JP2009176969A - Semiconductor laser device and image forming device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor laser device which improves a heat radiating efficiency of the semiconductor laser device, and improves a reduction (droop) of an optical output of the semiconductor laser device. <P>SOLUTION: This semiconductor laser device comprises: a semiconductor laser element; a sub-mount jointed to the board side of the semiconductor laser element; and a heat sink jointed to the rear side of the sub-mount. In this semiconductor laser device, a metal film is formed on an upper face of the semiconductor laser element, on a side face of the semiconductor laser element, a face of the sub-mount and a face of the heat sink, and the upper face of the semiconductor laser element is connected to the face of the heat sink through the metal film. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor laser device and an image forming apparatus using the same, and the cost of the semiconductor laser device is reduced by forming the wiring of the semiconductor laser element as a metal film and forming the metal film using an ink jet technique. Semiconductor laser device, semiconductor laser device that improves heat dissipation effect of semiconductor laser element to suppress output decrease due to thermal influence, and image forming apparatus reduced in cost by using the semiconductor laser device, or laser light The present invention relates to an image forming apparatus that suppresses a decrease in image density caused by a decrease in output.

  In the semiconductor laser element, when electrical energy is converted into light energy, energy loss occurs and the energy is converted into thermal energy. If the temperature of the semiconductor laser element rises due to the generated thermal energy, an undesirable effect on the laser characteristics occurs. Therefore, in order to dissipate heat generated in the semiconductor laser element and reinforce the strength of the semiconductor laser element, the substrate side of the semiconductor laser element is usually joined to the heat sink via a submount with a solder layer.

  The configuration of a conventional semiconductor laser device will be described with reference to FIGS. The conventional semiconductor laser element includes a semiconductor laser element 1, a submount 2 bonded to the substrate side of the semiconductor laser via a first solder layer 4, and a submount 2 via a second solder layer 8. And a heat sink 7 bonded to the back side. The electrode of the semiconductor laser element 1 and the wiring 3 of the submount 2 are joined via the first solder layer 4, and the wiring 3 of the submount 2 and the electrode pad 6 that is a wiring mechanism part are bonded by a wire 5. The semiconductor laser element 1 is connected to an external device via the electrode pad 6.

  The semiconductor laser element 1 is not limited to one semiconductor laser element, and a plurality of semiconductor laser elements may be arranged in an array. As the material of the submount 2, usually, copper tungsten (CuW), silicon carbide (SiC), or the like having a thermal expansion coefficient close to that of the semiconductor laser element is used.

  When manufacturing the semiconductor laser device, first, the semiconductor laser element 1 is placed on the solder layer 4 such as gold tin (AuSn) formed on the bonding surface of the submount 2 and the melting temperature of gold tin is 280 ° C. For example, the solder layer is melted by heating at 300 ° C. or higher. Next, when the submount 2 is allowed to cool while the semiconductor laser element 1 is mounted, the solder layer is solidified and the submount 2 and the semiconductor laser element 1 can be joined. Subsequently, a thin plate of silver tin antimony (AgSnSb) is placed on the joining surface of the heat sink, and the submount 2 to which the semiconductor laser element 1 is joined is placed thereon, and a temperature of 233 ° C. or higher, which is the melting temperature of silver tin antimony, For example, by heating at 250 ° C., gold tin antimony is melted. Subsequently, the gold tin antimony is solidified by cooling, and the heat sink 7 and the submount 2 are joined.

JP 2002-299744 A

  However, in the conventional semiconductor laser device, the heat generated in the semiconductor laser element 1 is almost radiated through one surface where the semiconductor laser element 1 and the submount 2 are joined, and there is a limit to the reduction of the thermal resistance. However, a decrease in optical output (droop) due to heat generated in the semiconductor laser element has been a problem.

  In particular, in the semiconductor laser array 1 in which a plurality of semiconductor lasers are arranged in an array, the amount of generated heat is large, and the heat generated by the droop or one-channel semiconductor laser element affects the optical output of other channels. Talk was a problem. In particular, when a semiconductor laser device is used as a writing light source for an electrophotographic image forming apparatus, a decrease in light output leads to a decrease in image density, which is one of the causes of image quality degradation.

  In addition, the semiconductor laser element wiring is performed by wire bonding the common electrode or submount wiring of the semiconductor laser element and the electrode pad which is the wiring mechanism part, and the semiconductor laser array element having a large number of electrodes. However, it is necessary to bond a large number of wires to the integrated wiring, which is difficult to manufacture and expensive.

