To improve connecting reliability of a circuit substrate, having a low rigidity to a wire.
A method for manufacturing an electronic module comprises the steps of forming a wiring, having an electroless nickel plating film as an intermediate layer on a fluororesin substrate, and bonding a gold wire on the wiring. When a peel test for tensioning this gold wire at a constant speed in substantially the normal direction of the substrate is executed, as shown by a curve for connecting a mark '' or a mark '', the thicker the electroless nickel plating film is, the larger the force for releasing the gold wire from the wiring will become. When the nickel plating film becomes 7 μm or more in thickness, the gold wire is broken without releasing from the wiring pattern. A working accuracy by etching is, as shown by a curve for connecting a mark '', the thinner the electroless nickel plating film is, the more the film will be improved. When the nickel plating film becomes 40 μm or less in thickness, the gold wire becomes ±20 μm or less. Then, the method further comprises a step of forming a wiring having the electroless nickel plating film having 7 μm to 40 μm as the intermediate layer on the fluororesin substrate.
NAKAZAWA TERUMI
ISONO TADASHI
SASADA YOSHIYUKI
HITACHI CAR ENG CO LTD
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