JP2004006824A - Package for optical semiconductor and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package excellent in heat dissipation available for a high power semiconductor laser. <P>SOLUTION: This package for an optical semiconductor is characterized by forming the front surface of a portion 14 on which the semiconductor of an eyelet main body 18 is mounted with a heat sink 17. Also, this package for the optical semiconductor is provided with an eyelet main body whose disc-shaped front surface is mounted with a block portion shaped like a square pole and a cap, and the side face of the block portion on which the optical semiconductor is mounted is characterized by consisting of at least two regions, that is, a region where thermal conductivity is small and a region interposed between the regions where the thermal conductivity is small, where the thermal conductivity is larger than that of those regions from the relative point of view. This method for manufacturing the package for the optical semiconductor is characterized by press-molding a clad material where a disc-shaped eyelet main body 18 and a disc-shaped heat sink and an annular material layer 16 suitable for resistance welding are successively laminated. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a package for mounting an optical semiconductor and a method for manufacturing the package.
[0002]
[Prior art]
The optical semiconductor package 10 has a structure in which an electric signal lead 15 penetrates a through hole formed in an eyelet 11 and is fixed by an insulating material 13. Further, the electric signal lead 15 may be directly welded to the eyelet 11. On the upper surface of the eyelet 11, a section 14 for mounting an optical semiconductor is provided.
[0003]
In general, a semiconductor laser has a characteristic that a threshold value increases with an increase in temperature and an optical output decreases in low-current driving. Therefore, in order to keep the driving temperature constant at a low temperature, a means for releasing heat by using a heat radiating plate 20 installed on the outer periphery of the stem bottom shown in FIG. 2 is used.
[0004]
[Problems to be solved by the invention]
In the case of the above-described conventional semiconductor laser package, for example, as in Patent Document 1, an eyelet body forming member 18, a heat sink forming member 17, and a cladding material 12 shown in FIG. By press-molding with a die and punching, an integrally molded package FIG. 4 close to the shape of the die is created. Therefore, in the cross section of the portion for joining the optical semiconductors shown in FIG. 5, a material layer 16 suitable for resistance welding, for example, soft iron, is formed so as to cover the heat sink 17. Further, in an optical semiconductor package in which the clad material shown in FIG. 3 composed of an eyelet body, a heat sink forming member, and a material suitable for resistance welding is press-molded by a mold, the optical semiconductor package must be formed at the tip of the optical semiconductor mounting part. Irregular thickness of iron is generated during pressing. The thickness unevenness is particularly large, for example, at a portion on the side where laser light is emitted when a semiconductor laser is mounted as an optical semiconductor. It is difficult to control the thickness unevenness, and this is a major cause of the lack of reliability of the optical semiconductor whose temperature rises due to heat generation. This is disadvantageous in terms of heat dissipation, especially for GaN-based optical semiconductor elements that require power consumption.
[Means for Solving the Problems]
The optical semiconductor package of the present invention has an eyelet body having a rectangular column-shaped block portion on a disk-shaped surface, and a cap, and mounts an optical semiconductor located on a side surface of the block portion of the eyelet body 18. The surface of the portion 14 is formed by a heat sink 17. With such a configuration, it is possible to remarkably improve heat dissipation.
[0005]
Furthermore, in the optical semiconductor package of the present invention, the heat sink 17 is made of Cu or a material containing Cu as a main component. As a heat sink, Cu has a high thermal conductivity and is preferable because heat generated by the optical semiconductor can be efficiently radiated to the block portion.
[0006]
Furthermore, the region where the two side surfaces of the block portion are joined is made of a material suitable for resistance welding with the cap.
[0007]
Furthermore, the disk-shaped surface is made of a material suitable for resistance welding with the cap. Preferred materials for the resistance welding with the cap include Fe and Kovar, which can firmly join the cap with the eyelet body on which the optical semiconductor is mounted, preventing the cap from peeling off, and inert nitrogen. Further, it is preferable because a conventional semiconductor laser element which needs to maintain hermeticity such as oxygen can be hermetically sealed.
