Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With stress relief
Reexamination Certificate
2001-10-04
2004-03-23
Lee, Eddie (Department: 2811)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With stress relief
C257S666000, C257S670000, C257S674000, C257S676000, C257S784000, C257S787000
Reexamination Certificate
active
06710431
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin-sealed type semiconductor device, and especially to a one-side resin-sealed type semiconductor device in which a surface of a lead frame on which a semiconductor element is mounted is sealed with a resin and a lead frame used therefor.
2. Description of Related Art
Resin-sealed type semiconductor devices each provided with a lead frame for electrically connecting electrodes of the semiconductor to an outer wiring and the like are widely used. In such a semiconductor device, a lead frame generally comprises a supporting portion for mounting a semiconductor element thereon, hanging lead portions for supporting the supporting portion, and lead terminal portions for connecting metal wires thereto. A lead frame used in the process of fabricating semiconductors includes a plurality of unit regions corresponding to a plurality of semiconductor devices so that the plurality of semiconductor devices can be fabricated at the same time. One unit region has a substantially rectangular shape. Each of the hanging lead portions extends inwardly from a corner portion of this rectangle, and in many cases, the lead terminal portions extend inwardly from side parts of the unit region.
FIG. 5
is an enlarged schematic pan view showing a part in the vicinity of a corner of a unit region.
In the central part of the substantially rectangular unit region (in the direction of arrow G), a supporting portion
51
is disposed. A hanging lead portion
52
extends from the supporting portion
51
toward the corner portion. In the side parts of the unit region, substantially rectangular lead terminal portions
53
are provided. Base end portions of the lead terminal portions
53
are connected to a peripheral frame part
50
. The longitudinal direction of the hanging lead portion
52
and the longitudinal direction of the lead terminal portion
53
makes an angle of substantially 45°.
In a lead frame, a plurality of unit regions each having such a structure are arranged and connected to the frame part
50
. In the process of fabricating semiconductor devices, a lead frame is sealed with a sealing resin in such a manner that the bottom surface of the lead terminal portion
53
is exposed. Thereafter, each unit of lead frame is cut along a cutting line M shown in broken line, and the cut end face is substantially in the same plane with the side surface of the sealing resin.
In order to obtain a small-sized semiconductor device, it is preferable that the length of the lead terminal portion
53
is as short as possible. However, since the lead terminal portion
53
functions as a lead for connection with outer wiring substrate, the lead terminal portion
53
needs to have a length (area) more than a predetermined length (area). From these reasons, the lead terminal portion
53
is formed to have a predetermined necessary minimum length L
1
.
The minimum distance between the hanging lead portion
53
and the lead terminal portion
53
A adjacent to the hanging lead portion
53
must be large enough to ensure insulating reliability between them. However, in order to obtain a small-sized semiconductor device, it is preferable that the minimum distance between them is small. From these reasons, the minimum distance between them is designed to be a predetermined necessary minimum distance L
2
.
However, since the predetermined length L
1
and the predetermine distance L
2
are required to be secured, miniaturization of mounting area of a semiconductor device is limited.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a semiconductor device in which each lead terminal portion has a length (area) necessary for outer connection and at has a length (area) necessary for outer connection and at the same time insulating reliability between the hanging lead portions and lead terminal portions is secured, and a lead frame used for the semiconductor device.
Another object of the present invention is to provide a semiconductor device having a small mounting area, and a lead frame used for the semiconductor device.
A semiconductor device according to the present invention comprises a semiconductor chip having electrodes on the surface thereof, a lead frame having a plurality of lead terminal portions for electric connection and a plurality of hanging lead portions each extending obliquely with respect to the lead terminal portions and supporting a supporting portion on which the semiconductor chip is mounted, metal wires for connecting the lead terminal portions and the electrodes of the semiconductor device, and a sealing resin for sealing the semiconductor element, the lead frame and the metal wires in such a manner that a part of each lead terminal portion is exposed. The plurality of lead terminal portions include chamfered lead terminal portions each having, at its head, a chamfered portion formed substantially in parallel with the hanging lead portion so as to avoid interference with the hanging lead portion.
Further, a lead frame according to the present invention comprises a plurality of lead terminal portions for electric connection and a plurality of hanging lead portions each extending obliquely with respect to the lead terminal portions and supporting a supporting portion on which the semiconductor chip is mounted. The plurality of lead terminal portions include chamfered lead terminal portions each having, at its head, a chamfered portion formed substantially in parallel with the hanging lead portion so as to avoid interference with the hanging lead portion.
According to this invention, the lead terminal portions are chamfered substantially in parallel with the hanging lead portion so as to avoid interference with the hanging lead portions. Accordingly, even if the chamfered lead terminal portion is disposed nearer to the hanging lead portion in comparison with the case of the conventional lead terminal portion, a distance more than a predetermined distance can still be secured between the lead terminal portion and the hanging lead portion.
That is, in a conventional lead frame, a lead terminal portion has a corner portion protruding toward a hanging lead portion. Therefore, it has been necessary to dispose the lead terminal portion substantially on the peripheral part side in order to avoid interference between an edge of the corner portion and the hanging lead portion and secure a distance more than a predetermined value therebetween. As a result, a unit region in a lead frame corresponding to a semiconductor becomes large, and the size in the plane direction of a semiconductor device using this unit region becomes large.
On the contrary, according to the present invention, the lead terminal portion has a chamfered portion at its head and is opposed to the hanging lead portion at this chamfered portion. Therefore, the hanging lead portion can be disposed at a more inner portion in comparison with the case of the conventional structure. Accordingly, a unit region of lead frame can be small-sized. As a result, the size in the plane direction of a semiconductor device can be reduced and the mounting area of the same can be also reduced.
The chamfered portion is preferably comprises a linear side (C chamfering side) in parallel with the lateral side of the hanging lead portion. However, other shapes are similarly effective as long as the portion is chamfered so as to avoid interference by the hanging lead portion. For example, the chamfered portion may comprise a curved side (for example, R chamfering side). Further, in the chamfered portion, the oblique side may extend through only a part or the whole width of the lead terminal portion.
It is preferable that the abovementioned chamfered lead terminal portion is disposed adjacent to the hanging lead portion.
Not only the lead terminal portion adjacent to the hanging lead portion but also another lead terminal portion adjacent to this chamfered lead terminal portion may be a chamfered lead terminal portion. However, in this case, the chamfered lead
Lee Eddie
Parekh Nitin
Rabin & Berdo P.C.
Rohm & Co., Ltd.
LandOfFree
Semiconductor device and lead frame used therefor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Semiconductor device and lead frame used therefor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor device and lead frame used therefor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3273162