| 摘要 |
PURPOSE:To form a surface mounting substrate excellent in matching properties of thermal expansion coefficient with an insulating resin layer and an Si chip, by constituting the substrate of at least three layers formed by coating both surfaces of a core material composed of Fe-Ni alloy with Al having a conductivity higher than or equal to a specified value or Al alloy layers. CONSTITUTION:A substrate 1 is formed by coating both surfaces of a core material 2 composed of Fe-Ni alloy with Al whose conductivity is higher than or equal to 50% IACS (international standard soft copper) or Al alloy layers 3 and 4. The Al or Al alloy layers 3, 4 are excellent to the adhesion to an insulating layer such as epoxy resin. The thermal expansion coefficient of the layers 3, 4 is smaller than that of epoxy resin, and larger than that of an Si chip of IC elements to be mounted. Therefore, in order to decrease the thermal expansion coefficient of the whole part of the surface mounting substrate 1 and make it approach to the thermal expansion coefficient of the Si chip, the combination of Fe-Ni alloy having a low thermal expansion coefficient is applied to the core material 2.
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