glycidyl ether. Examples of the crosslinkable monomer include divinylbenzene, diallyl phthalate, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and pentaerythritol triacrylate. The ratio of the crosslinking monomer constituting the rubber component (B) in the present invention is not particularly limited as long as it is not substantially compatible with the epoxy resin and the epoxy resin curing agent and is dispersed in particles. However, the ratio of the crosslinkable monomer to all the monomers used for copolymerization is usually 1 to 2
0% by weight, preferably 1.5 to 15% by weight, more preferably 2 to 10% by weight. Examples of other monomers include butadiene, isoprene, dimethylbutadiene, chloroprene, 1,3-pentadiene, (meth) acrylonitrile, α-chloroacrylonitrile, α-chloromethylacrylonitrile,
Unsaturated nitrile compounds such as α-methoxyacrylonitrile, α-ethoxyacrylonitrile, nitrile crotonic acid, nitrile cinnamate, dinitrile itaconate, dinitrile maleate, dinitrile fumarate; (meth) acrylamide, N, N′-methylenebis (meta) ) Acrylamide, N, N′-ethylenebis (meth) acrylamide, N, N′-hexamethylenebis (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide, N-bis (2-hydroxyethyl) (meth)
Unsaturated amides such as acrylamide, crotonic amide, cinnamic amide, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,
(Meth) acrylates such as butyl (meth) acrylate, hexyl (meth) acrylate, lauryl (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, styrene, α-methylstyrene, 0 An epoxy (meth) acrylate obtained by reacting an aromatic vinyl compound such as -methoxystyrene, a diglycidyl ether of bisphenol A, a diglycidyl ether of glycol, and the like with (meth) acrylic acid, hydroxyalkyl (meth) acrylate, and the like; Examples thereof include urethane (meth) acrylate obtained by reacting hydroxyalkyl (meth) acrylate with polyisocyanate.

Further, the manufacturing method I will be described in detail. The polymerization method in the production method I is not particularly limited, but may be an emulsion polymerization method. That is, emulsifying the monomer in water using a surfactant,
Using a radical polymerization initiator such as a peroxide catalyst or a redox catalyst as a polymerization initiator, in the presence of a molecular weight regulator such as mercaptan or a halogenated hydrocarbon, 0 to
Emulsion polymerization is performed at 50 ° C., and after reaching a predetermined polymerization addition rate, a reaction terminator such as N, N-diethylhydroxylamine is added to stop the polymerization reaction, and then the unreacted monomer of the polymerization system is subjected to steam distillation. The rubber component can be produced by removing the rubber component with the above method. Further, a latex containing a rubber component obtained by polymerization is coagulated by a method such as salting out, washed with water and dried to obtain a solid rubber component (B).
Can be obtained. As a method of coagulating the rubber component, in addition to the method by salting out, when a surfactant containing at least a nonionic surfactant is used as the surfactant,
The rubber component can be coagulated by heating to a temperature higher than the cloud point of the nonionic surfactant. Further, when the polymerization is carried out using a surfactant other than the nonionic surfactant, the rubber component can be coagulated by adding the nonionic surfactant after the polymerization and heating the mixture to a temperature higher than the cloud point. Also,
By pulverizing the obtained rubber component (B), it can be used as a powder. Alternatively, a latex containing a rubber component obtained by polymerization can be directly used as a powder by a method such as spray drying. When used as a powder, the rubber component (B) is preferably used in the step of dispersing the rubber component (B) in the epoxy resin (A) because it is not only easy to measure and handle, but also has a high dispersion efficiency. The particle size of the rubber component (B) powder to be used is not particularly limited as long as it can be usually handled as a powder, but preferably 0.5 mm or less is 60% by weight or more, more preferably 0.25 mm or less is 60% by weight. Those having the above particle size distribution are used. When the rubber component (B) is used as a powder, it is preferable to add an inorganic powder as a powdering agent at the time of powderization in order to prevent blocking.

