JPH07103263B2 - Silica for filling sealing resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to silica for filling an IC encapsulating resin, and particularly to an IC encapsulating material filler having excellent filling property and fluidity for a thermosetting resin. Silica for use.

[Prior Art] Conventionally, crushed or spherical silica having an average particle size of 7 to 30 μm is generally used as this type of sealing resin-filling silica.

However, crushed or spherical silica having such a particle size, when filled as a filler in the resin,
About 20% by volume of interparticle voids with a size of 3 μm or less is present, and the filler filling rate in this resin is necessarily limited to 80% by volume or less. The good fluidity of the compound of silica and silica cannot be obtained, silica cannot be added at a high addition rate, and when it is used as an IC encapsulant, its coefficient of thermal expansion and water absorption are reduced, and moisture resistance is improved. It will be difficult to improve.

20 to 97% by weight of fused silica powder having an average particle size of 1 μm or more
It has also been proposed to mix 80 to 3% by weight of spherical siliceous powder having an average particle size of 10 to 800 mμ (JP-A-59-204,633). Fused silica powder and Aerosil (spherical siliceous powder) having an average particle size of 20 mμ are mixed and used.

However, even in this method, the particle size of Aerosil having an average particle size of 20 mμ is too small, and therefore, the influence of the Van der Waals force acting between these particles becomes too large, and the filling property is rather lowered. However, regarding this Aerosil, it is not possible to obtain a particle size of 100 mμ or more because of its manufacturing method.

By the way, when crushed silica is used as the packed silica, it is possible to obtain a certain degree of packing property by appropriately mixing particles having different degrees of crushing to adjust the particle size, but in this case also, it is sufficiently satisfactory. It wasn't something.

[Problems to be Solved by the Invention] As a result of intensive studies in view of such viewpoints, the present inventors have selected silica having a specific particle size distribution and particle shape as sealing resin-filling silica. According to the above, it was found that the filling property and the fluidity in the resin, particularly in the thermosetting resin can be remarkably improved, and the present invention has been completed.

Therefore, an object of the present invention is to provide a sealing resin-filling silica having excellent filling properties and fluidity with respect to the sealing resin.

[Means for Solving the Problems] That is, according to the present invention, crushed or spherical coarse silica having an average particle diameter D in the range of 7 to 30 μm has an average particle diameter d of 0.1 to
A silica for filling a sealing resin, which is obtained by mixing 5 to 40% by weight of monodisperse spherical fine silica particles in the range of 3 μm.

The coarse-grain silica used in the present invention may be pulverized silica or spherical silica, but the average particle diameter D thereof is 7 to 30 μm, preferably 8 to 15 μm.
When the average particle size is less than 7 μm, the fluidity of the resin compound decreases sharply.
If the particle size exceeds μm, the coarse silica particles are likely to damage the surface of the object to be encapsulated, and especially in the case of IC encapsulation, the fine pattern of the IC is damaged by the corners of the silica particles, causing wire flow and wire opening of the bonding wire. It may cause it. Incidentally, in the case of pulverized silica, it is possible to achieve a certain packing property by adjusting the particle size as described above, but in the case of spherical silica, such particle size adjustment is difficult, so that The effect is exerted more effectively.

The average particle size d of the monodisperse spherical fine particle silica blended with the coarse particle silica having such an average particle size D (7 to 30 μm) is 0.1.
It is necessary to be in the range of 1 to 3 μm, preferably 0.2 to 1 μm, and the blending ratio is 5 to 40% by weight, preferably 10 to 30% by weight of the whole. Average particle size d is 0.1
If it is smaller than μm, the tendency of agglomeration between the fine particles is increased and the filling rate is lowered. On the contrary, if the average particle diameter d is larger than 3 μm, it is larger than the void formed by the coarse silica and the void filling effect is impaired. Occurs. Also, the mixing ratio is 5
If it is less than wt%, the amount will be insufficient in filling the voids of the coarse-grained silica, and conversely, if the blending ratio is more than 40 wt%, there will be a problem that it will be excessively larger than the voids of the coarse-grained silica.

Further, in the present invention, in order to achieve higher packing property and higher fluidity, 0.02D <d <0.1 between the average particle diameter D of the coarse silica and the average particle diameter d of the fine silica. There should be a relationship of D, more preferably a relationship of 0.03D <d <0.07D. By using the coarse-grained silica and the fine-grained silica having such a relationship, and selecting the compounding ratio from the above range, the voids formed at the time of filling the coarse-grained silica are densely packed with the monodisperse spherical fine-grained silica. That can be filled with silica and can be densely filled with silica as a filler for an IC encapsulant in a sealing resin, preferably a thermosetting resin, and yet enables high fluidity of the obtained compound. You can

Although it is possible to use irregularly crushed finely divided silica for the purpose of filling voids, its filling property is inferior to that of monodispersed spherical finely divided silica, and silica having a wide distribution is used even for the same spherical finely divided silica. However, it is difficult to determine the optimum blending ratio with the coarse-grained silica due to the particle size distribution.

