HEAT SINK MATERIAL

PROBLEM TO BE SOLVED: To make the heat radiation good to avoid cracking in a temp. cycle, by bonding Cu plates to both surfaces of an Al nitride board, and setting the thickness ratio of the Al nitride board to each Cu plate to specified range. SOLUTION: Al nitride and assistant Y2 O3 are compounded with a binder and solvent to form a tape, the tape is laminated into a double layer, and cut into pieces of 60 mm squares. It is degreased at about 600 deg.C, baked at about 1800 deg.C for about 5 hrs. to form an AIN(AIN board) 1 of about 50 mm squares. A braze is printed on both sides of AIN 1, dried and degreased at about 500 deg.C, Cu plates 2 are set on these brazes to bond in a vacuum of 10 Torr at about 850 deg.C and cut into chips of 2 mm squares, wherein the thickness ratio of the AIN board 1 to each Cu plate 2 is set to a range of Cu:AIN:Cu=0.1:1:0.1 to 0.3:1:0.3.