JPS6358860B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing an epoxy resin composition for semiconductor encapsulation that has excellent crack resistance and moisture resistance and is more stable. [Prior art] Currently, resin encapsulation methods are widely used to encapsulate semiconductor devices such as ICs and LSIs using silicone resin or epoxy resin. Of these, epoxy resin has relatively excellent airtightness. It is widely used as a resin for semiconductor encapsulation because of its high yield and low cost. However, when a large-capacity semiconductor element is sealed with this epoxy resin, the bonding wires of the element may be deformed or disconnected due to stress caused by shrinkage during curing or stress caused by the difference in expansion coefficient between the internal element and the epoxy resin. or cause a crack in device passivation. Therefore, in order to reduce these stresses, methods such as adding a flexibility imparting agent to the epoxy matrix or increasing the amount of inorganic filler added to reduce the expansion coefficient are being considered. However, when adding a flexibility-imparting agent, the interface between the flexibility-imparting agent dispersed in the epoxy resin and the epoxy resin deteriorates under high temperature and high humidity, resulting in a decrease in moisture resistance and resulting in unfavorable results. There are drawbacks. On the other hand, in order to increase the amount of inorganic filler added and reduce the expansion coefficient, it is necessary to add an amount of 70 wt% or more, but in this case, the melt viscosity of the resin composition increases and the fluidity decreases significantly, causing the When sealing the
Furthermore, high pressure molding is required. Moreover, the increase in melt viscosity causes wire flow and wire breakage during molding, resulting in undesirable conditions. In order to solve the above-mentioned drawbacks, we proposed the prior art (filed by the same applicant, patent application 1983-
When adding a silicone resin known as a flexibilizing agent to an epoxy matrix (see epoxy resin composition for semiconductor encapsulation in specification No. 192059), a mixture of silicone resin and powdered silica in advance is added to the epoxy matrix. It has been found that a stable dispersion state that does not cause phase separation can be obtained by mixing the two. [Problems to be Solved by the Invention] As described above, the epoxy resin composition for semiconductor encapsulation obtained by our prior art exhibits excellent crack resistance and moisture resistance, but the composition also has excellent crack resistance and moisture resistance. Stabilization and lower stress are desired. The present invention was made in response to such a demand, and an object of the present invention is to obtain a method for producing an epoxy resin composition for semiconductor encapsulation that exhibits excellent crack resistance and moisture resistance, and is more stabilized and has lower stress. With the goal. [Means for Solving the Problems] The method for producing the epoxy resin composition for semiconductor encapsulation of the present invention is based on the general formula (In the formula, R ₁ and R ₂ are vinyl group, methyl group,
A type of phenyl group, hydroxyl group and hydrogen, R ₃
and R ₄ is one of a methyl group, a phenyl group, and hydrogen, and n is an integer of 100 to 1000. ) and 2 to 80 parts by weight of powdered silica are mixed to obtain a silicone resin mixture, and then 1 to 25 parts by weight of the above silicone resin mixture and 100 parts by weight of an inorganic filler are mixed. After mixing, an epoxy resin, a curing agent for the epoxy resin, a curing accelerator, and a surface treatment agent are mixed to obtain an epoxy resin composition for semiconductor encapsulation. [Function] Silicone resin, which is generally known as a flexibilizing agent, is incompatible with epoxy resin, but by mixing silicone resin and powdered silica in advance, the powdered silica can absorb hydrogen from the silicone resin. It exists in the network created by the bond and becomes a grease-like and stable state. Next, by mixing the pre-mixed silicone resin mixture with an inorganic filler, the silicone resin is more uniformly mixed into the epoxy resin composition for semiconductor encapsulation through physical adsorption to the surface of the inorganic filler. This makes it possible to further stabilize these compositions. Furthermore, by using a mixture of the above-mentioned silicone resin mixture and an inorganic filler, it is believed that the silicone resin mixture has the effect of reducing the internal stress that occurs at the interface of the inorganic filler, and a low stress composition can be achieved. Ru. Furthermore, it is believed that lower stress and higher moisture resistance in the epoxy resin composition for semiconductor encapsulation can be achieved by the silicone resin slightly oozing out at the element interface and covering the entire element. [Example] General formula related to this invention In the formula, R ₁ and R ₂ are one type of vinyl group, methyl group, phenyl group, hydroxyl group, and hydrogen, R ₃ and R ₄ are one type of methyl group, phenyl group, and hydrogen, and n is 100 to 1000. is an integer. The liquid silicone resins shown are used alone or in combination of two or more. The powdered silica according to this invention has an average diameter of 5 to
A material having a diameter of 50 μm is preferably used, and is uniformly mixed in a range of 2 to 30 parts by weight with respect to 100 parts by weight of the liquid silicone resin. If it is less than 2 parts by weight, the silicone resin mixture lacks stability when mixed with other compositions and phase separation occurs, which is not preferable. If the amount exceeds 30 parts by weight, the viscosity of the epoxy resin for semiconductor encapsulation obtained by mixing it with other compositions will increase, resulting in an unfavorable condition during molding, and the silicone resin will not ooze out during curing, making it difficult to resist various stresses. It becomes impossible to remove it. The inorganic filler used in this invention is, for example, fused silica, crystalline silica, alumina, etc., and a pre-mixed silicone resin mixture is uniformly added in a range of 1 to 25 parts by weight per 100 parts by weight of the inorganic filler. Mix with If it is less than 1 part by weight, various stresses cannot be removed, and if it is more than 25 parts by weight, the inorganic filler will aggregate, which is not preferable. Further, as the inorganic filler, a flame retardant aid such as antimony trioxide may be used in combination, if necessary. Epoxy resins according to this invention include those having two or more epoxy groups in the molecule, such as phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol A epoxy resins, and alicyclic epoxy resins. At least one of these is used. In addition to these epoxy resins, brominated novolak epoxy resins, brominated bisphenol A epoxy resins, and the like may be used in combination, if necessary. Further, it is preferable to blend the silicone resin mixture in an amount of 2 to 30 parts by weight per 100 parts by weight of the epoxy resin. If it is less than 2 parts by weight, there is no effect of reducing stress, and if it is more than 30 parts by weight, there will be a lot of oozing, which will stain the mold and spoil the appearance of the sealed product. Examples of the curing agent according to the present invention include phenolic compounds such as phenol novolak, acid anhydride compounds such as methylhexahydrophthalic anhydride, and methyltetrahydrophthalic anhydride;
Also, amine compounds are used. Examples of the coupling agent as a surface treatment agent according to the present invention include silane compounds such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and phenyltrimethoxysilane. is preferably used. Examples of the curing accelerator used in this invention include imidazole compounds and tertiary amines. Furthermore, the epoxy resin composition for semiconductor encapsulation of the present invention may contain a coloring agent such as carbon black, and a mold release agent such as carnauba wax or synthetic wax, if necessary. The epoxy resin composition for semiconductor encapsulation of the embodiments of the present invention can be prepared using known mixing equipment used for preparing conventional semiconductor encapsulation materials, such as rolls, kneaders, Raikai machines, and Henschel mixers. It can be easily adjusted by using Hereinafter, the present invention will be explained in more detail by referring to intermediate products and semiconductor encapsulating epoxy resins according to Examples and Comparative Examples of the present invention, but the present invention is not limited thereto. Table 1 shows the composition of the silicone resin mixture used in Examples and Comparative Examples. The silicone resin and powdered silica were mixed by a conventional method using a roll. In addition, polydimethylsiloxane oil (60 poise/25℃) corresponds to N=400, polydimethylsiloxane oil (500 poise/25℃) corresponds to n=650, and polydimethylsiloxane (terminal hydroxyl group) ) is Shin-Etsu Chemical's KE108 (trade name), and n=100 to 1000. Also, polysiloxane (vinyl terminal group) is manufactured by Shin-Etsu Chemical.
KE106 (product name) is distributed between n=100 and 1000. From these, n in the general formula preferably ranges from 100 to 1000.

