JPH0528744B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a synthetic resin composition for encapsulating electronic components such as semiconductors. More specifically, the present invention relates to rounded silica fine powder particles suitable as a filler in the composition, and to a synthetic resin composition containing the same and a thermosetting resin as main components. (Prior Art) (Problems to be Solved by the Invention) Semiconductors and electronic components are encapsulated with ceramic packages or resin to protect them from the external environment, but these encapsulation materials are expensive and expensive. From the viewpoint of productivity, etc., synthetic resin compositions containing inorganic fillers have become popular. This synthetic resin composition is composed of a thermosetting resin such as an epoxy resin and an inorganic filler such as silica, but these compositions have a small coefficient of thermal expansion, good thermal conductivity, and low moisture permeability. Since it is desirable to have excellent mechanical properties and low cost, we use this inorganic filler as long as its moldability allows.
It is necessary to mix as much as possible. However, since the inorganic powder used as a filler is mainly ground into powder with appropriate size and distribution, its shape generally has corners, and thermosetting resins such as epoxy resins are used as fillers. When mixed to form a sealing material, the fluidity is insufficient, the filling and workability are poor, and the equipment in the molding process is significantly worn out. It has also been reported that the sharp edges of filler particles can damage the surface of semiconductor devices, causing soft errors. Generally, stress is generated by shrinkage of thermosetting resin when it cures, but in addition to this stress, stress is generated due to the large difference in thermal expansion coefficient between the semiconductor element and the encapsulating resin composition due to the heat generated from the semiconductor. exists. In order to alleviate the latter of these internal stresses, it is generally desirable to fill in as much inorganic filler as possible, which has a small coefficient of thermal expansion. However, in this aspect as well, with square fillers produced by pulverization, increasing the filling amount causes an extreme decrease in fluidity, so there is no choice but to be limited in quantity, and it is difficult to alleviate internal stress. is of no use. In order to solve such problems, for example, Japanese Patent Application Laid-Open No. 58-145613 or Japanese Patent Application Laid-Open No. 61-118131
According to the publication, a method is proposed in which spherical fused silica powder is produced by jetting crystalline fine powder silica from a nozzle together with a gas flow and controlling particle dispersion, melting, cooling, etc. under appropriate conditions. . However, this method has the disadvantage of high cost. On the other hand, no example of producing crystalline type spherical silica has been proposed to date. In view of this situation, the present inventors studied a method for manufacturing rounded silica fine powder particles, and filed a patent application on May 13, 1988 as Japanese Patent Application No. 62-117612 (Method for manufacturing silica fine powder particles). I applied on the day. The fine silica powder obtained by the method of Japanese Patent Application No. 117612/1987 has rounded particles with a maximum particle diameter of 300 μm or less, and is excellent as a filler for synthetic resin compositions for encapsulating semiconductor devices. . After that, the inventors continued their studies and found that the maximum particle size was 200 μm or less, and the average particle size was
Fine silica powder containing 12% by weight or more (hereinafter referred to as weight%) of silica particles with a particle diameter of 7 μm or more and 35 μm or less and a content of 3 μm or less and 2% or more of silica particles with a particle diameter of 1 μm or less is better as a filler. The present invention was developed based on the knowledge that the present invention has certain characteristics. Furthermore, in the present invention, the filler obtained as described above is blended into a thermosetting resin, which has good filling properties and workability, and reduces wear on equipment during the molding process.
Another object of the present invention is to provide a thermosetting resin composition that has low internal stress and is suitable for transfer molding. (Means for Solving the Problems) That is, the first aspect of the present invention is to grind the particles together in the presence of an aqueous medium while applying external pressure to the crushed silica, thereby removing the corners of the silica particles. A fine rounded silica powder with a maximum particle size of 200μm or less and an average particle size of 7μm or more and 35μm.
m or less, and contains 12% or more of fine silica particles of 3 μm or less, and 2% or more of fine silica particles of 1 μm or less, and the silica filler of the present invention is a thermosetting resin. When blended with the above, it not only provides good fluidity but also enables high blending. The second is a resin composition containing 100 parts by weight of a thermosetting resin and 60 to 600 parts by weight of the silica filler of the first invention. The crushed silica used in the present invention includes crystalline silica,
