JP2714451B2 - Epoxy resin composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent solder heat resistance, thermal shock resistance and moldability.

(Prior Art) In recent years, semiconductor-related technology has progressed in a direction of improving a packaging density due to a tendency to be light, thin and short.

For this reason, the degree of memory integration has been improved, and the mounting method has been shifting from through-hole mounting to surface mounting.

Therefore, the package is a small, thin flat package surface-mounted from the conventional DIP type, such as SOP, S
It has been replaced by OJ and PLCC, and has problems such as crack generation due to internal stress and deterioration of moisture resistance due to these cracks.

In particular, when the leads are soldered in the surface mounting process, the package undergoes a rapid change in temperature, and as a result, the problem of cracks in the package has been greatly highlighted.

In order to solve these problems, a thermoplastic oligomer was added for the purpose of reducing thermal shock during soldering (Japanese Patent Laid-Open No. Sho 62-62).
No. 115849) and the addition of various silicone compounds (Japanese Unexamined Patent Publication
62-115850, JP-A-62-116654, JP-A-62
-128162), and further modified with silicone (Japanese Patent Laid-Open No. 62-62).
However, in any case, cracks are generated in the package at the time of soldering, and it has not been possible to obtain a highly reliable epoxy resin composition for semiconductor encapsulation.

On the other hand, in order to obtain a heat-resistant epoxy resin composition having excellent solder heat resistance, use of a polyfunctional epoxy resin as a resin system (Japanese Patent Laid-Open No. 61-168620) has been studied.
The use of a polyfunctional epoxy resin increases the crosslink density and improves heat resistance, but especially when exposed to high temperatures such as 200 to 300 ° C, the solder heat resistance is insufficient, and it becomes hard and brittle, so it is heat resistant. The impact properties were extremely unsatisfactory.

In order to solve these problems, the present inventors have already proposed an epoxy resin product containing a random copolymerized silicone-modified polyfunctional epoxy resin,
As a result, it has been found that the solder heat resistance and the thermal shock resistance can be significantly improved.

However, thinner packages and larger chips are being developed at a high tempo, and the required properties for epoxy resin compositions for semiconductor encapsulation are becoming increasingly severe. In addition, resin compositions that are excellent in solder heat resistance and thermal shock resistance Things are required.

(Problems to be Solved by the Invention) The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor encapsulation having good solder heat resistance, heat shock resistance, and moldability. An object of the present invention is to provide an epoxy resin composition.

(Means for Solving the Problems) The present inventors have conducted intensive studies in order to obtain a well-balanced and excellent epoxy resin composition for semiconductor encapsulation that could not be overcome by the prior art. The following formula (I) having good heat resistance and an effect of improving solder heat resistance
Polyfunctional phenolic resin with the structure shown by The following formulas (II) and / or (III) having the effect of imparting remarkable toughness and low elasticity without impairing moldability.
By reacting with an organopolysiloxane of a specific structure represented by A resin composition consisting of a curing agent and an inorganic filler obtained by blending a random copolymerized silicone-modified polyfunctional phenolic resin in an amount of 50 to 100% by weight based on the total phenolic resin is molded into a thin and large chip package. It was found that all of the properties, solder heat resistance and thermal shock resistance were significantly improved, and the present invention was completed.

(Function) The epoxy resin used in the present invention may be any resin as long as it has two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin,
Examples include bisphenol F type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, alicyclic epoxy resin and modified resins thereof, and these epoxy resins may be used alone or in combination of two or more. I can do it.

Among these epoxy resins, the epoxy equivalent is 150 to 2
50, those having a softening point of 60 to 130 ° C. and containing as little ionic impurities as possible such as Na ⁺ and Cl ⁻ are preferable.

The random copolymer silicone-modified polyfunctional phenol resin curing agent used in the present invention is a very important component having an effect of improving both the solder heat resistance and the thermal shock resistance.

The polyfunctional phenol resin having the structure represented by the formula (I) used as a raw material of these random copolymer silicone-modified polyfunctional phenol resin curing agents is a polyfunctional phenol resin having three or more hydroxyl groups in one molecule.

