SURFACE WAVE DEVICE HAVING GOOD TEMPERATURE CHARACTERISTICS

摘要

PURPOSE:To obtain a surface wave device which has good temperature characteristics with a small change with time, by selecting the best value for the relative relation between the mean thickness of standardized film of an electrode provided in the direction of an axis Z' of the substrate surface which is obtained after rotation of a crystal rotary Y plate and the cutting direction of a crystal substrate. CONSTITUTION:For a crystal rotary Y plate 1 which is expressed by (YXl)theta in terms of the IRE standard, the lengthwise measurement l is set at an axis X and both crosswise direction Z' and thickness direction Y' are cut out at the positions turned by angle theta from crystal axes Z and Y and on the basis on the axis X. Then cross-finger type transducer electrodes 2 and 3 consisting of gold electrodes are provided on the surface of a substrate 1. The relative relation is decided between the mean thickness of the standaridized film of the electrode and the cutting direction theta of the crystal substrate so that the primary frequency-temperature coefficient of a surface wave device is set at 0 and at the same time the secondary frequency-temperature coefficient is reduced as less as possible.