Tuning fork type crystal unit and bar type crystal unit

摘要

A tuning fork type quartz crystal unit has a base and a pair of arms extending from respective ends of the base in a crystallographic Y direction of quartz crystal. Each of the arms comprises a first crystal member and a second crystal member which extend in the Y direction. The first crystal member and the second crystal member are joined to each other in a crystallographic YZ plane by a direct bonding such that the first crystal member and the second crystal member have respective crystallographic X directions oriented away from each other and extending parallel to each other. Each of the arms has excitation electrodes disposed respectively on a pair of exposed surfaces thereof which lie in the YZ plane. The direct bonding comprises, for example, a siloxane bond by which the first crystal member and the second crystal member are joined to each other.