R _{1 to} R ₅ are preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. If the number of carbon atoms exceeds 4, the reactivity with the epoxy resin tends to decrease, and the curability tends to decrease.

The value of n must be in the range of 0 to 10.
When the value of n is larger than 10, the fluidity is reduced and the moldability is deteriorated.

In addition, a bifunctional or less epoxy resin does not increase the crosslink density, is inferior in heat resistance, and cannot obtain the effect of solder stress resistance.

The organopolysiloxane used as the other raw material has a structure represented by the formulas (II) and (III), (R ₆ : phenyl group or ethylphenyl group, R ₇ : methyl group, phenyl group or ethylphenyl group 10 ≦ (k + 1 + m + 2) ≦ 200 and 0 ≦ l / (k + 1 + m + 2) ≦ 0.1, 5 ≦ (k + 1 + m + 2) / m ≦ 50 R ₈ : phenyl or ethylphenyl group, R ₉ : methyl, phenyl or ethylphenyl group 10 ≦ (o + p + q + 2) ≦ 200, 0 ≦ p / (o + p + q + 2) ≦ 0.1, 5 ≦ (o + p + q + 2) / q ≦ 50) Has the effect of improving solder heat resistance and thermal shock resistance without impairing moldability. And a siloxane polymerization degree (k + l + m + 2 and o + p + q +) having a specific ratio of an epoxy group-containing organic group capable of reacting with a phenolic hydroxyl group.
2) is in the range of 10 to 200, and the structure of the organopolysiloxane may be linear or branched.

Also, the molar fraction of the phenyl group or ethylphenyl group modified part [l / (k + 1 + m + 2) and p / (o + p + q +
2)] is 0.1 or less, siloxane polymerization degree / functional group number [(k
+ L + m + 2) / m and (o + p + q + 2) / p] must be 5 or more and 50 or less.

Siloxane polymerization degree (k + l + m + 2 and o + p + q
If the value of (+2) is less than 10, the molecular weight of the silicone reaction part becomes too small, and the Usbari characteristics of the composition deteriorate.
If it exceeds 200, the compatibility with the other components of the composition is reduced, so that the viscosity of the composition is increased, the deformation of the gold wire is easily caused, the printing property is reduced, and the mold stain is easily generated. It is necessary to use those having a siloxane polymerization degree of 10 or more and 200 or less.

Molar fraction of phenyl group or ethylphenyl group modified part [l / (k + 1 + m + 2) and p / (o + p + q + 2)]
Is 0.1 or less, preferably around 0.05, when the silicone-modified polyfunctional phenolic resin curing agent is synthesized, the organopolysiloxane has appropriate compatibility with the polyfunctional phenolic resin curing agent or an organic solvent, and In a composition using a silicone-modified polyfunctional phenolic resin curing agent, the silicone-modified polyfunctional phenolic resin curing agent is suitably used because it has appropriate compatibility with other components.

The molar fraction of the phenyl group or ethylphenyl group modified part is
If it exceeds 0.1, in the composition using the silicone-modified polyfunctional phenolic resin curing agent, the compatibility between the silicone-modified polyfunctional phenolic resin curing agent and many components becomes too good, and the glass transition point and solder heat resistance decrease. .

Degree of siloxane polymerization / number of functional groups [(k + 1 + m + 2) / m
And (o + p + q + 2) / p] are extremely important parameters, and the degree of siloxane polymerization / the number of functional groups is 5 or more, 50
The following can improve strength, thermal shock resistance, and solder heat resistance without impairing moldability.

When this parameter is less than 5, in the composition using the silicone-modified polyfunctional phenol resin curing agent, the compatibility with other components becomes too good, the glass transition point and the solder heat resistance decrease, and the silicone reaction part is deteriorated. Has an excessively large molecular weight, and the viscosity of the composition increases, so that the gold wire modification is likely to occur. On the other hand, if it exceeds 50, the resin becomes opaque, and the phase separation of the silicone reaction portion is easily caused, and the strength, fluidity, and printing property are reduced, and the mold is easily stained. These organopolysiloxanes having an epoxy group-containing organic group can be prepared by subjecting an organohydrogenpolysiloxane and an unsaturated double bond-containing epoxy such as allyl glycidyl ether to an addition reaction in an organic solvent using chloroplatinic acid as a catalyst. can get.

