Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting – Positioning of a mold part to form a cavity or controlling...
Reexamination Certificate
2000-02-23
2003-01-28
Ortiz, Angela (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
Positioning of a mold part to form a cavity or controlling...
36, 36, 36, 36, 36, C425S121000, C425S141000
Reexamination Certificate
active
06511620
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to semiconductor production methods and metal molds for producing semiconductor devices, and, more particularly, to a method of producing semiconductor devices each having a chip-size package structure and a metal mold for producing such semiconductor devices.
In recent years, there has been an increasing demand for smaller electronic equipment. In response to such a demand, semiconductor devices have been becoming smaller with higher densities. Such semiconductor devices include a chip size package type (hereinafter referred to as “CSP”) of a size as close as possible to a semiconductor chip. A semiconductor device of the CSP type is partially provided with resin to improve its reliability while maintaining its smallness. Meanwhile, there is also a demand for semiconductor devices which can be manufactured at high efficiency. To satisfy the two demands, it is necessary to improve productivity and efficiency in the process of providing the resin for a semiconductor device of the CSP type.
2. Description of the Related Art
FIG. 1A
shows a CSP-type semiconductor device
1
. As shown in this figure, the semiconductor device
1
comprises a semiconductor chip
2
, a resin layer
3
, and electrodes
4
. The resin layer
3
has a predetermined thickness and is formed on a circuit-formation surface having the electrodes
4
of the semiconductor chip
2
, so that the circuit-formation surface of the semiconductor chip
2
can be protected by the resin layer
3
. The resin layer
3
also, encapsulates the electrodes
4
except the top ends of the electrodes
4
(that are used for electric connection). By encapsulating the electrodes
4
, the resin layer
3
also strengthens the attaching of the electrodes
4
to the semiconductor chip
2
. The top ends of the electrodes
4
are attached to electrode pads
6
of a printed circuit board
5
, thereby mounting the semiconductor device
1
on the printed circuit board
5
.
Japanese Laid-Open Patent Application No. 10-71944 discloses a method of forming the resin layer
4
and a metal mold for producing semiconductor devices employed in the method.
FIG. 2
shows a metal mold
20
for producing semiconductor devices. The metal mold
20
can be divided into an upper mold
21
and a lower mold
22
. The upper mold
21
and the lower mold
22
each have a heater inside (not shown) to heat and melt an encapsulation resin
35
mentioned later. The upper mold
21
moves up and down in directions indicated by arrows Z
1
and Z
2
in FIG.
2
. The lower surface of the upper mold
21
serves as a cavity surface
21
a
that is almost flat. Accordingly, the upper mold
21
has a very simple shape, and can be produced at a low cost.
Meanwhile, the lower mold
22
is made up of a first sub lower mold
23
and a second sub lower mold
24
. The first sub lower mold
23
has a shape corresponding to the shape of a substrate
16
, and more specifically, the first sub lower mold
23
has a diameter slightly larger than the diameter of the substrate
16
. The substrate
16
is mounted on a cavity surface
25
formed on the upper surface of the first sub lower mold
23
. Also, a cavity surface
26
is formed on the side surface of the second sub lower mold
24
. In this example, the first sub lower mold
23
is fixed.
The second sub lower mold
24
has an annular shape, surrounding the first sub lower mold
23
. The second sub lower mold
24
moves up and down in the directions of the arrows Z
1
and Z
2
with respect to the first sub lower mold
23
.
Immediately after the start of the resin encapsulation process, the second sub lower mold
24
is in a higher state in the direction of the arrow Z
2
with respect to the first sub lower mold
23
, so that the substrate
16
is mounted in a cavity portion formed by the first and second sub lower molds
23
and
24
. Here, the surface of the substrate
17
, on which the bumps
12
are provided, faces upward, so that the bumps
12
face the upper mold
21
in the substrate-mounted state.
After the mounting of the substrate
16
in the lower mold
22
, a film sheet
30
is attached only to the lower surface of the upper mold
21
, and the encapsulation resin
35
is placed on the bumps
12
on the substrate
16
.
FIG. 3
shows the encapsulation resin
35
placed on a semiconductor chip
11
.
The above substrate mounting process is followed by a resin layer forming process. In the resin layer forming process, the metal mold
20
heated to a temperature high enough to melt the encapsulation resin
35
, and the upper mold
21
is then moved down in the direction of the arrow Z
1
.
By moving the upper mold
21
in the direction of the arrow Z
1
, the upper
21
is first brought into contact with the upper surface of the second sub lower mold
24
. Since the lower surface of the upper mold
21
is covered with the film sheet
30
as described above, the film sheet
30
is clamped between the upper mold
21
and the second sub lower mold
24
, with the upper mold
21
being in contact with the second sub lower mold
24
, as shown in FIG.
4
. At this point, a cavity
28
surrounded by the cavity surfaces
21
a
,
25
, and
26
is formed inside the metal mold
20
.
Since the encapsulation resin
35
is pressed by the descending upper mold
21
via the film sheet
30
and is heated to a melting temperature, the encapsulation resin
35
can be spread on the substrate
16
to some extent, as shown in FIG.
4
.
Once the upper mold
21
is brought into contact with the second sub lower mold
24
, the upper mold
21
and the second sub lower mold
24
move further down in the direction of the arrow Z
1
, with the film sheet
30
being in the clamed state. On the other hand, the first sub lower mold
23
remains in the fixed state. As a result, the cavity
28
becomes smaller as the upper mold
2
and the second sub lower mold
24
move downward, and hence the encapsulation resin
35
is compressed and molded inside the cavity
28
. This resin molding technique is called compression mold technique.
FIG. 5
shows a state after the resin layer forming process. In this state, the film sheet
30
is pressed onto the substrate so hard that the top ends of the bumps
12
are lodged in the film sheet
30
. Also, the encapsulation resin
35
is spread on the entire surface of the substrate
16
, thereby forming a resin layer
13
which encapsulates the bumps
12
.
The above resin layer forming process is followed by a separation process. In this process, the upper mold
21
is first moved up in the direction of the arrow Z
2
. Since the resin layer
13
adheres to the cavity surface
26
of the second sub lower mold
24
, only the upper mold
12
is moved upward and separated from the film sheet
30
.
The second sub lower mold
24
is then moved down in the direction of Z
1
with respect to the first sub lower mold
23
. In
FIG. 6
, the left half defined by a vertical center line shows the state in which the upper mold
21
has been moved up and the second sub lower mold
24
has been moved down. By moving the second sub lower mold
24
downward with respect to the first sub lower mold
23
, the resin layer
13
can be separated from the cavity surface
26
of the second sub lower mold
24
.
As the resin layer
13
and the cavity surface
26
are separated, the second sub lower-mold
24
starts moving up in the direction of the arrow X
2
. By doing so, the upper surface of the second low sub mold
24
is brought into contact with the film sheet
30
, and the cavity surface
26
is brought into contact with the side face of the resin layer
13
. As a result, the substrate
16
is moved upward. Since the film sheet
30
and the resin layer
13
adhere to each other, the substrate
16
is separated from the first sub lower mold
23
when the film sheet
30
is moved upward. The substrate
16
with the resin layer
13
is thus separated from the metal mold
20
, as shown in the right half defined by the center line in FIG.
6
.
As described so fa
Fukasawa Norio
Hamanaka Yuzo
Hozumi Takashi
Kawahara Toshimi
Matsuki Hirohisa
Armstrong Westerman & Hattori, LLP
Fujitsu Limited
Ortiz Angela
LandOfFree
Method of producing semiconductor devices having easy... 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 producing semiconductor devices having easy..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing semiconductor devices having easy... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3059108