| 摘要 |
PROBLEM TO BE SOLVED: To suppress occurrence of stripping of a circuit pattern from an insulating substrate by providing a recessed section on the surface of the substrate and forming the pattern on almost the whole surface of the recessed section. SOLUTION: An insulating substrate 1 having two circuit pattern forming surfaces A1 and A2 is provided with a recessed section 11 on its surface. A plurality of projecting sections 13 are formed in the recessed section 11, and a circuit pattern 3 is formed on almost the whole surface of the recessed section 11 so as to cover the projecting sections 13 and recessed section 11. In addition, the pattern 3 is formed so that the upper surface of the pattern 3 may become lower in height than a non-circuit surface C other than a lower plated layer and, at the same time, the edge section of the surface C is closely adhered to the pattern 3 by pressing the edge section against the pattern 3. Therefore, occurrence of stripping of the circuit pattern 3 from the insulating substrate 1 can be suppressed, because adhesion of the pattern 3 to the substrate is increased and the thermal resistance of a product can be improved.
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