| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly reliable aluminum nitride circuit board which can suppress the occurrence of cracks caused by heat cycles. SOLUTION: In a circuit board, a metallic circuit 3 of copper, etc., is formed on an aluminum nitride substrate 1 in a state where the circuit 3 is joined to the substrate 1 and the surface of the circuit 3 is plated with nickel 4. The heat cycle resistance of the circuit board is improved by adjusting the maximum thickness 5 of the plated nickel 4 on the side face of the end section of the metallic circuit 3 to 1.5-5μm and, in addition, making the ratio of the maximum thickness to the minimum thickness of the plated nickel 4 on the same side face 1-3.
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