JPH0710939B2 - Resin composition for electronic component encapsulation - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin composition for encapsulating electronic parts, which is excellent in heat conductor and metal abrasion resistance.

"Conventional technology" In recent years, resin encapsulation of electronic parts such as semiconductors, resistors, capacitors, and coils using thermosetting molding materials has become popular, but there are demands for the reliability of various electronic parts. The property is increasing more and more, and accordingly, the improvement in properties of the encapsulant is strongly desired. One of them is the integration of semiconductors, and the amount of heat generated is also increasing, and the heat dissipation of resin-sealed electronic components has become a major issue.
In order to satisfy this, use of a sealing material having high thermal conductivity is desired.

Most conventional sealing agents use epoxy resin as a thermosetting resin from the viewpoint of economy, heat resistance, moisture resistance and adhesion, and improve thermal conductivity and mechanical strength as an inorganic filler. Therefore, silica powder is added. Most of silica powder is made of crystalline silica or fused silica.

However, the resin encapsulation materials using these silica powders are not yet sufficient in thermal conductivity for encapsulating highly integrated electronic components that generate a large amount of heat, and silica powders have high hardness, so The resin encapsulating material used is not yet satisfactory for long-term use due to abrasion of a molding machine or a mold during transfer molding or injection molding, and a further excellent resin encapsulating material is desired.

"Problems to be solved by the invention" Therefore, as a result of intensive studies from the above viewpoint, when single crystal magnesium oxide powder was used as the inorganic filler, good results were obtained in thermal conductivity and metal wear resistance. And has completed the invention.

"Means for Solving Problems" That is, the present invention relates to a resin composition for electronic component encapsulation, which is obtained by mixing single crystal magnesium oxide with an epoxy resin.

The present invention is described in detail above.

Magnesium oxide used in the present invention is ultra-high purity single crystal magnesium oxide obtained by the method described below.

Usually, magnesium oxide is produced by thermal decomposition of magnesium hydroxide, acetate, basic carbonate, oxalate or the like. However, it is known that the magnesium oxide synthesized by these salt decompositions has a strong secondary aggregation property and a large secondary particle size. Therefore, when it is kneaded with a resin, the dispersibility is not sufficient, the thermal conductivity is as high as expected, and the purity is low. In addition, there are similar defects in polycrystals.

The high-purity single-crystal magnesium oxide powder used in the present invention has the following features: (a) average particle size is in the range of 0.01 to 20 μm, (b) purity is 99.9% or more, (c) The content of chlorine ion and bromine ion is 5p
pm or less and also contains a very small amount of other impurities. (d) Its hardness is lower than that of silica.

(E) The composition blended with the resin has a high volume resistivity of 5 × 10 ¹³ Ω · cm or more, and (f) exhibits excellent dispersibility when kneaded with the resin. This excellent dispersibility is realized in the high Charpy impact strength of the obtained molded product. The above-mentioned high-purity single crystal magnesium oxide powder used in the present invention is obtained by the following method: Purity generated by heating magnesium to a temperature of 700 ℃ or higher in an inert gas atmosphere 9
9.9% or more of magnesium vapor and oxygen-containing gas are contacted in parallel with each other, and the reaction is performed so that the following conditions are satisfied: Magnesium vapor partial pressure is less than 1 atm, oxygen partial pressure of oxygen-containing gas is magnesium 1 / steam partial pressure
2 or more, reaction temperature is 800 ~ 2000 ℃.

In the present invention, by using a single crystal magnesium oxide having excellent dispersibility in a resin as a filler, a sealing material having high thermal conductivity can be obtained, and heat dissipation of electronic parts can be satisfied, and It is possible to use a molding machine or a mold for a long period of time with less metal wear.

The electronic component sealing resin composition of the present invention is obtained by blending single crystal magnesium oxide with an epoxy resin, adding a curing agent and various additives thereto, and mixing the blended composition with usual mixing and kneading means such as a pot. It is prepared by uniformly mixing or kneading by a method such as melt kneading according to, melt kneading with a roll, melt kneading with an extruder, or the like.

