JPS5947744A - Filler material for ic package - Google Patents

Abstract

PURPOSE:To eliminate causes of corrosion of aluminum wiring and alpha-ray software error by using a silica which does not contain uranium and thorium but contains an alkali metal oxide and impurities within the specified rate in total. CONSTITUTION:A silica used does not substantially contain uranium and thorium but contains alkali metal oxide of 10PPM or less and impurities in total contents of 100PPM. Such a high purity silica powder can be obtained by the following process. Namely, a high purity crystal silica or soluble silica is heated up to 2,000-2,500 deg.C under existence of carbon and is vaporized. The vaporized silica is collected and thereby higher purity silica can be obtained. The silica powder has a grain size of 0.1mum or less. Thereby any corrosion of aluminum wiring cannot be found even under the high temperature and high humidity ambient because it contains a very little amount of alkali and moreover even in case it is used for VLSI, and alpha-ray soft ware error is not detected because UO2 and ThO2 are not substantially contained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to filler materials for plastic packaging of ICs.

Conventional filler materials for IC plastic packages used silica powder, but the electrical insulation properties tended to change over time, and corrosion of At wiring occurred, resulting in unsatisfactory results.

These silica powders are usually ground powders of crystalline silica or fused silica, but the present inventors clarified the cause of the above-mentioned drawbacks, and as a result, the At20a+ Fe2031 NazO contained in these raw materials.

It became clear that the existence of K2O1UO2, Th0z cannot be ignored. Therefore, the presence of Fe2O3 changes the frost and air-bacteria insulation properties over time, and the presence of Na20. I
(zO is π of At wiring [easily promotes corrosion. Father, UO3
It is clear that the presence of radioactive elements such as 6Jff and Th02 causes sonotometry errors.

% in the silica powder of the present invention 5. By eliminating the g component, we were able to improve the reliability by 1/1 of PiL.
PPM or less, and the muntin blunt content is 1 (1(l P
A filler phase for IC plastic packages was immediately obtained by controlling the content to be less than PM.

The l/C to obtain such high purity silica powder is, for example, high purity polished crystalline silica or fused silica in the presence of carbon. (1(1(1~2.5(111℃+?s t
By vaporizing it and collecting it in the air, it is possible to further improve the purity and obtain spherical silica powder with a particle size of n, IIt or less. In this case, when heating is performed under reduced pressure, the temperature is 1500~2 (l fl (1℃
It can also be vaporized at low temperatures. 1. When the vapor is collected in the air, those in the early stages of heating or those in the final stage are not suitable for the present invention because impurities other than 5 iOz often volatilize intensively.

Further, even when a high-purity silicon compound is thermally decomposed and converted into an oxide through a chemical reaction, a product containing few impurities can be similarly obtained.

The components of the silica powder of the present invention obtained by heating and evaporating crystalline silica at 22 (+ (1'C) and conventional high-purity crystalline silica powder and fused silica powder are shown below.

When we compared the differences in properties when silica powders with such compositional differences were used as filler materials for IC plastic packages, we found that the silica powder of the present invention has extremely low alkali content, so it is difficult to resist At Corrosion of the wiring was observed - 40 (> 40 in the bias test at 85°C and 85% RH. No change was observed for more than 1 hour. Also, even when used for VLSI, it contains substantially UO2 and Th02. VLS
Even when used for I, no α-ray soft error was observed.

On the other hand, with conventional silica powder, corrosion was observed in the At wiring due to the impurities mentioned above, and UO2 and Th
α-ray soft errors were also observed due to the presence of 02.

The powder of the examples of the present invention has an extremely small powder diameter of 01 μm or less and is spherical, so it has sufficient chicken tropism when mixed with resin and also exhibits the effect of forming a strong matrix. I was able to do it.

Claims (1)

[Claims] A filler for an IC package characterized by being substantially free of uranium and thorium, containing an alkali gold parrot oxide of 1 (l PPM or less), and having a muntin dull substance content of 1 (+ (l PPM or less) of silica) Material.