JPS6235546A - Sealing resin for semiconductor element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention combines a low melting point substance that expands during solidification into the filler, so that the overall thermal expansion of the sealing resin is made to closely approximate that of a semiconductor element. The present invention relates to a sealing resin for semiconductor devices.

[Conventional technology]

Conventionally, when semiconductor elements are encapsulated with resin by low-pressure transfer molding, etc., there is a large difference in coefficient of thermal expansion between semiconductor elements and lead frames made of inorganic materials and organic resin, which causes distortion and stress due to temperature changes. This not only reduces the reliability of the sealing element, but also
In severe cases, cranking occurs, resulting in a decrease in manufacturing yield.

In particular, since epoxy resins are usually molded at a temperature in the range of 150 to 190°C, the resin, which has a larger thermal expansion coefficient than the semiconductor element, experiences relative thermal contraction during cooling to room temperature after molding. As a result, large stress strains are generated in the encapsulated semiconductor element. This stress strain not only deteriorates the characteristics and reliability of the semiconductor element, but also causes cracks and cranks, which may cause the semiconductor device to be defective.

In order to reduce this stress strain, appropriate inorganic fillers have been added to conventional resins for encapsulating semiconductor devices. Addition of an inorganic filler has the advantage that the thermal expansion coefficient of the sealing resin decreases in accordance with the amount added and approaches that of a semiconductor element. However, there is a practical limit to the amount added, and sufficient thermal expansion matching cannot be achieved, so improvements are required for sealing large semiconductor devices.

[Problem that the invention seeks to solve]

Conventional encapsulating resins for semiconductor devices have the above structure, so there is a large difference in coefficient of thermal expansion between them and the semiconductor device and lead frame, and there is a limit to the amount of filler added to alleviate this difference. There is a problem in that stress distortion is generated in the semiconductor element, which not only deteriorates the characteristics and reliability of the semiconductor element, but also causes cracks and cracks.

The object of the present invention is to provide a fat that solves the above-mentioned problems.

[Means for solving problems]

The encapsulating resin for semiconductor elements according to the present invention uses metal particles that expand upon solidification as fillers instead of conventionally used inorganic fillers with a small coefficient of thermal expansion.

[Effect]

In this invention, by using metal particles that expand during solidification as a filler, the thermal expansions of the semiconductor element or lead frame and the resin almost match, and stress distortion does not occur in the semiconductor element.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a sealing resin for a single conductor element according to an embodiment of the present invention. In the figure, 1 is a sealing resin made of an organic polymer, such as an epoxy resin, and preferably has a glass transition temperature as high as possible. .

2 is a lead for taking out electrical signals etc. of the semiconductor element 3 to the outside, 4 is a gold wire for electrically connecting the lead 2 and the semiconductor element 3, and 11 is a filling compounded in the above-mentioned sealing resin. It is made of a material that expands when it solidifies. For example, some bismuth alloys have approximately 3%
Since it expands during solidification, when using it, it is sufficient to add about 0.2% by weight in order to make the apparent thermal expansion of the sealing resin match that of silicon, which is a semiconductor element material. At this level of blending ratio, no deterioration of electrical properties due to contact between fillers is observed, and distortion due to thermal stress can be significantly reduced.

-m, molding of the sealing resin is performed by a transfer molding method. That is, a pre-shaped solid resin tablet is heated and melted, then press-fitted into a mold and solidified. At this time, first, when the organic polymer component in the resin solidifies and reaches a suitable temperature at which it becomes a semi-solid, the selected filler, which solidifies at that temperature, becomes trapped and dispersed in a molten state in the form of islands. The resin solidifies and applies compressive stress to the previously solidified resin region. After that, you can freely obtain the desired result by changing the shrinkage stress that acts during the gradual cooling process (here, it acts as tensile stress) and the amount added.

Since the resin of this example contains metal particles that expand during solidification as a filler, stress caused by temperature changes is alleviated. Therefore, a semiconductor device using this device does not cause stress distortion in the semiconductor element, and has a high yield and high reliability.

In addition, in the above example, fine particles of a single metal were used, but
In order to ensure electrical insulation, it is more effective to cover the metal particles with a suitable insulator in advance.

〔Effect of the invention〕

As described above, according to the present invention, metal particles that expand during solidification are added to the sealing resin made of an organic resin as a filler, so that thermal stress remaining during molding of the sealing resin is absorbed by the organic resin and filler. This has the effect of providing an extremely reliable and inexpensive semiconductor device.

[Brief explanation of drawings]

The drawing is a sectional view of a semiconductor device using a resin for semiconductor elements according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Sealing resin, 2... Lead, 3... Semiconductor element, 11... Filler.

Claims (3)

[Claims] (1) A encapsulating resin for semiconductor devices characterized by being made of an organic resin containing metal particles as a filler that expands during solidification. (2) The encapsulating resin for semiconductor elements according to claim 1, wherein the metal particles are coated with an organic polymer in advance. (3) The encapsulating resin for semiconductor devices according to claim 1 or 2, wherein the metal particles have a melting point lower than the glass transition temperature of the organic resin.