Method of producing heat-dissipating unit

[Purpose] To provide is a method capable of producing a heat-dissipating unit easily and at low cost.[Solution] The method of producing a heat-dissipating unit 12 includes: inserting pins 17 punched out of a second plate member 22 for pins into a plurality of through-holes 16 formed in a first plate member 20 for a substrate. In the first plate member 20, a plurality of substrate forming portions 25 is provided side by side in the longitudinal direction of the first plate member 20. In the second plate member 22, a plurality of pin punch-out portions 26 is provided side by side in the longitudinal direction of the second plate member 22. The method includes: a step A of forming the through-holes 16 in the substrate forming portion 25 of the first plate member 20; a step B of subjecting the pin punch-out portion 26 of the second plate member 22 to a half-punch out process to form half-punched-out pin forming portions 27 protruding from one surface side of the second plate member 22; a step C of forming the pins 17 by punching out the pin forming portions 27 from the second plate member 22 and simultaneously inserting the pins 17 into the through-holes 16 in the first plate member 20; and a step D of forming a substrate by cutting the substrate forming portion 25 with the pins 17 inserted in the through-holes 16 from the first plate member 20.

FIELD OF THE INVENTION

The present invention relates to a method of producing a heat-dissipating unit used in a cooling apparatus for cooling a heating element composed of electronic components such as a semiconductor element.

Note that in this specification and claims, upper and lower sides ofFIG. 6andFIGS. 7A, 7B, and 7Cwill be referred to as “upper” and “lower” sides.

BACKGROUND ART

For example, as a liquid cooling type cooling apparatus for cooling a power device (semiconductor element), such as, e.g., an IGBT (Insulated Gate Bipolar Transistor), for use in a power conversion device mounted on an electric vehicle, a hybrid vehicle, a train, etc., the present applicant proposed the following cooling device (see Patent Document 1). The cooling device is provided with a casing having a top wall and a bottom wall and having a cooling fluid passage therein and a heat radiator arranged in the cooling fluid passage in the casing. The heat radiator is configured by a single heat-dissipating unit. The heat-dissipating unit is composed of a substrate having a plurality of through-holes formed therein and pins fixed to the substrate in a state in which the pins are inserted in the through-holes of the substrate with both longitudinal end portions of the pin protruded from the through-hole by the certain length, and the portion of the pin protruding from the through-hole serves as a fin.

The heat-dissipating unit of the cooling apparatus described in Patent Document 1 is produced as follow. That is, a substrate in which a plurality of fin-insertion through-holes are formed and pins integrally provided with a plurality of protrusions outwardly protruding from the outer peripheral surface at the middle part of the outer peripheral surface in the longitudinal direction are prepared. The size of the virtual shape drawn by connecting protruding ends of the plurality of protrusions of the pin is made larger than the through-hole of the substrate. The pin is press-fitted into the through-hole of the substrate to thereby plastically deform at least the protrusion of the pin among the protrusion of the pin and the peripheral portion of the through-hole of the substrate to fix the pin to the substrate.

The heat-dissipating unit of the cooling apparatus described in Patent Document 1 is produced as follow. That is, a substrate in which a plurality of fin-insertion through-holes are formed and pins integrally provided with a plurality of protrusions outwardly protruding from the outer peripheral surface at the middle part of the outer peripheral surface in the longitudinal direction are prepared. The size of the virtual shape drawn by connecting protruding ends of the plurality of protrusions of the pin is made larger than the through-hole of the substrate. The pin is press-fitted into the through-hole of the substrate to thereby plastically deform at least the protrusion of the pin among the protrusion of the pin and the peripheral portion of the through-hole of the substrate to fix the pin to the substrate.

However, in the above-described method of producing a heat-dissipating unit, the work of producing the pin is troublesome and the cost increases. Moreover, it is troublesome to press-fit the plurality of pins integrally provided with a plurality of protrusions on the outer peripheral surface into the through-holes of the substrate. Thus, the heat-dissipating unit cannot be produced simply and at low cost.

PRIOR ART DOCUMENT

Patent Document

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

An object of the present invention is to solve the above-described problems and to provide a method capable of producing a heat-dissipating unit easily and at low cost.

