The present invention is enabling to easily solder again in
soldering of a surface
mount type piezoelectric vibrator. An external
electrode is formed by an
alloy metal of Cr and Ni, namely, NiCr. Further, on the surface of NiCr, an
oxidation resistant film for
oxidation resistance is formed by a film of Au. Therefore, in the structure of an external
electrode, the layer of NiCr is formed on the surface of glass, and further, the layer of Au is formed thereon. In the meantime, NiCr and Au are deposited by spattering (a spatter method) as a film with a
low stress. In the external
electrode of such a structure, the layer of Au is dispersed in the solder by
soldering, however, since Cr in NiCr reduces the
diffusion speed of Ni into the solder, Ni is remained in the external terminal. Since Ni is a
metal to make the
alloy metal with the solder, it is possible to perform
soldering again by removing this
quartz crystal vibrator.