JP2005223189A - Optical semiconductor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical semiconductor module, wherein a semiconductor laser element (LD) can operate stably, by arranging a temperature sensor for measuring the temperature of the semiconductor laser element (LD) allocated in the optical semiconductor module. <P>SOLUTION: In the optical semiconductor module 10, an optical semiconductor element (semiconductor laser) 13 is mounted on a mounting part 12, which is formed in a carrier base 11 in a projecting shape and used as a heat sink. And moreover, a cap which covers the mounting part 12 is fixed to the carrier base 11. Furthermore, the temperature sensor 15 for detecting the temperature in the optical semiconductor module 10 is arranged in the cap, so that the output of the optical semiconductor element (semiconductor laser) 13 is adjusted, according to the output of the temperature sensor 15. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical semiconductor module provided with an optical semiconductor element such as a semiconductor laser used in an optical communication device, and in particular, the optical semiconductor element is mounted on a mount portion serving as a heat sink formed protruding from a carrier base, The present invention also relates to an optical semiconductor module in which a cap that covers the mount is fixed to a carrier base.

  With the increase in capacity of optical communication, high-power semiconductor laser elements have come to be used for optical semiconductor elements used in optical semiconductor modules. As an optical semiconductor module including this type of high-power semiconductor laser element (LD: Laser Diode), a butterfly type, a DIP (Dual Inlin Package) type, a coaxial type using a stem, and the like have been put into practical use. Among these, the butterfly type and the DIP type are expensive in package, and an expensive electronic cooling element (TEC: Thermo Electric Cooler) needs to be accommodated in the package for heat dissipation.

For this reason, coaxial type optical semiconductor modules that are relatively simple in structure and inexpensive have come into wide use. However, this type of optical semiconductor module of the coaxial type uses a relatively low output LD that is not cooled, and thus is unsuitable for high output applications. However, in recent years, the cost of high-power LDs has been reduced, and stable operation at high temperatures has become possible, increasing the use of coaxial-type optical semiconductor modules that are not equipped with an electronic cooling element (TEC). However, it has come to be used for long-distance communication modules or optical amplifiers with a high output type LD.
JP 2001-284700 A

  However, in these semiconductor laser elements (LD) used for long-distance communication modules or optical amplifiers, although the operation at high temperature is possible, the ambient temperature of the optical semiconductor module is If the temperature rises due to the cause, the temperature of the semiconductor laser element may exceed the design temperature. For this reason, it is desirable to directly measure the temperature of the semiconductor laser element and control it below the design temperature.

  However, in this type of optical semiconductor module, unlike the butterfly type or DIP type optical semiconductor module, there are two lead terminals for power supply, one lead terminal for signal output, and grounding. There is a problem that there is one lead terminal for use, and there is no space for arranging these lead terminals beyond this. There is also a problem that there is no space for installing a temperature sensor for measuring the temperature of the semiconductor laser element. For this reason, the problem that the temperature sensor for measuring the temperature of a semiconductor laser element cannot be arrange | positioned occurred.

  Accordingly, the present invention has been made to solve the above-described problems, and a temperature sensor for measuring the temperature of a semiconductor laser element disposed in an optical semiconductor module and a lead terminal for this purpose are optically connected. An object of the present invention is to provide an optical semiconductor module in which a semiconductor laser element can operate stably so that it can be arranged in a semiconductor module.

  The present invention is an optical semiconductor module in which an optical semiconductor element (semiconductor laser) is mounted on a mount portion serving as a heat sink that protrudes from a carrier base, and a cap that covers the mount portion is fixed to the carrier base. In order to achieve the above object, a temperature sensor for detecting the temperature in the optical semiconductor module is disposed in the cap, and the output of the optical semiconductor element (semiconductor laser) is adjusted according to the output of the temperature sensor. It is characterized by the above.

  Thus, when the output of the optical semiconductor element (semiconductor laser) is adjusted by the output of the temperature sensor, the environmental temperature changes (rises) and the temperature of the optical semiconductor element (semiconductor laser) becomes the design temperature. When approaching, the temperature sensor outputs a detection signal to the control circuit. Then, since the control circuit operates to reduce the output of the optical semiconductor element (semiconductor laser), the heat generation temperature of the optical semiconductor element is lowered. Thereby, the temperature of the optical semiconductor element (semiconductor laser) can be kept below the design temperature.