Means for Solving the Problems

The present invention has the following aspects in order to achieve the above-described object.

1) A method of producing a heat-dissipating unit, wherein the heat-dissipating unit comprises a substrate having a plurality of through-holes formed therein and a plurality of pins fixed to the substrate in a state in which the pins are inserted in the through-holes of the substrate with both longitudinal end portions of the pin protruded from the through-hole by a certain length, and portions of the pins protruding from the through-holes serve as fins, the method comprising:

inserting the plurality of pins into the plurality of through-holes formed in a first plate member for the substrate,

wherein the plurality of pins are simultaneously punched out of a second plate member for the pin.

2) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1), further comprising:

preparing a substrate having a required number of through-holes using the first plate member; and inserting the pins into the through-holes of the substrate.

3) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1), further comprising:

forming a certain number of the through-holes required for a single substrate in a substrate forming portion located at one end portion of the first plate member in which a plurality of substrate forming portions each having a size for forming one substrate is provided side by side in a longitudinal direction of the first plate member;

thereafter inserting the pins into the through-holes of the substrate forming portion; and

subsequently cutting the substrate forming portion in which the pins are inserted into the through-holes from the first plate member to produce a substrate.

4) The method of producing a heat-dissipating unit as recited in the aforementioned Item 3), further comprising:

forming a plurality of half-punched-out pin forming portions protruding on one surface side of the second plate member in a pin punch-out portion located at one end portion of the second plate member in which the plurality of pin punch-out portions, each from which a certain number of pins required for one substrate are punched out, are provided side by side in a longitudinal direction of the second plate member; and

punching the plurality of half-punched-out pin forming portions of the pin punch-out portion from the second plate member to produce the plurality of pins and simultaneously inserting the plurality of pins into the through-holes of the substrate forming portion located at the one end portion of the first plate member.

5) The method of producing a heat-dissipating unit as recited in the aforementioned Item 4), further comprising:

performing a Step A of forming the through-holes in the substrate forming portion of the first plate member, a Step B of subjecting the pin punch-out portion of the second plate member to a half-punch-out process to form a half-punched-out pin forming portion protruding on one surface side of the second plate member; a Step C of punching the pin forming portion from the second plate member to form the pins and simultaneously inserting the pins into the through-holes of the substrate forming portion of the one end portion of the first plate member; and a Step D of cutting the substrate forming portion in which the pins are inserted into the through-holes from the first plate member to produce the substrate by a single die.

6) The method of producing a heat-dissipating unit as recited in the aforementioned Item 5), further comprising:

performing a Step E of cutting the pin punch-out portion from the second plate member after forming the plurality of pins from the pin punch-out portion located at one end portion of the second plate member,

wherein the Step E is performed by the die for performing the Steps A to D.

7) The method of producing a heat-dissipating unit as recited in the aforementioned Item 6), further comprising:

arranging a first coil in which the first plate member is wound and a second coil in which the second plate member is wound so that feeding directions of both the plate members from both the coils are orthogonal as seen from a plane; and

performing the Steps A to E while intermittently feeding the first plate member from the first coil and intermittently feeding the second plate member from the second coil.

8) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein the second plate member is made of JIS A1000 series aluminum.

9) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein the second plate member is made of JIS A6000 series aluminum.

10) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein when the pins are inserted into the through-holes of the first plate member, the pins are press-fitted therein.

11) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein a brazing material layer is provided on at least one surface of the first plate member.

12) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein a brazing material layer is provided on at least one surface of the second plate member.

13) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein a cross-sectional shape of the pin to be punched is circular, and a ratio L/D of a length L of the pin to a diameter D is 1.7 or less.

14) The method of producing a heat-dissipating unit as recited in the aforementioned Item 1),

wherein a shape of the through-hole of the first plate member is a streamline shape, and a cross-sectional shape of the pin is a streamline shape having an arc edge and a pointed edge oriented in a same direction as an arc edge and a pointed edge of the through-hole, respectively.

Effects of the Invention

According to the methods as recited in the aforementioned Items 1) to 14), the methods include: inserting the plurality of pins into the plurality of through-holes formed in the first plate member for a substrate, wherein the plurality of pins are simultaneously punched out of the second plate member for pins. Therefore, the plurality of pins can be made at once, making it easier to produce the plurality of pins, which in turn makes it possible to produce the heat-dissipating unit easily and at low cost.

