JP2004193315A - Semiconductor laser - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure an external-form-of-stem recognizing area and a bonding area at the time of performing wiring bonding. <P>SOLUTION: A groove 27 is formed on the flat surface 22a of a heat radiating stand 22 by highly rising both outer sides of the surface 22a and a sub-mount 26 is mounted on the bottom face of the groove 27. Consequently, the external-form-of-stem recognizing area and the bonding area for driving an Au wire 30, both of which are required at the time of performing wire bonding from the sub-mount 26, can be secured easily, because the spread of Ag paste 29 can be limited after the sub-mount 26 is die-bonded. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor laser device, and more particularly, to a semiconductor laser device used as a light source for an optical disk.
[0002]
[Prior art]
As a conventional semiconductor laser device, there is one as shown in FIGS. 4 and 5 (for example, see Patent Document 1). 4 (a) is a perspective view of the cap, and FIG. 4 (b) is a perspective view of the main body. FIG. 5 is a front view (FIG. 5 (a)), a side view (FIG. 5 (b)) and a plan view (FIG. 5 (c)) of the main body. Hereinafter, the conventional semiconductor laser device will be described with reference to FIGS.
[0003]
Two of the three leads 3, 4, 5 have penetrated the reference surface 1a, which is the installation surface of the radiator 2, in the substantially disk-shaped stem 1 constituting the main body. . One end of the remaining one lead 5 is attached to the back surface of the reference surface 1a, and is electrically connected to the reference surface 1a.
[0004]
A radiator 2 is provided on the reference surface 1a side of the stem 1. The heat radiator 2 is provided with a flat surface 2a, on which an Ag paste 6 is applied, and a submount 7 on which a laser element 8 is mounted is mounted on the Ag paste 6. The laser element 8 is electrically connected to the lead 4 by an Au wire 9, and the submount 7 is electrically connected to the plane 2 a of the radiator 2 by an Au wire 10. In this case, the light emitting point of the laser element 8 is located substantially at the center of the circular stem 1.
[0005]
A cap 11 is mounted on the reference surface 1a of the stem 1 to protect the laser element 8 and the Au wires 9, 10. At this time, the cap 11 is attached to the reference surface 1a by resistance welding in which a part of the projection 12 in the cap 11 is melted using resistance.
[0006]
The outer diameter of the reference surface 1a of the stem 1 is 3.3 mmφ, and the outer peripheral space when the cap 11 is attached is about 0.35 mm (of which the flat portion is only about 0.1 mm). The outer peripheral space on the reference surface 1a becomes a substantial reference surface for a mounting position when the present semiconductor laser device is incorporated into an optical disk pickup, and is required for adjusting the rotational position of the present semiconductor laser device.
[0007]
[Patent Document 1]
JP-A-5-129712
[Problems to be solved by the invention]
However, the above-described conventional semiconductor laser device has the following problems. That is, in the configuration of the conventional semiconductor laser device, the width of the flat portion where the laser element 8 is die-bonded on the plane 2a of the radiator 2 is about 1.0 mm, which is extremely narrow. Furthermore, since the center distance between the two leads 3 and 4 located on the outside is about 1.3 mm (about 1.0 mm in consideration of the thickness of the leads 3 and 4), laser die bonding and wire bonding are performed. In addition, the difficulty of assembly in a post process such as a cap seal is high.
[0009]
Furthermore, when the amount of the Ag paste 6 is small during the laser device die bonding in the case of the laser device 8 with the submount (about 0.8 mm square) 7 as shown in FIGS. In some cases, laser degradation due to failure occurs. Therefore, if an attempt is made to fix the paste with an appropriate amount of paste, the Ag paste 6 spreads in a circle having a diameter of 1.0 mm to 1.4 mm.
[0010]
If the Ag paste 6 spreads excessively, when performing second wire bonding with the Au wire 10 from the submount 7 to the plane 2a of the radiator base 2, the Ag paste 6 will invade the stem outer shape recognition area, and the wire bonding equipment will be used. In some cases, poor recognition of the outer shape of the stem may occur, or the second wire bonding area may actually be reduced. Also, at the time of cap sealing, the distance between the outer peripheral surface on the back surface side of the flat surface 2a of the heat radiator 2 and the inner diameter of the cap 11 is only about 100 μm, and high positional accuracy is required when the seal is fixed.