The proportion of single-crystal magnesium oxide used increases as the amount of magnesium oxide increases, but on the other hand, the fluidity of the composition decreases, and if it is too large, the electronic component cannot be completely sealed. As a result, unfilling and voids frequently occur, which may lead to deterioration in moisture resistance. Further, when pressure is applied to inject the resin, there is a risk of cutting a weak portion of the electronic component, such as a bonding wire connecting the semiconductor element and the lead portion. On the other hand, if the amount of magnesium oxide is too small, the hardening is so small that the object of the present invention cannot be achieved. Therefore, it is preferably 10 to 85% by weight in the total composition.

In the present invention, single crystal magnesium oxide alone can be used as the filler, and single crystal magnesium oxide and other inorganic fillers, for example, silica such as crystalline silica or fused silica, alumina, calcium carbonate, talc, etc. However, the amount of these inorganic fillers used is preferably 15 to 85% by weight based on the total composition, together with the single crystal magnesium oxide. If the inorganic filler is less than 15% by weight, defects are conspicuous and not preferable in terms of thermal expansion coefficient and mechanical strength.

Examples of the epoxy resin used in the present invention include cresol novolac type epoxy resin, phenol novolac type epoxy resin, bisphenol A type epoxy resin, brominated phenol novolac type epoxy resin and alicyclic epoxy resin. Further, as a curing agent for this resin, an amine-based curing agent such as diaminodiphenylmethane, diaminodiphenylsulfone, or metaphenylenediamine, an acid anhydride-based curing agent such as phthalic anhydride, pyromellitic dianhydride, maleic anhydride, or phenol novolac. Known curing agents can be used for the resin and novolac-based curing agents such as cresol novolac resin. A curing accelerator such as imidazole or its derivative, a tertiary amine derivative, or a phosphine derivative may be added to this, and a release agent, a coupling agent, a flame retardant, etc. are required as other additives. Used according to.

As described above, the resin composition for encapsulating electronic parts of the present invention has the following advantages: (a) The molding machine and the mold are slightly worn at the time of molding, and (b) the thermal conductivity is large, that is, We can manufacture resin-sealed electronic parts with high heat dissipation, (d) Large Charpy impact strength of molded products, and (e) Large volume resistivity (150 ° C).

Therefore, the above composition is a material that provides a very useful sealing material industrially.

The above-described resin composition of the present invention is molded into an appropriate shape after blending, and the sealing of electronic parts by this can be performed by any of conventionally known casting molding, compression molding, transfer molding, and injection molding. it can.

"Examples" Hereinafter, specific examples will be described, but the present invention is not limited thereto.

Reference Example (Production of Single Crystal Magnesium Oxide) Magnesium having a purity of 99.9% heated and vaporized to 900 ° C. and argon gas having a purity of 99.9% as a diluting agent were introduced into an oxidation reactor so that the magnesium vapor pressure was 0.04 atm. To purity 9
Oxidation was carried out at a temperature of 1000 ° C. while introducing 9.9% oxygen gas to obtain single-crystal magnesium oxide having a particle size of 0.01 to 20 μm and a purity of 99.9%.

Example 1 198 parts by weight of orthocresol novolac epoxy resin (epoxy equivalent 214, softening point 84 ° C.), brominated phenol novolac epoxy resin (epoxy equivalent 275, softening point 84 ° C.) 22
Parts by weight, phenol resin (softening point 80 ° C.) 110 parts by weight, antimony trioxide 33 parts by weight, single crystal magnesium oxide 826 parts by weight obtained in the reference example, 2-ethyl-4-methylimidazole 4 parts by weight, carnauba wax 4 Parts by weight, and 4 parts by weight of a silane coupling agent (A-187 manufactured by Nippon Unica Co., Ltd.) are mixed and melt-kneaded with a two-roll at 80 to 100 ° C., followed by pulverization to obtain a resin composition for sealing electronic parts. It was

Example 2 Instead of 826 parts by weight of single crystal magnesium oxide in Example 1, 413 parts by weight of the same single crystal magnesium oxide and 413 parts by weight of fused silica (RD-8 manufactured by Tatsumori Co., Ltd.) were used to prepare a molding material.

Comparative Example 1 A molding material was prepared by using 826 parts by weight of fused silica (the same product as in Example 2) instead of 826 parts by weight of the single crystal magnesium oxide in Example 1.