[0008]
Further, the optical semiconductor package of the present invention has an eyelet body having a rectangular column-shaped block portion on a disk-shaped surface, and a cap, and the side surface of the block portion on which the optical semiconductor is mounted is relatively viewed. It is characterized by comprising at least two regions of a region having a small thermal conductivity and a region having a large thermal conductivity sandwiched between the regions having a small thermal conductivity. By mounting the optical semiconductor on the side surface of such a block portion, it is possible to obtain an optical semiconductor package having excellent heat dissipation and high reliability.
[0009]
Still further, the optical semiconductor is mounted on the surface of the region having a high thermal conductivity in the side surface of the block portion. By mounting the optical semiconductor on the surface of the region having a high thermal conductivity, heat generated from the optical semiconductor is efficiently radiated.
[0010]
Still further, a material suitable for resistance welding with the cap is exposed on the disk-shaped surface. Preferred materials for the resistance welding with the cap include Fe and Kovar, which can firmly join the cap with the eyelet body on which the optical semiconductor is mounted, preventing the cap from peeling off, and inert nitrogen. Further, it is preferable because a conventional semiconductor laser element which needs to maintain hermeticity such as oxygen can be hermetically sealed.
[0011]
Furthermore, the region having a small thermal conductivity is characterized in that a material suitable for resistance welding with the cap is exposed.
[0012]
Still further, the region having a high thermal conductivity is characterized in that Cu or a material containing Cu as a main component is exposed. As a heat sink, Cu has a high thermal conductivity and is preferable because heat generated by the optical semiconductor can be efficiently radiated to the block portion.
[0013]
In the method for manufacturing an optical semiconductor package according to the present invention, it is preferable to press-mold a clad material in which a disc-shaped eyelet body 18, a disc-shaped heat sink, and a material layer 16 suitable for ring-shaped resistance welding are sequentially laminated. Features.
[0014]
The present invention is characterized by the following configuration as a manufacturing method for solving the above-described problem. That is, a hole is provided in the center of a material layer 16 suitable for resistance welding, and a clad material composed of an eyelet body 18 mainly composed of iron and a heat sink 17 mainly composed of Cu is punched out by press molding with a mold. A stem having a material layer suitable for resistance welding at least at a portion where the cap is resistance-welded is produced. FIG. 8 is a schematic sectional view showing the technique of the present invention. As a result, the optical semiconductor can be directly mounted on the heat sink 17 without forming the material layer 16 suitable for resistance welding so as to cover the heat sink 17, so that the thermal resistance of the package is reduced and the heat radiation is reduced. It is possible to improve the performance.
[0015]
The present invention is particularly effective for lasers with high power consumption. In this case, a nitride semiconductor laser will be described as an example, but the present invention is not limited to this.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
In the prior art, the cross section of the part 14 for joining the optical semiconductors has a material layer 16 (for example, iron: thermal conductivity of 50 W / mK) suitable for resistance welding, and a heat sink (for example, a material mainly composed of Cu: thermal conductivity). 400 W / mK), the heat generated from the optical semiconductor cannot be sufficiently efficiently released to the heat sink.
[0017]
In the present invention, the stem is provided with a material layer 16 suitable for resistance welding on the surface excluding the portion 14 for joining the optical semiconductor, and the optical semiconductor support portion is constituted only by the heat sink 17.
[0018]
A thermal resistance was evaluated by mounting a nitride semiconductor laser, which generates a large amount of heat, on the package thus formed.
[0019]
Thermal resistance was evaluated based on the temperature dependence of voltage in nitride semiconductor lasers. FIG. 6 shows the results of measuring the temperature dependence of the voltage in the nitride semiconductor laser for the PULSE drive and the CW drive. This is a method used, for example, when examining the temperature difference between the heat sink and the light emitting point (heating source) temperature. For example, the temperature (point A in FIG. 6) when the CW drive is performed at the heat sink temperature of 20 ° C. and the voltage (point B in FIG. 6) when the voltage when the PULSE drive is performed are the same (point B in FIG. 6). C point) is equal to the light emitting point (heating source) temperature when the CW drive is performed at a heat sink temperature of 20 ° C. As a result, the thermal resistance becomes
Thermal resistance = {light-emitting point (heating source) temperature-heat sink temperature} / {input power-optical output}
Given by Here, the input power is the power when the CW drive is performed at the point A in FIG.