In addition, the random copolymerized silicone-modified polyfunctional phenol resin is one or more selected from imidazoles, organic phosphines, and tertiary amines in an organic solvent containing an epoxy group-containing organopolysiloxane and a polyfunctional phenol resin. And a method of causing a ring-opening addition reaction using the above catalyst.

A conventional phenolic resin may be mixed with the obtained random copolymerized silicone-modified polyfunctional phenolic resin to use as a curing agent for the epoxy resin. It is necessary to mix 50% by weight or more based on the amount of resin.

If the compounding amount is less than 50% by weight, both the solder heat resistance and the thermal shock resistance decrease and are insufficient.

The conventional phenol resin referred to here includes phenol novolak, cresol novolak, and modified resins thereof, and these can be used alone or in combination of two or more. The phenolic resin used has a hydroxyl equivalent of 80 to 150, a softening point of 60 to 120 ° C, and Na
It is preferable that ionic impurities such as ⁺ and Cl ⁻ are as small as possible.

Crystalline silica as the inorganic filler used in the present invention,
Examples thereof include fused silica, alumina, calcium carbonate, talc, mica, and glass fiber.

These are used alone or in combination of two or more. Of these, crystalline silica or fused silica is particularly preferably used.

In addition, a curing accelerator or the like is used as necessary as a component other than these, and any curing accelerator may be used as long as it promotes a reaction between an epoxy group and a phenolic hydroxyl group, and is generally used for a sealing material. For example, tertiary amines such as BDMA, imidazoles, and 1,8-diazabicyclo [5,4,0] undecene-7 can be used.
Organic phosphorus compounds such as (DBU) and triphenylphosphine (TPP) may be used alone or in combination of two or more. Further, if necessary, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, a coloring agent such as carbon black and red iron, a release agent such as a natural wax and a synthetic wax, etc. Various additives such as low-stress additives such as silicone oil and rubber may be appropriately blended.

To produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, an inorganic filler, a curing accelerator, and other additives are sufficiently uniformly mixed by a mixer or the like, and then further mixed. It can be obtained by melt-kneading with a hot roll or a kneader, cooling, and pulverizing after cooling. These molding materials can be used for sealing, covering, insulating and the like of electronic parts or electric parts.

(Example) Next, an example is described together with a comparative example.

First, 20 parts by weight of an organopolysiloxane and 100 parts by weight of a polyfunctional phenol resin are reacted in 200 parts by weight of a butanol solvent in the presence of a catalyst to obtain a silicone-modified polyfunctional phenol resin (I to H) shown in Table 1. Was.

Example 1 The following composition: Cresol novolak type epoxy resin (Epoxy equivalent: 200, softening point: 65 ° C) 90 parts by weight Brominated phenol novolak type epoxy resin (Epoxy equivalent: 272, softening point: 75 ° C, bromine content: 32%) 10 parts by weight Silicone-modified polyfunctional phenol novolak resin Curing agent (a) 60 parts by weight Fused silica 450 parts by weight Antimony trioxide 25 parts by weight Silane coupling agent 2 parts by weight Triphenylphosphine 2 parts by weight Carbon black 3 parts by weight Carnauba wax 3 parts by weight The mixture was sufficiently mixed at room temperature, then kneaded at 95 to 100 ° C. with a biaxial roll, cooled and pulverized into tablets to obtain the epoxy resin composition for semiconductor encapsulation of the present invention.

This material is molded using a transfer molding machine (molding conditions: mold temperature: 175 ° C., curing time: 2 minutes).
After curing at 175 ° C. for 8 hours, the printability, thermal shock resistance, solder moisture resistance and solder heat resistance were evaluated. Table 2 shows the results.