(Characteristic Evaluation of Resin Composition for Encapsulating Electronic Parts) The resin compositions of Examples 1 and 2 and Comparative Example were transfer molded, and the characteristics of the molded products were evaluated. The results are shown in Table 1. Compared with the comparative example, the examples 1 and 2 show the peculiarity that the metal wear is small when they are rubbed with the metal, and the thermal conductivity of the molded product is large, and there is no particular problem with respect to electrical properties and mechanical properties. It was confirmed.

Example 3 Oxocresol novolac epoxy resin (epoxy equivalent 214, softening point 84 ° C.) 198 parts by weight, bromine phenol novolac epoxy resin (epoxy equivalent 278, softening point 84 ° C.) 2
2 parts by weight, phenol resin (softening point 80 ° C) 110 parts by weight, antimony trioxide 33 parts by weight, single crystal magnesium oxide 826
2 parts by weight, 4 parts by weight of 2-ethyl 4-methylimidazole, 4 parts by weight of carnauba wax and 4 parts by weight of a silane coupling agent [trade name: A-187 (manufactured by Nihon Unica Co., Ltd.)] are mixed in a double roll. After melt-kneading at 80 to 100 ° C., it was pulverized to obtain a resin composition for sealing electronic parts. The thermal conductivity, tensile strength, Charpy impact strength and volume resistivity (150 ° C) of the molded product obtained by transfer molding of this composition
Table 2 shows the results of the measurement.

Comparative Example 2 A resin composition was prepared in the same manner by using 826 parts by weight of magnesium oxide (prepared by melting at 3200 ° C.) instead of 826 parts by weight of the single crystal magnesium oxide used in Example 1 of the present application. Table 2 shows the results of measurement of thermal conductivity, tensile strength, Charpy impact strength and volume resistivity (150 ° C).

Comparative Example 3 A resin composition was similarly prepared using 826 parts by weight of magnesium oxide (prepared by baking at 2100 ° C.) instead of 826 parts by weight of the single crystal magnesium oxide used in Example 1 of the present application,
Table 2 shows the results of measuring the thermal conductivity, tensile strength, Charpy impact strength, and volume resistivity (150 ° C) of the molded product.

Comparative Example 4 A resin composition was similarly prepared using 826 parts by weight of magnesium oxide (prepared by firing at 1200 ° C.) instead of 826 parts by weight of the single crystal magnesium oxide used in Example 1 of the present application,
Table 2 shows the results of measuring the thermal conductivity, tensile strength, Charpy impact strength, and volume resistivity (150 ° C) of the molded product.

"Effects of the Invention" As is apparent from the above, according to the present invention, by mixing magnesium oxide in the form of a single crystal, the dispersibility in a thermosetting resin is excellent, and as a result, the magnesium oxide has excellent thermal conductivity. By utilizing the above, it has become possible to provide a resin composition for encapsulating electronic parts, which has an unprecedentedly excellent heat dissipation property and is excellent in molding workability with less metal abrasion.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kozaburo Yoshida 5 1978, Ogushi, Ube City, Yamaguchi Prefecture, Ube Laboratory, Ube Institute of Industrial Manufacturing (56) Reference JP-A-49-66761 (JP, A) JP-A-SHO 62-115757 (JP, A) JP-A-61-85474 (JP, A) JP-A-61-101524 (JP, A)

Claims (2)

[Claims] 1. A resin for encapsulating an electronic component, which comprises an epoxy resin containing 10 to 85% by weight of single crystal magnesium oxide satisfying the following requirements and having a volume resistivity of 5 × 10 ¹³ Ω · cm or more. Composition: average particle size 0.01 to 20 μm, purity ≧ 99.9%, chloride ion content ≦ 5 ppm and bromine ion content ≦ 5 pp
m. 2. The electronic component encapsulation according to claim 1, wherein the epoxy resin contains single crystal magnesium oxide produced by the following method, and its volume resistivity is 5 × 10 ¹³ Ω · cm or more. Resin composition: Purity generated by heating magnesium to a temperature of 700 ° C. or higher in an inert gas atmosphere in a magnesium evaporator 9
9.9% or more of magnesium vapor and oxygen-containing gas are contacted in parallel with each other, and the reaction is performed so that the following conditions are satisfied: Magnesium vapor partial pressure is less than 1 atm, oxygen partial pressure of oxygen-containing gas is magnesium 1 / steam partial pressure
2 or more, reaction temperature is 800 ~ 2000 ℃.