  In this case, when the temperature sensor is disposed on the side opposite to the position of the mount portion on which the optical semiconductor element (semiconductor laser) is mounted, the temperature sensor is disposed on the mount portion. In this case, if the lead terminal for grounding in the vicinity of the mount portion where the temperature sensor is disposed is used as the lead terminal for temperature sensor, there is no need to newly provide a lead terminal for temperature sensor. If the temperature sensor is disposed on the side opposite to the position where the optical semiconductor element (semiconductor laser) is disposed, the temperature of the optical semiconductor element is directly propagated to the temperature sensor. As a result, the temperature sensor can accurately know the temperature of the optical semiconductor element, and can accurately adjust the output of the optical semiconductor element.

  In addition, since the mount part used as a heat sink is formed of any one of the high thermal conductive materials selected from CuW alloy, CuMo alloy, CuO-Cu composite, and AlN, the heat dissipation at the mount part is improved. The heat generated in the optical semiconductor element (semiconductor laser) can be released, and the temperature rise of the optical semiconductor element (semiconductor laser) can be reduced. In this case, if the carrier base is also made of a high thermal conductivity material selected from CuW alloy, CuMo alloy, CuO-Cu composite, and AlN, and the mount portion is also integrally formed, the optical semiconductor module Since heat dissipation as a whole improves, it is possible to further reduce the temperature rise of the optical semiconductor element (semiconductor laser).

  Here, in the CuW alloy, the thermal conductivity increases as the proportion of Cu increases, but the thermal expansion coefficient also increases. This is because Cu is a metal excellent in heat conduction, and as the proportion of Cu increases, the coefficient of thermal expansion increases. For this reason, in order to obtain a CuW alloy having a low coefficient of thermal expansion, it is necessary to regulate the ratio of Cu. And if the ratio of Cu is 5 wt% or more, thermal conductivity will improve, and if the ratio of Cu is 30 wt% or less, it will become a low coefficient of thermal expansion. From this, it can be said that the Cu content in the CuW alloy is desirably 5 wt% or more and 30 wt% or less with respect to the mass of the CuW alloy.

  On the other hand, in the CuMo alloy, as in the CuW alloy, the thermal conductivity increases as the Cu ratio increases, but the thermal expansion coefficient also increases. This is because Cu is a metal excellent in heat conduction, and as the proportion of Cu increases, the coefficient of thermal expansion increases. For this reason, in order to set it as the CuMo alloy of a low thermal expansion coefficient, it is necessary to regulate the ratio of Cu. And if the ratio of Cu is 10 wt% or more, thermal conductivity will improve, and if the ratio of Cu is 50 wt% or less, it will become a low coefficient of thermal expansion. From this, it can be said that the Cu content in the CuMo alloy is preferably 10 wt% or more and 50 wt% or less with respect to the mass of the CuMo alloy.

  Next, an optical semiconductor module according to an embodiment of the present invention will be described with reference to the drawings. However, the present invention is not limited to this embodiment, and may be changed as appropriate without changing the object of the present invention. Can be implemented. FIG. 1 is a perspective view schematically showing a carrier as a main part of the stem type optical semiconductor module of the present invention. FIG. 2 is a perspective view schematically showing an enlarged main part in a state where lead terminals are mounted on the carrier of FIG.

  FIG. 3 is a perspective view schematically showing a state in which each element is arranged on the carrier of FIG. 1, each element is connected to a lead terminal, and a cap is attached to form an optical semiconductor module. FIG. 4 is a diagram showing the relationship between the heating time (elapsed time) by the heater and the temperature of the optical semiconductor module when there is no temperature sensor. FIG. 5 is a diagram showing the relationship between the heating time (elapsed time) by the heater and the temperature of the optical semiconductor module when there is a temperature sensor.

