JPS62243630A - Inorganic filler - Google Patents

Abstract

PURPOSE:To provide such inorganic filler having particular specific surface area as to enable, when incorporated in a resin, the internal stress in said resin to be significantly reduced and also enable a resin composition outstanding in thermal shock resistance, moisture resistance and moldability to be obtained. CONSTITUTION:Inorganic powder with a maximum particle size pref. <=140mum and average particle size pref. 5-35mum, prepared by e.g. size regulation, through e.g. classification or mixing, of crystalline silica or fused silica is treated with e.g. dilute hydrofluoric acid. aqua regia, to effect regulation of the surface unevenness, thus obtaining the objective inorganic filler with a specific surface area S <=5m<2>/g, satisfying the relationship: 3<S<So [So is the theoretical specific surface area calculated with the equation (p is true specific gravity of the inorganic filler g/cm<3>; ai is content % of particles with a size imum; i=min and i=max are minimum size and maximum size, respectively, determined by size distribution measuring equipment)]. This inorganic filler is normally incorporated in a resin (pref. an epoxy resin in case of semiconductor sealing use) in an amount of 150-450pts.wt. per 100pts.wt. of the resin.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to inorganic fillers, specifically resins used in the production of encapsulating materials for electronic components such as semiconductors, insulating substrates, heat dissipation sheets, etc. It relates to an inorganic filler passed through the composition.

(Prior Art) In recent years, W resin injection has become the mainstream for sealing electronic components such as semiconductors, and the type of resin also depends on its adhesion to the element. Epoxy resin compositions are widely used because of their cost. However, the resin sealing method has problems with poor moisture resistance reliability and internal stress caused by the difference in coefficient of thermal expansion between the resin and the element when the resin cures and shrinks. In particular, due to the recent increase in the degree of integration of semiconductors, devices have become larger, and cracks in resin due to internal stress and internal stress during thermal shock have become a major problem.

For this reason, various studies have recently been conducted with the aim of reducing this internal stress, such as adding inorganic fillers with a small coefficient of thermal expansion to the resin, or adding flexibility-imparting agents. ing.

The former is known to usually use silica powder,
If the silica powder is of the crushed type, it cannot be filled in a sufficient amount to reduce internal stress, and there is a risk of damage to the element surface, wires, etc. Spherical type silica powder is also being considered as a solution to this drawback, but it has the problem of a flat surface. The latter is known to use a rubber component, silicone resin, etc. as a toughness imparting agent, but this has had the problem of lowering heat resistance and temperature resistance.

(Problems to be Solved by the Invention) As a result of various studies aimed at solving the above-mentioned drawbacks, the inventors have developed a resin composition completely containing an inorganic filler having a specific specific surface area, such as an epoxy resin composition. The inventors have discovered that when used as a sealing material on a resin composition, it is possible to obtain a m-lipid group acid having significantly reduced internal stress and excellent thermal shock resistance, moisture resistance, and moldability, and has developed the present invention. It is completed.

(Means for Solving the Problems) That is, the present invention provides a method that has a specific surface area S of 51112/i or less and a relationship with the theoretical specific surface area SO calculated from the particle size distribution of 3<s/so. It is an inorganic filler characterized by:

The present invention will be explained in more detail below.

Examples of the material for the inorganic filler of the present invention include crystalline silica, bath-fused silica, calcium silicate, alumina, calcium carbonate, Merck, barium sulfate, etc., but crystalline silica-fused silica is usually used. . Although the particle size distribution is not particularly limited, it is preferable that the maximum particle size is 140 μm or less and the average particle size is 5 to 65 μm.

However, in the present invention, the relationship between the specific surface area S ("2/l and the theoretical specific surface area So (m2/M) calculated from the particle size distribution u 3 < s/so te, and S ≤ 5 m"/11. If S/So≦6, it is not preferable because the contact area between the filler and the resin decreases, resulting in poor adhesion and a decrease in moisture resistance.-10,000,5m2/J
i? In the case of <8, it is not preferable because the fluidity and moldability of the composition will be significantly reduced if the optical filler f required to significantly reduce the internal stress of the sealing material is filled.

Calculation # of the theoretical specific surface area sO in the present invention is defined as follows. Assuming that the shape of the inorganic filler is spherical, the specific surface area 5i (-2/&) of particles with a particle size of 1 (μm) is 5t-
6/ρ・1 (ρ is the true specific gravity of the inorganic filler (9/cm”)
) is calculated. Therefore, the particle size distribution of the inorganic filler is measured using a particle size distribution analyzer, and if the ownership ratio of the particles with particle size i (μnL) is ai (%), the theoretical specific surface area SO of the inorganic filler is calculated as Ru.

There are different methods for manufacturing inorganic fillers for each color, but for example, inorganic powder that has been roughly adjusted by classification, mixing, etc. is treated with dilute hydrogen heptadide dispersion, aqua regia, etc., and the surface This is a method for adjusting the uneven state tl of.

