Fuji Electric Systems Co. Ltd.

Tecnisco Limited

Nippon Chemi-Con Corporation

Atsushi Yanase

Masato Takahashi

Yukihiro Kaneda

Tetsuhiko Shimpo

Isao Fujihata

A method for producing a heat sink for cooling a semiconductor device including forming plural base members, the base member being each in plate or block-shape, the base member each having paths shaped on one or both sides of surfaces thereof, and the base member each having connecting regions on one or both sides of surfaces thereof, coating a coating layer of Au onto the base members, putting a solder of Sn or Au&#x2014;Sn alloy onto connecting regions, the connecting region being coated with the coating layer of Au, assembling the base members together such that the base members are bonding to each other at the connecting region and the paths shaped on each of the surfaces of the base members form a communicating flow path for a cooling medium inside the bonded base members, and heating to diffuse Sn from the solder of Sn or Au&#x2014;Sn alloy into the coating layer of Au, and to make a bond layer of alloy containing at least 91 wt % of Au and at most 9 wt % of Sn, the bond layer being interposed between connecting regions to which the base member each connects.

Heat sink and method for its production

The present invention provides a liquid-cooling type heat sink which has a high pressure-resistibility and is resistible against the corrosion or erosion-corrosion or electrolytic etching, and a method for its production. The heat sink of the present invention comprises plural base membersandthe base member being each in plate or block-shape, the base member each having pathsshaped on one or both sides of surfaces thereof, and the base members being bonded to each other, wherein a communicating flow pathincluding paththrough holesandis formed for a cooling medium to flow in and out. The base members are bonded to each other with a solder layermade of Au&#x2014;Sn alloy or Sn, while a coating layer of Auis formed on each of the inner surfaces of the bonded base members. At the time of making a bond between the base members, the coating layer of Auand the solder layerare diffused to each other, resulting in formation of a bond layer of alloycontaining at least 91 wt % of Au and at most 9 wt % of Sn.

A switching circuit is improved in efficiency by including a switching corrector circuit for feeding back reversed polarity, differentiated switching pulses to the base of the switching transistor. In addition, temperature stability is achieved by providing a constant current source for a drive transistor which drives the switching transistor and for a control transistor which controls the drive transistor on the basis of the detected output of the circuit.

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Tokyo, Japan

Atsushi Yanase