  It is an object of the present invention to improve the heat dissipation efficiency of a semiconductor laser device, and to improve the problem of optical output drop (droop) of a semiconductor laser element, or optical output drop (droop) of a semiconductor laser array element, and thermal crosstalk. Droop or thermal crosstalk by using the semiconductor laser device, the semiconductor laser device in which the wiring formation in the semiconductor laser device is reduced, and the semiconductor laser device as a writing light source of an electrophotographic image forming apparatus It is an object of the present invention to provide an image forming apparatus that does not deteriorate image quality due to a decrease in image density caused by the image quality, and an image forming apparatus that is reduced in cost.

  The first means of the present invention for solving the above-mentioned problems is a semiconductor laser element, a submount bonded to the substrate side of the semiconductor laser element, and a heat sink bonded to the back side of the submount. A metal film is formed on the upper surface of the semiconductor laser element, the side surface of the semiconductor laser element, the submount surface, and the heat sink surface, and the upper surface of the semiconductor laser element and the heat sink surface are formed of a metal film. It is characterized by being connected by.

  According to a second means of the present invention, in the first means of the present invention, the semiconductor laser element is a semiconductor laser array element.

  According to a third means of the present invention, in the first and second means of the present invention, the metal film is formed by applying an ink in which metal fine particles are dispersed in a liquid and performing a heat treatment. To do.

  According to a fourth means of the present invention, in the first, second, and third means of the present invention, the metal film is applied by discharging an ink in which metal fine particles are dispersed in a liquid by an inkjet head, and heat treatment. It is formed by doing.

  According to a fifth means of the present invention, in the first to fourth means of the present invention, a wiring connected to the substrate of the semiconductor laser element exists on the submount, and extends from the wiring to the insulating film. There exists a wiring that exists and is electrically connected to the wiring mechanism section.

  According to a sixth means of the present invention, in the fifth means of the present invention, the insulating film comprises a solution in which an organic insulator is dissolved in a solvent, a suspension in which a particulate inorganic insulator is dispersed in a liquid, and It is characterized in that it is formed by applying and heat-treating any solution in which an inorganic insulator is dissolved in a solvent by an inkjet head.

  According to a seventh means of the present invention, in the fifth means of the present invention, the wiring that extends on the insulating film and is electrically connected to the wiring mechanism section is an ink in which metal fine particles are dispersed in a liquid. It is characterized in that it is formed by applying and heat-treating.

  An eighth means of the present invention is the third, fourth, or seventh means of the present invention, wherein the genus fine particles are gold fine particles.

  According to a ninth means of the present invention, in the third, fourth and seventh means of the present invention, the genus fine particles are silver fine particles.

  According to a tenth aspect of the present invention, there is provided a semiconductor laser device that emits a plurality of beams, a scanning optical system that modulates and scans a plurality of beams emitted from the semiconductor laser device on a photosensitive member, and a latent image by the plurality of beams. A developing member that develops a latent image on the photosensitive member to form an image, a transfer device that transfers the developed image onto a sheet, and an image transferred onto the sheet. In the image forming apparatus having the fixing device for fixing the toner on the sheet, the semiconductor laser device is a semiconductor laser device of any one of the first to ninth means.

  A semiconductor laser device in which the heat dissipation efficiency of the semiconductor laser device is improved, and the problem of the optical output drop (droop) of the semiconductor laser element, or the optical output drop (droop) of the semiconductor laser array element and thermal crosstalk is improved Alternatively, the wiring in the semiconductor laser device is made into a metal film, and the metal film is formed by using an ink jet technique, so that the cost is reduced, and the semiconductor laser device is written in an electrophotographic image forming apparatus. By using the light source, it is possible to provide an image forming apparatus that does not deteriorate image quality due to a decrease in image density caused by droop or thermal crosstalk, and an image forming apparatus that is reduced in cost.

  Next, examples of the present invention will be described. In this embodiment, the case where the semiconductor laser element is the semiconductor laser array 1 will be described.

  Bonding between the semiconductor laser array element 1 and the submount 2 will be described with reference to FIGS. The material of the submount 2 is silicon carbide (SiC), which is larger than the semiconductor laser array element 1 and has 10 wirings on the mounting surface equal to the sum of the electrodes of the respective elements of the semiconductor laser array element 1 and the electrodes of the dummy elements. Is provided. Of these ten wires, four wires 3 facing each element extend in parallel from one end of the submount 2 to the inside. And the solder layer 4 is formed in the part facing each element and a dummy element. The solder layer 4 is made of, for example, gold tin (AuSn).

  The semiconductor laser array element 1 is fixed by face-down bonding. In this face-down bonding, the electrodes of the semiconductor laser array element 1 are positioned and stacked on the solder layer, and are heated at 280 ° C. or higher, for example, 300 ° C., which is a temperature at which the gold-tin solder is melted. 1 is joined to the submount 2.