1. Optical Semiconductor Module As shown in FIGS. 1 to 3, the optical semiconductor module 10 of the present invention includes a carrier 10 a composed of a carrier base 11 and a mount portion 12, and a semiconductor laser element (LD) 13 mounted on the mount portion 12. And a light receiving element (PD) 14, a temperature sensor element (thermistor) 15, and a cap 16 that keeps them airtight. In this case, the mount portion 12 is formed of a hexahedron having a trapezoidal cross section, and a semiconductor laser element (LD) 13 is formed on the upper surface of the smooth surface, and a light receiving element (PD) is formed on the lower portion. ) 14 is attached, and a temperature sensor element (thermistor) 15 is attached to the opposite side of this surface.

  Here, the carrier base 11 is formed of a CuW alloy in a three-step staircase shape, and the flat shape forming the bottom portion in the first step is a rectangular and flat plate-shaped mounting portion 11a, and the cap is fixed in the second step. It consists of a cylindrical cap fixing part 11b and a terminal part 11c formed in a cylindrical shape having a smaller diameter than the second stage by fixing a plurality of leads in the third stage. The mount portion 12 is formed of a CuW alloy so as to be positioned above the carrier base 11. The carrier base 11 and the mount portion 12 are integrally formed of a sintered body.

  Also, the carrier base 11 is formed with four through holes 18, 18, 18, 18 opened on the upper surface of the terminal portion 11c, and leads are provided in these four through holes 18, 18, 18, 18. Terminals 18a, 18b, 18c and 18d are inserted, and the lead terminals 18a, 18b, 18c and 18d are hermetically sealed with glass. Note that the upper portions of the plurality of lead terminals 18 a, 18 b, 18 c, 18 d extend to the upper surface of the terminal portion 11 c of the carrier base 11. A semiconductor laser element 13, a light receiving element 14, and a temperature sensor element (thermistor) 15 are connected to the extended portion by a gold wire.

  Further, a cap 16 for holding the semiconductor laser 13, the light receiving element 14, and the temperature sensor (thermistor) 15 in an airtight manner is joined to the carrier base 11 made of a CuW alloy. In this case, nickel plating is applied to the surface of the cap fixing portion 11b in order to improve the bonding between the cap fixing portion 11b made of the CuW alloy and the cap 16, and a Kovar ring (not shown) is formed on the nickel plating. ) Is brazed. A cap 16 is joined to the Kovar ring by resistance welding. An optical fiber 17 is attached to the tip of the cap 16, and a lens (not shown) is accommodated in the cap 16 so that laser light is efficiently incident on the optical fiber 17.

2. Next, a manufacturing procedure of the optical semiconductor module 10 configured as described above will be described in detail below. First, W powder with an average particle diameter of 1 μm adjusted so that the content ratio of tungsten (W) is 95 to 70 mass% and the content ratio of copper (Cu) is 5 to 30 mass% is mixed with Cu powder. did. To this mixed powder, an acrylic resin as a binder was added in an amount of 45% by mass with respect to the mass of the mixed powder and mixed and kneaded with a kneader to obtain a molding composition. Subsequently, the obtained molding composition was pelletized with a pelletizer. This was put into a hopper of an injection molding machine and injection molded into a mold having an injection temperature of 160 ° C. and a mold temperature of 25 ° C.

  Thereafter, the mold was water-cooled to solidify the injection, and a green body (molded body) to become the carrier 10a as shown in FIG. 1 was obtained. Next, this green body was placed in a binder removal apparatus (not shown). Thereafter, nitrogen gas was introduced into the binder removal apparatus to create a nitrogen atmosphere. And it heated to predetermined | prescribed temperature (for example, 500-550 degreeC) with a predetermined | prescribed temperature increase rate, hold | maintained only for the predetermined | prescribed time (for example, 30 minutes-2 hours), and the green body was debinder-processed. By the binder removal process, the above-described binder is volatilized (removed) to obtain a brown body made of W and Cu. Then, it cooled to room temperature and took out the brown body from the binder removal apparatus.