Then, as a method for producing such monodisperse spherical fine silica used in the present invention, for example, silicon alcoholate is hydrolyzed in an alcohol-water-ammonia solution, and the obtained spherical silica particles are dried and calcined. Manufacturing method (W. Stober et al., J. Colloid Interface Sci., Vol.26, p62
(1968)), the average particle size is 0.1 to 3μ by this method.
It is possible to produce monodisperse spherical fine silica particles having a specific surface area of 30 m ² / g or less in m. The monodisperse spherical fine silica particles obtained in this manner, even if they are hexagonal close-packed by themselves, still have a porosity of about 25% and high packing property cannot be obtained. Excellent filling properties and fluidity can be obtained by adding an appropriate ratio, that is, the fine silica particles to the coarse silica particles in the range of 5 to 40% by weight.

In addition, when mixing the coarse-grained silica and the monodisperse spherical fine-grained silica, a ball mill or a Henschel mixer is suitable, but when a ball mill is used, a plastic ball is used as a ball so that crushing of the monodisperse spherical silica does not occur. Need to use.

Filling silica of the present invention, various resins, for example, epoxy resin, can be blended as a filler for the IC encapsulant resin such as a polyimide resin, as a blending method,
As with the conventionally known silica for sealing material, a method of kneading with a means such as a heating roll can be adopted.

[Examples] Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples.

Examples 1 to 6 and Comparative Examples 1 to 4 80 parts by weight of orthocresol novolac epoxy resin (epoxy resin A) having an epoxy equivalent of 200, 20 parts by weight of brominated phenol novolac epoxy resin (epoxy resin B),
50 parts by weight of phenol novolac resin (curing agent) with phenol equivalent of 105, 2-methylimidazole (curing accelerator)
0.5 parts by weight, carnauba wax (release agent) 1 part by weight, antimony trioxide (flame retardant) 4 parts by weight, γ-glycidoxypropyltrimethoxysilane (coupling agent) 1 part by weight and carbon black (colorant) 1 part by weight, crushed silica having an average particle size of 16 μm (silica A), crushed silica having an average particle size of 7 μm (silica B), monodispersed spherical silica having an average particle size of 1.0 μm (silica C), having an average particle size of 0.2 μm Monodispersed spherical silica (silica D) and crushed finely divided silica (silica E) having an average particle size of 1.0 μm were blended in the proportions shown in Table 1, kneaded with a heating roll, cooled and then pulverized to obtain each Example and The epoxy resin composition of the comparative example was obtained.

The spiral flow and gel time of the epoxy resin compositions of these Examples and Comparative Examples were measured, and the filling property of silica in the resin and the fluidity of the obtained epoxy resin composition were evaluated. The results are shown in Table 1.

The spiral flow was measured according to the EMMI-1-66 method, and the gel time was measured at 175 ° C according to the JIS K-6911 method.

In Examples 1 and 3, coarse silica particles having an average particle size of 16 μm were blended with monodisperse spherical fine particle silica particles having an average particle size of 1 μm, and the spiral flow was longer than that of Comparative Example 1, but in Example 2, the blended single particles were blended. Since the dispersed spherical fine particle silica is too small, the effect is small. In Example 4, the average particle size is 7μ.
This is a case in which monodisperse spherical fine silica particles having an average particle diameter of 1 μm are blended with m coarse silica particles, and the effect is small because the fine silica particles are too large. In Examples 5 and 6, the same coarse particle silica having an average particle size of 7 μm was blended with monodisperse spherical fine particle silica having an average particle size of 0.3 μm, but the fluidity was improved as compared with Comparative Example 2. The improvement in fluidity is due to the improvement in the filling property of silica.

In addition, coarse-grained silica, that is, silica A and silica B,
When the monodispersed spherical silica (that is, silica C and D) and the crushed fine particle silica (that is, silica E) were mixed in various combinations, the presence or absence of the fluidity improving effect by the blend was examined. . The results are shown in Table 2. In Table 2, the case where the fluidity-improving effect by the blending is exhibited is indicated by ◯, and the case where the blending effect is small is indicated by Δ.

[Effects of the Invention] The silica for sealing resin filling of the present invention significantly improves the filling property into the sealing resin and the fluidity at the time of molding of the sealing resin composition prepared using the same. Can solve the problems of moldability such as unfilling and generation of voids, and can reduce the thermal expansion coefficient and water absorption rate by high density packing of silica to solve the problems of thermal stress and moisture.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masayuki Nozawa Inventor Masayuki Nozawa 4-7-9-9 Nakai, Kokurakita-ku, Kitakyushu City, Fukuoka (56) References JP-A-59-22955 (JP, A) JP-A-61- 254619 (JP, A) JP-A-63-297436 (JP, A)

Claims (2)

[Claims] 1. A crushed or spherical coarse silica having an average particle diameter D in the range of 7 to 30 μm is mixed with 5 to 40% by weight of monodispersed spherical fine silica having an average particle diameter d in the range of 0.1 to 3 μm. A silica for filling a sealing resin, characterized in that 2. The sealing resin-filling silica according to claim 1, wherein the average particle diameter D of the coarse silica particles and the average particle diameter d of the monodisperse spherical fine silica particles have a relationship of 0.02D <d <0.1D. .