[0020]
As a result of the evaluation of the thermal resistance based on the temperature dependence of the voltage in the nitride semiconductor laser, the thermal resistance of the package according to the present invention was about one digit [° C./W].
[Embodiment 2]
The eyelet of the present invention, having a square pillar block portion, a disk-shaped eyelet body, a disk-shaped heat sink, and a clad material in which materials suitable for ring-shaped resistance welding are sequentially laminated, from the lower surface and the upper surface. It is formed by press molding. Pressing from the upper surface is obtained by using a press plate having a rectangular opening so that a block portion is formed inside the disk, and pressing to a depth that reaches the heat sink. By pressing in this way, the surface of the eyelet is formed of a material suitable for resistance welding, and can be firmly joined to the cap, and at least the inside of the block portion for mounting the optical semiconductor is formed of a heat sink, and the Heat can be efficiently dissipated.
[0021]
The material suitable for the resistance welding of the present invention has a ring shape as shown in FIG. That is, it has a disk shape and further has a circular opening inside. This opening is provided as follows. FIG. 9 illustrates the relationship between the circular opening 25 and the rectangular block portion bottom surface 24 when viewed from the eyelet surface side. Here, the center of the circle serving as the opening is made to coincide with the center of gravity of the square serving as the bottom of the block. At this time, the diameter of the circle is equal to or longer than one side of the rectangle and equal to or shorter than the diagonal line of the rectangle. By determining the diameter of the circle in this manner, the region having a small thermal conductivity and the thermal conductivity sandwiched by the region having a small thermal conductivity are relatively viewed from the side surface of the block portion on which the optical semiconductor is mounted. At least two regions are formed. By mounting the optical semiconductor in a region having a high thermal conductivity, an eyelet having excellent heat dissipation is formed, and heat is appropriately dissipated.
[0022]
Here, when the diameter of the circle is shorter than one side of the rectangle, the portion for mounting the optical semiconductor on the side surface of the block portion is made of a material suitable for resistance welding, and since the material is thicker, the thermal conductivity is small. , Is not suitably dissipated. In addition, uneven thickness of a material suitable for resistance welding occurs at a portion where the optical semiconductor is mounted. As a specific example, when a semiconductor laser is mounted as an optical semiconductor, the thickness is particularly large at a portion where the laser light is emitted. Since the emission end face of the laser beam generates heat in particular, the unevenness of the thickness particularly deteriorates the heat radiation. In addition, when the diameter of the circle is equal to one side of the rectangle, the portion of the block portion where the optical semiconductor is mounted is made of a material suitable for resistance welding without thickness unevenness, and the material suitable for resistance welding is very thin, and heat dissipation This is not much different from when the heat sink is exposed. The term “thin” means that a material suitable for resistance welding is approximately 50 μm or less.
[0023]
Conversely, if the diameter of the circle is longer than the diagonal of the rectangle, the volume of the block will increase and the heat dissipation will further increase, but part of the cap joint on the eyelet surface will become a heat sink, making it impossible to make a strong joint. The airtightness also worsens. When the diameter of the circle is equal to the diagonal line of the square, all the cap joints are made of a material suitable for resistance welding, the cap can be mounted with high reliability, and the heat dissipation is the most excellent.
[0024]
So far, the circular opening made of a material suitable for resistance welding has been described in relation to one side and the diagonal of the square on the bottom of the block. However, the present invention is not limited to this, and at least the optical semiconductor of the block is It suffices that the side of the side surface to be mounted, which is in contact with the eyelet, and the circle of the opening be formed so as to be in contact with or intersect with each other. The case where the block bottom surface is not limited to a square is included. The side in contact with the eyelet on the side surface on which the optical semiconductor is mounted is usually formed parallel to the chord of the circle on the eyelet surface.