[0011]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor laser device capable of restricting the spread of Ag paste after submount die bonding and securing a stem outline recognition area and a bond area required for a second wire bond.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a semiconductor laser device according to the present invention has a groove for mounting a laser element formed on a laser element mounting surface of a heat radiator provided on a stem having a circular shape or a shape obtained by cutting off a part of a circle. ing.
[0013]
According to the above configuration, by mounting the laser element or the submount in the groove formed on the laser element mounting surface of the heat sink, for example, the spread of the Ag paste at the time of die bonding using the Ag paste is restricted. It is possible to have. Therefore, a stem outer shape recognition area and a bond area necessary for performing wire bonding to the laser element or the submount are easily secured.
[0014]
In the semiconductor laser device of one embodiment, the laser element or a submount on which the laser element is mounted is mounted in the groove.
[0015]
According to this embodiment, for example, when the submount is die-bonded using an Ag paste, the spread of the Ag paste is limited, and the outer shape of the stem necessary for performing the wire bonding to the laser element or the submount is recognized. An area and a bond area are secured.
[0016]
In the semiconductor laser device of one embodiment, the depth of the groove is set to 100 μm or more and 200 μm or less.
[0017]
According to this embodiment, the depth of the groove is set to 100 μm or more and 200 μm or less, so that the Ag paste is prevented from flowing out of the groove within a range where the radiator pedestal does not contact the lead. The spread of the paste is limited.
[0018]
In the semiconductor laser device of one embodiment, at least two leads are attached to the stem through the stem, and a distance between a plane passing through the center of the two leads and the center of the stem is 100 μm or more. It is 150 μm or less.
[0019]
According to this embodiment, the distance between the plane passing through the centers of the two leads and the center of the stem is set to 100 μm or more and 150 μm or less, so that even if the radius of the cap is the same as the radius of the conventional cap, The distance between both leads is secured up to 1.0 mm. Therefore, a space for passing the submount and the tip of the die bonding collet at the time of die bonding is secured.
[0020]
Further, in the semiconductor laser device of one embodiment, the stem is provided with two lead holes through which the two leads penetrate, and a plane including the laser element mounting surfaces on both sides of the groove in the radiator is connected to the lead. It is located approximately at the edge of the hole on the side of the heat sink.
[0021]
According to this embodiment, both ends of the radiator are located near the lead holes of the stem, and the radiator has a function of a cap that covers the leads, laser elements, wires, and the like from below. Becomes possible. Therefore, the cap can be formed in a semi-cylindrical shape that covers the leads, the laser element, the wires, and the like from above.
[0022]
In one embodiment, the semiconductor laser device has a semi-cylindrical shape or a shape in which a part of the semi-cylindrical is cut out, and at least the laser element and the laser element are provided on the laser element mounting surfaces on both sides of the groove in the heat sink. A protective cap is provided to cover the leads.
[0023]
According to this embodiment, the protective cap does not need to cover the leads, laser element, wires, and the like from below. Therefore, there is no need to secure a clearance between the protective cap and the outer peripheral surface of the heat radiator, and the seal can be easily fixed to the cap.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a perspective view of a semiconductor laser device according to the present embodiment, and FIG. 2 is a front view (FIG. 2A), a side view (FIG. 2B), and a plan view (FIG. 2C). is there. Hereinafter, the semiconductor laser device according to the present embodiment will be described with reference to FIGS.
[0025]
In the above-mentioned semiconductor laser device, 21 is a stem, 22 is a radiator, 23 and 24 are two leads penetrating the reference surface 21a of the stem 21, and 25 is one end attached to the back surface of the reference surface 21a of the stem 21. Are electrically connected to the reference surface 21a.
[0026]
A laser device mounting groove 27 having a depth of 100 μm to 200 μm is provided on the flat surface 22 a as the laser device mounting surface on which the submount 26 is mounted on the heat radiating table 22. Here, the distance from the center of the stem 21 on the bottom surface of the groove 27 is the same as the distance from the center of the stem 1 on the plane 2a of the radiator 2 in the conventional semiconductor laser device shown in FIGS. That is, the groove 27 is formed by raising both outer sides of the flat surface 22a of the heat radiating base 22 to a high level. The submount 26 on which the laser element 28 is mounted is die-bonded on the bottom surface of the groove 27.
[0027]
By doing so, the spread of the Ag paste 29 after the submount die bonding can be restricted to maximize the width of the groove 27. As a result, it is possible to easily secure a stem outline recognition area necessary for performing second wire bonding from the submount 26 and a bond area where the Au wire 30 is actually driven.