According to the method as recited in the aforementioned Item 4), in the method recited in the aforementioned Item 3) which includes: forming a certain number of through-holes required for one substrate in a substrate forming portion located at one end portion of the first plate member in which a plurality of the substrate forming portions having a size for forming one substrate are provided side by side in the longitudinal direction of the first plate member; inserting pins into the through-holes of the substrate forming portion; and then cutting the substrate forming portion in which the pins are inserted into the through-holes from the first plate member to forma substrate, the method as recited in the aforementioned Item 4), further includes:

forming a plurality of half-punched-out pin forming portions protruding on one surface side of the second plate member in a pin punch-out portion located at one end portion of the second plate member in which the plurality of pin punch-out portions portion of which a certain number of pins required for one substrate are punched out are provided side by side in a longitudinal direction of the second plate member; and

punching the plurality of half-punched-out pin forming portions of the pin punch-out portion from the second plate member to produce the plurality of pins and simultaneously inserting the plurality of pins into the through-holes of the substrate forming portion located at the one end portion of the first plate member.

Therefore, it is possible to punch out the plurality of pins from the pin punch-out portion of the second plate member and simultaneously insert the punched pins into the plurality of through-holes of the substrate forming portion of the first plate member. Thereafter, the substrate forming portion in which the pins are inserted is cut from the first plate member to thereby form the substrate. With this, it is possible to produce a heat-dissipating unit simply and at low cost, wherein the heat-dissipating unit includes a substrate having a plurality of through-holes formed therein and pins fixed to the substrate in a state in which the pins are inserted in the through-holes of the substrate with both longitudinal end portions of the pin protruded from the through-hole by the certain length. Further, in the state in which the plurality of pin forming portions are formed so as to protrude on one surface side of the second plate member by subjecting the pin punch-out portion of the second plate member located at one end portion thereof to a half-punch-out process, the pin forming portions can be adjusted to the positions of the through-holes of the substrate forming portion of the first plate member. For this reason, it is possible to align all of the pin forming portions and all of the through-holes, which makes it possible to accurately insert the punched pins into the through-holes.

According to the methods as recited in the aforementioned Items 5) and 6), it is possible to shorten the time required for producing the heat-dissipating unit.

According to the method as recited in the aforementioned Item 7), the heat-dissipating unit can be produced continuously and efficiently.

According to the heat-dissipating unit produced by the method as recited in the aforementioned Item 8), the heat conductivity of the fin becomes excellent.

According to the heat-dissipating unit produced by the method as recited in the aforementioned Item 9), the heat conductivity of the fin becomes excellent. Further, the load resistance of the pin in the longitudinal direction thereof is improved.

According to the method as recited in the aforementioned Item 10), the heat transfer performance between the substrate and the fin in the produced heat-dissipating unit is improved.

In cases where the heat-dissipating unit produced by the method as recited in the aforementioned Item 11) is used for configuring a heat radiator in a cooling apparatus equipped with a casing having a top wall and a bottom wall and provided with a cooling fluid passage inside and a heat radiator having at least one heat-dissipating unit arranged in the cooling fluid passage in the casing, the following effects are obtained. That is, a casing is generally produced by brazing two or more constituent elements, but simultaneously with the brazing of the constituent elements, the substrate composed of the first plate member and the pin forming the fin are brazed together, which improves the heat transfer performance between the substrate and the fin.

In cases where the heat-dissipating unit produced by the method as recited in the aforementioned Item 12) is used for configuring a heat radiator in a cooling apparatus equipped with a casing having a top wall and a bottom wall and provided with a cooling fluid passage inside and a heat radiator having at least one heat-dissipating unit arranged in the cooling fluid passage in the casing, the following effects are obtained. That is, a casing is usually produced by brazing two or more constituent elements. However, in cases where the heat radiator consists of one heat-dissipating unit, simultaneously with the brazing of the constituent elements, at least one end portion of the pin of the heat-dissipating unit can be brazed to the top wall or the bottom wall of the casing. Further, in cases where the heat radiator is provided with a plurality of heat-dissipating units arranged in a stacked manner in the vertical direction and an intermediate plate arranged between adjacent heat-dissipating units, at least one end portion of the pin of the heat-dissipating unit can be brazed to the top wall or the bottom wall of the casing or the intermediate plate. Therefore, it becomes unnecessary to separately use a member having a brazing material for brazing. In addition, the pressure resistance of the cooling apparatus improves by performing the aforementioned brazing.