  The wiring that supports the solder layer on which the electrodes of the respective elements of the semiconductor laser array element 1 are overlapped extends outside the chip fixing region.

The joining of the submount 2 to which the semiconductor laser array element 1 is joined to the heat sink 7 will be described with reference to FIGS. The heat sink is made of copper (Cu) having high thermal conductivity. A thin plate of silver tin antimony (AgSnSb) is placed on the surface to which the submount 2 of the heat sink 7 is bonded, and the submount 2 is stacked on the thin plate, and the silver tin antimony (AgSnSb) is dissolved at 233 ° C. or higher, for example, 250 ° C. The submount 2 is bonded onto the heat sink 7 by being heated and melted temporarily and cooled. Here, the thermal conductivity of GaAs which is the material of the semiconductor laser array element 1 is 54 (W / m · k), the thermal expansion coefficient is 6.5 (× 10 ⁻⁶ / ° C.), and the material of the submount 2. The thermal conductivity of SiC is 270 (W / m · k), the thermal expansion coefficient is 3.7 (× 10 ⁻⁶ / ° C.), and the thermal conductivity of Cu which is the material of the heat sink 7 is 390 (W / m · k). ), The thermal expansion coefficient is 17.7 (× 10 ⁻⁶ / ° C.). The submount also serves to absorb stress generated by the difference in thermal expansion coefficient between the heat sink and the semiconductor laser array element.

  Conventionally, as shown in FIGS. 4 and 7, the wiring 3 of the submount 2 and the electrode pad 6 which is a wiring mechanism part are connected by wire bonding, and the common electrode and heat sink on the upper surface of the semiconductor laser array element are connected. Were connected by direct wire bonding. However, as the number of channels of the semiconductor laser array element increases, the wiring becomes dense, and it is difficult to connect all the wirings by wire bonding, which increases the cost.

  In the present invention, as shown in FIG. 5, ink in which silver or gold fine particles are dispersed is applied to the upper and side surfaces, the submount surface, and the heat sink surface of the semiconductor laser array element using an inkjet head. Then, the liquid is volatilized by performing heat treatment at 150 to 200 ° C. By repeating this process several times, a metal film 31 having a thickness of about 10 μm is formed. The metal film 31 connects the upper surface of the semiconductor laser array element and the heat sink surface, electrically connects the common electrode of the semiconductor laser array and the heat sink surface, and dissipates heat from the upper surface of the semiconductor laser array element to the heat sink portion. Also fulfills.

  In addition, as shown in FIG. 6, on the heat sink that connects the wiring on the submount to the electrode pad, a solution in which an organic insulator is dissolved in a solvent, a suspension in which fine inorganic inorganic insulator is dispersed in a liquid, And a solution obtained by dissolving an inorganic insulator in a solvent is ejected using an inkjet technique, and heat treatment is performed at 100 ° C. or higher to form an insulating film. Next, an ink in which silver or gold fine particles are dispersed is applied by being ejected using an ink jet technique, and heat treatment is performed at 150 to 200 ° C. to connect the wiring on the submount to the electrode pad with a film thickness of 1 μm. About a metal wiring pattern is formed.

  FIG. 9 shows a schematic diagram of an optical system when the semiconductor laser device of the present invention is used as a light source of an image recording apparatus. The multi-beams emitted from the semiconductor laser array element 1 in the semiconductor laser device of the present invention are converted into parallel light by the lens 10 and optically scanned on the photosensitive drum 14 by the rotary polygon mirror 12 at a time. Since the distance between the light spot rows obtained on the photosensitive drum 14 is larger than the size of the light spot, the arrangement direction of the light spot rows is set obliquely with respect to the light scanning direction, and a close light scanning line is formed. I try to do it.

  The image forming apparatus of the present invention will be described with reference to FIG. The surface of the photosensitive drum 14 is charged by the charger 16, and light corresponding to the image is applied by the exposure device 17 to drop the potential on the photosensitive drum 14. That portion reaches the developing roller 18 by the rotation of the photosensitive drum 14, and charged toner adheres to the photosensitive drum 14 when it contacts the toner layer. The toner image on the photosensitive drum 14 is transferred onto the intermediate transfer belt 24 at a portion where the primary transfer roll 21 presses the intermediate transfer belt 24.