Any type of fused silica may be used, but natural high-purity silica stone, silica sand, crystal, etc. are generally used as the crystalline silica, and the fused silica is obtained by melting these crystalline silicas at a high temperature to form an ingot. Usually, these are coarsely crushed using a dior crusher, roll crusher, etc., and these coarsely crushed products are further finely crushed using a ball mill, etc., and used as crushed silica in the present invention. The average particle diameter of the crushed finely ground silica obtained here must be slightly larger than that of the rounded silica filler of the final product. The silica filler of the present invention significantly improves fluidity when mixed with a thermosetting resin, but its mechanism of action is not clear. However, in addition to the rounded corners of the particles, it is thought that the generated fine particles, including submicron particles, greatly contribute to the formation of an optimal particle size distribution. In the present invention, the particles are ground together in the presence of an aqueous medium while applying a pressing force to the crushed silica from the outside. However, in the absence of an aqueous medium, the pressing force is not smoothly transmitted to the powder, and the grinding process is interrupted. Efficiency will be extremely low. Usually, the presence of an aqueous medium of 0.5 to 18%, preferably 3 to 13%, based on the crushed silica, has an effective effect on the grinding. The aqueous medium to be used may be any liquid that allows fine silica particles to interact with each other and easily transmits pressure from the outside to the powder, and liquid substances such as water, alcohols, and mineral oil can be advantageously used. From the viewpoint of cost, ease of handling during operation, ease of separation after operation, etc., water alone or a medium prepared by dissolving an alcohol such as ethanol or methanol in water is most advantageously used industrially. In addition, the pressure applied to the roller from the outside cannot be numerically limited because the method of pressure differs depending on the machine, but if the pressure is too strong, not only the corners will be removed, but the volume of the particles will also be destroyed, and pulverization will progress. Cornering is inhibited. Furthermore, if it is too weak, the efficiency of cornering will decrease, so it should be determined appropriately depending on the equipment, raw materials, type (crystalline, amorphous), etc. Furthermore, it is also possible to send coarsely crushed products of several mm or less directly to this squaring process, and perform the squaring operation at the same time as crushing to a desired particle size. Although there are various methods for grinding particles together while applying pressure from the outside, a roller mill is the most effective method in terms of energy cost and efficiency. The silica filler of the present invention has a maximum particle size of 200 μm.
The thickness is preferably 100 .mu.m or less; if it is 200 .mu.m or more, it cannot be used because it will cause clogging during the process of resin encapsulation of semiconductors. Furthermore, the average particle is 7μm
It is 35 μm or more, preferably 12 μm or more and 20 μm or less, and whether it is 7 μm or less or 35 μm or more, the good fluidity of the resin composition is impaired. Next, regarding the amount of fine silica particles present, 12% or more, preferably 14% or more, of 3 μm or less, and 1 μm or less
Good fluidity can be obtained when the following is present in an amount of 2% or more, preferably 3% or more. However, the fine particles of 3 μm or less do not necessarily have to have rounded corners, and may be crushed fine particles. In either case, if it is less than this, the fluidity of the resin composition will decrease. Above, an average particle diameter of 7 to 35 μm, and
A silica filler with fine particles present in a desired proportion is
It can be obtained by appropriately adjusting the pressing force, rotation speed, amount of aqueous medium, etc.
It can also be obtained by adding crushed silica of 3 μm or less before, during, or after this treatment. The resin composition of the second invention is one in which the silica filler of the first invention is blended with a thermosetting resin. As the thermosetting resin, any resin such as epoxy resin, phenol resin, polyester resin, silicone resin, etc. can be used, and among these resins, epoxy resin can be used industrially advantageously.
A desired resin composition can be obtained by blending 60 to 600 parts by weight of the silica filler of the present invention with 100 parts by weight of these thermosetting resins. If it is less than 60 parts by weight, no effect of reducing internal stress will be observed, and if it exceeds 600 parts by weight, the fluidity of the resin will be significantly reduced, which is not preferable. As a method for kneading the filler into the thermosetting resin, a kneader, roll mill, mixer, etc. may generally be used. (Example) Next, the present invention will be described in detail with reference to Examples. [Manufacture of filler] Example 1 Coarsely crushed crystalline silica was finely pulverized using a ball mill,
500 g of crushed crystalline silica having an average particle size of 23.2 μm was obtained. This was placed in a roller mill (MPV-0.5 model manufactured by Matsumoto Cast Iron Works), and 60 ml of water was added at the same time.
The pressing force of the roller is 40Kg/cm (linear pressure), the clearance between the roller and the bottom plate is 3mm, and the number of rotations of the bottom plate is
It was set at 42 rpm and processed for 1 hour. As a result of drying and crushing the obtained processed material, the average particle size was 19.4μ
m, the amount of fine particles present was 22.1% below 3 μm and 4.4% below 1 μm. The particle size distribution was measured using a laser diffraction particle size distribution analyzer (CILAS, model
715). An electron micrograph of the silica filler thus produced is shown in FIG. Example 2 By changing the particle size of the crushed crystalline silica used in Example 1 and the roller mill treatment conditions, A,
Silica fillers shown in B, C, D, and E were produced.

