| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit board which can prevent the occurrence of circuit failures, based on cold/heat load in an electronic controller mounted on the board, even if the working environment of the controller is high in cooling load. SOLUTION: This circuit board 1 is provided with a substrate 10 and circuit wiring layers 20, which are wired on the surface of the substrate 10 and formed by baking. In the circuit board 1, glass layers 30 having a coefficient of thermal expansion lower than that of the substrate 10 has are interposed between the wiring layers 20 and substrate 10 for joining the wiring layers 20 to the substrate 10. Since the compressive stresses, corresponding to the temperature widths until the glass layers 30, are cooled to normal temperatures after baking are left in the glass layers 30 and can suppress generation of tensile stresses against tensile loads, the joining strengths between the wiring layers 20 and substrate 10 can be improved.
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