Metal deforming – With cutting – By shearing tool-couple
Reexamination Certificate
2000-10-06
2002-09-03
Crane, Daniel C. (Department: 3725)
Metal deforming
With cutting
By shearing tool-couple
C072S340000, C257S704000
Reexamination Certificate
active
06442990
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plate-shaped member having a recess, a method of manufacturing the plate-shaped member, and a press die for forming the recess. More particularly, the present invention relates to a plate-shaped member having a recess for electronic parts which recess is formed without bending a metallic plate, a method of manufacturing such plate-shaped member, and a press die, for forming the recess, having a punch for forming the recess on the metallic plate by means of press forming and a die, on which the metallic plate is put, arranged opposed to the punch.
2. Description of the Related Art
As illustrated in
FIG. 19
, which is referred to hereinafter to explain a semiconductor device to which the present invention can be applied, a semiconductor device containing a cap-shaped heat dissipation plate adhered to semiconductor element is mounted on a circuit board.
Not only the semiconductor device but also other various electronic parts such as a chip capacitor can be mounted on the circuit board. Therefore, the upper surface and lower surface of the heat dissipation plate, the profile of which is formed into a cup-shape, must be flat.
Generally, the cap-shaped heat dissipation plate has been produced from a metallic plate by press forming the metallic plate. The press forming, as disclosed in the “prior art” section of Japanese Unexamined Patent Publication (Kokai) No. 2000-42642 and shown in
FIGS. 1A
to
1
C of this application for reference, comprises the steps of providing a metallic plate
90
as a raw material as shown in
FIG. 1A
, and then placing the metallic plate
90
on a die
91
of the pressing machine, followed by pressing the metallic plate
90
from a side of the surface
90
a
of the plate
90
with a pressing punch
92
as shown in FIG.
1
B. As a result, as is shown in
FIG. 1C
, a recess
93
is formed on the surface
90
a
of the plate
90
. Further, a bottom portion
90
c
having the predetermined thickness is formed in a bottom surface of the recess
93
. A semiconductor element (not shown) is contained in a space
95
formed by the recess
93
.
In the press forming illustrated in
FIGS. 1A
to
1
C, a material of the recess
93
can move, in the direction of the arrows shown in
FIG. 1B
, in the metallic plate
90
during pressing the plate
90
with the punch
92
. Thus, as is shown in
FIG. 1C
, a rounded corner part
93
a
is produced as a result of sagging of the material in the opening ends of the recess
93
, along with the formation of a tapered inner wall
93
b.
Further, the metallic plate
90
is warped, because the outer ends are lifted at an angle &thgr; due to the stress applied to the plate
90
by the punch
92
.
Due to the above problems, it is difficult for the prior art press forming method to ensure that the inside and outside of the heat dissipation plate are formed completely flat. Note that Japanese Kokai NO. 2000-42642 teaches a method for forming a recess, in a metallic plate, with a recess having a perpendicular inner wall. However, it is still difficult to produce a heat dissipation plate having completely flat inside and outside surfaces.
To avoid the above problems, there has been suggested a cutting method, in place of the press forming method, in the formation of the cap-shaped heat dissipation plate. That is, as illustrated in
FIG. 2
, a metallic plate
90
is cut to form a recess
93
which defines a space
95
for receiving a semiconductor element or other part (not shown), followed by cutting off the unnecessary end portions at the cutting line, shown by a dotted line in the drawing, to obtain a cap-shaped heat dissipation plate having the predetermined configuration and size. As illustrated, the recess
93
has a perpendicular inner wall
93
b,
along with a bottom portion
90
c
with a predetermined thickness.
When the recess is formed in the metallic plate by cutting as described above, the inside and outside of the finally obtained cap-shaped heat dissipation plate can be made flat. Note, however, work time necessary for the process of forming the heat dissipation plate is mainly determined by the process of forming the recess on the metallic plate by means of cutting and it is very difficult to enhance the cutting speed.
Further, in order to form the cap-shaped heat dissipation plate by cutting, it is necessary to provide a metallic plate, the thickness of which is at least the same as the thickness between the upper end and the lower end of the side wall
90
d
which defines the heat dissipation plate. In order to satisfy this requirement, it is generally necessary to use a metallic plate, the thickness of which is much larger than the thickness of the side wall
90
d,
thus the material cost is increased.
If it were possible to produce the cup-shaped heat dissipation plate by using press forming, the speed of producing the heat dissipation plate could be remarkably increased, and further a metallic plate could be used which is thinner than a metallic plate used in the production of the cap-shaped heat dissipation plate by cutting.
SUMMARY OF THE INVENTION
The present invention is directed to solve the prior art problems discussed above.
One object of the present invention is to provide a plate-shaped member, having a recess, the inside and outside of which are formed as flat as possible by using press forming, particularly useful for electronic parts.
Another object of the present invention is to provide an improved method of manufacturing the plate-shaped member, having a recess, by press forming.
Still another object of the present invention is to provide a press die for forming recesses which is useful in the production of the plate-shaped member, having a recess, from a metallic plate.
The above objects and other objects of the present invention will be easily understood from the following detailed description of the present invention.
The present inventors have made investigation into the above problems, and as a result, they have found the following facts and accomplished the present invention. That is, if the fabrication is conducted on a metallic plate to form a first recess and, on the bottom face of the thus formed first recess, a second recess is formed by punching, while metal extruded by punching at this time is protruded in such a manner that a bottom portion of the first recess between the first and the second recess is protruded to form a protuberance portion, followed by making an upper face of this protuberance portion flat, the thickness, between the upper end and the lower end, of the side wall of the produced recess can be made larger than the thickness of the metallic plate on which press forming is applied.
In one aspect thereof, the present invention provides a plate-shaped member having a recess, defined by a bottom wall portion and a side wall portion extending from a peripheral end of the bottom wall portion, formed by press forming a metallic plate without bending the same, characterized in that an upper surface and lower surface of the side wall portion and bottom wall portion each has a flat and parallel surface, the thickness of the bottom wall portion is smaller than the thickness of the metallic plate (before press forming), and the thickness, between an upper end surface and a lower end surface, of the side wall portion is larger than the thickness of the metallic plate (before press forming).
The plate-shaped members with recesses according to the present invention can be advantageously used for a variety of parts based on the flat inside and outside of the recesses, preferably as electronic parts, more preferably as a cap-shaped heat dissipation plates for semiconductor elements in semiconductor devices.
Further, in another aspect thereof, the present invention provides a method of manufacturing a plate-shaped member having a recess, defined by a bottom wall portion and a side wall portion extending from a peripheral end of the bottom wall portion, by press forming a metallic plate without bending
Komatsu Hiroyuki
Nagamine Yoshihisa
Takahashi Akira
Crane Daniel C.
Paul & Paul
Shinko Electric Industries Co. Ltd.
LandOfFree
Method of manufacturing a plate-shaped member having a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of manufacturing a plate-shaped member having a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of manufacturing a plate-shaped member having a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2856280