[Manufacture of resin composition]

Examples 6-10 The filler produced in Examples 1-2 (obtained by processing crushed crystalline silica with a roller mill) was mixed with 100 parts by weight of epoxy resin in the parts by weight shown in Table 2. After kneading in a kneader for 15 minutes, the mixture was cooled and pulverized to obtain an epoxy resin composition. In order to examine the fluidity of these compositions, spiral flow was measured based on EMMI standard 1-66.

[Table] Comparative Examples 1 to 4 Using the crystalline silica fine particles obtained in Example 1, Examples 2D, 2E, and Example 3 as a filler, Example 6
An epoxy resin composition was obtained in the same manner as in 10.
(Table 3) It is clear that fluidity deteriorates when the amount of filler blended exceeds 600 parts, the average particle size is too small, or the content of silica fine powder of 1 μm or less is less than 2%. It became.

【table】

[Table] Examples 11 and 12 Fused silica fine particles obtained by the method of Example 4 in which crushed fused silica was processed with a roller mill were used as a filler, and thereafter mixed with an epoxy resin in the same manner as in Examples 6 to 10. , an epoxy resin composition shown in Table 4 was obtained. Comparative Examples 5 and 6 Comparative Example 5 is one in which 610 parts of the fused silica fine particles obtained in Example 4 are blended with 100 parts by weight of epoxy resin, and Comparative Example 6 is one in which crushed fused silica is not treated with a roller mill. This is the case when it is used as a filler. Comparative example 1 for crystalline silica fine particles
As in the case of No. 4, when fused silica fine particles were used, a decrease in fluidity was observed as shown in Table 4.

[Table] Example 13 An epoxy resin composition containing 70% by weight of the fillers obtained in Examples 1, 3, 4, and 5 was produced, and these were mixed into a 50 mmφ gold plate. The mixture was filled into a mold and molded under pressure to produce a tablet with an outer diameter of 50 mm and a height of 10 mm. A wear test was conducted using this. The results are shown in Figures 3 and 4. When the rounded silica particles of the present invention were used as a filler, the abrasion properties were clearly improved. (Effects of the Invention) By using the thermosetting resin composition containing the silica filler of the present invention for sealing electronic components such as semiconductors, fluidity and abrasion resistance in the transfer molding process are improved, and This also helps reduce the internal stress of the sealed product, and can improve both workability and performance.

[Brief explanation of the drawing]

FIG. 1 is an electron micrograph showing the crystal structure of crushed crystalline silica fine particles with rounded corners obtained by the method of the present invention, and FIG. 2 is an electron micrograph showing the crystal structure of crushed crystalline silica fine particles before carrying out the method of the present invention. This is an electron micrograph showing the crystal structure of . Figures 3 and 4 show the results of Taber abrasion tests of epoxy resin compositions prepared by incorporating fillers produced using the method of the present invention.

Claims (1)

[Scope of Claims] 1. A fine silica powder obtained by grinding the particles together in the presence of an aqueous medium while applying an external pressing force to crushed silica, thereby rounding the corners of the silica particles and giving them a rounded appearance. The maximum particle size is 200 μm or less, the average particle size is 7 μm or more and 35 μm or less, and
12% by weight or more of fine silica particles of 3 μm or less, 1 μm
A resin composition containing 100 parts by weight of the thermosetting resin and 60 to 600 parts by weight of the silica filler, the main components of which are a silica filler containing 2% by weight or more of the following particulate silica and a thermosetting resin. 2. The composition according to claim 1, wherein the thermosetting resin is an epoxy resin.