METHOD OF PRODUCING HEAT PIPE-TYPE SEMICONDUCTOR COOLING DEVICE

Abstract: A method of producing a heat pipe-type semiconductor cooling device wherein one or a plurality of through holes are provided in a long metallic member, which is then cut into a predetermined length to obtain predetermined metallic blocks. The ends of the through holes of the metallic blocks are sealed and the heat-absorbing portion is constituted of the heat-junction and then one end of a heat pipe is fitted thereto. Or the end of the heat pipe is fitted to the through hole, the end of the through hole is sealed, and they are heat-joined to constitute the heat-absorbing portion. Then, a fin is forced into the other end of the heat pipe to constitute the heat-radiating portion.

Description: SPECIFICATION Technical Field The present invention relates to a method of manufacturing a heat pipe semiconductor cooling apparatus for cooling a power semiconductor such as a thyristor. Background Art The present inventors have disclosed a cooling apparatus using a heat pipe as a semiconductor cooling apparatus for, e.g., a thyristor in Published Unexamined Japanese Patent Application No. 60-57956 as a patent application in Japan. As shown in Figs. 7 and 8, in this heat pipe semiconductor cooling apparatus, fins 2 consisting of a metal such as aluminum having high heat conductivity are fitted on heat pipes 1 consisting of a metal such as copper having high heat conductivity to form a radiating portion 3. Lower end portions of the heat pipes 1 are fitted in a metal block 4 consisting of, e.g., copper or aluminum. A semiconductor element such as a thyristor is mounted on the metal block 4. Heat generated by the semiconductor element is conducted to the heat pipes 1 and radiated from the fins 2 by natural or forcible cooling. As a result, an operation efficiency of the semiconductor element is improved. In addition, an insulating heat pipe semiconductor cooling apparatus in which an insulating cylinder consisting of, e.g., aluminum is arranged in an intermediate portion of the heat pipe or a portion between the heat pipe and the metal block has been developed. In the manufacture of these heat pipe semiconductor cooling apparatuses, boring processing is performed one or a plurality of times for the metal block 4 by using a drill or the like to form (non-through) holes 5 having a predetermined depth. Subsequently, a pre-treatment such as oxide film removal is performed for the holes 5. Thereafter, one end portion of the heat pipe 1 is inserted in the hole 5. A solder 6 or the like is filled in a gap between the heat pipe 1 and the hole 5 to integrally bond the heat pipe 1 and the metal block 4. In such a conventional method, however, the boring processing is performed by an individual NC (numerically controlled) drill machine. Therefore, a long time period is required for the boring processing, and precision of the processing is poor. In addition, the boring processing increases manufacturing cost. Disclosure of Invention The present invention is a method of manufacturing a heat pipe semiconductor cooling apparatus, comprising the steps of: forming one or a plurality of through holes in a metal elongated member; cutting the metal elongated member into a predetermined length to obtain a metal block having a predetermined shape; sealing one end portion of each of the through holes; inserting a low-temperature solder and one end portion of a heat pipe in the sealed through hole and bonding the parts by heating, thereby constituting a heat-absorbing portion; and mounting fins on the other end portions of the heat pipes by press fitting to constitute a radiating portion. Brief Description of Drawings Fig. 1 is a front view showing a heat pipe semiconductor cooling apparatus manufactured in accordance with an embodiment of the present invention; Fig. 2 is a plan view showing the heat pipe semiconductor cooling apparatus shown in Fig. 1; Fig. 3 is a front view showing an elongated member for manufacturing a metal block; Fig. 4 is a perspective view showing a metal block manufactured from the elongated member shown in Fig. 3; Fig. 5A is a bottom view showing a metal block having through holes each having a substantially elliptical sectional shape; Fig. 5B is a bottom view showing a metal block having through holes having a substantially semicircular sectional shape; Fig. 5C is a bottom view showing a metal block having rectangular through holes; Fig. 5D is a bottom view showing a plurality of through holes each having a substantially circular sectional shape; Fig. 5E is a bottom view showing through holes arranged in a zig-zag manner and each having a substantially circular sectional shape; Fig. 6 is a front view showing an insulating heat pipe semiconductor cooling apparatus manufactured by a method of the present invention; Fig. 7 is a front view showing a heat pipe semiconductor cooling apparatus manufactured by a conventional method; and Fig. 8 is a plan view showing the heat pipe semiconductor cooling apparatus shown in Fig. 7. Best Mode of Carrying Out the Invention An embodiment of the present invention will be described below with reference to the accompanying drawings. Embodiment Fig. 1 is a front view showing a heat pipe semiconductor cooling apparatus manufactured by the method of the present invention, and Fig. 2 is a plan view showing the heat pipe semiconductor cooling apparatus shown in Fig. 1. A method of manufacturing the heat pipe semiconductor cooling apparatus is performed as follows. That is, as shown in Fig. 3, an elongated member 