Wireworking – Crimping
Reexamination Certificate
2000-02-02
2002-04-02
Larson, Lowell A. (Department: 3725)
Wireworking
Crimping
C072S021400
Reexamination Certificate
active
06363976
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor manufacturing apparatus and a method of manufacturing a semiconductor device and, more particularly, to a technique for forming a lead of a semiconductor device.
2. Description of the Background Art
Background art first and second lead forming apparatuses
100
P and
200
P will be described hereinafter with reference to
FIGS. 13 through 17
.
First, a semiconductor device
10
P is prepared which has leads
11
P projecting from a package
12
P in first and third directions D
1
and D
3
(both horizontal) perpendicular to each other. Only leads
11
P projecting in the first direction D
1
are shown in
FIGS. 13 through 16
, and the forming of these leads
11
P will be mainly described. The semiconductor device
10
P is placed on a die
151
P fixed to a lower body of a press (not shown) of the first lead forming apparatus
100
P.
An upper body of the press including a punch holder
110
P, an openable block
120
P, a stripper
181
P and the like moves downwardly in a second direction D
2
(vertical). At the start of the downward movement, the stripper
181
P and the die
151
P together hold therebetween part of the lead
11
P which is near the package
12
P. As the upper body continues moving downwardly, an end portion
101
T
1
P of a punch
101
P comes into contact with the lead
11
P.
A structure of the upper body will be described below. The punch
101
P is mounted on the punch holder
110
P for pivotal movement about a shaft
105
P both in a direction indicated by the arrow A
11
P (also referred to hereinafter as an “opening direction A
11
P”) and in a direction indicated by the arrow A
12
P (also referred to hereinafter as a “closing direction A
12
P”). An end portion
101
T
2
P of the punch
101
P opposite from the end portion
101
T
1
P with respect to the shaft
105
P and the punch holder
110
P are coupled to each other by a spring
106
P. The spring
106
P urges, or exerts a pivoting force on, the end portion
101
T
2
P in the opening direction A
11
P. A roller
101
RP is mounted on the end portion
101
T
2
P and is in contact with a vertical surface
120
S
1
P or an inclined surface
120
S
2
P of the openable block
120
P. The openable block
120
P and the punch holder
110
P are movable in the second direction D
2
independently of each other. At the start of the downward movement of the upper body, the roller
101
RP is in contact with the vertical surface
120
S
1
P, and the end portion
101
T
1
P is at the limit of the pivotal movement of the punch
101
P in the opening direction A
11
P. Although only the single punch
101
P and the components associated with the operation thereof are shown in
FIGS. 13 through 16
for purposes of illustration, the background art lead forming apparatus
100
P comprises a plurality of such structures. For example, for the package
12
P (known as a QFP (Quad Flat Package)) of a quadrilateral configuration as viewed in the second direction D
2
with the leads
11
P projecting from the four end surfaces
12
SP (as shown in
FIG. 17
) of the package
12
P which correspond, respectively, to the four sides of the quadrilateral configuration, the punch
101
P and its associated components are provided for each of the end surfaces
12
SP. This holds true for the second lead forming apparatus
200
P to be described later.
The upper body stops moving downwardly when the end portion
101
T
1
P comes into contact with the lead
11
P. Thereafter, the openable block
120
P moves upwardly. As the openable block
120
P moves upwardly, the roller
101
RP moves along the inclined surface
120
S
2
P, and the end portion
101
T
1
P accordingly pivots about the shaft
105
P in the closing direction A
12
P. Such a pivotal movement causes the lead
11
P to be bent in a direction indicated by the arrow A
1
P of FIG.
13
. Specifically, the pivotal movement of the end portion
101
T
1
P in contact with the lead
11
P in the closing direction A
12
P forces a punch-side forming surface
101
SP (shown in
FIG. 14
) to bend the lead
11
P toward a die-side forming surface
151
SP (shown in FIG.
14
).
When the lead
11
P is bent into a predetermined configuration, the openable block
120
P stops and then starts moving downwardly. This causes the end portion
101
T
1
P to pivot in the opening direction A
11
P to bring the punch
101
P out of contact with the lead
11
P. Thereafter, the upper body and the stripper
181
P move upwardly, and the upper body returns to its original position. This completes a series of operations.
After the first lead forming apparatus
100
P forms a shoulder of the lead
11
P, the second lead forming apparatus
200
P forms a distal portion of the lead
11
P. This forms the lead
11
P into a final configuration.
As illustrated in
FIGS. 15 and 16
, the second lead forming apparatus
200
P is similar in construction to the first lead forming apparatus
100
P except that a die-side forming surface
252
SP of a die
252
P and a punch-side forming surface
201
SP of a punch
201
P differ in configuration from the above described forming surfaces
151
SP and
101
SP (shown in FIG.
14
). The forming surfaces
252
SP and
201
SP of the second lead forming apparatus
200
P are configured and sized to conform to the final configuration of the lead.
The second lead forming apparatus
200
P performs an operation similar to that of the first lead forming apparatus
100
P described above to finish the semiconductor device
10
P having the leads
11
P shown in FIG.
17
.
The background art lead forming apparatuses
100
P and
200
P present problems to be described below. Although the problems with the first lead forming apparatus
100
P are described below, the description applies equally to the second lead forming apparatus
200
P.
<Problem (1): Scratch on Lead Being Formed>
As above described, the background art lead forming apparatus
100
P bends the lead
11
P by pivoting the end portion
101
T
1
P in contact with the lead
11
P in the closing direction A
12
P. Since the end portion
101
T
1
P moves or lowers in the second direction D
2
while being pivoted during the bending, i.e., slides on the lead
11
P, the lead
11
P is scratched or a metal plating is removed from the lead
11
P. It is contemplated that the background art lead forming apparatus
100
P can alleviate the sliding movement to some extent by rendering the punch
101
P pivotable about the shaft
105
P. In the lead forming apparatus
100
P, however, the center of curvature of the lead
11
P being bent does not always coincide with the center (of curvature) of a path of movement of the end portion
101
T
1
P. In other words, the shape of the lead
11
P being bent is not taken into consideration to pivot the end portion
101
T
1
P. This might causes an intensive pressure to be applied between the end portion
101
T
1
P and the lead
11
P. It is therefore difficult to completely prevent the above described scratches and the like.
Additionally, the lead
11
P held between the stripper
181
P and the die
151
P might be dented. When a force that lifts the semiconductor device
10
P is developed by the above described sliding movement and exerted upon the lead
11
P, such a dent is significantly great.
The scratches and the like on the lead
11
P give rise to the oxidation or corrosion of the lead
11
P to result in the increase in resistance of the lead
11
P or a break in the lead
11
P, causing the semiconductor device
10
P to be incapable of performing a predetermined operation.
<Problem (2): Nonuniform Lead Configurations>
As above described, the background art lead forming apparatus
100
P comprises the punch
101
P and its associated components which are provided for each end surface
12
SP of the package
12
P. Thus, variations in size of the punch
101
P and the die
151
P occur due to, for example, manufacturing accuracy and wear with time to cause differences in clearance between the punch
101
P and the die
151
P. In view of the fact that the punches
101
P
Aoki Hideji
Kamachi Katsuhito
Manabe Hidekazu
Larson Lowell A.
Mitsubishi Electric Engineering Co. Ltd.
LandOfFree
Semiconductor manufacturing apparatus and method of... 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 manufacturing apparatus and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Semiconductor manufacturing apparatus and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2867657