JPS63248712A - Inorganic filler and production thereof - Google Patents

Abstract

PURPOSE:To produce an inorg. filler having no acute angles and improving the flowability and moldability of its resin compound by heat treating a pulverized product of molten silica under special conditions. CONSTITUTION:Natural silica, rock crystal or synthesized silica powder is melted until the crystal content is reduced to <=0.2%. The resulting molten silica is pulverized to <=149mum max. particle size and the pulverized product is passed through a flame kept at a temp. above the m.p. of silica at a concn. of 6-20kg powder in the flame per 1Nm<3> combustible gas to obtain an inorg. filler made of siliceous powder having <=149mum max. particle size, 1-50mum average particle size, <=10m<2>/g specific surface area and <=0.2% crystal content. The inorg. filler has no acute angles.

Description

DETAILED DESCRIPTION OF THE INVENTION (Fields of Application on Lian Dong) The present invention relates to inorganic fillers, specifically resins used in the production of sealing materials for electronic components such as peninsular bodies, insulating substrates, heat dissipation sheets, etc. This relates to inorganic fillers missing in the composition.

(Prior technology) Resin encapsulation is the mainstream method for encapsulating electronic components such as semiconductors. The sealing material is required to have a low expansion coefficient. Therefore, fused silica powder is usually used, which is obtained by melting silica stone or crystal to add an inorganic filler to the resin, converting it into an ingot, and adjusting the particle size through a process such as crushing, classification, etc. However, since the particles are pulverized, they have sharp edges, and therefore, when filled with resin resin, the fluidity and moldability of the resin decreases, which is insufficient to function as a sealant. jl cannot be filled. Moreover, there is a risk of damage to the element surface, wires, etc. Spherical type fused silica powder is known to overcome these drawbacks (Japanese Unexamined Patent Publication No. 58-15
8740).

When obtaining a spherical type, use silica powder etc. whose particle size has been adjusted.
The mixture of combustible gases such as hydrocarbons and hydrogen with combustible gases such as oxygen (excessively high temperature flame obtained from the gas) must be minimized to give a large amount of heat Ik to the particles, which improves productivity. is extremely bad and uneconomical. Fillers that do not require such sphericity and have a shape that has substantially no sharp corners are also known as fillers (Japanese Patent Laid-Open No. 61-64754
No.Ko@). In this case, it is possible to increase the concentration of soot in the flame, but the unmelted crystalline portion remains in a non-quantitative manner, making the thermal conductivity and coefficient of thermal expansion of the sealing material unstable. There is a problem.

(Metal assembly point to be solved by the invention) As a result of various studies aimed at solving the above-mentioned drawbacks, the present inventor has found that a filler with good productivity and economical efficiency, and which is equivalent to a filler with a shape close to a true sphere. The present invention has been provided by developing an inorganic filler that can provide sealing properties.

(Means for solving the problems) That is, the present invention consists of a heat-treated product of pulverized fused silica, and consists of a siliceous powder having a crystal content of less than 0.2% and having substantially no sharp edges. An inorganic filler characterized by
? The powder is made of siliceous powder with a crystal content of less than 0.2% and having substantially no sharp edges, characterized by being passed through and heat-treated so that the amount of combustible gas (NrrL5) exceeds 6 and falls below 20. This is a method for producing an inorganic filler.

The present invention will be explained in more detail below.

The inorganic filler of the present invention is a heat-treated product of pulverized fused silica, and is composed of a silica-negative powder having a crystal content of less than 0.2% and having substantially no sharp edges. By satisfying these conditions, as shown in the examples, it is possible to produce a sealing material having properties equivalent to those of conventional siliceous powder having a shape similar to that of a pearl. Therefore, according to the present invention, an inorganic filler having such excellent properties can be produced with high productivity.

In the present invention, the crystal content is determined from the peak intensity ratio of α-quartz by X-ray diffraction, and "having substantially no sharp corners" means that the angular parts have been smoothed by crushing. meaning, it does not necessarily have to be spherical.

The particle size distribution and specific surface area of the inorganic filler of the present invention are not particularly limited; It is desirable that it is 10 m2/9 or less.

Next, a method for producing the inorganic filler of the present invention will be explained.

The raw material is an ingot made by melting natural silica stone, crystal, etc. or silica powder obtained by a synthetic method until the content of crystalline parts is less than 0.2%.It is crushed and classified at °C as necessary. is used. The preferred maximum particle size of the ground fused silica is 149 μm or less. Next, this pulverized material is passed through a flame to form a powder with no sharp edges, but it can be done in the summer until the sharp edges are simply removed and the powder becomes clear. Therefore, the flame only needs to be at a temperature of 1, which is higher than the melting point of fused silica.For example, a combustible gas such as hydrogen or propane and a support such as air or oxygen are sufficient. It is preferable that it exceeds 20 or less. 6
If it is below, it is disadvantageous in terms of productivity and economy when obtaining a shape that merely smooths out sharp corners.
Moreover, if it is larger than 20, sharp corners remain, which is not a good case.

The amount of the inorganic filler used in the present invention is generally 100% of the resin.
It is approximately 150 to 450 parts by weight. As the resin, thermosetting or thermoplastic resins such as epoxy, phenol, acrylic, polyester, and ABS, and rubbers such as silicone rubber, fluororesin, and ethylene propylene are used. Among these, epoxy resins, specifically bisphenol A, are used as resins for semiconductor encapsulation.
Epoxy resins such as Jj, phenol novolac type, and cresol novolac type are preferred, and those with less impurities and hydrolyzable chlorine are especially desirable! Yes. 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 resin, an amine curing agent, or an acid anhydride curing agent is used.

