| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit board which has improved reliability in a temperature cycle even though a dimension is equivalent with that in the past.SOLUTION: A circuit board of the embodiment comprises: a cavity 10 formed on an insulating substrate 3b at the top; and a back electrode 4a on which a power semiconductor 4 is mounted and which is provided on a second conductor layer 3b as an exposed conductor layer exposed in the cavity. Because of this, even though tensile stress or compressive stress occurs at regions of insulating substrates 3a, 3b, 3c and the power semiconductor 4 which have linear expansion coefficients different from each other, the stress is absorbed and suppressed by the cavity 10 thereby to decrease the possibility of generation of cracks to improve reliability in a temperature cycle.SELECTED DRAWING: Figure 3 |