11 which is a cast product or an extruded product consisting of a material having high heat conductivity such as aluminum or copper and having through holes 10 formed in advance is prepared. This extruded product can be easily manufactured by hot extrusion using, e.g., aluminum and its alloy or copper and its alloy. The elongated cast product can be manufactured by a conventional method. This elongated member 11 is cut into a predetermined length to obtain a metal block 12 having through holes 10 each having a predetermined size as shown in Fig. 4. Subsequently, a plug 13 consisting of the same material as that of the metal block 12 is screwed in or welded to an end portion of each through hole 10, thereby constituting a heat-absorbing portion 14 for mounting a semiconductor device. A pickling treatment or a brushing treatment is performed to remove an oxide film from the through holes 10. One end portion of a heat pipe 15 is inserted in the through hole 10. A low-temperature solder 16 of, e.g., an Sn-Pb-Cd type is buried in a gap from the heat pipe 15 to the through hole 10 and the plug 13 and heated to integrally bond the heat pipe 15 and the metal block 12, thereby improving heat contact properties. Fins 17 are mounted on the other end portions of the heat pipes 15 by means of press fitting to constitute a radiating portion 18. In this case, the metal block 12 may be placed on a heat-resistant flat plate consisting of a refractory to close the holes without using the plugs 13, and the heat pipes 15 and the metal block 12 may be directly bonded to be integrated by the low-temperature solder 16. As shown in Fig. 5A, the metal block may be a metal block 12A having through holes 12Al each having a substantially elliptical sectional shape so that a heat contact area of the heat-absorbing portion corresponding to the heat pipes 15 is increased. As shown in Fig. 5B, the metal block may be a metal block 12B having through holes 12Bl each having a substantially semicircular sectional shape so that a heat contact area of the heat-absorbing portion corresponding to one side of the heat pipes 15 is increased. As shown in Fig. 5C, the metal block may be a metal block 12C having rectangular through holes 12Cl so that substantially uniform heat-absorbing surfaces are formed on the surfaces of the metal block 12C. As shown in Fig. 5D, the metal block may be a metal block 12D having a large number of through holes 12Dl each having a substantially circular sectional shape so that a heat contact area of the heat-absorbing portion 14 is increased. As shown in Fig. 5E, the metal block may be a metal block 12E in which through holes 12El each having a substantially circular sectional shape are arranged in a zig-zag manner so that a heat contact area corresponding to an object to be cooled is obtained. A heat pipe semiconductor cooling apparatus 20 having the above arrangement is used as, e.g., a thyristor cooling apparatus as follows. That is, a flat power semiconductor device such as a thyristor is mounted on one surface of the metal block 12. Heat generated during an operation of the thyristor is absorbed from the metal block 12 of the heat-absorbing portion 14 to one end portion of each heat pipe 15. This heat evaporates an operating fluid in the heat pipe 15 and is conducted to the radiating portion 18 at the other end of the heat pipe 15. The heat is externally radiated by natural or forcible cooling by the fins 17 of the radiating portion 18. In the method of manufacturing the heat pipe semiconductor cooling apparatus as described above, boring processing of the metal block 12 is not performed for each through hole 10 but performed by cutting the elongated member 11 into a predetermined length. Therefore, the boring processing which is essential in conventional methods can be omitted. In addition, since the shapes of the metal block 12 and all the through holes 10 can be determined by one cutting processing, shape precision of the heat-absorbing portion 14 can be increased. As a result, a pre-treatment for the through holes 10 can be easily performed, and the quality of the heat-absorbing portion 14 can be improved to improve the performance of the cooling apparatus. Furthermore, since the conventionally essential boring processing can be omitted to facilitate the manufacture of the heat pipe semiconductor cooling apparatus 20, manufacturing cost can be reduced. Note that a normal operating fluid such as water, freon, or fluorocarbon can be used as the operating fluid of the heat pipe 15. In addition, as shown in Fig. 6, an electrically insulating cylinder 21 consisting of aluminum may be arranged in an intermediate portion of the heat pipe 15 to obtain an electrically insulating heat pipe semiconductor cooling apparatus 24. Experiments conducted to confirm the effects of the present invention will be described below. Experiment 1 An 80-mm wide, 25-mm thick, and 3,000-mm long aluminum extruded elongated member 11 having two through holes 10 each having an inner diameter of 13 mm as shown in Fig. 3 was cut into a length of 100 mm to obtain a metal block 12 of a cooling apparatus as shown in Fig. 4. After the inner surface of each through hole 10 was washed by pickling, an aluminum plug 13 was screwed in an end portion of the hole 10. One end portion of a copper/water-based heat pipe 15 having an outer diameter of 12.7 mm was inserted in each through hole 10. An Sn-Pb-Cd-based low-temperature solder 16 was filled in a gap portion from the heat pipe 15 to the through hole 10 and the plug 13 and heated to integrally