In addition, when blending the inorganic filler of the present invention into the resin, r-
Silane coupling agents such as glycidoxypropyltrimethoxysilane, curing accelerators such as imidazole, flame retardants such as brominated epoxy resins and antimony trioxide, pigments such as carbon black, and montana wax and carnauba wax. A j11 type agent can be added if necessary.

In addition, the inorganic filler of the present invention can be used alone or in combination with pulverized fused silica powder, crystalline silica powder, or spherical fused silica powder with good sphericity to be blended into the resin. be.

(Example) Next, the present invention will be described in more detail with reference to Examples.

Examples 1 to 5 Production of inorganic filler Coarsely crushed natural silica stone (10 to 60φ group) was heated and melted in a hydrogen-oxygen flame to form an ingot, and then crushed, finely crushed, and
A pulverized fused silica product having a predetermined particle size distribution was prepared through classification. When the ownership ratio of the crystalline portion was examined by X#11 diffraction, it was found to be less than 0.2%. When I inspected the shape during a visit to S, I noticed that it had sharp corners.

Next, these pulverized products were put into a hydrogen-oxygen flame under the conditions of the sorcerous concentration shown in Table 1. After that, 1
Inorganic filler A-D by removing particles larger than 49 μm
I got it.

On the other hand, inorganic filler E was produced in the same manner except that synthetic silica powder obtained by hydrolyzing silicon tetrachloride was used as the raw material instead of the crushed natural silica stone.

For these fillers, the content of crystalline parts was measured by xi diffraction, and the particle length/breadth ratio and the presence or absence of sharp corners were confirmed.
The average particle size was measured using a laser beam diffraction particle size distribution analyzer. The results are shown in Table 1.

Preparation of epoxy resin composition Cresol novolac resin 851 with epoxy equivalent weight 260
to a composition consisting of 153 kJi parts of brominated epoxy resin, 501 parts of phenol novolak resin, 5fLji parts of 2-undecylimidazole, 1 part of carnauba wax 2.5 mJ, 1 part by weight of carbon black, and 10 parts by weight of antimony trioxide. After adding 3,503 parts of the inorganic fillers shown in A to E in Table 1, they were mixed in a mixer, kneaded in a roll, cooled, and pulverized to produce a five-grade molding material.

The following evaluation trials were conducted on these molding materials. The results are shown in Table 2.

1) t & dynamics (spiral flow) Molding temperature 160° using metal temperature according to EMM I standard
0, molding pressure cuff 0 kll/am2. The larger this value is, the better the moldability is.

2) Heat shock resistance A 16-bin lead frame with an island size of 4 x 7.5 tomilli was formed by transfer using each composition.

The occurrence rate of cracks on the surface of the 16-bin DIP molded product was determined from 50 samples by repeatedly immersing it in a liquid at t--196°C and a liquid at +260°C for 30 seconds each.

6) A semiconductor element designed for reliability disconnection and leakage current measurement is coated with a resin composition using a transfer solder, and the resin composition is applied between the electrodes at 125°C and under a steam pressure of 2.5 atm.
Applying a bias current of V, open defect rate (disconnection rate) and leak defect rate (rate of leakage current between aluminum wires exceeding 10 nA) for up to 200 hours.
Reliability was evaluated by measuring . At this time, the open defect rate is calculated from the number of defective items out of 50 evaluated items. The leak defect rate was calculated from the number of defective pieces out of 25 pieces. These defective rates indicate that the smaller the value, the better.

4) Stress evaluation In order to evaluate the internal stress applied to the semiconductor element, a piezoresistive element (a piezoresistor whose resistance value changes depending on stress is formed on a semiconductor chip) was set in a 16-bin DIP type IC frame, and each composition was Transfer molding was performed, and the stress applied to the element was measured by resistance change.

Comparative Examples 1 to 5 Class 6a molding materials were produced using the inorganic fillers shown in F-H in Table 1 in the same manner as in the examples.

Fillers P~H were manufactured using natural silica stone as raw materials under the conditions shown in Table 1, and F and G were free from sharp corners. l! The filler H is an inorganic filler with sharp edges. These evaluation results are shown in Table 2.

From the results in Table 2, the characteristics of the resin compositions for sealing materials (Examples 1 to 5) using the inorganic fillers (A to E) of the present invention are as follows:
It can be seen that the characteristics are almost the same as those using the conventional filler (F) having a shape close to a perfect sphere (Comparative Example 1). Therefore, the first
As shown in the table, the inorganic filler of the present invention can be produced with a high dust concentration, resulting in improved productivity.

In addition, if the crystal content is 0.2% or more as in Comparative Example 2 or has sharp edges as in Comparative Example 6, it is difficult to produce a good resin composition for encapsulant. I can't.

(Effects of the Invention) According to the present invention, it is possible to produce a resin composition for an encapsulant that exhibits excellent properties equivalent to that of a true sphere without having to have a shape close to a true sphere as in the past. This has the effect of increasing productivity and ease of handling.

Claims (2)

[Claims] (1) An inorganic filler comprising a heat-treated product of pulverized fused silica, and comprising a siliceous powder having a crystal content of less than 0.2% and having substantially no sharp edges. (2) The dust concentration (amount of powder kg in the flame/amount of combustible gas Nm^3) containing crushed fused silica in a flame maintained at a temperature higher than the melting point of silica is more than 6 and less than 20. Crystal content: 0
．． A method for producing an inorganic filler comprising less than 2% siliceous powder having substantially no sharp edges.