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Heat sink and laser diode

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20120291995 patent thumbnailZoom

Heat sink and laser diode


The present invention is directed to improve reliability by preventing deterioration in the structure of an inner wall of a water channel caused by galvanic corrosion. A heat sink in which a water channel of a cooling fluid is formed by stacking and bonding a plurality of thin plates, in which a surface in the water channel is made of the same metal material except for at least an end of a bonded part of the thin plates.
Related Terms: Water Channel

Browse recent Sony Corporation patents - Tokyo, JP
Inventors: Kenji Sasaki, Hidekazu Kawanishi, Yuichi Hamaguchi
USPTO Applicaton #: #20120291995 - Class: 16510411 (USPTO) - 11/22/12 - Class 165 
Heat Exchange > Intermediate Fluent Heat Exchange Material Receiving And Discharging Heat

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The Patent Description & Claims data below is from USPTO Patent Application 20120291995, Heat sink and laser diode.

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RELATED APPLICATION DATA

This application is a division of U.S. patent application Ser. No. 12/128,142, filed on May 28, 2008, the entirety of which is incorporated herein by reference to the extent permitted by law. The present invention claims priority to and contains subject matter related to Japanese Patent Application No. JP 2007-144640 filed in the Japanese Patent Office on May 31, 2007, the entire contents of which being incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat sink in which a channel (water channel) of a cooling fluid is formed by stacking and bonding a plurality of thin plates and to a laser diode obtained by mounting a semiconductor laser device in such a heat sink.

2. Description of the Related Art

In a laser diode of a few W to tens W class, a water cooling system is often employed to realize a higher output and higher reliability. As a heat sink structure for realizing high heat exhaust efficiency, a heat sink of a micro-channel type is well known (refer to, for example, Japanese Unexamined Patent Application Publication No. 2006-294943).

FIG. 8 shows an example of a sectional structure of a laser diode of the related art.

The laser diode is constructed by mounting a semiconductor laser chip 102 on a heat sink 101 having a fine channel structure of a micro-channel type. The heat sink 101 has a structure obtained by stacking and bonding a plurality of thin plates. In the heat sink 101, a water channel 103 (a supply water channel 103A, an intermediate water channel 103B, and an exhaust water channel 103C) through which a cooling fluid passes is formed. In the example of FIG. 8, five thin plates of a first layer 121 as a top layer to a fifth layer 125 are stacked. The first layer 121 is a laser chip mounting plate on which the semiconductor laser chip 102 is mounted. In the second and fourth layers 122 and 124, a radiator fin is formed. In the second to fifth layers 122 to 125, a hole for forming the water channel 103 is formed. The layers are bonded with an insert metal (bonding metal) 105.

A concrete manufacturing procedure of the heat sink 101 having such a structure includes the following steps. (1) manufacture of base sheets of the layers (2) etching of sheet materials (formation of a water channel structure) (3) plating of the sheet materials with an inert metal (bonding metal) (4) bonding of the sheet materials (5) heating and pressure-bonding of the sheet materials

As the material of the base sheet, generally, copper (Cu) having high heat conductivity and which is processed easily is used. As the insert metal 105, for example, gold (Au) or silver (Ag) is used. As a bonding method, liquid-phase diffusion bonding, soldering, or the like is used.

SUMMARY

OF THE INVENTION

In the above-described manufacture procedure, to prevent a fine structure part from being buried by the insert metal 105 which is melt at the time of performing liquid-phase diffusion bonding or the like, the second and fourth layers 122 and 124 in which the pattern of the radiator fin is formed are not plated with the insert metal 105 but the first, third, and fifth layers 121, 123, and 125 are plated with the insert metal 105 as shown in FIG. 9. When bonding is performed after alternately plating the layers, as shown in FIG. 8, different metals appear in the inner wall of the water channel 103. Specifically, a part 201 in which the metal (copper or the like) of the base material and a part 202 in which the insert metal 105 (gold, silver, or the like) is exposed mixedly exist in the water channel 103. Due to such a structure, in the past, there is an issue such that galvanic corrosion occurs with use time. The galvanic corrosion denotes a phenomenon such that when dissimilar metals come into contact in the cooling fluid, ions move, and the metal having a lower ionization tendency is thinned (etched). When a potential difference occurs between dissimilar metals in the heat sink via the cooling fluid and water is passed for a long period of about thousands of hours, a noble metal side (for example, gold or silver) in the heat sink is thinned and a corrosion product is deposited and adhered onto a base metal side (for example, copper). Due to the phenomenon, destruction of the structure in the water channel (decrease in the cooling capability in a few thousands of hours of passing of water) and continuity with the heat sink outer wall (water leakage in a few thousands of hours of passing of water) occurs. It largely deteriorates the reliability of the heat sink.

