Coherent light generators – Particular active media – Semiconductor
Reexamination Certificate
1998-01-16
2001-01-30
Arroyo, Teresa M. (Department: 2881)
Coherent light generators
Particular active media
Semiconductor
C372S036000
Reexamination Certificate
active
06181720
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin molding type of semiconductor laser device, and to a method for manufacturing the same.
2. Description of the Related Art
Semiconductor laser devices have been utilized in the past for optical disk players, laser printers, and other such optical response devices. Semiconductor laser devices come in can types and resin molding types, for example, with a laser chip mounted to a frame.
As shown in
FIG. 13
, a can type of semiconductor laser device
1
comprises a laser chip
2
that emits laser light, and this laser chip
2
is mounted on the side of a rectangular heat-radiating body
3
that is parallel to the optical axis. This heat-radiating body
3
is erected on the top of a disk-shaped stem
4
, and a cylindrical cap
5
is mounted around its periphery. A glass window is provided to the top of the cap
5
, and the laser chip
2
faces the glass window
6
from the inside of the cap
5
. Because the outside diameter of the stem
4
is larger than that of the cap
5
, the outer periphery of the stem
4
that sticks out further than this cap
5
becomes a flange
7
.
With the can type of semiconductor laser device
1
described above, when the laser chip
2
inside the cap
5
emits laser light, this laser light is emitted through the glass window
6
. The laser chip
2
generates heat at this time, but because the inside of the cap
5
is hollow, this heat is radiated by the stem
4
, which acts as a heat-radiating fin.
With the can type of semiconductor laser device
1
described above, since in structural terms the laser chip
2
is fixed with good precision to the stem
4
, as shown in
FIG. 14
, laser light can generally be emitted accurately with respect to a device housing
8
if the shape of the flange
7
is utilized for mounting in a stepped hole
9
of the device housing
8
.
However, the can type of semiconductor laser device
1
comprises numerous parts and has a complicated construction. In view of this, a semiconductor laser device in which the laser chip is sealed with a resin molding has been developed in an effort to simplify the construction and improve productivity.
For instance, as shown in
FIG. 15
, the resin molding type of semiconductor laser device
11
disclosed in Japanese Laid-Open Patent Application No. Hei7-170019 has the laser chip
2
mounted to a lead frame
13
via a sub-mount layer
12
, and the laser chip
2
is sealed along with the upper portion of this lead frame
13
by a transparent resin molding
14
. Furthermore, this resin molding
14
is formed in the same shape as in the above-mentioned can type, so interchangeability is ensured so that mounting to the device housing
8
can be performed just as with a can type.
As shown in
FIG. 16
, the resin molding type of semiconductor laser device
21
disclosed in Japanese Laid-Open Utility Model Application No. Hei2-54263 has a convex component
23
that serves as a heat-radiating fin formed on both sides of a lead frame
22
, and these convex components
23
protrude to the outside of a resin molding
24
, which enhances the heat radiation of the laser chip
2
sealed by the resin. The resin molding type of semiconductor laser devices
11
and
21
discussed above offer a simple construction and good productivity.
However, although interchangeability is good with the semiconductor laser device
11
in Japanese Laid-Open Patent Application No. Hei7-170019 because the resin molding
14
is formed in the same shape as that of a can type, the thermal radiation of the laser chip
2
sealed by this resin molding
14
is difficult. Furthermore, with the semiconductor laser device
11
, the lead frame
13
to which the laser chip
2
is fixed is inserted into the resin molding
14
, but it is difficult to position the lead frame
13
accurately with respect to this resin molding
14
. Accordingly, the positioning precision of the laser chip
2
with respect to the resin molding
14
is low, and it is difficult to direct the laser light at the proper location when the semiconductor laser device is mounted in the device housing
8
at the resin molding
14
portion.
In contrast, since convex components
23
that serve as heat-radiating fins are formed on the lead frame
22
with the semiconductor laser device
21
discussed in Japanese Laid-Open Utility Model Application No. Hei2-54363, the heat generated by the laser chip
2
can be eliminated very well, and the lead frame
22
can be inserted at the proper location with respect to the resin molding
24
by means of these convex components
23
. However, since the convex components
23
of the lead frame
22
stick out on both sides of the resin molding
24
, it is difficult for the shape thereof to be formed the same as that of a can type and thereby ensure interchangeability.
Also, with the resin molding type of semiconductor laser devices
11
and
21
discussed above, the laser chip
2
is also sealed with the resin moldings
14
and
24
along with the lead frames
13
and
22
, but this is undesirable since the laser chip
2
is subjected to high temperature and pressure during the molding of the resin moldings
14
and
24
with this configuration, and there is the possibility of breakage.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a resin molding type of semiconductor laser device with which interchangeability with a conventional can type is ensured, while the thermal radiation of the laser chip is also good, the positioning precision of the laser light is high, and there is no danger of breakage in the laser chip during molding.
In order to achieve the above-mentioned object, according to a first aspect of the present invention, there is provided a semiconductor laser device in which a laser chip that emits laser light is mounted on the surface of a lead frame that is parallel to the optical axis, and part of the lead frame is sealed with a resin molding having a main body, wherein the semiconductor laser device is such that the resin molding is formed in a shape such that a flange protrudes from around the outside at the end of this main body, a heat-radiating fin for cooling the laser chip is provided to the lead frame, and the heat-radiating fin is exposed on the side of at least one of the two end faces of the flange.
Therefore, according to the above-mentioned first aspect, heat generated by the laser chip can be eliminated favorably since a heat-radiating fin for cooling the laser chip is provided to the lead frame, and this heat-radiating fin is exposed on the side of at least one of the two end faces of the flange of the resin molding. With this configuration, the resin molding is shaped roughly the same as in a conventional can type, so interchangeability with a conventional can type is ensured. Furthermore, since the lead frame can be positioned in the cavity of the metal mold by the heat-radiating fin when the resin molding is molded, there is an improvement in the precision of the relative positions of the optical axis of the laser chip and the shape of the resin molding.
In the above-mentioned first aspect, the laser chip can be sealed if a separate resin cap is mounted to the resin molding, so the laser chip can be protected favorably against humidity and the like in the external atmosphere. It is also preferable to provide the heat-radiating fin to the back side of the lead frame. When mounting to the device housing is taken into account, it is preferable for the heat-radiating fin to be exposed on the side of at least one of the two end faces of the flange and in roughly the same plane as the end face corresponding to the flange.
The lead frame and the heat-radiating fin may also be formed integrally. The heat-radiating fin may also consist of a plurality of parts.
If a wiring lead frame is provided to the side of the lead frame on which the laser chip is mounted, and a convex component is provided at a location on the rear end face of the resin molding where the lead frame protrudes,
Kanemoto Mitsunori
Kawata Seiji
Arroyo Teresa M.
Foley & Lardner
Leung Quyen P.
NEC Corporation
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