According to the method as recited in the aforementioned Item 13), the pins can be punched out of the second plate member with high precision, so the number of pins to be fixed to one substrate can be relatively increased, which improves the heat transfer performance between the fins and the substrate.

In cases where the heat-dissipating unit produced by the method as recited in the aforementioned Item 14) is used for configuring a heat radiator in a cooling apparatus equipped with a casing having a top wall and a bottom wall and provided with a cooling fluid passage inside and a heat radiator having at least one heat-dissipating unit arranged in the cooling fluid passage in the casing, it is possible to reduce the resistance to the cooling fluid flowing through the cooling fluid passage in the casing.

DESCRIPTION OF REFERENCE SYMBOLS

EMBODIMENT FOR CARRYING OUT THE INVENTION

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. This embodiment is directed to a heat-dissipating unit used in a liquid-cooling type cooling apparatus by the method of the present invention.

Note that in this specification, the term “aluminum” is used to include the meaning of an aluminum alloy in addition to pure aluminum.

Note that in the following description on the cooling apparatus, the upper, lower, left, and right sides inFIG. 2will be referred to as the upper, lower, left, and right side, respectively.

Further note that the same symbols are allotted to the same items and the same portions throughout the drawings.

FIG. 1andFIG. 2show an overall structure of a cooling apparatus having a heat-dissipating unit produced by the method of the present invention, andFIG. 3shows the structure of the main part thereof.FIG. 4shows a heat radiator used in the cooling apparatus ofFIG. 1. Further,FIG. 5toFIG. 8show a method of producing a heat-dissipating unit according to the present invention.

InFIG. 1andFIG. 2, the liquid-cooling type cooling apparatus1is provided with a hollow casing2having a top wall2a, a bottom wall2b, and a peripheral wall2cand provided with a cooling fluid passage3therein, and a heat radiator4arranged in the cooling fluid passage3in the casing2.

At one longitudinal end portion in the casing2(at the right end portion in this embodiment), an inlet header5into which a cooling fluid flows from the outside is provided, while at the other longitudinal end portion in the casing2(at the left end portion in this embodiment), an outlet header6from which the cooling fluid flows to the outside is provided. Thus, the cooling fluid passage3is configured to flow the cooling fluid flowed into the inlet header5to the outlet header6. To the top wall2aof the casing2, an aluminum inlet pipe7for supplying a cooling fluid to the inlet header5in the casing2and an aluminum outlet pipe8for discharging the cooling fluid from the outlet header6in the casing2are connected. Further, it is configured such that on at least one of the outer surface of the top wall2aand the outer surface of the bottom wall2bof the casing2(the outer surface of the top wall2ain this embodiment), a heating element (not shown), such as, e.g., a power device such as an IGBT, an IGBT modules integrated with a control circuit and housed in the same package, an intelligent power module in which a protection circuit is further integrated with the IGBT module and housed in the same package, is attached.

The casing2is composed of a plate-shaped aluminum upper constituent element9forming the top wall2aand an upwardly opened box-like aluminum lower constituent element11forming a bottom wall2band a peripheral wall2c. The lower surface peripheral edge portion of the upper constituent element9is joined with a brazing material (hereinafter referred to as “brazed”) to the upper end portion of the portion forming the peripheral wall2cof the lower constituent element11.

