Semiconductor device with resin package

Details Semiconductor device with resin package Semiconductor device with resin package

2001-02-16

2003-06-10

Flynn, Nathan J. (Department: 2826)

Active solid-state devices (e.g., transistors, solid-state diode

Lead frame

With structure for mounting semiconductor chip to lead frame

C257S684000, C257S787000, C257S796000

Reexamination Certificate

active

06576986

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device with a resin package to enclose a semiconductor chip.
2. Description of the Related Art
FIGS. 5-7
of the accompanying drawings show a conventional package type semiconductor device. The illustrated device includes a first lead
1
′, a second lead
2
′, a semiconductor chip
3
′ and a synthetic resin package
4
′ to enclose the chip
3
′, the inner portion
1
a
′ of the first lead
1
′ and the inner portion
2
a
′ of the second lead
2
′. As seen from
FIGS. 6 and 7
, the inner portion
1
a
′ has a width W
1
′ which is greater than the width of the remaining portion of the lead
1
′. Similarly, the inner portion
2
a
′ has width W
2
′ which is greater than the width of the remaining portion of the lead
2
′. The width W
1
′ is equal to the width W
2
′. The chip
3
′ is mounted on the enlarged inner portion
1
a
′ of the first lead
1
′, while also being connected to the enlarged inner portion
2
a
′ of the second lead
2
′. With this structure, the heat generated at the chip
3
′ is efficiently conducted to the first and the second leads
1
′,
2
′, which is advantageous to maintaining the proper function of the device.
However, the enlarged inner portions
1
a
′ and
2
a
′ of the leads
1
′ and
2
′ are not readily bent when the resin package
4
′ is bent upon application of an external force. Thus, unfavorably, a crack may be generated in the bent package
4
′ by the rigid inner portions
1
a
′ and
2
a
′. One way to address this problem is to enlarge the height H′ and/or the width S′ of the package
4
′. The enlargement of the package
4
′, however, leads to an increase in size and weight of the resulting semiconductor device.
FIGS. 8 and 9
show another conventional semiconductor device in which a relatively narrow connector
5
′ is used for connecting the semiconductor chip
3
′ to the second lead
2
′. In this device, a crack is less liable to form in the package
4
′ since the narrow connector
5
′ can be readily bent together with the package
4
′. However, the illustrated structure will cause an increase in production cost since the auxiliary connector
5
′ must be prepared separately from the first and the second leads
1
′,
2
′. In addition, since the connector
5
′ is not integrally formed with the second lead
2
′, the unfavorable heat may not be conducted efficiently from the semiconductor chip
3
′ to the lead
2
′.
SUMMARY OF THE INVENTION
The present invention has been proposed under the circumstances described above, and its object is to provide a semiconductor device free from the above-discussed problems.
According to the present invention, there is provided a semiconductor device which includes: a first one-piece lead including an enlarged end; a semiconductor chip mounted on the enlarged end; a second one-piece lead including a flexible end connected to the chip and an outer end; and a resin package for enclosing the enlarged end, the chip and the flexible end. The first and the second leads may partially project from the package in the opposite directions. To prevent the inner portion of the second lead from damaging the package, the flexible end of the second lead is rendered smaller in width than its outer end projecting from the package.
Preferably, the width of the flexible end of the second lead may be equal to &thgr;×the width of the enlarged end of the first lead, where 0.4≦&thgr;≦0.6.
Preferably, the length of the flexible end may be greater than half the total length of the second lead.
Preferably, the flexible end may includes a first portion and a second portion, wherein the first portion is connected to the chip via a conductive material, while the second portion extends from the first portion at a predetermined angle. With such an arrangement, the flexible end of the second lead can be sufficiently long without increasing the size of the resin package.
In a preferred embodiment, the first portion of the flexible end may be generally parallel to the enlarged end of the first lead.
Preferably, the first portion of the flexible end may be longer than the second portion, so that the first portion is more flexible than the second portion.
In the preferred embodiment of the present invention, the package includes a top surface and a bottom surface opposite to the top surface, wherein the first portion is disposed closer to the top surface than to the bottom surface.
Preferably, the first and the second leads may be exposed in the bottom surface of the package, so that the two leads are reliably soldered to a printed circuit board.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.


REFERENCES:
patent: 4945398 (1990-07-01), Kurita et al.
patent: 5508557 (1996-04-01), Sunada
patent: 5528079 (1996-06-01), McIver
patent: 5821611 (1998-10-01), Kubota et al.

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