It is desirable to provide a heat sink and a laser diode realizing improved reliability by preventing deterioration in the structure of an inner wall of a water channel due to galvanic corrosion.

According to an embodiment of the present invention, there is provided a heat sink in which a water channel of a cooling fluid is formed by stacking and bonding a plurality of thin plates. A surface in the water channel is made of the same metal material except for at least an end of a bonded part of the thin plates.

According to an embodiment of the invention, there is provided a laser diode including a heat sink in which a water channel of a cooling fluid is formed by stacking and bonding a plurality of thin plates, and a semiconductor laser device mounted on the heat sink. The surface in the water channel in the heat sink is made of the same metal except for at least an end of a bonded part of the thin plates.

In the heat sink or the laser diode of the embodiment of the present invention, in the water channel, the surfaces made of the same metal material including the end of the bonded part are exposed, or the surfaces made of the same metal material excluding an end of the bonded part are exposed. With the configuration, the surfaces in the water channel are made of substantially the same metal material, and no dissimilar metals exist in the water channel. Consequently, even when dissimilar metals exist, the amount of the dissimilar metals is very small in the surface area of in the water channel. Thus, galvanic corrosion is minimized, and reliability improves.

In the heat sink and the laser diode of the embodiment of the present invention, the surfaces in the water channel are made of the same metal material except for at least an end of a bonded part of the thin plates. Consequently, dissimilar metals do not exist or hardly exist in the surface area in the water channel. As a result, deterioration in the structure of the inner wall of the water channel caused by galvanic corrosion is prevented, and reliability may be improved.

Other and further objects, features and advantages of the invention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross section showing an example of a laser diode as a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing an example of a heat sink in the first embodiment of the invention.

FIGS. 3A to 3D are manufacture process drawings showing an example of a method of manufacturing a heat sink in the first embodiment of the invention.

FIG. 4 is a cross section showing an example of a laser diode as a second embodiment of the invention.

FIGS. 5A to 5C are manufacture process drawings showing an example of a method of manufacturing a heat sink in the second embodiment of the invention.

FIG. 6 is a cross section showing an example of a laser diode as a third embodiment of the invention.

FIGS. 7A to 7D are manufacture process drawings showing an example of a method of manufacturing a heat sink in the third embodiment of the invention.

FIG. 8 is a cross section showing an example of a laser diode of the related art.

FIG. 9 is a manufacture process drawing showing an example of a method of manufacturing a heat sink of the related art.

DETAILED DESCRIPTION

OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described in detail hereinbelow with reference to the drawings.

First Embodiment

FIG. 1 shows a configuration example of a laser diode as a first embodiment of the present invention. FIG. 2 is an exploded view showing a concrete example of the internal structure of a heat sink 1A applied to the laser diode.

The laser diode is constructed by mounting a semiconductor laser device 2 on the heat sink 1A having a fine channel structure of a micro-channel type. The heat sink 1A has a structure obtained by stacking and bonding a plurality of thin plates. In the heat sink 1A, a water channel 3 (a supply water channel 3A, an intermediate water channel 3B, and an exhaust water channel 3C) through which a cooling fluid passes is formed. In the embodiment, five thin plates of a first layer 21 as a top layer to a fifth layer 25 are stacked.

