Active solid-state devices (e.g. – transistors – solid-state diode – Lead frame – With separate tie bar element or plural tie bars
Reexamination Certificate
1999-11-12
2001-01-23
Hardy, David (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Lead frame
With separate tie bar element or plural tie bars
C257S690000, C257S692000, C257S697000
Reexamination Certificate
active
06177720
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device wherein a pair of radiating terminals and a plurality of lead terminals are formed from a single lead frame.
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 apparatus as just mentioned, a pellet comprising a semiconductor circuit is encapsulated in a resin member, and a plurality of lead terminals each formed from an elongated conductive plate are provided on the opposite sides of the resin member. Since those 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, a semiconductor device for use with a portable telephone set consumes a large amount of power, and consequently, a pellet of the semiconductor device generates a large amount of heat. Therefore, the generated heat of the pellet must be radiated efficiently.
A conventional example of a semiconductor device which solves the subject just described is described below with reference to FIG.
1
.
In integrated circuit device
1
which is a semiconductor device shown as an example here, a pellet of an integrated circuit formed from a semiconductor circuit is mounted on a radiating plate in the form of an island (not shown), and a pair of radiating terminals
2
having a comparatively large width are provided on the opposite left and right sides of the radiating plate.
A plurality of lead terminals
3
having a comparatively small width are arranged at positions forwardly and rearwardly of and adjacent to radiating terminals
2
. Lead terminals
3
are connected to connection pads of the pellet by bonding wires (not shown).
Since the pellet, the radiating plate, the bonding wires, inner portions of radiating terminals
2
and inner portions of lead terminals
3
are encapsulated in resin member
4
, outer portions
5
and
6
of terminals
2
and
3
are provided projectingly on the left and right side faces of resin member
4
.
Outer portions
5
and
6
of terminals
2
and
3
are bent downwardly, and each of radiating terminals
2
has a hole
7
in the form of a slit formed at the bent portion thereof.
When integrated circuit device
1
having such a construction as described above is to be mounted onto an upper surface of a circuit board, the plurality of lead terminals
3
of integrated circuit device
1
are connected to a plurality of signal lines of the circuit board by solder, and the pair of radiating terminals
2
are connected to conductor patterns such as grounding lines of the circuit board.
Thus, the pellet can input and output various information signals to and from the signal lines of the circuit board, and when the pellet generates heat, the heat is radiated from radiating terminals
2
.
A method of manufacturing integrated circuit device
1
having such a construction as described above is described briefly below with reference to
FIGS. 2 and 3
.
First, lead frame
11
is formed by etching a thin metal plate as seen in FIG.
2
. On this lead frame
11
, a plurality of frame patterns
12
of integrated circuit devices
1
are arranged in rows and columns, and radiating plate
13
is positioned at the center of one frame pattern
12
.
A pair of radiating terminals
2
having a comparatively large width are provided on the opposite left and right sides of radiating plate
13
. A plurality of lead terminals
3
having a comparatively small width are arranged on the opposite front and rear sides, which are upper and lower sides in
FIG. 2
, of radiating terminals
2
.
Intermediate portions of terminals
2
and
3
are connected to each other by a plurality of tie bars
14
. Outer end portions of terminals
2
and
3
are connected to outer frame portion
16
of frame pattern
12
by suspending pins
15
.
Inner portions
17
of lead terminals
3
are formed such that they are directed radially toward the center of radiating plate
13
. Inner portions
18
of radiating terminals
2
are formed integrally with radiating plate
13
.
Holes
7
each in the form of a slit are formed at portions of outer portions
5
of radiating terminals
2
at which radiating terminals
2
are to be bent later.
A pellet comprising a semiconductor circuit is placed onto an upper face of radiating plate
13
of lead frame
11
formed in such a manner as described above, and a plurality of connection pads of the pellet and the plurality of lead terminals
3
are individually connected to each other with bonding wires (not shown).
Lead frame
11
on which the pellet and the bonding wires are mounted integrally in this manner is placed into a cavity of a set of mutually removable metal molds such that it is held at outer portions
5
and
6
of radiating terminals
2
and
3
thereof by and between the metal molds, and in this state, molten resin is filled into the cavity of the metal molds and is then left so as to be solidified to form resin member
4
.
Then, as shown in
FIG. 3
, tie bars
14
and suspending pins
15
of lead frame
11
which are exposed to the outside from resin member
4
are cut away by punches
19
to
21
so that outer portions
5
and
6
of radiating terminals
2
and lead terminals
3
are separated from each other, and outer portions
5
and
6
are bent downwardly, thereby completing integrated circuit device
1
.
When outer portions
5
and
6
of terminals
2
and
3
are bent in this manner, although radiating terminals
2
generally have a comparatively large width, since holes
7
are formed at the bent portions of radiating terminals
2
, radiating terminals
2
can be bent readily similarly to lead terminals
3
having a comparatively small width.
However, since radiating terminals
2
and lead terminals
3
have different widths, punches
19
to
20
for cutting away tie bars
14
and suspending pins
15
cannot be arranged in an equal pitch.
Where punches
19
and
20
cannot be arranged in an equal pitch, operations for setting punches
19
and
20
to a press machine (not shown) are cumbersome, and also the universality of thus set punches
19
and
20
is low.
Further, in order to cut away suspending pins
15
of lead terminals
3
having a comparatively small width and suspending pins
15
of radiating terminals
2
having a comparatively large width, punches
20
having a comparatively small width and punches
21
having a comparatively large width are required. In other words, since a plurality of kinds of punches
20
and
21
having different widths are required, the productivity of integrated circuit device
1
is deteriorated thereby.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method of manufacturing a semiconductor device which is high in productivity and a lead frame which contributes to improvement in productivity of a semiconductor device.
In a conventional method of manufacturing a semiconductor device to which the present invention is applied, a lead frame is formed first.
In the lead frame, a single radiating plate and a plurality of lead terminals of a comparatively small width are connected integrally to each other by tie bars and suspending pins. The single radiating plate has a pair of radiating terminals of a comparatively large width formed projectingly on the opposite sides thereof, and the plurality of lead terminals of a comparatively small width are arranged at positions adjacent to the radiating terminals.
A pellet comprising a semiconductor circuit having a plurality of connection pads provided on an upper surface thereof is placed onto an upper surface of the radiating plate of the lead
Ichikawa Seiji
Kitakoga Toru
Miya Tatsuya
Nishibe Toshiaki
Nishimura Yoshikazu
Cruz Lourdes
Hardy David
Hayes, Soloway, Hennessey Grossman & Hage, P.C.
NEC Corporation
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