JPH02264458A - Lead frame - Google Patents

Abstract

PURPOSE:Not only to protect a chip against cracks but also to enable the fixing of an external heat dissipating fin to a lead frame by a method wherein one or more partially bent leads are led out of a sealing resin just under a semiconductor chip. CONSTITUTION:Heat dissipating leads 7 and a soldering groove 6 are formed at a time by bending a monolithic lead frame. Therefore, a soldering part 8 becomes small in size, so that solder is prevented from spreading over all the semiconductor chip 2 even if solder molten by heating is applied onto the soldering part 8, and consequently partial soldering can be realized. By this setup, a chip is protected against cracks even if a copper lead frame is employed. Moreover, if the heat dissipating leads 7 are exposed out of a resin 5, they serve as a heat dissipating fin, whereby a package can be made low in thermal resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to improvements in lead frames, and particularly to lower thermal resistance of packages.

[Conventional technology]

FIG. 4 is a top view of the vicinity of the mounting table of the lead frame shown in, for example, No. 63-134552, and (1)
is a chip mounting table (August 2013). The material used for the chip mounting table (1) is copper alloy, iron alloy, etc. Figure 5 shows the lead frame shown in Figure 4. FIG.

In the figure, (2) is a semiconductor chip, (3) is a gold wire for wiring, (4) is an external lead, and (5) is a resin.

Next, the operation will be explained.

For soldering on the chip mounting table (1), apply heated and melted solder to the part (8), place the semiconductor chip (2) on top of it, perform soldering, and place the semiconductor chip (2) on the chip mounting table (1). Fixed to. Thereafter, gold wires (3) for wiring are bonded from the semiconductor chip (2) to external leads (4), and this is sealed with resin (5) to produce a product.

[Problem to be solved by the invention]

Conventional lead frames were constructed as described above, but when the semiconductor chip size is large, the coefficient of thermal expansion between the copper alloy lead frame and the semiconductor chip is too different, which sometimes causes chip cracking during soldering. Only alloy lead frames could be used. On the other hand, since iron alloy frames are more expensive than copper alloy lead frames and have lower thermal conductivity, they have a problem in that they have a higher thermal resistance, which is the coefficient of temperature rise of the semiconductor chip due to the power consumption of the semiconductor chip.

This invention was made to solve the above problems, and aims to provide an inexpensive copper alloy lead frame that prevents chip cracking and allows attachment of external heat dissipation fins.

[Means to solve the problem]

The lead frame according to the present invention is molded in one piece and is simultaneously provided with grooves for partial soldering and leads for heat dissipation.

[Effect]

The heat dissipation leads of this invention can achieve low thermal resistance, and since partial soldering is done only in the center using grooves, chip cracking can be prevented, and even with large semiconductor chips, low thermal resistance Alloy lead frame can be used.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
2 is a side view of FIG. 1, and FIG. 3 is a side view of a semiconductor device completed using the lead frame of FIG. 1. In the figure, (1) to (5), and (8) are the same as the conventional one, so their explanations will be omitted. (6) is a groove for partial soldering;
(7) is a heat radiation lead.

Next, the operation will be explained.

The heat dissipation leads (7) of the lead frame are shown in Figures 1 and 2.
As shown in the figure, heat dissipation leads (7) and partial soldering grooves (6) are simultaneously formed by bending a single lead frame. Therefore, the soldering is part (8
) becomes small, and even if heated and molten solder is applied thereto, it will not spread over the entire semiconductor chip (2), making partial soldering possible. This can prevent the problem of chip cracking even with copper alloy lead frames.

Furthermore, if the heat dissipation leads (7) are exposed outside the resin (5), they can be used as heat dissipation fins, making it possible to lower the thermal resistance of the package.

Further, this heat dissipation lead (7) can be used as a ground pin.

In the above embodiment, the partial soldering grooves (6) are shown in two places, but one or more grooves (6) may be provided.

In addition, in the above embodiment, the heat dissipation lead (7) was bent into a rectangular shape, but the heat dissipation lead (7) was bent into a rectangular shape.
7) can be of any shape as long as it is outside the resin (5).
The same effects as in the above embodiment are achieved.

〔Effect of the invention〕

As described above, according to the present invention, since the single-piece lead frame is configured to be bent, it is possible to obtain an inexpensive package with low thermal resistance.

[Brief explanation of drawings]

FIG. 1 is a top view of the vicinity of a chip mounting table of a lead frame according to an embodiment of the present invention, FIG. 2 is a side view of FIG. 1,
FIG. 3 is a side view of a semiconductor device completed using the lead frame shown in FIG. FIG. 2 is a side view of a semiconductor device completed using the method. In the figure, (1) is a chip mounting table, (2) is a semiconductor chip, (3) is a gold wire for wiring, (4) is an external lead, and (5) is a semiconductor chip.
) is a resin, (6) is a groove for partial soldering, (7) is a heat dissipation lee, and (8) is a soldering part. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A lead having at least one partially bent lead directly below a mounted semiconductor chip on a chip mounting table, and at least one of the leads protruding outside the resin after resin sealing. flame.