bond the heat pipe 15 and the metal block 12. Thereafter, a plurality of aluminum fins 17 were mounted on the other end portions of the heat pipes 15 by press fitting to constitute a radiating portion 18. Since the heat pipe semiconductor cooling apparatus 20 is manufactured as described above, no boring processing is required. Therefore, the number of manufacturing steps can be reduced by about 20% as compared with a conventional method in which boring processing is performed for each hole in the manufacture of a metal block. In addition, a bonded portion of the obtained heat pipe semiconductor cooling apparatus 20 was perfect, and its shape precision was very high. Experiment 2 A 100-mm wide, 30-mm thick, and 5,000-mm long aluminum extruded elongated member 11 having five through holes 10 each having an inner diameter of 23 mm was cut into 50 100-mm long metal blocks 12. A brushing treatment was performed for the through holes 10. Subsequently, as shown in Fig. 6, one end portion of an electrically insulating heat pipe 22 consisting of a copper pipe having an outer diameter of 22.23 mm and having an alumina glass cylinder 21 at its intermediate portion was inserted in each through hole 10 of the metal block 12. A low-temperature solder 16 was filled in a gap between the heat pipe 22 and the through hole 10, and the metal block 12 was placed on a refractory plate to close the through hole 10. The metal block 12 was heated to bond the heat pipe 22 and the metal block 12, thereby constituting a heat-absorbing portion 14. A large number of metal fins 17 were mounted on the other end portions of the heat pipes 22 (containing fluorocarbon as an operating fluid) by press fitting to constitute a radiating portion 18. The insulating heat pipe semiconductor cooling apparatus 24 manufactured as described above was perfectly sechu bonded and had very high shape precision. In addition, in the embodiment, it was confirmed that since the number of the through holes 10 formed in the metal block 12 was five, the number of manufacturing steps was reduced by about 35% to 40% with respect to the conventional manufacturing method. Industrial Applicability In a method of manufacturing a heat pipe semiconductor cooling apparatus according to the present invention, a metal elongated member having one or a plurality of through holes is cut into a predetermined length to obtain a metal block having through holes each having a predetermined shape. A heat pipe semiconductor cooling apparatus is manufactured by using these through holes of the metal block. Therefore, since a step of forming through holes by drill processing or the like to be performed after the metal block is formed need not be performed, the number of manufacturing steps can be reduced to improve productivity and reduce manufacturing cost. In addition, the quality of a bonded portion of a heat-absorbing portion can be stabilized, and its shape precision can be increased to significantly improve cooling performance. Furthermore, since a heat pipe having another sectional shape such as an ellipse can be effectively used in the heat-absorbing portion, the present invention is very useful in the field of semiconductor cooling apparatus.

Claims: A method of manufacturing a heat pipe semiconductor cooling apparatus (20), comprising the steps of: forming one or a plurality of through holes (10) in a metal elongated member (11); cutting said metal elongated member (11) into a predetermined length to obtain a metal block (12) having a predetermined shape; sealing (13) one end portion of each of said through holes (10); inserting a low-temperature solder (16) and one end portion of a heat pipe (15) in the sealed through hole and bonding the parts by heating, thereby constituting a heat-absorbing portion (14); and mounting fins (17) on the other end portions of said heat pipes by press fitting to constitute a radiating portion (18). A method according to claim 1, wherein a sectional shape of said through hole is one of a substantially elliptic shape (12Al), a substantially semicircular shape (12Bl), a rectangle (12Cl), and a substantially circular shape (12Dl, 12El). A method according to claim 1, wherein a pickling treatment or a brushing treatment is performed for said through holes (10) in order to remove an oxide film. A method according to claim 1, wherein a material of said metal elongated member (11) is aluminum or copper. A method according to claim 1, wherein said metal elongated member (11) is constituted by a cast product or an extruded product. A method according to claim 1, wherein said sealing one end portion of each of said through holes is by means of fitting a plug (13) in one end portion of said through hole or by means of welding a plug (13) in one end portion of said through hole. A method according to claim 1, wherein an operating fluid of said heat pipe (15) is water, freon, or fluorocarbon. A method according to claim 1, wherein said heat pipe (15) is an electrically insulating heat pipe having an electrically insulating cylinder (21) in an intermediate portion thereof. A method according to claim 1, wherein said electrically insulating cylinder (21) consists of alumina. A method according to claim 1, wherein said step of sealing said one end portion of each of said through holes (10) is accomplished by; placing said metal block (12) on a refractory flat plate.

Inventors: MURASE TAKASHI, MURASE, TAKASHI
Applicants: FURUKAWA ELECTRIC CO LTD, THE FURUKAWA ELECTRIC CO., LTD.
Application year: 1990
Main classification: H01L23
IPC codes: H01L23, F28D15