[Table] Table 2 shows the blending ratio and composition of the silicone resin mixture and inorganic filler used in Examples and Comparative Examples. The silicone resin mixture and the inorganic filler were mixed using a Henschel mixer (manufactured by Mitsui Miike Co., Ltd., for example).

[Table] The storage stability of the mixture of silicone resin mixture and inorganic filler shown in Table 2 was examined visually for the presence or absence of phase separation after being left at room temperature for one week. The results are shown in Table 3.

[Table] Based on the results in Table 3, an epoxy resin composition for semiconductor encapsulation was prepared in a conventional manner by removing phase-separated K and L from the mixture of silicone resin mixture and inorganic filler, and the results are shown in Table 4. Their resin compositions are shown below. According to this, in Comparative Example 21, the cohesive force of the inorganic filler was strong and uniform dispersion could not be performed, making it impossible to prepare a sample for evaluation. In addition, Comparative Example 23 has dirt on the mold,
This resulted in unfavorable results such as staining of the exterior of the device encapsulation. In addition, silicon elements for moisture resistance evaluation and samples for general characteristic measurement were prepared using the resin compositions shown in Table 4.
Mold at 170℃ for 3 minutes, and
After curing at 170° C. for 8 hours, samples for moisture resistance tests and samples for measuring general characteristics were obtained.

【table】

〔Effect of the invention〕

As explained above, the present invention is based on the general formula

【table】

【table】

[Table] (In the formula, R ₁ and R ₂ are vinyl group, methyl group,
A type of phenyl group, hydroxyl group and hydrogen, R ₃
and R ₄ is one of a methyl group, a phenyl group, and hydrogen, and n is an integer of 100 to 1000. ) and 2 to 30 parts by weight of powdered silica are mixed to obtain a silicone resin mixture, and then 1 to 25 parts by weight of the above silicone resin mixture and 100 parts by weight of an inorganic filler are mixed. By mixing epoxy resin, epoxy resin curing agent, curing accelerator, and surface treatment agent after mixing, it is possible to create a semiconductor that exhibits excellent crack resistance and moisture resistance, and is more stable and has lower stress. A method for producing an epoxy resin composition can be obtained.

Claims (1)

[Claims] 1. General formula (In the formula, R ₁ and R ₂ are vinyl group, methyl group,
A type of phenyl group, hydroxyl group and hydrogen, R ₃
and R ₄ is one of a methyl group, a phenyl group, and hydrogen, and n is an integer of 100 to 1000. ) and 2 to 30 parts by weight of powdered silica are mixed to obtain a silicone resin mixture, and then 1 to 25 parts by weight of the above silicone resin mixture and 100 parts by weight of an inorganic filler are mixed. A method for producing an epoxy resin composition for semiconductor encapsulation, which comprises mixing an epoxy resin, a curing agent for the epoxy resin, a curing accelerator, and a surface treatment agent after mixing.