The conductor wire surface for constituting a circuit formed by print or junction on a substrate formed from a composite member of ceramics, resin, and an inorganic member and from a resin member is coated with glass, resin, solder, or silver paste, thus the corrosion resistance can be improved, and a highly reliable electronic device for car use can be provided. Further, the probing portion necessary for adjustment of the resistance and characteristics and the mounting portion for mounting parts are formed in a shape having no corners at 90.degree. or less, for example, in a circular shape, in an elliptical shape, or in a shape that the corners of a tetragon are rounded (R) or chamfered (C).