| 摘要 |
PROBLEM TO BE SOLVED: To reduce the strain in a bonded solder layer to avoid the fatigue breakdown of the solder layer by forming recesses at a part of a base underlying a semiconductor chip. SOLUTION: A plurality of semiconductor chips 1 are bonded with a solder layer 3 on an insulation substrate 2 bonded with a solder layer 5 on a base 4 with recesses 4a provided on the opposite surface of the base 4 to parts to which the semiconductor chips 1 are bonded and an intermediate plate 7 is bonded to the base 4 through a braze so as to cover the recesses 4a. Heat generated from the chips 2 at operating escapes via the base beneath the chips 12 to a cooling liq. 11, resulting in a temp. rise of the base 4 underlying the chips 1, but because of the recesses 4a formed at the base 4, temp. is distributed in the base 4 such that a thin wall part 4b is at a higher temp. and a thick wall part 4c at a lower temp., and if the thin wall part 4b is going to expand, the surrounding lower temp. thick wall part 4c restricts the expansion. Thus a high strain is never exerted on the solder layer 3 on the thick wall part 4b and the fatigue breakdown can be avoided. |