As shown inFIG. 2toFIG. 4, the heat radiator4is provided with a plurality of heat-dissipating units12(two heat-dissipating units12in this embodiment), arranged in a stacked manner in the vertical direction and an aluminum intermediate plate13arranged between adjacent heat-dissipating units12. The heat-dissipating unit12is composed of a horizontal aluminum substrate14and a plurality of aluminum fins15provided on both surfaces of the substrate14so as to protrude from the substrate14with its longitudinal direction oriented in the vertical direction. A plurality of circular through-holes16is formed in the substrate14, and an aluminum round bar-shaped pins17are inserted in the circular through-holes16and secured to the substrate14with the longitudinal central portion positioned in the circular through-hole16. The portions of the pin17protruding upward and downward from the circular through-hole16serve as both the upper and lower fins15. The substrate14is made of, for example, JIS A3000 series aluminum, JIS A1000 series aluminum, or JIS A6000 series aluminum, and the pin17is made of, for example, JIS A1000 series aluminum or JIS A6000 series aluminum. Securing of the pin17to the substrate14is performed by press-fitting into the circular through-hole16or brazing.

The tip of the upper fin15of the upper heat-dissipating unit12is in thermal contact with the inner surface of the top wall2aof the casing2. In the same manner, the tip of the lower fin15is in thermal contact with the upper surface of the intermediate plate13. Further, the tip of the lower fin15of the lower heat-dissipating unit12is in thermal contact with the inner surface of the bottom wall2bof the casing2. In the same manner, the tip of the upper fin15is in thermal contact with the lower surface of the intermediate plate13. In this way, the substrates14of both the heat-dissipating units12and the intermediate plate13are vertically spaced apart. The cross-sectional shapes of both the upper and lower fins15of both the heat-dissipating units12arranged adjacently in the vertical direction are each a circular shape of the equal size, and all of the upper and lower fins15of both the heat-dissipating units12arranged adjacently in the vertical direction are overlapped at least partly (entirely in this embodiment) as viewed from a plane.

The cooling apparatus1is produced by the method including: arranging two heat-dissipating units12in the lower constituent element11in a state of being stacked via the intermediate plate13; placing the upper constituent element9thereon; and brazing both the upper and lower constituent elements9and11. In the production method, in cases where the tip of the upper fin15of the upper heat-dissipating unit12is brazed to the inner surface of the top wall2aof the casing2and the tip of the lower fin15is brazed to the upper surface of the intermediate plate13, or in cases where the tip of the lower fin15of the lower heat-dissipating unit12is brazed to the inner surface of the bottom wall2bof the casing2and the tip of the upper fin15is brazed to the lower surface of the intermediate plate13, a separately prepared sheet-like brazing material is used.

In the cooling apparatus1described above, the cooling fluid flowed into the inlet header5of the casing2through the inlet pipe7enters the cooling fluid passage3, flows between the fins15in between the substrates14of both the upper and lower heat-dissipating units12and the top wall2aand the bottom wall2bof the casing2and in between the substrate14of each heat-dissipating unit12and the intermediate plate13, enters the outlet header6, and then is discharged from the outlet header6through the outlet pipe8. The heat emitted from the heating element attached to the outer surface of the top wall2aof the casing2is transmitted to the top wall2a, and then transmitted to the substrates14and both the upper and lower fins15of both the heat-dissipating units12, and then transmitted from the intermediate plate13to the cooling fluid flowing in the cooling fluid passage3. Thus, the heating element is cooled.

The heat transfer path of the heat emitted from the heating element and transferred to the top wall2aof the casing2to the cooling fluid flowing in the cooling fluid passage3is as follows. The first path that transmits the heat emitted from the heating element attached to the outer surface of the top wall2aof the casing2to the cooling fluid is a path through which the heat is transmitted directly from the top wall2ato the cooling fluid. The second path is a path through which the heat is transmitted from the top wall2ato both the upper and lower fins15of the upper heat-dissipating unit12and then transmitted from both the upper and lower fins15to the cooling fluid. The third path is a path through which the heat is transmitted from the top wall2ato the substrate14via the upper fin15of the upper heat-dissipating unit12and then transmitted from the substrate14to the cooling fluid. The fourth path is a path through which the heat is transmitted from the top wall2ato the intermediate plate13via both the upper and lower fins15of the upper heat-dissipating unit12and then transmitted from the intermediate plate13to the cooling fluid. The fifth path is a path through which the heat is transmitted from the top wall2ato the upper and lower fins15of the lower heat-dissipating unit12via both the upper and lower fins15of the upper heat-dissipating unit12and the intermediate plate13and then transmitted from both the upper and lower fins15to the cooling fluid. The sixth path is a path through which the heat is transmitted from the top wall2ato the upper fin15of the lower heat-dissipating unit12via both the upper and lower fins15of the upper heat-dissipating unit12and the intermediate plate13and further transmitted to the substrate14via the upper fin15and from the substrate14to the cooling fluid.

In the cooling apparatus1described above, the heat radiator4is composed of two heat-dissipating units12, but the heat radiator may be composed of three or more heat-dissipating units12and an intermediate plate13arranged between adjacent heat-dissipating units12.

Next, with reference toFIG. 5toFIG. 8, a method of producing the heat-dissipating unit12used in the heat radiator4of the cooling apparatus1ofFIG. 1will be described. The method shown inFIG. 5toFIG. 8is directed to a method of producing a heat-dissipating unit of a type in which the pins17are press-fitted into the through-holes16of the substrate14.

In the following description, the left and right sides ofFIG. 5will be referred to as left and right sides, respectively, and the lower side ofFIG. 5will be referred to as a front side.

As shown inFIG. 5toFIG. 8, for example, a first coil21in which the first plate member20for the substrate14made of JIS A3000 series aluminum is wound, a second coil23in which the second plate member22for the pin17made of JIS A1000 series aluminum or JIS A6000 series aluminum is wound, and a die24for performing various processing on the first plate member20fed from the first coil21and the second plate member22fed from the second coil23are prepared. The second coil23is arranged on the left front side of the first coil21, and the die24is arranged on the front side of the first coil21and on the right side of the second coil23.

In the first plate member20wound on the first coil21, a plurality of substrate forming portions25each having a size for forming one substrate14is provided side by side in the longitudinal direction of the first plate member20. In the second plate member22wound on the second coil23, a plurality of pin punch-out portions26each having the same size as the substrate forming portion25of the first plate member20for punching a required number of pins17for one substrate14is provided side by side in the longitudinal direction of the second plate member22.

The first coil21is configured to intermittently feed the first plate member20toward the die24by the length of one substrate forming portion25. The second coil23is configured to feed the second plate member22to the right side toward the die24by the length of one pin punch-out portion26. It is configured such that the first plate member20fed from the first coil21comes to the underside of the second plate member22fed out from the second coil23, and the feeding directions of both the plate members20and22are orthogonal as viewed from a plane.

The die24is provided with a punching portion for forming the through-holes16by punching the substrate forming portion25of the first plate member20, a half-punching portion for forming a plurality of pin forming portions27(seeFIG. 7A) protruding toward the lower surface side of the second plate member22by subjecting the pin punch-out portion26of the second plate member22to half-punching processing, a pin inserting portion for forming pins17by punching the pin forming portion27from the second plate member22and simultaneously inserting the pins17into the through-holes16of the substrate forming portion25of the one end portion of the first plate member20, a cutting portion for cutting the substrate forming portion25having the pins17inserted into the through-holes16from the first plate member20to form the substrate14, and a scrapping portion for cutting the pin punch-out portion26after forming the plurality of pins17from the pin punch-out portion26located at one end of the second plate member22from the second plate member22.

In producing the heat-dissipating unit12, the substrate forming portion25of the tip portion is moved to the punching portion of the die24while intermittently feeding the first plate member20forward from the first coil21by the length of one substrate forming portion25, and at the punching portion, the number of through-holes16required for one substrate14are simultaneously formed in the substrate forming portion25of the tip portion of the first plate member20(see Step A, andFIG. 8). Simultaneously with this, the second plate member22is moved to the half-punching portion of the die24while intermittently feeding the second plate member22rightward by the length of one pin punch-out portion26from the second coil23, and at the half-punched portion, the pin punch-out portion26is subjected to half-punching to form a plurality of half-punched-out pin forming portions27protruding to the lower surface side of the second plate member22(see Step B,FIG. 7AandFIG. 8).

Next, the substrate forming portion25of the first plate member20in which the through-holes16are formed is moved to the pin inserting portion of the die24, and the pin punch-out portion26of the second plate member22in which the pin forming portion27is formed is moved to the pin-inserting portion of the die24. At this time, the positions of all of the pin forming portions27coincide with the positions of all of the through-holes16.

