JPH021184B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a resin composition for semiconductor encapsulation that has less burrs during molding and has good crack resistance. [Technical background of the invention and its problems] Conventionally, epoxy resin compositions used for semiconductor encapsulation have been made by blending epoxy resin with a curing agent such as a phenol resin, an acid anhydride, or an amine, and then adding a filler as a filler. Products containing silica, clay, etc. are known. Such epoxy resin compositions have extremely low viscosity and good fluidity when melted compared to conventional thermosetting resin compositions such as phenolic resin compositions, so they are used in ICs and transistors. It is effective in minimizing damage to fine patterns and wires, and has the advantage of having good moisture resistance and other properties. However, due to this good fluidity, resin burrs tend to adhere to the parts of the lead frame that serve as lead terminals for ICs and transistors during sealing molding, which interferes with the subsequent plating process and requires a deburring process. There was a drawback that it had to be done. In addition, recently the package shape has become smaller,
The trend is for materials to become thinner, and there is a need for materials with extremely low resin burrs during molding, as well as materials that can meet even more severe usage conditions.
There is a growing need for more reliable materials.
To counter this burr, methods have been adopted such as applying various burr-preventing treatments to the lead frame side, adjusting the viscosity of the raw resin, and considering various methods of processing the filler. Each had drawbacks such as a lack of harmony with moisture resistance and crack resistance. [Purpose of the Invention] The present inventors have carried out intensive research in order to eliminate such drawbacks, and as a result, by adjusting the crystallinity and meltability of silica used as a filler, as well as its average particle size, moisture resistance, It has been found that a well-balanced resin composition for semiconductor encapsulation with excellent clutch resistance and moldability can be obtained. The present invention was made based on such knowledge, and an object of the present invention is to provide a resin composition for semiconductor encapsulation that has excellent moisture resistance, clutch resistance, and moldability. [Summary of the Invention] That is, the epoxy resin composition of the present invention is a semiconductor encapsulation resin composition containing an epoxy resin and a filler as main components, in which the filler has an average particle size of 25 to 35 μm.
Consisting of fused silica (silica A) with a maximum particle size of 80 μm or less, fused silica (silica B) with an average particle size of 10 to 20 μm, and crystalline silica (silica C) with an average particle size of 5 μm or less, silica A and silica B The ratio is 4:1~
3:2, the ratio of silica C is 15 to 30 vol% in the filler
It is characterized by the fact that it occupies the Epoxy resins used in the present invention include, but are not particularly limited to, bisphenol type epoxy resins, novolak type epoxy resins, etc. These include acid anhydrides, phenolic resins, various amines, and mixtures thereof. is used as a hardening agent. It is also possible to mix other thermosetting resins with the epoxy resin. In the present invention, commonly used curing accelerators such as imidazole and tertiary amine can be used. The filler used in the present invention has an average particle size of 25
Used by mixing fused silica (Silica A) with ~35μ (maximum particle size 80μ or less), fused silica (Silica B) with average particle size 10-20μ, and crystalline silica (Silica C) with average particle size 5μ or less do. Silica A and Silica B
A ratio of 4:1 to 3:2 is suitable; if silica A is larger than this ratio, the viscosity will be too low, resulting in more resin burrs and poor crack resistance.If silica A is smaller than this ratio, sealing This is not preferable as the viscosity becomes too high as a stopper material, especially when used in a flat package where the distance between adjacent gates is small, as it causes a lot of wire flow and reduces reliability. Only when the ratio of silica A and silica B is within the above range, flow is promoted due to the tendency of gate dimensions to decrease as the package shape becomes smaller and thinner, and the number of pins increases due to higher integration. By streamlining the lead frame, excessive flow of material can be prevented. In particular, when fused silica produced by wet milling is used as silica B, unlike ordinary dry milled silica, which has the same average particle size, the edges of the particles are removed and the particles become polyhedrons that are close to spheres.
It has the advantage that the viscosity is relatively low even when the amount of the compound is increased. In the present invention, the blending ratio of silica C in the filler is
An amount of 15 to 30 vol% is suitable.The reason for this is that at less than 15 vol%, resin burrs will increase and the number of steps after formation will increase, which is not practical, and if it exceeds 30 vol%, the crack resistance will deteriorate. This is because the occurrence rate of cracks is increasing. In the present invention, the epoxy resin, filler, curing agent, and curing accelerator are kneaded using a roll or the like, and after kneading, the product is cooled and pulverized for use. [Embodiments of the Invention] Next, embodiments of the present invention will be described. Example 1 100 parts by weight of cresol novolac type epoxy resin (epoxy equivalent 215, softening point 70°C), 50 parts by weight of phenol novolak resin (softening point 85°C), 1.2 parts by weight of 2-methylimidazole, carnauba wax
A total of 380 parts by weight of 2.5 parts by weight and silica as a filler in the proportions shown in Table 1 were sufficiently kneaded in a roll kneader at about 90°C, then cooled and pulverized.
A molding material with a diameter of 4 mm or less was obtained. The obtained molding material was tested for melt viscosity, wire flow, spiral flow length, resin burr length, and crack resistance. The obtained results are shown in the same table. In addition, Comparative Examples 1 to 3 in the table have a silica C ratio outside the range of the present invention, and Comparative Example 4 has an average particle size of 30μ, but those with a maximum particle size of 80μ or more are % of fused silica (silica D), and Comparative Examples 5 and 6 are examples in which silica B is not blended.

[Table] As can be seen from the test results in Table 1, the average particle size
Crystalline silica with a size of 5 μ or less is included in the total amount of silica.
It can be seen that when more than 30 vol% is used, the spiral flow length becomes extremely small, and at the same time, the crack occurrence rate becomes extremely large. Also 15vol%
If it is less than that, there will be less cracking, but there will be more burrs, and various problems will occur during actual use. It can also be seen that Comparative Examples 4 to 6 all have lower melt viscosities than Examples, but the wire flow becomes larger and the burrs become longer. Example 2 The mixing ratio of silica C was fixed as in the sample of Example 1, and only the mixing ratio of silica A and silica B was changed as shown in Table 2, and tests were conducted in the same manner. The results are shown in the same table.

[Table] As is clear from Table 2, if the blending ratio of silica A is high, the melt viscosity will be low, but there will be more burrs, and conversely, if the blending ratio of silica B is too high, the viscosity will become too high and the wire flow will increase. It's too impractical. [Effects of the Invention] As explained above, the resin composition for semiconductor encapsulation of the present invention is easy to mold, generates few burrs, and has excellent crack resistance.

Claims (1)

[Scope of Claims] 1. In a resin composition for semiconductor encapsulation containing an epoxy resin and a filler as main components, the filler has an average particle size of
It consists of fused silica (Silica A) with an average particle size of 25 to 35μ (maximum particle size 80μ or less), fused silica (Silica B) with an average particle size of 10 to 20μ, and crystalline silica (Silica C) with an average particle size of 5μ or less. The ratio of A and silica B is 4:1 to 3:2, and the proportion of silica C is 15 to 15 in the filler.
A resin composition for semiconductor encapsulation, characterized in that it accounts for 30 vol%. 2. The resin composition for semiconductor encapsulation according to claim 1, wherein the fused silica of silica B is obtained by a wet pulverization method.