Examples 2 to 3 Compounded according to Table 2 and obtained an epoxy resin composition for semiconductor encapsulation in the same manner as in Example 1. Table 2 also shows the evaluation results of the epoxy resin composition for semiconductor encapsulation.

Comparative Examples 1 to 7 The components were blended according to Table 2, and an epoxy resin composition for encapsulating a semiconductor was obtained in the same manner as in Example 1. Table 2 also shows the evaluation results of the epoxy resin composition for semiconductor encapsulation.

(Effect of the Invention) According to the present invention, it is possible to obtain an epoxy resin composition having high heat resistance, thermal shock resistance and molding processability, which could not be obtained by the prior art, so that the rapid temperature caused by the soldering step Excellent in crack resistance and thermal shock resistance when subjected to thermal stress due to change, so when used for sealing, covering, insulating, etc. of electronic parts and electric parts, especially mounted on surface mount package It is suitable for applications requiring a high degree of reliability, such as thin and highly integrated large chip ICs.

Claims (3)

(57) [Claims] 1. A random copolymer obtained by reacting (A) an epoxy resin (B) with a polyfunctional phenol resin having a structure represented by the following formula (I) and an organopolysiloxane having a structure represented by the following formula (II): 50% of silicone-modified polyfunctional phenol resin to total phenol resin
Epoxy resin curing agent containing up to 100% by weight (N is an integer of 0 to 10, and R _{1 to} R ₅ are hydrogen, halogen,
Atom or group selected from alkyl groups) (R ₆ : phenyl group or ethylphenyl group, R ₇ : methyl group, phenyl group or ethylphenyl group 10 ≦ (k + 1 + m + 2) ≦ 200, and 0 ≦ l / (k + 1 + m + 2) ≦ 0.1, 5 ≦ (k + 1 + m + 2) / m ≦ 50) (C) A resin composition for semiconductor encapsulation containing an inorganic filler as an essential component. 2. A random copolymer obtained by reacting (A) an epoxy resin (B) with a polyfunctional phenol resin having a structure represented by the following formula (I) and an organopolysiloxane having a structure represented by the following formula (III): Silicone-modified polyfunctional phenol resin to total phenol resin amount
Epoxy resin curing agent containing 50-100% by weight (N is an integer of 0 to 10, and R _{1 to} R ₅ are hydrogen, halogen,
Atom or group selected from alkyl groups) (R ₈ : phenyl group or ethylphenyl group, R ₉ : methyl group, phenyl group or ethylphenyl group 10 ≦ (o + p + q + 2) ≦ 200, and 0 ≦ p / (o + p + q + 2) ≦ 0.1, 5 ≦ (o + p + q + 2) / q ≦ 50) (C) A resin composition for semiconductor encapsulation containing an inorganic filler as an essential component. 3. An epoxy resin (B) by reacting a polyfunctional phenol resin having a structure represented by the following formula (I) with an organopolysiloxane having a structure represented by the following formulas (II) and (III): Resin curing agent containing 50-100% by weight of random copolymerized silicone-modified polyfunctional phenolic resin based on the total amount of phenolic resin (N is an integer of 0 to 10, and R _{1 to} R ₅ are hydrogen, halogen,
Atom or group selected from alkyl groups) (R ₆ : phenyl group or ethylphenyl group, R ₇ : methyl group, phenyl group or ethylphenyl group 10 ≦ (k + 1 + m + 2) ≦ 200 and 0 ≦ l / (k + 1 + m + 2) ≦ 0.1, 5 ≦ (k + 1 + m + 2) / m ≦ 50 R ₈ : phenyl or ethylphenyl group, R ₉ : methyl, phenyl or ethylphenyl group 10 ≦ (o + p + q + 2) ≦ 200, and 0 ≦ p / (o + p + q + 2) ≦ 0.1, 5 ≦ (o + p + q + 2) / q ≦ 50) (C) A resin composition for semiconductor encapsulation containing an inorganic filler as an essential component.