  Next, the obtained brown body was placed in a deoxygenation device (not shown). Thereafter, hydrogen gas is allowed to flow into the deoxygenator, and the brown body is sufficiently exposed to a hydrogen gas stream in a temperature environment (for example, 500 ° C. to 1000 ° C.) below the melting point temperature of copper. Deoxygenated. By this deoxygenation treatment, the oxide layer on the surface of the W particles constituting the brown body is sufficiently reduced, and the wettability with copper is improved. Next, the deoxidized brown body was placed in a sintering furnace and sintered in a hydrogen stream to produce a semiconductor carrier 10a made of a WCu alloy sintered body as shown in FIG.

  Next, two opposing side surface portions of the mounting portion 12 of the semiconductor carrier 10a manufactured as described above are machined to have a surface roughness of TIR (maximum height) of maximum 3 μm and Ra (average roughness). Smooth polishing was performed so that the thickness was 0.5 μm or less. Thereafter, the processing burr was removed by a blast machine, and nickel plating (for example, 2 μm in thickness) was applied to the entire surface. Next, after inserting Kovar lead terminals 18a, 18b, 18c, 18d through the glass sealing material into the through holes 18, 18, 18, 18 in a reflow furnace (maximum temperature is about 1000 ° C.). These lead terminals 18a, 18b, 18c, and 18d were glass sealed.

  Next, after placing a Kovar ring on the cap fixing portion 11b via silver wax, the Kovar ring was joined on the cap fixing portion 11b in a reflow furnace (maximum temperature was 850 ° C.). Then, after nickel plating (for example, thickness 1 micrometer) was given to these whole surfaces, gold plating (for example, thickness 1 micrometer) was performed on it. Thereafter, the semiconductor laser element (LD) 13 was fixed with AuSn solder so that the laser was emitted upward on the smooth surface of the mount portion 12. A light receiving element (PD) 14 for monitoring and controlling the output of the laser was fixed to the smooth surface below the semiconductor laser element (LD) 13 with AuSn solder. Further, a temperature sensor element (thermistor) 15 was fixed to the smooth surface opposite to these surfaces with AuSn solder.

  Thereafter, the lead terminals 18a and 18c and the semiconductor laser element (LD) 13 were joined with a gold wire. Further, the lead terminal 18b and the light receiving element (PD) 14 were joined by a gold wire, and the lead terminal 18d and the temperature sensor element (thermistor) 15 were joined by a gold wire. On the other hand, a cap 16 for holding the semiconductor laser (LD) 13, the light receiving element (PD) 14, and the temperature sensor element (thermistor) 15 in an airtight manner was prepared. Next, the cap 16 was joined by resistance welding onto a Kovar ring joined to the cap fixing portion 11c of the carrier base 11 to produce the optical semiconductor module 10.

  In this case, since resistance welding is generally performed in an atmosphere of nitrogen gas, nitrogen gas may be enclosed during welding. An optical fiber 17 is attached to the tip of the cap 16, and a lens (not shown) is accommodated so that laser light can be efficiently incident on the optical fiber 17. In the optical semiconductor module 10 configured as described above, the laser light emitted upward from the semiconductor laser 13 is efficiently coupled to the optical fiber 17 by the lens.

  A temperature control circuit is provided outside the optical semiconductor module 10. A lead wire extending from a lead terminal 18 d connected to the temperature sensor element (thermistor) 15 is connected to the signal input portion of the temperature control circuit. On the other hand, lead wires extending from lead terminals 18a and 18c connected to the semiconductor laser (LD) 13 are connected to the output portion of the temperature control circuit. As a result, the power applied to the semiconductor laser (LD) 13 can be controlled by the temperature detected by the temperature sensor element (thermistor) 15, so that the amount of heat generated by the semiconductor laser (LD) 13 can be controlled to be constant. become.