  The toner image on the photosensitive drum 14 of each developing unit is transferred onto the intermediate transfer belt 24 to form a color toner image. As the intermediate transfer belt 24 is conveyed, the toner image is transferred onto the conveyed continuous paper 27 at the position of the transfer drum 26 in the contact area with the continuous paper. Heat and pressure are applied to the continuous paper 27 to which the toner image has been transferred by a fixing device 28, and the toner is melted and fixed to form a color image. The present invention is also applicable to cut paper.

  The present invention relates to a semiconductor laser device and an electrophotographic image forming apparatus using the semiconductor laser device.

It is a perspective view of the submount part concerning the Example of this invention. It is a perspective view of the submount part which bonded the semiconductor laser array element concerning the Example of this invention. It is a perspective view of the heat sink part upper surface which bonded the submount part which bonded the semiconductor laser array element concerning the Example of this invention. It is a perspective view of the conventional semiconductor laser apparatus. It is a perspective view of the heat sink part upper surface which bonded the submount part which bonded the semiconductor laser array element concerning the Example of this invention. It is a perspective view of the heat sink part which bonded the submount part which bonded the semiconductor laser array element concerning the Example of this invention. It is the schematic of the conventional semiconductor laser apparatus. It is the schematic of the heat sink part which bonded the submount part which bonded the semiconductor laser array element concerning the Example of this invention. 1 is a schematic diagram of an optical system of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic view of an image forming apparatus according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor laser array element, 2 ... Submount, 3 ... Wiring, 4 ... 1st solder layer, 5 ... Wire, 6 ... Electrode pad, 7 ... Heat sink, 8 ... 2nd solder layer, 9 ... Photo detector, DESCRIPTION OF SYMBOLS 10 ... Lens, 11 ... Cylindrical lens, 12 ... Polygon mirror, 13 ... F (theta) lens, 14 ... Photosensitive drum, 15 ... Static eliminator, 16 ... Charger, 17 ... Exposure device, 18 ... Developing device, 19 ... Potential sensor, 20 DESCRIPTION OF SYMBOLS ... Cleaner, 21 ... Primary transfer roller, 22 ... Drive roller, 23 ... Adhesion amount sensor, 24 ... Intermediate transfer belt, 25 ... Belt cleaner, 26 ... Secondary transfer roller, 27 ... Continuous paper, 28 ... Fixing device, 29 ... paper container before printing, 30 ... paper container after printing, 31 ... metal film, 32 ... insulating film, 33 ... metal film

Claims (10)

In a semiconductor laser device comprising: a semiconductor laser element; a submount bonded to the substrate side of the semiconductor laser element; and a heat sink bonded to the back side of the submount.
A metal film is formed on the semiconductor laser element upper surface, the semiconductor laser element side surface, the submount surface, and the heat sink surface, and the semiconductor laser element upper surface and the heat sink surface are connected by a metal film. Semiconductor laser device.   2. The semiconductor laser device according to claim 1, wherein the semiconductor laser element is a semiconductor laser array element.   3. The semiconductor laser device according to claim 1, wherein the metal film is formed by applying an ink in which metal fine particles are dispersed in a liquid and performing a heat treatment.   3. The semiconductor laser device according to claim 1, wherein the metal film is formed by applying and heat-treating ink in which metal fine particles are dispersed in a liquid by ejecting the ink with an inkjet head.   A wiring connected to the substrate of the semiconductor laser element exists on the submount, and there is a wiring that extends from the wiring to an insulating film and is electrically connected to a wiring mechanism. The semiconductor laser device according to claim 1.   The insulating film ejects either a solution in which an organic insulator is dissolved in a solvent, a suspension in which a fine-particle inorganic insulator is dispersed in a liquid, or a solution in which an inorganic insulator is dissolved in a solvent by an inkjet head. 6. The semiconductor laser device according to claim 5, wherein the semiconductor laser device is formed by coating and heat treatment.   The wiring extending on the insulating film and electrically connected to the wiring mechanism is formed by applying and heat-treating ink in which metal fine particles are dispersed in a liquid. A semiconductor laser device according to claim 5 or 6.   8. The semiconductor laser device according to claim 3, wherein the metal fine particles are gold fine particles.   8. The semiconductor laser device according to claim 3, wherein the metal fine particles are silver fine particles. A semiconductor laser device that emits a plurality of beams, a scanning optical system that modulates and scans the plurality of beams emitted from the semiconductor laser device on the photoconductor, a photoconductor on which a latent image is formed by the plurality of beams, A developing device that develops a latent image on a photoconductor to form an image, a transfer device that transfers the developed image onto a sheet, and a fixing device that fixes the image transferred onto the sheet onto the sheet In an image forming apparatus having
An image forming apparatus, wherein the semiconductor laser device is the semiconductor laser device according to claim 1.

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