Abstract: Since split electrodes are disposed along the x-axis of an AT cut quartz crystal plate on its ultrathin vibratory portion formed integrally with a thick frame-like marginal portion surrounding it, desired acoustic coupling can be obtained although the split electrodes are disposed closely to such an extent as not to cause shorting between them. It is therefore possible to obtain, with a satisfactory yield, filter elements which have center frequencies in the range greater than about ten megahertz and sufficiently wide passbands.

Abstract: In a resonator which has an ultrathin vibratory portion formed integrally with a thick frame-like rib surrounding it, a pair of opposed thick marginal portions of the frame-like rib are formed so that their widths gradually decreases toward another marginal portion of the rib from the other remaining one perpendicular to the above-noted pair of opposed marginal portions and to be fixed to a resonator case. This structure substantially increases the mechanical strength of the piezoelectric resonator, even if it is held in a cantilever fashion, and protects it from breakage by an external vibration or shock.

Abstract: In a piezoelectric resonator having an ultrathin vibratory portion formed by a cavity made in a piezoelectric block and a thick frame-like rib formed integrally with said vibratory portion and surrounding it, an excess adhesive receiving groove or the like is cut in one marginal portion of the frame-like rib between an adhesive coated region. The resonator is fixedly housed in a package by use of an adhesive coated on one marginal portion of the frame-like rib along the z-axis direction, or by means of elastic pawls without using the adhesive. In this case, one marginal portion of the frame-like rib on the opposite side from a pad deposited on one side of the piezoelectric resonator is bonded to the bottom of the package.