JPS636084B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thermosetting epoxy resin composition, and particularly to a thermosetting epoxy resin composition that exhibits excellent physical properties for use in sealing electronic components. For sealing electronic and electrical parts (packaging), epoxy resin,
Silicone resins, polybutadiene, polyurethane, phenolic resins, etc. are used, but of these, epoxy resins are the most widely used in terms of mechanical properties, electrical properties, heat resistance, adhesive properties, and even moldability. Used in large quantities. However, with the recent trend toward thinner layers, miniaturization, and increased integration of electronic components, the properties required of this encapsulant are becoming even more stringent. In addition to further improving the purity of the composition, improvements in electrical properties, shortening of molding cycles to improve productivity, high thermal conductivity for heat dissipation, low stress to reduce physical stress on elements, thermal cycle There is a need to improve impact resistance and crack resistance, but it is extremely difficult to satisfy all of these properties, so we need to improve specific physical properties.
Studies are underway to avoid deteriorating other physical properties as much as possible. In fact, the above-mentioned epoxy resin composition for encapsulating semiconductor devices is made by filling a bisphenol or novolac type epoxy resin with amorphous or crystalline silica powder, and heating it in the presence of a crosslinking agent and a curing agent. It is hardened and contains various flexibilizing agents to improve its crack resistance, but this has the disadvantage of lowering the glass transition point, fire resistance, and heat resistance. If a large amount of crystalline silica is used alone as a filler for the purpose of improving thermal conductivity, the crack resistance will decrease and the stress or expansion coefficient will increase. The present invention relates to a thermosetting epoxy resin composition which solves such disadvantages and has particularly improved crack resistance, and which comprises (a) 100 parts by weight of an epoxy resin containing a phenol novolak resin as a curing agent; (b) Ethylene-propylene copolymer, polybutadiene, styrene-incompatible with component (a) above.
1 to 50 parts by weight of at least one polymer selected from ethyl butylene copolymers, aromatic polyester-ether copolymers, and organosilicon compound adducts thereof; and (c) 50 to 800 parts by weight of fillers. It is characterized by: To explain this, the present inventors conducted various studies on improving the physical properties of epoxy resin compositions for encapsulating electronic components, and as a result, they selected a phenol-curable epoxy resin in particular, and added synthetic rubber or synthetic rubber to this epoxy resin. The present inventors have discovered that dispersing or co-crosslinking an organosilicon compound adduct can provide a product with excellent crack resistance and low stress properties.The present invention was completed after further investigation. Hereinafter, each component constituting the composition of the present invention will be explained in detail. First, component (a) of the composition of the present invention is a curable composition consisting of an epoxy resin having at least two epoxy groups in one molecule and a phenol novolak resin as a curing agent. There are no particular restrictions on its molecular structure or molecular weight as long as it can be cured by the phenol novolac resins described below. Examples of this include epichlorohydrin and bisphenol, epoxy resins synthesized from various novolac resins, alicyclic resins, etc. Examples include formula epoxy resins, and epoxy resins into which halogen atoms such as chlorine and bromine are introduced. In addition, this component (a) may be used in combination with various known monoepoxy compounds as appropriate, and examples of this monoepoxy compound include styrene oxide, cyclohexene oxide, propylene oxide, octyl oxide, dodecene oxide, and methyl glycidyl ether. , ethyl glycidyl ether, phenyl glycidyl ether, allyl glycidyl ether, and the like. Furthermore, this phenol novolak resin is synthesized from a phenol derivative and formaldehyde, and the phenol derivatives used here include mono- or polyhydric phenols such as phenol and resorcinol, or substituted phenols thereof, For example, cresol, xylenol, propylphenol, amylphenol, butylphenol, octylphenol, phenylphenol, allylphenol, etc. are used alone or in combination, and these are ortho and meta to the phenolic hydroxyl group. , a halogen-substituted phenol substituted with a halogen at the para position, and further bisphenol A as a polyhydric phenol. Note that this formaldehyde may be paraformaldehyde or formalin. Next, the organic synthetic rubber as component (b) in the present invention is selected from olefin-based organic synthetic rubber, diene-based organic synthetic rubber, and polyester-based thermoplastic organic synthetic rubber, which are incompatible with component (a). Examples of these include thermoplastic elastomers such as ethylene-propylene copolymers, polybutadiene, and aromatic polyester elastomers (Hytrel manufactured by DuPont, USA, Helplen manufactured by Toyobo); It may also be an adduct of an elementary compound. This organosilicon compound adduct can be easily obtained by subjecting the unsaturated groups in these organic elastomers to an addition reaction with organomonohydrodiene silane or siloxane. These organic elastomers and their organic silicon compound adducts are preferably used after removing impurities by washing with water, hot water, or solvent washing before blending with the component (a) described above. Since the composition of the present invention is used for encapsulating electronic components, it can be washed with water in advance, for example.
It is preferable to remove impurity ions, alkali ions, and halogen ions such as chlorine by a method such as filtration or reprecipitation. These organic elastomers and component (a) may be blended simply by kneading, and according to this method, the organic elastomer
Since it is not compatible with component (a), this compound forms a sea-island structure by mechanical dispersion of these components, but in order to improve this dispersion, it is necessary to add an inorganic filler to this organic elastomer as described below. Combine this with
(a) It is better to knead the ingredients. The viscosity of this organic elastomer does not need to be particularly limited, but
For blending with component (a), it is preferable to have a relatively low viscosity, and this may be in liquid form. If the amount of component (B) added to component (A) is less than 1 part by weight, the effect of reducing stress will not necessarily be sufficient, and if it is added in excess of 50 parts by weight, fluidity will deteriorate and mechanical strength will deteriorate. Therefore, the amount is 1 to 50 parts by weight, preferably 5 to 30 parts by weight, per 100 parts by weight of component (a). In addition, the inorganic filler as component (c) may be one that is known in the art for this type of composition, and inorganic or organic fine powders, fibrous materials, etc. can be used, for example, synthetic or organic fillers. Natural silica powder, fused silica powder, mica, alumina, boxide, titanium oxide, calcium carbonate, antimony trioxide, silicon nitride, silicon carbide, boron nitride, barium sulfate, clay, talc, carbon black, graphite, etc. Examples include inorganic powders, synthetic resin powders, river sand, slate powders, glass fibers, raw wool, synthetic fibers, etc., but these may be used alone or in combination of two or more thereof. However, before use, this filler is preferably dried to a moisture content of 0.3% or less, which also improves its adhesion to the epoxy resin, which is the main component of the composition of the present invention. It may be used in combination with a silane coupling agent or other processing aids to achieve this. Although the amount of this filler varies depending on its type and viscosity, it is generally 50 to 800 parts by weight per 100 parts by weight of component (a) above.
Preferably, the amount may be 50 to 600 parts by weight. The composition of the present invention can be obtained by uniformly kneading the above-mentioned components (a), (b), and (c) using a mixing device such as a Henschel mixer, roll, kneader, or extruder. However, in order to accelerate the reaction between the above-mentioned epoxy resin and phenolic resin, various curing accelerators such as imidazole or its derivatives, tertiary amine derivatives,
Phosphine derivatives, cycloamidine derivatives, etc. may be added, and further processing aids such as various colorants, flame retardants, antioxidants, stabilizers, mold release agents, lubricants, etc. may be added as necessary. good. There are no particular restrictions on the mixing order of these components, but (b)
In order to improve the dispersion of the component polymer into the epoxy resin component (a), component (b) and filler as component (c) are kneaded in advance to form a compound. b) Mixing with the ingredients or
It is desirable to adopt a method in which component (b) is diluted with a solvent and mixed with component (a) in the form of a solution, and then the solvent is removed. Next, examples of the present invention will be given, and various physical properties in the examples are the results obtained by the following measuring methods. (1) Mechanical strength (bending strength) According to JIS K6911, a 10 x 4 x 100 mm bar was transfer-molded at 160℃, 70Kg/cm ² and 3 minutes for forming time, and after 4 hours at 180℃. Measured on vulcanized material (2) Expansion coefficient Using the above test piece for measuring mechanical strength
Measured according to ASTM D696 (3) Resin stress Piezoresistance whose resistance value changes due to stress 3
Molded into a mm square semiconductor chip, this is 14PINIC
The initial resistance value (R ₀ ) of the element was die-bonded to the frame and connected to the external electrode by wire-bonding with gold wire.
Kg/cm ² and molding time of 3 minutes, the resistance value (R) was measured after resin sealing using an epoxy resin composition, and from this measured value (R-
R ₀ )/R ₀ was calculated and used as the resin stress. (4) Glass transition point 5mm from the above-mentioned test piece for measuring mechanical strength
A square prism with a length of 20 mm was cut out, and when the temperature was raised at a rate of 5°C per minute using a deft meter, the bending point of linear expansion was taken as the glass transition point. (5) Cracking resistance A semiconductor silicon wafer with a thickness of 0.35 mm is
Cut into 45mm rectangles and use 14PINIC frames (42
The epoxy resin composition was transfer-molded at 160°C for 2 minutes, and then vulcanized at 180°C for 4 hours.
When a heating/cooling cycle of -55°C/30 minutes to 150°C/30 minutes was repeated, the number of cycles until the crack occurrence rate reached 50% was expressed. Example 1 Cresol novolac epoxy resin EOCN102 (Nippon Kayaku Co., Ltd., trade name) with an epoxy equivalent of 220, phenol novolac epoxy resin with a phenol equivalent of 110, organic synthetic rubber, crystalline quartz powder, 3-
glycidoxypropyltrimethoxysilane
KBM403 [Shin-Etsu Chemical Co., Ltd., trade name], carnauba wax, carbon black, 2 as a curing accelerator
- Phenylimidazole and Kyuazol 2PZ [Shikoku Kasei Co., Ltd., trade name] are blended in the amounts shown in Table 1,
Samples A to D were prepared by kneading with two hot rolls, and the physical properties of these samples were measured, and the results shown in Table 2 were obtained.