[0025]
In the present invention, a cross section of the block portion will be described. The section when the cross section of the block portion is viewed in the AA ′ direction and the BB ′ direction in the perspective view shown in FIG. 10 will be described with reference to the drawings. When the diameter of a circle that becomes an opening of a material suitable for resistance welding is equal to one side of a square on the bottom surface of the block portion, a diagram viewed in the AA ′ direction is as shown in FIG. In this case, the portion of the block portion where the optical semiconductor is mounted is made of a material suitable for resistance welding without thickness unevenness, and this material is also thin. FIG. 13 shows the view taken in the direction BB ′ at this time. In the direction BB ′, the material suitable for resistance welding has uneven thickness, and the material suitable for resistance welding is thick.
[0026]
Next, when the diameter of the circle is larger than one side of the rectangle and shorter than the diagonal line of the rectangle, AA ′ is as shown in FIG. 12. In this case, the portion of the block portion where the optical semiconductor is mounted is a heat sink. FIG. 13 shows the view taken in the direction BB ′ at this time. In the direction BB ′, the material suitable for resistance welding has uneven thickness, and the material suitable for resistance welding is thick.
[0027]
Next, when the diameter of the circle is equal to the diagonal of the rectangle, AA ′ is as shown in FIG. 12, and in this case, the portion of the block portion where the optical semiconductor is mounted is formed of a heat sink. FIG. 11 shows a view taken in the direction of BB ′ at this time, and is made of a material suitable for resistance welding without thickness unevenness.
[0028]
By determining the diameter of a circle serving as an opening of a material suitable for resistance welding in these ranges, an eyelet excellent in heat dissipation and highly reliable can be formed.
[0029]
In the present invention, the block portion is a quadrangular prism. However, a polygonal prism may be used as long as at least a side contacting the eyelet on the side surface on which the optical semiconductor is mounted is parallel to a chord of a circle on the surface of the eyelet.
[0030]
Preferably, the eyelet body of the present invention is made of Fe, the heat sink is preferably made of Cu, and Fe is preferably used as a material suitable for resistance welding. This is not the case.
【Example】
[Example 1]
In Example 1, as the eyelet, a circular opening was provided in a material suitable for resistance welding, and the diameter of the circle was longer than one side of the square on the bottom surface of the block portion, and a clad material shorter than the diagonal line was press-formed. A nitride semiconductor laser having a large calorific value was mounted on the formed eyelet, and the thermal resistance was evaluated.
[0031]
As a result of the evaluation described in Embodiment 1, the thermal resistance was about one digit [° C./W].
[Example 2]
Example 2 As Example 2, a circular opening was formed in a material suitable for resistance welding, and the diameter of the circle was made equal to one side of a square on the bottom surface of the block portion. A large nitride semiconductor laser was mounted and thermal resistance was evaluated. The thermal resistance was almost the same as that of Example 1.
[Example 3]
As Example 3, as an eyelet, a circular opening was formed in a material suitable for resistance welding, and the diameter of the circle was equal to the square diagonal line of the bottom of the block portion. The thermal resistance was evaluated by mounting a nitride semiconductor laser having a large calorific value. The thermal resistance was almost the same as that of Example 1.
[Comparative Example 1]
As a conventional eyelet, a thermal resistance of a nitride semiconductor laser formed in the same manner as in Example 1 using an eyelet formed by press-molding a clad material having no opening in a material suitable for resistance welding was evaluated as a comparative example. did. The thermal resistance of the package was about 10 [° C./W].
[Comparative Example 2]
As a comparative example 2, a circular opening was formed in a material suitable for resistance welding, and the diameter of the circle was made shorter than one side of a square on the bottom of the block. A large nitride semiconductor laser was mounted and thermal resistance was evaluated. The thermal resistance was equivalent to that of Comparative Example 1, and no improvement in heat dissipation due to the provision of the circular opening was observed.
[Comparative Example 3]
As Comparative Example 3, as an eyelet, a circular opening was provided in a material suitable for resistance welding, and the diameter of the circle was longer than the square diagonal line on the bottom of the block portion. The thermal resistance was evaluated by mounting a nitride semiconductor laser having a large calorific value. Although the heat resistance was almost the same as that of Example 1, the heat sink was sometimes exposed at the resistance welding portion of the cap, and the eyelet and the cap could not be firmly joined, and the cap could peel off. there were.