[0028]
In this case, the stem 21 has a circular shape, and the light emitting point of the laser element 28 is located substantially at the center of the stem 21. When the stem 21 is rotated to correct the inclination of the semiconductor laser 28, In addition, the position of the light emitting point of the laser element 28 does not shift.
[0029]
The reason for setting the depth of the groove 27 to 100 μm to 200 μm is as follows. That is, if the depth of the groove 27 is smaller than 100 μm, the Ag paste 29 flows out when performing the second wire bonding. Therefore, it is impossible to secure a bond area by restricting the spread of the Ag paste 29. If the depth of the groove 27 is deeper than 200 μm, the heat radiating base 22 hits the leads 23 and 24. That is, the position of the light emitting point of the laser element 28 is located substantially at the center of the stem 21. Therefore, increasing the depth of the groove 27 is the same as increasing the outer sides of the flat surface 22a of the heat radiator 22. When the groove 27 is deeper, the heat radiator 22 hits the leads 23 and 24. In that case, in order to increase the heat radiation effect, the volume of the heat radiation base 22 should be as large as possible. Therefore, it is more advantageous in terms of heat radiation to raise the plane 22a of the radiator 22 by positioning the leads 23 and 24 above the center of the stem 21 as much as possible. However, in this case, as will be described in detail later, the interval between the leads 23 and 24 becomes narrower, and the maximum value of the depth of the groove 27 is eventually limited to 200 μm.
[0030]
The plane passing through the center of the two leads 23 and 24 penetrating the reference plane 21a is set to be 100 μm higher than the center of the stem 21. By doing so, it is possible to secure a space through which the submount 26 and the tip of the die bonding collet pass during die bonding. Further, it is possible to secure clearance for avoiding conduction between the submount 26 after the die bonding and the leads 23 and 24 and conduction between the Ag paste 29 and the leads 23 and 24 which spread after the die bonding.
[0031]
Further, by arranging a plane including the planes 22a, 22a on both sides of the groove 27 in the heat sink 22 substantially at the lower ends of the lead holes 31, 32, the depth of the groove 27 is increased, and the effect of avoiding the conduction is prevented. Can play. Further, since the volume on both sides of the groove 27 in the heat radiating table 22 is increased by the depth of the groove 27, there is an effect on heat radiation during oscillation of the laser element 28. Further, the positions of the flat surfaces 22a, 22a on both sides of the groove 27 in the heat sink 22 can be made as close as possible to the leads 23, 24, and the leads 23, 24, the submount 26, the laser element 28, the Au wire 30, etc. Can be provided with a function of a cap for covering the cover from below. As a result, the shape of the cap 33 that covers the leads 23, 24, the submount 26, the laser element 28, the Au wire 30, and the like from above can be made substantially semi-cylindrical. Therefore, there is no need to secure a clearance between the cap 33 and the outer peripheral surface of the heat radiating base 22 when the seal is fixed by the cap 33, and the seal of the cap 33 is easily fixed. The cap 33 is attached to the stem reference surface by resistance welding in which a part of the projection 34 in the cap 33 is melted using resistance.
[0032]
Further, measures against thermal runaway during use are facilitated, and securing the reference surface 21a of the stem 21 is facilitated. As shown in FIGS. 1 and 2, both sides of the cap 33 are cut off at a plane perpendicular to the joint surface of the radiator base 22 with the plane 22a to form a plane 33a, so that a wider reference can be obtained at this plane 33a. The surface 21a can be secured.
[0033]
Hereinafter, the distance from the center of the stem 21 to a plane passing through the centers of the two leads 23 and 24 passing through the reference surface 21a will be described.
[0034]
FIG. 3 is a front view corresponding to FIG. 5 (a) of the conventional semiconductor laser device having a cap having a projection outside diameter of 3.1 mmφ shown in FIG. When the 0.8 mm square submount 7 is used, the distance between the leads 3 and 4 needs to be about 1.0 mm or more including the clearance at the time of die bonding. In order to secure this clearance, it can be seen from FIG. 3 that the distance from the center of the stem 4 to the plane passing through the centers of the leads 3 and 4 needs to be about 100 μm to 150 μm. When the distance is set to 150 μm or more, in order to avoid contact between the leads 3 and 4 and the cap 11, it is necessary to narrow the interval between the leads 3 and 4 to 1.0 mm or less. In that case, when the submount 7 of 0.8 mm □ is die-bonded, the submount 7 and the tip of the die bonding secrete cannot pass between the leads 3 and 4.
