JPS6040189B2 - Resin-encapsulated semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin-sealed semiconductor device, and more particularly to a resin-sealed semiconductor device using a silicone resin for sealing together with silica powder as a reinforcing filler.

Silicone resin sealing materials are made by mixing a silicone base polymer with reinforcing fillers such as diatomaceous earth, silica fine powder glass fiber, aluminum oxide, hardening accelerators, mold release agents, pigments, etc.

Silicone resin encapsulant materials have higher heat resistance,
Because it has excellent properties such as flame resistance, electrical properties, and water resistance, it is used as a resin for sealing semiconductor devices. However, although resin-sealed semiconductor devices have good initial characteristics,
It has the disadvantage of poor reliability.

In particular, in high-temperature voltage application life tests and high-temperature high-temperature tests, leakage current increases and reverse breakdown voltage deteriorates, resulting in low reliability. As an example, FIG. 1 shows a curved example of the results of a high humidity voltage EO power test of a 500V class planar thyristor using a silicone resin sealing material. Figure 1 is a curve obtained by applying a voltage of 500V DC to a 30M test thyristor at a temperature of 12500C and measuring the increase in leakage current after 100 cycles. (
time), and the vertical axis shows the leak IL (France A), respectively.
Among these 300 thyristors, there were three thyristors whose leakage current was more than twice the initial value after 100 feeding hours, clearly indicating a high incidence of defective products and a lack of reliability (
In the graph, representative curves are selected and shown). Previously, the present inventors have found that the cause of the lack of reliability is that moisture contained in the silicone resin sealing material has an adverse effect. In addition, semiconductor devices encapsulated using a silicone resin encapsulating material that has been sufficiently dried by leaving it in a dry atmosphere or heating at 60 to 100 oo have a lower defective rate in the above-mentioned high-temperature voltage application life test. I found out what to do. However, if the silicone resin sealing material is left in a dry atmosphere,
If a semiconductor device is sealed with resin in a dry state heated at ~10,000 ℃, molding workability is poor due to a decrease in spiral flow and a large number of burrs appearing after molding. In addition, in order to improve the conventional drawbacks mentioned above, we have changed the reinforcing filler and template agent, applied overcoating to prevent moisture from entering after molding, and improved the post-cure method. However, reliability could not be improved.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art and provide a resin-sealed semiconductor device that is highly reliable and easy to work with.

The present invention is characterized by using a silicone resin sealing material in which the water content contained in the fine silica powder as a reinforcing filler mixed with a silicone base polymer is 12% by weight or less.

The present inventors, when manufacturing a silicone resin sealing material,
We focused on the high hygroscopicity of fine silica powder, which is a reinforcing filler mixed with a silicone base polymer.

That is, when the silica powder was heated to 45,000 ℃ to remove the adsorbed moisture from the silica powder, the weight of the silica powder gradually decreased, and after 5 hours of heating showed a decrease of about 28% by weight, it became approximately constant.

Figure 2 is a graph showing this state by plotting the heating time TH (hours) on the horizontal axis and the weight loss rate Rw (wt%) on the vertical axis.The silica powder contains approximately 26% by weight of adsorbed water. It turned out that Therefore, a silicone resin sealing material was manufactured using sufficiently dried silica.

When a semiconductor device was resin-sealed using this silicone resin sealing material, it was found that a stable and highly reliable semiconductor device could be obtained in a high-temperature voltage application life test. Incidentally, the silica fine powder sufficiently dried in the present invention includes amorphous silica, fused quartz powder, fume silica, and the like.

This will be explained in detail below using examples.

10 parts of silicone base polymer, 18 parts of silica fine powder as a reinforcing filler, 12 parts of glass fiber, and a small amount of hardening accelerator, mold release agent, and pigment are added and blended on a hot roll mill to make silicone. A resin sealing material was manufactured.

As a pretreatment of silica fine powder, 250
00 for 0 to 4 feeding hours, and the water content measured from the amount of weight loss was 0 to 27%. These silicone resins have a spiral flow of 34 to 40 inches (molding condition 17).
5oo, 56k9/c cedar, 3 min), all were successfully molded. A 500V class planar thyristor was resin-sealed using the silicone resin sealing material produced by the above method, and a high-temperature voltage application life test was conducted to examine reliability. 12500, DC500V, 1 as in the conventional example
In the 000-hour test, those whose leakage current increased by more than twice the initial value were judged to be defective. Figure 3 is a graph showing the results of the above test, with the water content W (wt%) of fine silica powder as a filler on the axis and the incidence Y (%) of defective products as defined above on the vertical axis. be.

As is clear from the figure, the water content of fine silica powder is l
When the water content exceeds a weight %, the incidence of defective products increases rapidly, and when the water content is about 15 weight %, the incidence reaches 8%. On the other hand, when the water content is 12% by weight or less, the incidence of defective products is 2% or less. As mentioned above, the moisture content of the silica powder in the silicone resin sealing material greatly affects the reliability of the Brehner-type silitor, and as shown in this example, the moisture content of the fine silica powder is By doing so, it is possible to significantly reduce the incidence of defective products and significantly improve the reliability of the obtained device.

In this embodiment, a case where a 500V class planar type thyristor is resin-sealed has been described, but the present invention can be generally applied to various silicone resin-sealed semiconductor devices. As described above, according to the present invention, a highly reliable silicone resin-encapsulated semiconductor device can be obtained.

[Brief explanation of drawings]

Figure 1 is a diagram showing the characteristics of a conventional resin-sealed semiconductor device obtained by a high-temperature voltage application test, Figure 2 is a diagram showing the results of a measurement test of water content in fine silica powder, and Figure 3 is an example of the present invention. FIG. 3 is a diagram showing characteristics obtained by a high temperature voltage application test. *'Zumai Figure 2 Figure 3

Claims (1)

[Claims] 1. In a resin-sealed semiconductor device sealed using a silicone resin as a sealing substrate material and a silica powder as a reinforcing filler, the sealing is performed using the silica powder with a water content of 12% by weight or less. The resin-sealed semiconductor device is characterized by: