Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Making plural separate devices
Reexamination Certificate
1999-10-14
2001-11-20
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Making plural separate devices
C438S126000, C438S127000, C257S675000, C257S696000, C257S707000
Reexamination Certificate
active
06319753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a semiconductor device, and more particularly to a semiconductor device having lead terminals bent in a J-shape and a method of manufacturing the semiconductor device.
2. Description of the Related Art
Conventionally, semiconductor devices such as an LSI (Large Scale Integrated Circuit) and a transistor are utilized in various electronic apparatus.
In such a semiconductor device as just mentioned, a pellet of a semiconductor circuit is encapsulated in a resin member, and a large number of lead terminals each formed from an elongated conductive plate are provided on the opposite sides of the resin member. Since the lead terminals are connected to connection pads of the pellet in the inside of the resin member, if the semiconductor device is mounted on a circuit board and the lead terminals are connected to signal lines, then various signals can be inputted to and outputted from the pellet.
While such semiconductor devices are utilized to various applications, for example, for a semiconductor device for use with a portable telephone set, it is required to minimize the mounting area. Thus, a semiconductor device wherein outer portions of lead terminals extending outwardly from side faces of a resin member are bent in a J-shape and the free ends of the lead terminals are positioned on a lower face of the resin member to reduce the mounting area has been put into practical use.
Such semiconductor devices are disclosed, for example, in Japanese Patent Laid-open No. 221242/95, Japanese Patent Laid-open No. 263607/95, and Japanese Patent Laid-open NO. 88296/96.
In a semiconductor device wherein lead terminals are bent in a J-shape and the free ends thereof are positioned on a lower face of a resin member as described above, since also the overall occupation area is decreased and the lead terminals are connected to a circuit board at positions of the lower face of the resin member, the mounting area can be reduced.
However, with such a semiconductor device as described above, since the free ends of the lead terminals are positioned on the lower face of the resin member, if a radiating plate made of a conductive island is exposed to the lower face of the resin member, then the radiating plate and the lead terminals are short-circuited to each other.
Therefore, a semiconductor device wherein the lead terminals are bent in a J-shape as described above is so structured that the radiating plate is not exposed to the lower face of the resin member, and consequently, it does not exhibit a good heat radiating property of the pellet. However, in a semiconductor device utilized for transmission of radio waves in a portable telephone set, the pellet generates a large amount of heat because it consumes a large amount of power, and therefore, it is required to radiate the heat efficiently.
In this connection, in the semiconductor device disclosed in Japanese Patent Laid-open No. 221242/95, the radiating plate is exposed to the lower face of the resin member while an insulating film is applied to the lower face of the radiating plate to prevent short-circuiting with the lead terminals. However, since this structure does not allow connection of the radiating plate to a grounding line of the circuit board, a good heat radiating property cannot be anticipated.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a semiconductor device having lead terminals bent in a J-shape with the free ends of the lead terminals positioned on a lower face of a resin member wherein a radiating plate is exposed to the lower face of the resin member to realize a good heat radiating property whereas the radiating plate and lead terminals are not short-circuited to each other.
In a conventional semiconductor device to which the present invention is applied, a pellet of a semiconductor circuit having a plurality of connection pads provided thereon is placed on an upper face of a radiating plate, and a plurality of lead terminals each formed from an elongated conductive plate are disposed on the outer sides of the pellet. The lead terminals and connection pads of the pellet are connected individually to each other by bonding wires, and at least a portion of the radiating plate, the pellet, the bonding wires and inner a portions of the lead terminals are encapsulated in a resin member. The outer portions of the lead terminals which extend outwardly from side faces of the resin member are bent in a J-shape such that free ends of the outer portions of the lead terminals bent in this manner are positioned on the lower face of the resin member.
According to a first aspect of the present invention applied to such a semiconductor device as described above, a recess are formed on an outer peripheral portion of the radiating plate, and the radiating plate is exposed to the lower face of the resin member. The free ends of the outer portions of the lead terminals are positioned in the recess of the resin member, and insulating elements are positioned in gaps between the free ends of the outer portions of the resin member and the recess of the radiating plate.
Accordingly, since the outer portions of the lead terminals which extend outwardly from the side faces of the resin member are bent in a J-shape and the free ends are positioned on the lower face of the resin member, the mounting area is reduced. Besides, since the radiating plate is exposed to the lower face of the resin member, the heat radiating property of the pellet is high.
Meanwhile, since the free ends of the outer portions of the lead terminals are positioned in the recess formed on the outer peripheral portion of the radiating plate and the insulating elements are positioned in the gaps between the free ends of the lead terminals and the recess of the radiating plate, the lead terminals are not short-circuited to the radiating plate. In short, the present invention can achieve both of reduction of the mounting area and augmentation of the heat radiating property of a semiconductor device.
It is to be noted that, in the present invention, the direction in which the pellet is mounted with respect to the radiating plate is referred to as upward direction while a direction perpendicular to the direction is referred to as sideward direction. However, such directions are used conveniently in order to simplify description and do not restrict any direction when the device is manufactured or used actually.
Further, the radiating plate in the present invention signifies a member on which a pellet is mounted and which contributes to radiation of heat from the pellet, and allows an island made of a metal. The recess of the radiating plate signify shapes from which material at the portions of the radiating plate at which the free ends of the lead terminals are positioned is removed, and they need not necessarily have recessed or concave outer shapes. The insulating elements may be any member or members which have an insulating property and can be disposed in the gaps between the lead terminals and the radiating plate, and thus allow, for example, a bonding agent or projections of the resin member.
Meanwhile, in a semiconductor device according to a second aspect of the present invention, a recess are formed on an outer peripheral portion of the radiating plate, and the radiating plate is exposed to the lower face of the resin member. Projections provided projectingly on an outer peripheral portion of the lower face of the resin member are positioned in the recess of the radiating plate, and recess are formed on the lower faces of the projections of the resin member. Further, the free ends of the outer portions of the lead terminals are positioned in the recess of the resin member.
Accordingly, in the semiconductor device of the present invention, since the outer portions of the lead terminals which extend outwardly from the side faces of the resin member are bent in a J-shape and the free ends of them are positioned on the lower face of the resin member, the mounting area is redu
Ichikawa Seiji
Kitakoga Toru
Miya Tatsuya
Nishibe Toshiaki
Nishimura Yoshikazu
Berezny Nema
Bowers Charles
Hayes, Soloway, Hennessey Grossman & Hage, P.C.
NEC Corporation
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