The surfactant used when the rubber component (B) is produced by emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants such as alkylnaphthalenesulfonate and alkylbenzenesulfonate. Agents, cationic surfactants such as alkyltrimethylammonium salts and dialkyldimethylammonium salts, nonionics such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and fatty acid monoglycerides Either a system surfactant, an amphoteric surfactant, or a reactive emulsifier, or a mixture of a plurality of surfactants can be used.

When the production method II is adopted as the production method of the rubber component (B), the constitution of each monomer can be exemplified as follows. Examples of the functional monomer include carboxylic acids such as half esters of dicarboxylic acids such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, tetraconic acid, succinic acid, and fumaric acid with unsaturated alcohols having an addition-polymerizable group. Hydroxyl-containing monomers such as group-containing monomers, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxypropyl methacrylate, allyl acrylate, allyl methacrylate, dicyclopentadienyl ethyl acrylate, ethylidene norbornene, acryloyloxyethyl maleate monoester, etc. Unequal diunsaturated monomer, vinyl monochloroacetate,
Examples thereof include halogen-containing monomers such as chloroethyl acrylate and chloroethyl methacrylate. The amount of the functional monomer used is not particularly limited as long as it is used so that the epoxy equivalent of the obtained rubber component (B) is from 1,000 to 40,000. The amount to be used is appropriately determined by calculating the chemical equivalent according to the type of the modifying compound to be used. The ratio of the crosslinking monomer constituting the rubber component (B) precursor may be the same as in the production method for obtaining the rubber component (B) by the production method I, and the ratio is not particularly limited. It is used so that the ratio of the crosslinking monomer to the monomer is in the range of 0.5 to 20% by weight, preferably 1 to 15% by weight, more preferably 2 to 10% by weight.

The method for introducing the epoxy group may be appropriately selected depending on the type of the functional group being copolymerized. For example, when the functional group is a vinyl group, allyl glycidyl ether,
A method in which an unsaturated glycidyl compound such as glycidyl acrylate or glycidyl methacrylate is introduced into an epoxy group by a graft reaction in the presence of a radical initiator. In the case of a carboxyl group, two or more epoxy groups such as a diglycidyl ether compound and a diglycidyl ester compound are used. A method of introducing an epoxy group by reaction with a polyfunctional epoxy compound having the same. In the production of the precursor of the rubber component (B), other monomers used are not particularly limited, but as in Production Method I, butadiene, isoprene, dimethylbutadiene, chloroprene, 1,3-pentadiene , (Meth) acrylonitrile, α-chloroacrylonitrile, α-chloromethylacrylonitrile, α-methoxyacrylonitrile, α-ethoxyacrylonitrile, nitrile crotonic acid, nitrile cinnamate, dinitrile itaconic acid, dinitrile maleate, dinitrile fumarate and the like. Saturated nitrile compounds; (meth) acrylamide, N, N '
-Methylenebis (meth) acrylamide, N, N'-ethylenebis (meth) acrylamide, N, N'-hexamethylenebis (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (meth) acrylamide , N, N-bis (2-
Unsaturated amides such as (hydroxyethyl) (meth) acrylamide, crotonic amide, cinnamic acid amide, methyl (meth) acrylate, ethyl (meth) acrylate,
(Meth) acrylates such as propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, lauryl (meth) acrylate, polyethylene glycol (meth) acrylate, and polypropylene glycol (meth) acrylate , Styrene, α-methylstyrene, aromatic vinyl compounds such as 0-methoxystyrene, diglycidyl ether of bisphenol A, diglycidyl ether of glycol, etc., and (meth) acrylic acid, hydroxyalkyl (meth) acrylate, etc. Examples include epoxy (meth) acrylate and urethane (meth) acrylate obtained by reacting hydroxyalkyl (meth) acrylate with polyisocyanate. As a method for introducing an epoxy group which is essential to the rubber component (B), the rubber component (B) precursor obtained above may be prepared by adding hydrogen peroxide / phase transfer catalyst, hydrogen peroxide / organic acid, or organic peroxide. A method of introducing an epoxy group with an oxide, a Mn (IV) porphyrin complex or the like can also be exemplified.

