Coherent light generators – Particular temperature control – Heat sink
Reexamination Certificate
2002-12-10
2004-11-09
Wong, Don (Department: 2828)
Coherent light generators
Particular temperature control
Heat sink
C372S043010
Reexamination Certificate
active
06816522
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor laser apparatus for use as a light source for reading signals from optical discs including CD (Compact Disc), CD-R (CD Recordable), DVD (Digital Versatile Disc) and DVD-R (DVD Recordable), and a method for manufacturing the same.
Conventionally, as an assembly structure of the semiconductor laser apparatus, there have been a frame type laser apparatus and a &PHgr;5.6 can type laser apparatus. Hereinbelow, the both apparatuses will be roughly described.
(1) Frame Type Laser Apparatus
(1) As shown in
FIG. 5
, the apparatus is structured such that on the top end of a metal lead frame
1
functioning as a lead terminal, a laser device
2
is mounted, and a mold resin
3
is used for molding. Part of a lead frame
1
a
positioned in both side portions is protruded from the lateral face of the mold resin
3
to lateral direction to constitute a plate-shaped portion
4
, and one end face
4
a
of the plate-shaped portion
4
constitutes a reference plane (eyelet).
(2) As shown in
FIG. 6
, similar to the case (1), the apparatus is structured such that on the top end of a metal lead frame
5
functioning as a lead terminal, a laser device
6
is mounted, and a mold resin
7
is used for molding. In this case, one end face
7
a
of the mold resin
7
constitutes a reference plane (eyelet).
(2) &PHgr;5.6 Can Type Laser Apparatus
As shown in
FIG. 7
, the apparatus is structured such that a laser device
13
is mounted, via a heat sink (unshown), on a top face
12
a
of a stem
12
made of a circular metal block having a lead terminal
11
protruding from a bottom face, and after the laser device
13
is wire-bonded to the lead terminal
11
, the laser device
13
and a wire (unshown) are covered with a protecting cap
14
. In this case, the top face
12
a
of the stem
12
constitutes a reference plane. It is noted that reference numeral
15
denotes a cutting for positioning.
However, the above-described conventional assembly structures of the semiconductor laser apparatuses suffer a following problem.
(a) Frame Type Laser Device
(i) In the case of the frame type laser apparatus as shown in
FIG. 5
, the plate-shaped portion
4
protruding from the lateral face of the mold resin
3
has a constant thickness. Consequently, the area of the reference plane constituted by the one end face
4
a
of the plate-shaped portion
4
is determined by the thickness of the plate-shaped portion
4
, which causes a problem that the strength of the reference plane is not fully secured and therefore heat dissipation is not sufficient.
(ii) In the case of the frame type laser apparatus as shown in
FIG. 6
, the reference plane is constituted by the one end face
7
a
of the mold resin
7
. Consequently, there is a problem that the reference plane is lower in strength than that of a metal reference plane, and also the reference plane has expansion and shrinkage due to temperature change, which decreases accuracy as a reference plane. Further, there is another problem that heat dissipation is not fully secured as it is limited by the thickness of the lead frame
5
.
(b) &PHgr;5.6 Can Type Laser Apparatus
As shown in
FIG. 7
, the reference plane and the heat dissipation portion are constituted by one plane of a metal block called the stem
12
. Consequently, the strength and the heat dissipation of the reference plane is superior to those of the above-described frame type laser apparatus. However, since assembly is conducted by using the cap
14
for protecting the laser device
13
and the wire against the stem
12
made of a circular metal block, individual manufacturing is necessary whether in the case of a package itself or a final product, which decreases productivity and makes the apparatus unsuitable for mass collective production
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a semiconductor laser apparatus capable of securing sufficient strength and heat dissipation of a reference plane and excellent in productivity, and to provide a method for manufacturing the same.
In order to achieve the above object, there is provided a semiconductor laser apparatus comprising: a base frame; a laser device mounting frame extensively disposed on one side of the base frame; and a lead frame extensively disposed on the other side of the base frame, all structured by one metal plate, wherein
the laser device mounting frame and the lead frame are bended so as to be opposite to each other against a plane of the base frame,
the base frame functions as a reference plane and a heat sinking base,
a semiconductor laser device is mounted on the laser device mounting frame, and
the lead frame becomes a lead terminal.
According to the above structure, the base frame functioning as a reference plane and as a heat sinking base is formed by bending a laser device mounting frame and a lead frame, which are structured together with the base from one metal plate, so that the laser device mounting frame and the lead frame are opposite to each other against the base frame. Therefore, the area of the reference plane and the heat sinking plane may be arbitrarily set by changing the bending position. This provides the frame type laser apparatus with high heat dissipation competing with that of &PHgr;5.6 can type laser apparatus.
Further, since the apparatus is a frame type laser apparatus, structuring plural sets of the laser device mounting frame, the base frame, and the lead frame in a multiple form enables collective packaging in large quantities, resulting in increase of productivity. Further, manufacturing of a final product may be performed in a multiple form, which enables further increase of productivity and enables manufacturing at low costs.
In one embodiment of the present invention, a configuration of the base frame is an approximate circle or an approximate oval partially in a shape of a circular arc.
According to this embodiment, the configuration of the base frame is an approximate circle or an approximate oval shape, which may provide strength and heat dissipation competing with those of the stem in the &PHgr;5.6 can type laser apparatus.
In one embodiment of the present invention, an optical axis of laser light from the semiconductor laser device mounted on the laser device mounting frame has an extension line traveling through an approximate center of the configuration of the base frame.
According to this embodiment, in addition to the fact that a configuration of the base frame is an approximate circle or partially a circular arc, the optical axis is not displaced when a mounting position is adjusted by rotating the base frame, which considerably simplifies adjustment of a mounting position.
In one embodiment of the present invention, at least a portion of the base frame to be the reference plane and the heat sinking base has an increased thickness.
According to this embodiment, a portion to be the reference plane and the heat sinking base has an increased thickness. This implements further increase of the strength and the heat dissipation of the reference plane.
In one embodiment of the present invention, on the base frame, there is formed a component protecting partition made of resin so as to surround the semiconductor laser device excluding a laser emitting side.
According to this embodiment, there is formed a component protecting partition so as to surround the semiconductor laser device. Therefore, though the apparatus is an open package, the semiconductor laser device, the wire, and the like are protected from careless touch. Further, the component protecting partition is structured not from a cap but a resin, so that collective packaging in large quantities is achieved.
In one embodiment of the present invention, the resin structuring the component protecting partition is formed with at least part of the laser device mounting frame and the lead frame being embedded therein, and the laser device mounting frame and the lead frame bended toward the base frame are fixed by the resin.
Accordi
Morrison & Foerster / LLP
Nguyen Phillip
Sharp Kabushiki Kaisha
Wong Don
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