Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Opposed registering coacting female molds
Reexamination Certificate
2001-01-29
2003-03-11
Davis, Robert (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Opposed registering coacting female molds
C425S116000, C425S125000, C425S544000, C425S556000, C425S437000, C425S440000, C425S443000
Reexamination Certificate
active
06530764
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin-sealing mold for encapsulating a semiconductor device by sealing a semiconductor element in a molding resin, a method of encapsulating a semiconductor device in a resin using the resin-molding mold, and a method of releasing the resin-sealed semiconductor device from the mold.
2. Description of the Related Art
FIG. 7
is a cross-sectional view that shows a conventional resin-sealing mold of a semiconductor device.
FIG. 8
is a cross-sectional view that shows a mold-releasing state of the conventional resin-sealing mold of a semiconductor device. In
FIGS. 7 and 8
, a semiconductor resin package
51
is formed as follows: A semiconductor element
22
is installed on a lead frame
21
with the semiconductor element
22
being connected to the lead frame
21
through a bonding wire
23
, and this is sealed with mold resin
29
set on a plunger
30
.
Moreover, the upper mold of the resin-sealing mold of semiconductor device is constituted by an upper-mold cavity insert
24
a
having a plurality of cavities
36
a
, a cull insert
26
, an upper-mold retainer
27
a
including the upper cavity insert
24
a
and the cull insert
26
, an elastic post
25
installed between an upper-mold backing plate
34
a
and the upper-mold retainer
27
a
, an eject pin
28
, an eject rod
31
and an upper-mold frame
35
a.
The eject pin
28
has one end sandwiched between an upper-mold ejector plate
32
a
and an upper-mold pressing plate
33
a
with the other end communicating with the upper-mold cavity
36
a
. Here, the eject pin
28
penetrates the upper-mold retainer
27
a
and the upper-mold cavity insert
24
a
. The eject rod
31
is attached to the upper-mold ejector plate
32
a
. The upper-mold frame
35
a
allows the upper-mold retainer
27
a
and the upper-mold backing plate
34
a
to engage each other.
Moreover, the lower mold of the resin-sealing mold of a semiconductor device is constituted by an lower-mold cavity insert
24
b
having a plurality of cavities
36
b
, a lower-mold retainer
27
b
that has a built-in chamber
11
and includes the lower-mold cavity insert
24
b
, an elastic post
25
installed between a lower-mold backing plate
34
b
and the lower-mold retainer
27
b
, an eject pin
28
, an eject rod
31
and an lower-mold frame
35
b.
The eject pin
28
has one end sandwiched between a lower-mold ejector plate
32
b
and a lower-mold pressing plate
33
b
with the other end communicating with the lower mold cavity
36
b
. Here, the eject pin
28
penetrates the lower-mold retainer
27
b
and the lower-mold cavity insert
24
b
. The eject rod
31
is attached to the lower-mold ejector plate
32
b
. The lower-mold frame
35
b
allows the lower-mold retainer
27
b
and the lower-mold backing plate
34
b
to engage each other. The plunger
30
and a molding resin
29
are placed inside the chamber
11
. Next, an explanation will be given of a resin-sealing method of a semiconductor device. A frame assembly, which has a semiconductor element
22
and a bonding wire
23
attached to the lead frame
21
, is arranged on the lower-mold cavity
36
b
of the lower-cavity insert
24
b
placed on the upper surface of the lower mold. Here, the upper and lower resin-sealing molds are preliminarily maintained at a high temperature by heaters, not shown.
Next, molding resin
29
is loaded into the chamber
11
. The upper mold of the resin-sealing mold and the lower mold of the resin-sealing mold are clamped together so that the upper-mold cavity insert
24
a
and the lower-mold cavity insert
24
b
sandwich the lead frame
21
. The plunger
30
is raised so that the molten molding resin
29
in the chamber
11
is injected into both of the upper-mold cavity
36
a
and the lower-mold cavity
36
b
through a runner
37
. Thus, a semiconductor resin package
51
, which is a resin-sealed semiconductor device, is formed.
Next, the semiconductor resin package
51
is maintained (cured) in this state for a predetermined time so as to be cured. Thereafter, the upper mold of the resin-sealing mold and the lower mold of the resin-sealing mold are opened, and the sequence proceeds to a mold-releasing process; however, the semiconductor resin package
51
is stuck to either the upper-mold cavity
36
a
or the lower-mold cavity
36
b
due to the adhering strength of its resin, with the result that it is difficult to release the package
51
from the mold.
Then, as the upper mold of the resin-sealing mold is raised, an upper-mold external driving means (not shown) pushes the eject rod
31
out. The eject rod
31
, thus pushed out, allows the eject pin
28
attached to the ejector plate
32
a
to penetrate the retainer
27
a
and the cavity insert
24
a
, thereby pressing the upper face of the semiconductor resin package
51
. The semiconductor resin package
51
has its upper face pushed by the eject pin
28
, and is released from the upper mold of the resin-sealing mold.
Next, the external driving means (not shown) pushes the eject rod
31
out. The eject rod
31
, thus pushed out, allows the eject pin
28
attached to the ejector plate
32
b
to penetrate the retainer
27
b
and the cavity insert
24
b
, thereby pressing the lower face of the semiconductor resin package
51
. The semiconductor resin package
51
has its lower face pushed by the eject pin
28
, and is released from the lower mold of the resin-sealing mold.
Since the conventional resin-sealing mold is arranged as described above, it requires a number of eject pins. The eject pin needs a great amount of time in its boring process with high precision and pin outer-diameter machining process, resulting in an increase in mold manufacturing costs and an lengthened manufacturing time. Moreover, because of limitations in the package designing, the resin-molding process has to be carried out with the tip of the eject pin protruding from the bottom face of the cavity in order to absorb dimensional errors of parts such as the cavity insert, retainer and eject pin; therefore, this structure tends to cause the inner semiconductor element, bonding wire and other parts to expose to the outside of a thin package that has been demanded in recent years. Furthermore, the conventional resin-sealing mold fails to absorb deviations in the frame thickness, causing burrs to be generated on the periphery of the semiconductor resin package and in the vicinity of the cull section.
SUMMARY OF THE INVENTION
The present invention has been devised to eliminate the above-mentioned problems, and its objective is to provide a resin-sealing mold for a semiconductor device which can reduce the molding costs and shorten manufacturing time as well as reduce damage to packages by eliminating a number of ejecting pins and having, consequently, a simplified structure. Moreover, another objective is to provide a resin-sealing mold for a semiconductor device which can accommodate deviations in the thickness of a lead frame and, consequently, eliminate thin burrs that tend to occur on the periphery of the semiconductor resin package and in the vicinity of a cull section. Furthermore, still another objective is to provide a method of resin-sealing a semiconductor device which is suitable for the resin-sealing mold. Still another objective is to provide a method of releasing a resin-sealed semiconductor device from the mold.
The present invention has been devised to achieve the above-mentioned objectives, and the resin-sealing mold of a semiconductor device of the first preferred mode of the present invention is provided with: two molds, that is, an upper mold and a lower mold, for resin-sealing a semiconductor device installed on a lead frame, the upper and lower molds forming a cavity, wherein: each of the upper and lower molds comprises: a first cavity insert for forming a cavity side face portion; a first elastic post for supporting the first cavity insert; an elastic plate, built in the first cavity insert, for forming a cavity bottom portion; a second cavity insert embedded at
Aoki Hideji
Hirose Tetsuya
Kato Kiyoharu
Mishima Yoshiyuki
Ueno Toru
Davis Robert
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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