| 摘要 |
PROBLEM TO BE SOLVED: To prevent lack, split, crack, etc., of an insulating board from being developed by a method wherein inorganic insulating material powder is combined by using thermosetting resin excellent in flexibility, to form the insulating board, and a wiring conductor formed by combining copper powder by using phenol resin is stuck on the board. SOLUTION: Insulating boards 1a, 1b, 1c constituting an insulating substrate 1 are formed by combining inorganic insulating material powder of 60-95wt.% by using thermosetting resin of 5-40wt.%. Thereby, when an external force is applied on the insulating substratum 1, lack, split, crack, etc., are not developed on the insulating substrate 1 by the external force. On the insulating substrate 1, a wiring conductor 2 formed by combining copper powder by using phenol resin is stuck and formed from the periphery of a recessed part 1d to the lower surface. Since phenol resin has the function of preventing surface oxidation of copper powder, oxide is not formed on the surface of copper powder, and electrical connection between the copper powders is improved.
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