Next, in the pin inserting portion of the die24, simultaneously with punching the pin forming portion27from the second plate member22to form a plurality of pins17, the pins17are press-fitted in the through-holes16of the substrate forming portion25of the one end portion of the first plate member20(see Step C,FIG. 7B, andFIG. 8). Here, it is preferable that the cross-sectional shape of the pin17be circular and the ratio L/D of the length L of the pin17to the diameter D thereof be 1.7 or less. In this case, the pin17can be punched out with high precision, and a number of pins17can be fixed to one substrate14.

Next, the substrate forming portion25in which the pins17is press-fitted in the through-holes16of the first plate member20is moved to the cutting portion of the die24. At the cutting position, the substrate forming portion25in which the pins17are inserted in the through-holes16is cut from the first plate member20to form the substrate14(see Step D). Thus, the portion of the pin17protruding from the through-hole16is served as a fin15. Thus, the heat-dissipating unit12is produced (seeFIG. 7CandFIG. 8). On the other hand, the pin punch-out portion26of the second plate member22from which the pins17are punched out is moved to the scrapping portion of the die24, and in the scrapping portion, the pin punch-out portion26is cut from the second plate member22into a scrap (Step E).

The above-described Steps A to E in the die24are simultaneously performed for different substrate forming portions25and pin punch-out portions26.

In the above-described embodiment, the first plate member20fed out from the first coil21comes to the lower side of the second plate member22fed out from the second coil23, but not limited to this. Depending on the type of the die24, the first plate member20fed from the first coil21may be arranged above the second plate member22fed from the second coil23.

FIG. 9toFIG. 12show modified embodiments of the heat-dissipating unit to be produced by the method of the present invention.

In the case of the heat-dissipating unit30shown inFIG. 9, one surface (upper surface) of the substrate14is covered with an aluminum brazing material layer31, and the substrate14is made using a first plate member20formed of an aluminum brazing sheet with one surface covered with an aluminum brazing material layer.

In the case of the heat-dissipating unit35shown inFIG. 10, both surfaces of the substrate14are each covered with an aluminum brazing material layer36, and the substrate14is made using a first plate member20formed of an aluminum brazing sheet with both surfaces each covered with an aluminum brazing material layer.

In the case of the heat-dissipating units30and35shown inFIG. 9andFIG. 10, simultaneously with brazing the upper and lower constituent elements9and11of the casing2at the time of producing the above-described cooling apparatus1, the substrate14and the pins17are brazed.

In the case of the heat-dissipating unit40shown inFIG. 11, both the upper and lower end surfaces of the pin17are each covered with an aluminum brazing material layer41, and the pin17is made using a second plate member22formed of an aluminum brazing sheet with both surfaces each covered with an aluminum brazing material layer.

In the case of the heat-dissipating unit40shown inFIG. 11, simultaneously with the brazing of both the upper and lower constituent elements9and11of the casing2at the time of producing the cooling apparatus1, the upper end surface of the upper fin15of the upper heat-dissipating unit40is brazed to the top wall2aof the casing2and the lower end surface of the lower fin15is brazed to the intermediate plate13, and the lower end surface of the lower fin15of the lower heat-dissipating unit40is brazed to the bottom wall2bof the casing2and the upper end surface of the upper fin15is brazed to the intermediate plate13.

In the case of the heat-dissipating unit45shown inFIG. 12, the shape of the through-hole46of the substrate14is a streamline shape in which the arc edges and the pointed edges of the through-holes46are oriented in the same direction. The cross-sectional shape of the pin is a streamline shape in which the arc edges and the pointed edges of the pins are directed in the same direction as the arc edges and the pointed edges of the through-holes, respectively. The shape of the pin47which will be served as the upper and lower fins15as seen from a plane is a streamline shape in which the arc edges and the pointed edges of the pins are oriented in the same direction as the arc edges and the pointed edges of the through-holes46, respectively.

However, the shape of the through-hole46of the substrate14does not necessarily have an arc edge and a pointed edge facing in the same direction, respectively.

INDUSTRIAL APPLICABILITY

The method according to the present invention is suitably used for producing a heat-dissipating unit of a cooling apparatus for cooling a power device, such as, e.g., an IGBT, in a power module, such as, e.g., a power conversion device to be mounted on an electric vehicle, a hybrid vehicle, or a train.