In the production of the rubber component (B), the production method II
When the rubber component (B) precursor is polymerized, an emulsion polymerization method is preferably used in the same manner as the polymerization method of the rubber component (B) in the production method I. The introduction of the epoxy group into the obtained rubber component (B) precursor may be performed, for example, by introducing the epoxy group by any of the above-described methods in a state where the rubber component (B) precursor is in a latex state. ,
Alternatively, the rubber component (B) precursor may be taken out as a solid, dispersed in an organic solvent, and then an epoxy group may be introduced by any of the methods described above.

In the present invention, the particle size of the rubber component (B) is usually from 20 to 500 nm, preferably from 30 to 200 nm.
nm. In the present invention, as a method of dispersing the rubber component (B) in the epoxy resin (A),
The rubber component (B) is not particularly limited as long as it is a method in which the rubber component (B) is dispersed in the epoxy resin (A) in the form of particles.
When a powdery rubber component (B) is used,
Method: A method using a kneader such as a roll, a kneader, an extruder, or a method using a liquid at room temperature as the epoxy resin (A) and a powdery material as the rubber component (B), in addition to the method, Method: A method using an emulsifying and dispersing machine such as a homomixer, a homomixer, and the like. Further, when an epoxy resin (A) is a liquid at room temperature and the rubber component (B) is used in a latex state, the method is emulsification. The rubber component (B) is converted to an epoxy resin (A) using a disperser.
And then dehydrated.
Further, as a method, a rubber component (B) in a latex state containing a nonionic surfactant is used as a method, mixed with a liquid epoxy resin (A), and then heated using the cloud point of the nonionic surfactant. It can also be produced by co-coagulating the epoxy resin (A) and the rubber component (B) and then dehydrating.

The epoxy resin composition of the present invention is used as a sealing material by mixing with an epoxy resin curing agent and curing. The epoxy resin curing agent is not particularly limited as long as it reacts with the epoxy resin and cures.
It is selected depending on the type of the epoxy resin (A), the method of use and application as a sealing material, and preferably a phenol resin, an acid anhydride, or the like having excellent electrical properties after curing is used. In the present invention, the compounding ratio of the curing agent is determined from the chemical equivalent ratio of the epoxy group / functional group that reacts with the epoxy group, and is usually compounded so that the chemical equivalent ratio is 0.8 to 1.2. Is preferred. In the present invention, a curing accelerator may be used to accelerate the curing reaction between the epoxy resin and the curing agent. Examples of the curing accelerator include organic phosphine compounds such as triphenylphosphine and tri (nonylphenyl) phosphine, imidazole compounds such as 2-methylimidazole and 2-phenylimidazole, benzyldimethylamine, and 1,8-diazabicyclo (5 And tertiary amine compounds such as (4,0) undecene. Further, the epoxy resin composition of the present invention may optionally contain an inorganic filler such as silica, and additives such as a release agent, a flame retardant, a coloring agent, and a coupling agent.

[0016]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. In the description in the examples, "parts" represents parts by weight.

(1) Production of Rubber Component (B)
Emulsion polymerization at a polymerization addition rate of 90%,
The polymerization was terminated by adding 0.2 parts of hydroxylamine sulfate to 0 parts. After removing residual monomers from the obtained latex by steam distillation, a rubber solid content of 1
Per 100 parts, 1.5 parts of an alkylated phenol is added as an antioxidant, coagulated with an aqueous solution of calcium chloride, washed with water, and dried at 90 ° C. for 2 hours with a hot air drier to obtain a solid crumb rubber component (B). I got Polymerization prescription Monomer 100 parts Water 220 parts Sodium dodecylbenzenesulfonate 3 parts Potassium chloride 0.04 parts Sodium ethylenediaminetetraacetate 0.09 parts Hydrosulfite 0.05 parts Tertiary dodecyl mercaptan 0.2 parts Ferrous sulfate 0.016 parts Sodium form art human sulfoxylate 0.05 parts Paramenthane hydroperoxide 0.05 parts The obtained crumb-like rubber component is pulverized by a turbo mill (a pulverizer manufactured by Turbo Kogyo Co., Ltd.) to a thickness of 0.5 mm. (20 mesh) A powdery rubber component (B) having a particle size distribution of 99% by weight or less was obtained. At the time of pulverization, 15 parts of talc were added to prevent blocking.

