| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a circuit board for high-density by providing, on a metal plate, a circuit which, comprising a composite layer of aluminum and copper, comprises an upper layer part whose cross-section is triangular through an insulating layer. SOLUTION: A circuit 3 comprising a composite layer of aluminum 4 and copper 5 is formed on a metal plate 1 of aluminum, copper, stainless, etc., having thickness, for example, about 0.5-4.0 mm through an insulating layer 2 of a resin comprising an inorganic filler, with the copper surface of the circuit 3 comprising the composite layer of aluminum and copper contacting the insulating layer 2. Here, at least, a part of the circuit comprising the composite layer of aluminum and copper comprises an upper layer part whose cross-section is triangular. Since the current value flowing a circuit is relatively low and a cross-section area is large if the current value is equal, a narrower conductor width and conductor interval are achieved.
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