[0035]
Therefore, in the present embodiment, the distance from the center of the stem 21 to the plane passing through the centers of the leads 23 and 24 is set to 100 μm or more and 150 μm or less. By doing so, even if the radius of the semi-cylindrical cap 33 is the same as the radius of the conventional cap 11, the distance between the leads 23 and 24 can be secured to about 1.0 mm or more. Therefore, even when the submount 26 of 0.8 mm square is used, a space for passing the submount 26 and the tip of the die bonding cradle can be secured between the leads 23 and 24 at the time of die bonding. In addition, conduction between the submount 26 and the leads 23 and 24 after die bonding and conduction between the Ag paste 29 and the leads 23 and 24 that spread after die bonding can be prevented.
[0036]
Further, in the present embodiment, the function of the lower cap is provided by raising both outer sides of the flat surface 22a of the heat radiating table 22 to a high level. Therefore, the cap 33 only needs to cover the upper sides of the leads 23 and 24, the submount 26, the laser element 28, the Au wire 30, and the like. In this case, the clearance can be more sufficiently secured.
[0037]
In addition, in the present embodiment, the groove 27 is formed by raising both sides of the flat surface 22a of the radiator base 22 to a high level, and the submount 26 is mounted on the lower surface thereof. Therefore, it is possible to limit the spread of the Ag paste 29 after the sub-mount die bond, and the stem outer shape recognition area necessary for performing the second wire bonding from the sub-mount 26 and the bond area for driving the Au wire 30 are formed. It can be easily secured.
[0038]
In the above embodiment, the stem 21 is described as having a circular shape. However, the stem 21 may have a shape in which a part of the circle is notched.
[0039]
【The invention's effect】
As is clear from the above, the semiconductor laser device of the present invention has a groove formed on the laser element mounting surface of the heat radiator provided on the stem having a circular shape or a partially cut-out circular shape. By attaching a laser element or a submount to the substrate, it is possible to limit the spread of the Ag paste at the time of, for example, die bonding using the Ag paste. Therefore, it is possible to easily secure a stem outer shape recognition area and a bond area necessary for performing wire bonding to the laser element or the submount.
[Brief description of the drawings]
FIG. 1 is a perspective view of a semiconductor laser device according to the present invention.
FIG. 2 is a front view, a side view, and a plan view of the semiconductor laser device shown in FIG.
FIG. 3 is a diagram illustrating a relationship between a distance between a center of a lead and a center of a stem and a lead interval in the semiconductor laser device.
FIG. 4 is a perspective view of a conventional semiconductor laser device.
5 is a front view, a side view, and a plan view of the semiconductor laser device main body shown in FIG.
[Explanation of symbols]
21 ... Stem,
21a: Reference plane,
22 ... heat sink,
23,24,25… lead,
26 ... Submount,
27 ... groove,
28 ... Laser element,
29 ... Ag paste,
30 ... Au line,
31, 32… Lead holes,
33 ... Cap,
34 Projection.

Claims (6)

In a semiconductor laser device in which a light emitting point of a laser element is located substantially at the center of a stem having a shape in which a circle or a part of a circle is cut out,
A semiconductor laser device, wherein a groove for mounting a laser element is formed on a laser element mounting surface of a radiator provided on the stem. The semiconductor laser device according to claim 1,
A semiconductor laser device, wherein the laser element or a submount on which the laser element is mounted is mounted in the groove. The semiconductor laser device according to claim 1,
The semiconductor laser device according to claim 1, wherein the depth of the groove is 100 μm or more and 200 μm or less. The semiconductor laser device according to claim 1,
At least two leads are attached to the stem through the stem,
A semiconductor laser device, wherein a distance between a plane passing through the centers of the two leads and the center of the stem is not less than 100 μm and not more than 150 μm. The semiconductor laser device according to claim 4,
The stem has two lead holes through which the two leads penetrate,
A semiconductor laser device, wherein a plane including the laser element mounting surfaces on both sides of the groove in the heat radiator is substantially located at an edge of the lead hole on the heat radiator side. The semiconductor laser device according to claim 5,
A protective cap having a semi-cylindrical shape or a shape in which a part of a semi-cylindrical is cut out, and provided on the laser element mounting surfaces on both sides of the groove in the heat sink, so as to cover at least the laser element and the lead. A semiconductor laser device comprising:

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