JPH05251587A - Resin sealed semiconductor device - Google Patents

Abstract

PURPOSE:To make a resin flow length of each flow path equal and to prevent generation of void due to unfilling by making uniform the resin flow path width on the semiconductor element upper surface and the island lower surface and the resin flow path width on the semiconductor element and the island side surface. CONSTITUTION:A resin sealed semiconductor device is constituted of a semiconductor element 1, a lead frame 2 composed of an island 4, an inner lead 6 and an external lead 7, resin 3 and a metal fine line 5, and has a cross section wherein the resin flow path thickness (a) on the upper surface of the semiconductor element 1, the lower surface of the island 4, and the upper and lower surfaces of the inner lead 6 at a side part is make uniform. Therefore, when resin is injected, the resin flow path width on the upper surface of the semiconductor element 1 and the lower surface of the island 4 and the resin flow width on the semiconductor element 1 and the island side surface are made uniform, thereby making resin flow length of each flow path equal. Generation of void can be prevented in this way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a resin-sealed semiconductor device.

[0002]

2. Description of the Related Art In a conventional resin-sealed semiconductor device, as shown in FIG. 3, a semiconductor element 1 is fixed on an island 4 with an adhesive such as silver paste, and the semiconductor element 1 and inner leads 6 are connected.
Are connected with a metal thin wire 5 and then sealed with a resin 3.
The thickness of the resin-encapsulated semiconductor device used for surface mounting is rapidly decreasing with the advent of memory cards, and resin-encapsulated semiconductor devices having a thickness of 1 mm or less have been commercialized. These are Thin-Small-Outline-
It is called “Page” (hereinafter abbreviated as “TSOP”), and the amount of production is increasing rapidly in recent years. Type 1 and type 2 are used for the TSOP depending on the pitch of the external leads of the semiconductor device and the lead-out direction.
There is. Type 2 is Single-Outline-Jlead, which is the mainstream package for current memory products.
It is predicted that the number will increase the most in the future because of the compatibility of the electrode position on the semiconductor element with (hereinafter abbreviated as SOJ).

[0003]

The conventional resin-encapsulated semiconductor device described above has a drawback that voids are easily generated when the device has a thickness of 1 mm or less. In the case of a thin resin-sealed semiconductor device, the resin flow path composed of the semiconductor element and the island and the wall surface of the encapsulating mold is very narrow. It is much slower than the flow velocity. Therefore, before filling the upper surface of the semiconductor element and the lower surface of the island with the resin, the bend hole is blocked by the resin advancing on the side surface,
The resin unfilled portions on the upper surface of the semiconductor element and the lower surface of the island remain as voids, and the appearance is significantly impaired.

[0004]

The resin-sealed semiconductor device of the present invention has a structure having a cross section in which the resin thickness from the lead frame and the semiconductor element is constant.

[0005]

The present invention will be described below with reference to the drawings. 1A and 1B are a perspective view and a sectional view taken along line AA of a resin-sealed semiconductor device according to a first embodiment of the present invention. The resin-sealed semiconductor device is composed of a semiconductor element 1, a lead frame 2 including an island 4, inner leads 6, and external leads 7, a resin 3, and a thin metal wire 5. After fixing the semiconductor element 1 to the island 4 with silver paste or the like, the inner leads 6 of the semiconductor element 1 are connected by the fine metal wires 5.

The lead frame 2 in which the connection of the inner leads 6 of the semiconductor element 1 is completed is set in an encapsulating mold, and FIG.
Resin is injected from the direction of the arrow in (a). The air in the mold is discharged from the opposite vent side. The resin is composed of the upper surface of the semiconductor element 1 and the lower surface of the island 4 and the mold wall surface, and is narrower than the flow path having a large flow resistance.
And proceed faster along the flow path on the side of the island 4. This difference in resin flow becomes more significant as the device becomes thinner, and when the thickness becomes 1.0 mm or less, the resin in the side flow passage reaches the vent side, and the upper surface of the semiconductor element 1 and the lower surface of the island 4 are reached. The resin filling has not been completed. The resin that has proceeded to the side portion after that and reached the bend side blocks the entire bend, and the unfilled portions of the upper surface of the semiconductor element 1 and the lower surface of the island 4 remain as voids. The present invention has a cross section in which the resin flow path thickness a of the upper surface of the semiconductor element 1 and the lower surface of the island 4 and the upper and lower surfaces of the inner lead 6 on the sides are made uniform, and the flow length of the resin is made uniform at each of the cross sections and the unfilled portion is formed. This is to prevent the occurrence of voids.

2 (a) and 2 (b) are a perspective view and an AA sectional view of a second embodiment of the present invention. This embodiment is characterized in that a cross section for equalizing the resin thickness a from the side surfaces of the semiconductor element 1 and the island 4 is provided in order to improve the uniformity of the resin flow path. The advantage of this embodiment is that the homogeneity of the resin flow is increased.

[0008]

As described above, according to the present invention, in the resin-sealed semiconductor device, the resin channel width on the upper surface of the semiconductor element and the lower surface of the island and the resin channel width on the side surface of the semiconductor element and the island are made uniform. Thus, the resin flow length is made equal in each flow path, and there is an effect of preventing the occurrence of voids due to unfilling. By having such a cross-sectional portion, the void generation rate of 5 to 20% in the conventional structure is reduced to 0%.

[Brief description of drawings]

1A and 1B are a perspective view and an AA sectional view of a first embodiment of the present invention.

2 (a) and 2 (b) are a perspective view and an AA sectional view of a second embodiment of the present invention.

3A and 3B are a perspective view and a sectional view taken along line AA of a conventional resin-sealed semiconductor device.

[Explanation of symbols]

 1 semiconductor element 2 lead frame 3 resin 4 island 5 thin metal wire 6 inner lead 7 external lead

Claims (1)

[Claims] 1. A resin-encapsulated semiconductor device having a cross section in which the resin from the lead frame and the semiconductor element has a uniform thickness.