In the past, even though Kyocera Crystal Device was considering combining a crystal having a positive temperature characteristic with a crystal having a negative temperature characteristic to realize an etalon filter that does not require temperature control, it could not commercialize such a filter because of problems related to bonding technologies.

This time, by using atomic diffusion bonding, the company realized a high bonding strength without affecting the properties of the filter, it said. The bonding strength of the new filter is more than five times higher than that of the "optical contact" technology, which the company used in the past.

There is another method for realizing a temperature characteristic free filter, and it is called "air gap type." But, with this method, the size of etalon filter becomes large.

Atomic diffusion bonding is a bonding technology that does not require any organic adhesive. And it was developed based on a research conducted by Takehito Shimatsu, professor at Tohoku University. Kyocera has been engaged in a research on atomic diffusion bonding in cooperation with the university. And it made an announcement about basic technologies for applying atomic diffusion bonding to crystal devices in May 2010.

This will the first time that a crystal device product developed based on atomic diffusion bonding has been actually released, Kyocera Crystal Device said. And the company plans to apply the bonding technology to other crystal parts in the future.