All of the layers 21 to 25 in the heat sink 1A are formed by thin plates made of a single metal material (such as copper, silver, or gold). The layers 21 to 25 as thin plates (base materials) are directly stacked and bonded without using an insert metal. As a result, in the surface (inner wall) in the water channel 3, all of the surfaces of the thin plates of the layers 21 to 25 including an end 41 of a bonding part 4 (an end on the water channel 3 side of the layers) are exposed.

The first layer 21 is a laser chip mounting plate on which the semiconductor laser device 2 is mounted. The second layer 22 is a plate in which a radiator fin is formed. As shown in FIG. 2, the second layer 22 has an intermediate water channel formation part 15 and radiator fins 15f. The intermediate water channel formation part 15 is formed so as to penetrate the second layer 22. A plurality of radiator fins 15f are disposed in parallel in a position corresponding to a lower part of the mounting position of the semiconductor laser device 2. A cooling water passes through the spaces between the radiator fins 15f.

The fourth layer 24 is similarly a plate in which a radiator fin is formed. As shown in FIG. 2, the fourth layer 24 has an intermediate water channel formation part 13 and radiator fins 13f. The fourth layer 24 also has a supply water channel formation hole 12 and an exhaust water channel formation hole 17. The supply water channel formation hole 12 and the exhaust water channel formation hole 17 are formed so as to penetrate the fourth layer 24.

The third layer 23 has an intermediate water channel formation part 14 and an exhaust water channel formation hole 16. The intermediate water channel formation part 14 and the exhaust water channel formation hole 16 are formed so as to penetrate the third layer 23. The intermediate water channel formation part 14 is formed in a rectangular shape and is positioned between the radiator fins 15f in the second layer 22 and the radiator fins 13f in the fourth layer 24.

The fifth layer 25 has a supply water channel formation hole 11 and an exhaust water channel formation hole 18. The supply water channel formation hole 11 and the exhaust water channel formation hole 18 are formed so as to penetrate the fifth layer 25.

The supply water channel formation hole 11 in the fifth layer 25 and the supply water channel formation hole 12 in the fourth layer 24 are provided in corresponding positions in the vertical direction, thereby forming the supply water channel 3A through which the cooling fluid passes from the lower layer side to the upper layer side. By the intermediate water channel formation part 13 and the radiator fins 13f in the fourth layer 24, the intermediate water channel formation part 14 in the third layer 23, and the radiator fins 15f and the intermediate water channel formation part 15 in the second layer 22 in order from the cooling fluid passage side, the intermediate water channel 3B through which the cooling fluid passed through the supply water channel 3A is formed. The exhaust water channel formation hole 16 in the third layer 23, the exhaust water channel formation hole 17 in the fourth layer 24, and the exhaust water channel formation hole 18 in the fifth layer 25 are provided in corresponding positions in the vertical direction. As a whole, the exhaust water channel 3C through which the cooling fluid passed through the intermediate water path 3B from an upper layer side to a lower layer side is formed.

An operation example of the laser diode will now be described.

In the laser diode, the supply water channel 3A and the exhaust water channel 3C of the heat sink 1A are connected to a not-shown circulation system called a chiller for supplying/discharging the cooling water. In the heat sink 1A, when the cooling water is supplied to the supply water channel 3A, the cooling water flows from the supply water channel 3A to the intermediate water channel 3B as described above. After that, the cooling water is discharged from the exhaust water channel 3C. The semiconductor laser device 2 converts an electric signal received from a not-shown driver element to a light signal and outputs the light signal. Heat generated when the semiconductor laser device 2 is driven is transmitted from the laser chip mounting plate (the first layer 21) into the heat sink 1A. Since the heat sink 1A has therein the radiator fins 13f and 15f in positions corresponding to the position on which the semiconductor laser device 2 is mounted, when the cooling water flows in the water channel 3, the heat received from the semiconductor laser device 2 is cooled down. In such a manner, the semiconductor laser device 2 is cooled.



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stats Patent Info
Application #
US 20120291995 A1
Publish Date
11/22/2012
Document #
13564250
File Date
08/01/2012
USPTO Class
16510411
Other USPTO Classes
International Class
28D15/00
Drawings
10


Water Channel


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