Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With dam or vent for encapsulant
Utility Patent
1997-09-12
2001-01-02
Saadat, Mahshid (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With dam or vent for encapsulant
C257S692000, C257S693000, C257S696000, C257S697000
Utility Patent
active
06169323
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a semiconductor device and a method for production thereof. More specifically, this invention relates to an improvement applicable to a semiconductor device packaged in a small outline nonlead plastic package and which is developed for the purpose to improve the mechanical reliability thereof and to enhance integration thereof and a method for producing a semiconductor device packaged in a small outline nonlead package, of which the connection strength between the lead and a wiring of a board on which the semiconductor device is mounted, is enhanced.
BACKGROUND OF THE INVENTION
A package employable for packaging a semiconductor device is typically classified into a ceramic package or a plastic package. Referring to
FIG. 1
, the plastic package originated from a Dual-Inline package evolved to a small outline package defined as a plastic package whose leads
4
horizontally extend from both sides of a plastic mold
1
and turn downward then toward the horizontal direction to extend along the surface of a board
5
on which the plastic package is mounted. In the drawing, a semiconductor device chip
2
bonded with the leads
4
by means of gold wires
3
is molded in the plastic mold
1
.
Referring to
FIG. 2
, the small outline package further evolved to a small outline nonlead package, in which leads
4
each of which is bonded with each of the pads of a semiconductor device chip
2
by means of a gold wire
3
are arranged along the bottom surface of a plastic mold
1
.
Referring to
FIG. 3
, a semiconductor device packaged in a small outline nonlead package is mounted on a board
5
, in a manner that each of the leads
4
is soldered to each of the wirings
6
printed on a board
5
made of a ceramic material, glass epoxy resin or the like, by application of solder, copper solder (copper paste), silver solder (silver paste) or the like.
The material usually employed for such a lead as was described above is a Ni—Fe alloy containing Ni by 42 weight % and Fe by 58 weight % or a copper alloy such as phosphor bronze. These materials have a less magnitude of wettability for solder, copper paste, silver paste and the like.
In the foregoing structure in which a semiconductor device packaged in a small outline nonlead package is mounted on a board, connection between the lead
4
and the wiring
6
is not necessarily reliable. During impulse tests and/or during practical operation, cracks grow in a soldering material
7
to cause disunion of the lead
4
from the wiring
6
. This is a serious drawback to reduce the mechanical reliability of a semiconductor device.
In the case of a semiconductor device packaged in a ceramic package, a semiconductor device having a plurality of ceramic packaged semiconductor devices piled on one another is available in the prior art. Such a piled structure is, however, not available for a semiconductor device packaged in a plastic package. Accordingly, a semiconductor device packaged in a plastic package on which one or more electronic components and/or plastic packaged semiconductor devices are arranged, is required to be developed.
OBJECTS AND SUMMARY OF THE INVENTION
A first object of this invention is to provide a semiconductor device packaged in a plastic package and having leads horizontally extending along the bottom surface of the plastic package, wherein the mechanical strength is enhanced for connection conducted by soldering the leads and a conductive object, such as wirings, with which the leads are mechanically and electrically connected.
A second object of this invention is to provide a method for producing a semiconductor device packaged in a plastic package and having leads horizontally extending along the bottom surface of the plastic package, wherein the mechanical strength is enhanced for connection conducted by soldering the leads and a conductive object, such as wirings, with which the leads are mechanically and electrically connected.
A third object of this invention is to provide a semiconductor device packaged in a plastic package on which one or more electronic components and/or plastic packaged semiconductor devices are arranged.
To achieve the first and second objects of this invention, this invention is based on a concept that the surface area for soldering is increased by making the end surface of a lead non-flat, uneven, pulsating or sawtooth shaped.
Accordingly, to achieve the first object of this invention, a semiconductor device in accordance with this invention comprises a semiconductor device chip, a plurality of leads each of which is bonded with each of the bonding pads of the semiconductor device chip, and a plastic mold packaging the semiconductor device chip bonded with the leads, allowing the leads to project themselves from the bottom surface thereof and to extend outward along the bottom surface thereof,
wherein each of the leads has a horizontal shape in which the surface of the edge thereof is uneven.
Following the foregoing concept, the horizontal shape of the edge of the lead can be a half circle, a half ellipse or a half polygon convex toward the inward direction.
Following the foregoing concept, one or more holes can be made for the lead.
Following the foregoing concept, the edge of the lead can be severed in the shape of a sector.
To achieve the first object of this invention, a semiconductor device in accordance with this invention comprises a semiconductor device chip, a plurality of leads each of which is bonded with each of the bonding pads of the semiconductor device chip, and a plastic mold packaging the semiconductor device chip bonded with the leads, allowing the leads to project themselves from the bottom surface thereof and to extend outward along the bottom surface thereof,
wherein the end of each of the leads is bent downward by 180° to make the side view the shape of J.
To achieve the first object of this invention, a semiconductor device in accordance with this invention comprises a semiconductor device chip, a plurality of leads each of which is bonded with each of the bonding pads of the semiconductor device chip, a plastic mold packaging the semiconductor device chip bonded with the leads, allowing the leads to project themselves from the bottom surface thereof and to extend outward along the bottom surface thereof, and a plurality of plated metal plates arranged along the sides of the plastic mold at locations corresponding to those of the leads.
To achieve the first object of this invention, a semiconductor device in accordance with this invention comprises a semiconductor device chip, a plurality of leads each of which is bonded with each of the bonding pads of the semiconductor device chip, a plastic mold packaging the semiconductor device chip bonded with the leads, allowing the leads to project themselves from the bottom surface thereof and to extend outward along the bottom surface thereof, a plurality of longitudinal recesses produced along the sides of the plastic mold at locations corresponding to those of the leads, and a plurality of plated metal plates arranged in the longitudinal recesses.
To achieve the first object of this invention, a semiconductor device in accordance with this invention comprises a semiconductor device chip, a plurality of leads each of which is bonded with each of the bonding pads of the semiconductor device chip, a plastic mold packaging the semiconductor device chip bonded with the leads, allowing the leads to project themselves from the bottom surface thereof, a plurality of longitudinal recesses produced along the sides of the plastic mold at locations corresponding to those of the leads, a plurality of plated metal plates arranged in the longitudinal recesses, and a plurality of plated metal plates arranged along the top surface of the plastic mold in continuation to the plated metal plates arranged along the sides of the plastic mold.
To achieve the second object of this invention, a method for producing a semiconductor device comnprises a step for fixing a semiconductor device chip on a lead f
Burdett James R.
Fenty Jesse A
Frank Robert J.
OKI Electric Industry Co., Ltd.
Saadat Mahshid
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