[Table] *3...Styrene-ethylbutylene copolymer manufactured by Aron Kasei Co., Ltd.

[Table] Example 2 Phenol novolac epoxy resin
EPPN201 [manufactured by Toto Kasei Co., Ltd., trade name], brominated bisphenol A glycidyl ether YDB340 [manufactured by the same company, trade name], phenol novolak resin, ethylene-propylene copolymer EP33 (mentioned above), or both ends epoxidized Organic synthetic rubber made by adding pentamethyl monohydrodiene disiloxane to polybutadiene R-45EPT [manufactured by Idemitsu Petrochemical Co., Ltd., trade name], crystalline silica powder, antimony trioxide,
KBM403 (mentioned above), carnauba wax, carbon black, and 2-phenylimidazole were blended in the amounts shown in Table 3 and kneaded using two heated rolls to prepare samples E and F. As a result of the measurement, the results shown in Table 4 were obtained.

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Claims (1)

[Scope of Claims] 1 (a) 100 parts by weight of an epoxy resin containing a phenol novolak resin as a curing agent (b) Elethene-propylene copolymer, polybutadiene, styrene-ethyl which is incompatible with the above component (a) At least one polymer selected from butylene copolymers or aromatic polyester-ether copolymers and organosilicon compound adducts thereof (c) 1 to 50 parts by weight (iii) Filler 50 to 800 parts by weight. Curable epoxy resin composition.