[0032]
【The invention's effect】
As a result, the portion of the block portion on which the optical semiconductor is mounted can be composed of only a heat sink, so that a package with excellent heat dissipation that can be used for a high-power semiconductor laser can be obtained. In particular, in this package, the variation in the thermal resistance of the laser has been reduced. In addition, a material suitable for resistance welding is provided at least at a portion where the cap is to be resistance-welded, and the resistance welding of the cap can be performed without any difference from the conventional package. Therefore, it is possible to provide a semiconductor laser which is excellent not only in heat dissipation but also in airtightness, and the reliability of the product is improved.
[0033]
In addition, the part for mounting the optical semiconductor in the block part is made of a material suitable for resistance welding without thickness unevenness, and since this material is also thin, the heat dissipation is not much different from when the heat sink is exposed, so the semiconductor with excellent heat dissipation It is possible to provide a laser.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a general optical semiconductor package.
FIG. 2 is a schematic cross-sectional view showing a general optical semiconductor package.
FIG. 3 is a schematic sectional view showing a conventional technique.
FIG. 4 is a schematic sectional view showing a conventional technique;
FIG. 5 is a schematic sectional view showing a conventional technique;
FIG. 6 is a diagram illustrating a method for evaluating thermal resistance.
FIG. 7 is a schematic disassembly diagram showing the present invention.
FIG. 8 is a schematic sectional view showing the invention.
FIG. 9 is a schematic sectional view showing the present invention;
FIG. 10 is a schematic perspective view illustrating the invention.
FIG. 11 is a schematic sectional view showing the present invention.
FIG. 12 is a schematic sectional view showing the present invention.
FIG. 13 is a schematic sectional view showing the present invention.
[Explanation of symbols]
10. Optical semiconductor package,
11 eyelets,
12 clad material,
13 insulating materials,
14 A part for mounting an optical semiconductor element,
15 electrical signal leads,
16 Materials suitable for resistance welding,
17 heat sink,
18 Eyelet body,
19 caps,
20 heat sink,
21 fixing jig,
22 screws,
23 block part,
24 Block bottom,
25 openings,
26 Optical semiconductor.

Claims (10)

In the package for an optical semiconductor, an eyelet having a block portion on a disk-shaped surface and a cap, and a surface of a portion for mounting an optical semiconductor, which is located on a side surface of the block portion of the eyelet, is formed by a heat sink. A package for an optical semiconductor. The optical semiconductor package according to claim 1, wherein the heat sink is made of Cu or a material containing Cu as a main component. 3. The optical semiconductor package according to claim 1, wherein a region where the two side surfaces of the block portion are joined is made of a material suitable for resistance welding with a cap. 4. The optical semiconductor package according to any one of claims 1 to 3, wherein the disk-shaped surface is made of a material suitable for resistance welding with the cap. In the package for an optical semiconductor, an eyelet having a rectangular column-shaped block portion on a disk-shaped surface, and a cap, and the side surface of the block portion for mounting the optical semiconductor is relatively small in the thermal conductivity when viewed relatively. An optical semiconductor package comprising at least two regions: a region and a region having a high thermal conductivity sandwiched between the regions having a low thermal conductivity. The optical semiconductor package according to claim 5, wherein the optical semiconductor is mounted on a surface of the region having a high thermal conductivity in a side surface of the block portion. 7. The optical semiconductor package according to claim 5, wherein a material suitable for resistance welding with the cap is exposed on the disk-shaped surface. The optical semiconductor package according to claim 5, wherein a material suitable for resistance welding with the cap is exposed in the region having a low thermal conductivity. 9. The optical semiconductor package according to claim 5, wherein the region having a high thermal conductivity is formed by exposing Cu or a material containing Cu as a main component. In a method of manufacturing a package for an optical semiconductor, a clad material in which a disc-shaped eyelet body, a disc-shaped heat sink, and a material layer suitable for ring-shaped resistance welding are sequentially laminated is press-formed to form a disc-shaped surface. Forming an eyelet having a block portion on which an optical semiconductor is mounted.

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