COMPOSITE SUBSTRATE, ELASTIC WAVE DEVICE USING THE SAME, AND METHOD FOR MANUFACTURING COMPOSITE SUBSTRATE

摘要

In a composite substrate 10, the piezoelectric substrate 12 which is capable of transmitting an elastic wave and a support substrate 14 which a smaller thermal expansion coefficient than the piezoelectric substrate 12 are bonded to each other. The in-plane maximum thermal strain amount which is the largest thermal strain amount in the plane of the composite substrate 10 has a minimum value and a maximum value when the piezoelectric substrate 12 and the support substrate 14 are relatively rotated 0° to 360°, and the piezoelectric substrate 12 and the support substrate 14 are bonded to each other so that the in-plane maximum thermal strain amount has the minimum value or a value in the vicinity thereof.