The use of the inorganic filler of the present invention is generally 1 oox of resin.
The amount is about 150 to 450 parts by weight based on the tray. As the material, thermosetting and thermoplastic A resins such as epoxy, phenol, acrylic, polyester, and ABS, as well as rubbers such as silicone rubber, fluororesin, and ethylene glopyrene are used. Among these, epoxy resins, specifically bisphenol A
Epoxy resins such as type, phenol novolac type, and cresol novolak type are preferred, and those containing less impurities and hydrolyzable chlorine are particularly preferred. As a curing agent when using an epoxy resin, for example, a phenolic curing agent such as a phenol novolac resin or a cresol novolac tree H'F1, an amine curing agent, or an acid anhydride curing agent is used.

Note that when placing the inorganic filler of the present invention in the resin, r-
Silane coupling agents such as glycidoxynolopyltrimethoxysilane, curing accelerators such as imidazole, flame retardants such as brominated epoxy resins and antimony trioxide, pigments such as carbon black, and release agents such as Montana wax and carnauba wax. A molding agent can be added if necessary.

(Example) Next, the present invention will be specifically explained using seven practical examples.

Examples 1 to 5 (Preparation of inorganic filler) High-purity silica fine powder obtained by hydrolyzing silicon tetrachloride is completely granulated and fired, then classified and mixed to produce a spherical type having a predetermined particle size distribution. silica powder was prepared. In addition, after melting the same high-purity silica imitation powder bed in a heating bath and making it into an ingot, it is subjected to coarse crushing, fine crushing, classification, and mixing to prepare an angular type silica powder having a predetermined particle size distribution 't-. did.

In addition to these silica powders'k 0.05 East it% hydrofluoric acid, a slurry with a roughness of 40% by weight was prepared and heated at 60°.
Stirring was performed for 10 to 60 minutes while heating to C. After step 7, washing with water, filtration, drying and crushing were performed to produce inorganic fillers A to E of the present invention.

(8! Calculation of theoretical surface area) The above-mentioned fillers A to H were measured using a particle size distribution generator IT (manufactured by Cirrus). The results of Section 7 are shown in Table 1. Next, based on this result, according to the theoretical specific surface area calculation method defined earlier, the theoretical specific surface area SO
I asked for

- As an example, the case of filler A is shown below.

Peng 0.64 (However, ρ-2,21...N due north of molten silica)
The actual ratio table for inorganic fillers thi horizontal 8 is Cantasorb (
The measurement was performed using Yuasa Ionics Co., Ltd. (JA).

(Preparation of epoxy resin composition) 15 parts by weight of brominated epoxy resin, 50 parts by weight of phenol novolac resin, 5 parts by weight of 2-undecylimidazole, and 2.5 parts by weight of carnauba wax based on 85 parts by weight of cresol novolak resin of F230 epoxy resin. Weight part, carbon black IJILfit part, antimony trioxide 10m [
After adding t-35031E value parts of inorganic fillers shown in A to H in Table 1 to the composition consisting of
The mixture was further kneaded with rolls, cooled, and pulverized to produce five types of molding materials.

Next, the following evaluation tests were conducted on these molding materials. The results are shown in Table 2.

1) Stress evaluation A nine-piece piezoresistive element (a piezoresistor whose abrasion value changes depending on stress is formed on a semiconductor chip) for evaluating the internal stress applied to a semiconductor element is set in the frame of a 16-gain DIP type IC. The composition was transfer molded, and the stress applied to the element was measured from the change in resistance.

2) Heat shock resistance evaluation A 16-bin lead frame with an island size of 4 x 7.5 m+ was transfer molded using each composition.
Bottle DIP molded body is heated to -196℃ liquid and +260℃.
The molded product was repeatedly immersed in liquid C for 60 seconds each time, and the crack occurrence rate on the surface of the molded product was determined from 50 samples.

3) Moisture resistance evaluation Using each composition, a device having aluminum wire electrodes facing each other was transfer molded, and the sealed sample was subjected to steam pressurization of 2.5 atm at a temperature of 125°C.
A bias voltage of 20 V DC was applied between the electrodes, and the open failure rate of the aluminum wire was measured over time with a sample value of 50.
Obtained from individuals. This test is called RPCT (Bias Pressure Test).Similarly, the test is also performed under non-bias conditions.
It is called CT (pressure cutter test).

4) When the moldable inorganic filler and the resin are mixed, the fluidity is markedly decreased as "poor", and the fluidity as above average is "good".

Comparative Examples 1 to 3 Next, as Comparative Examples, inorganic fillers (fused silica fillers) shown in F-H of Table 1 were produced in the same manner as in the Examples and tested. The results are shown in Table 2.

(Effects of the Invention) The NTH molded product using the inorganic filler of the present invention exhibits the effects of reducing internal stress, improving magnetic resistance, and preventing deterioration in moldability.

Claims (1)

[Claims] 1. The specific surface area S is 5 m^2/g or less, and the relationship with the theoretical specific surface area So calculated from the particle size distribution is 3<S/S
An inorganic filler characterized by having o.