[0018]

[Table 1] * 1: Measurement by tetraethylammonium bromide-perchloric acid method (unit: g / mol) * 2: Measurement by DSC

(2) Production and Evaluation of Epoxy Resin Composition Examples 1 and 2 The rubber component (B), epoxy resin and other components were kneaded at 100 ° C. by a hot roll in the composition shown in Table 2 and then cooled. The obtained product was pulverized to produce an epoxy resin composition, which was heated and cured at 180 ° C. for 5 minutes using a predetermined mold, and then heated at 180 ° C. for 6 hours to obtain an epoxy resin molded product for evaluation.

[0020]

[Table 2]

In Table 2, the compounding amount of the rubber component (B) includes talc in the powdery rubber component (B) used.
The following method was used as the evaluation method. Flexural strength and elastic modulus: Measured according to JIS K6911 by conducting a three-point bending test under the atmosphere shown in the table. Crack resistance: No. 12S specified in JIS B1251
Using a molded product with embedded washers,
A cooling / heating cycle test was performed with 0 ° C./5 minutes as one cycle, and the number of cycles at which the crack generation rate became 50% was shown. Adhesion: PCT (121 ° C., 96 hours) using a molded product coated with a 42 mm alloy resin layer and a 2 mm thick resin layer
Thereafter, the presence or absence of peeling between the adherend and the resin layer was confirmed, and the number of peelings in five samples was indicated (発 生 / 5). Water absorption: Measured according to JIS K6911. Volume resistivity: Measured according to JIS K6911.

Examples 3 to 6 With the composition shown in Table 2, the rubber component (B) was dispersed in an epoxy resin using an emulsifying and dispersing machine, and then the other components were mixed to produce an epoxy resin composition. Evaluation was performed in the same manner as in Example 1. Table 2 shows the results.

COMPARATIVE EXAMPLES 1 AND 2 [0023] The rubber composition is shown in Table 2 except that no rubber component was used in Comparative Example 1 and that a linear carboxyl-terminated liquid NBR was used as rubber component in Comparative Example 2. Evaluation was made in the same manner as in Examples. Table 2 shows the results. Among the components shown in Table 2, the following epoxy resins I to III and a curing agent were used. Epoxy resin I: Cresol novolak epoxy resin having an epoxy equivalent of 213 and a softening point of 67 ° C. Epoxy resin II: Liquid phenol novolak epoxy resin having an epoxy equivalent of 175 Epoxy resin III: Liquid bisphenol F diglycidyl ether epoxy resin having an epoxy equivalent of 180 Phenol resin: hydroxyl group Phenol novolak resin with an equivalent weight of 108 Acid anhydride: methyltetrahydrophthalic anhydride

[0024]

The sealing epoxy resin composition of the present invention comprises:
Since it is excellent in crack resistance and adhesiveness, it prevents cracking and peeling in the soldering process, that is, it has excellent solder heat resistance, high reliability, low elastic modulus and high strength epoxy resin composition for sealing material And is effectively used as a resin composition for sealing electronic components.

Claims (1)

[Claims] 1. A resin composition comprising (A) an epoxy resin and (B) a particulate rubbery polymer having an epoxy equivalent of 1,000 to 40,000, wherein the content of the (B) particulate rubbery polymer is An epoxy resin composition for a sealing material which is 0.1 to 30% by weight.