  Here, in order to perform a heat generation test, a small heater having a heat generation amount corresponding to the heat generation amount generated by the semiconductor laser (LD) 13 is mounted at the mounting position of the semiconductor laser (LD) 13 of the mount portion 12, and this optical semiconductor is mounted. When a thermometer was placed in the module 10 and the temperature in the module 10 was measured, a result as shown in FIG. 4 was obtained. In FIG. 4, curve A shows the case where the environmental temperature is 25 ° C., and curve B shows the case where the environmental temperature is 35 ° C. As is clear from the results of FIG. 4, when the environmental temperature is as low as 25 ° C., the design temperature does not exceed 60 ° C., but when the environmental temperature increases as 35 ° C., the design temperature exceeds 60 ° C. I understand that

  On the other hand, a small heater having a calorific value corresponding to the calorific value generated by the semiconductor laser (LD) 13 is attached to the mounting position of the semiconductor laser (LD) 13 of the mount portion 12, and the mount on the opposite side of the heater mounting position. A temperature sensor element (thermistor) 15 is attached to the section 12, and when the temperature detected by the temperature sensor element (thermistor) 15 reaches a set temperature (for example, 55 ° C.), the power applied to the heater is controlled. And when the thermometer was arrange | positioned in this optical semiconductor module 10 and the temperature in the module 10 was measured on the conditions whose environmental temperature is 35 degreeC, the result as shown in FIG. 5 was obtained.

  As is apparent from the results of FIG. 5, even when the environmental temperature is as high as 35 ° C., the power applied to the heater is controlled when the temperature in the optical semiconductor module 10 rises to the set temperature of 55 ° C. Therefore, it can be seen that the temperature in the module 10 does not exceed the design temperature of 60 ° C., and can be kept at a constant temperature of 55 ° C., which is the set temperature.

  In the above-described embodiment, the example in which the thermistor is used as the temperature sensor element has been described. However, if there is a space to arrange the temperature sensor element, a CMOS temperature sensor or a platinum resistance element may be used instead of the thermistor.

It is a perspective view which shows typically the carrier used as the principal part of the stem type optical semiconductor module of this invention. FIG. 2 is a perspective view schematically showing an enlarged main part in a state where lead terminals are mounted on the carrier of FIG. 1. FIG. 2 is a perspective view schematically showing a state where each element is arranged on the carrier of FIG. 1, each element is connected to a lead terminal, and a cap is attached to form an optical semiconductor module. It is a figure which shows the relationship between the heating time (elapsed time) by a heater in case there is no temperature sensor, and the temperature of an optical semiconductor module. It is a figure which shows the relationship between the heating time (elapsed time) by a heater in case there exists a temperature sensor, and the temperature of an optical semiconductor module.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical semiconductor module, 10a ... Carrier, 11 ... Carrier base, 11a ... Mounting part, 11b ... Cap fixing part, 11c ... Terminal part, 12 ... Mount part, 13 ... Semiconductor laser element, 14 ... Light receiving element, 15 ... Temperature Sensor, 16 ... cap, 17 ... optical fiber, 18 ... through hole, 18, 18b, 18c, 18d ... lead terminal

Claims (8)

An optical semiconductor module in which an optical semiconductor element is mounted on a mount portion serving as a heat sink that protrudes from a carrier base, and a cap that covers the mount portion is fixed to the carrier base,
A temperature sensor for detecting the temperature in the optical semiconductor module is disposed in the cap, and the output of the optical semiconductor element is adjusted according to the output of the temperature sensor. An optical semiconductor module. The optical semiconductor module according to claim 1, wherein the temperature sensor is disposed on a side opposite to a position of the mount portion on which the optical semiconductor element is mounted. 3. The optical semiconductor module according to claim 1, wherein an output signal lead terminal of the temperature sensor is disposed on the carrier base. 4. The optical semiconductor module according to claim 1, wherein four lead terminals including an output signal terminal of the temperature sensor are disposed on the carrier base. 5. 5. The mount part to be the heat sink is formed of any one of high thermal conductivity materials selected from CuW alloy, CuMo alloy, CuO—Cu composite, and AlN. An optical semiconductor module according to claim 1. The carrier base is also formed of any one of a high thermal conductivity material selected from a CuW alloy, a CuMo alloy, a CuO-Cu composite, and AlN, and the mount portion is also integrally formed. The optical semiconductor module according to any one of claims 1 to 5. The optical semiconductor module according to claim 5 or 6, wherein the CuW alloy has a Cu content of 5 mass% or more and 30 mass% or less. The optical semiconductor module according to claim 5 or 6, wherein the CuMo alloy has a Cu content of 10 mass% or more and 50 mass% or less.

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