Patent ID: 8008980

Claim:
A surface mount type crystal oscillator comprising a crystal blank, an IC chip having at least an oscillation circuit using said crystal blank, integrated thereon, and a hermetic package for accommodating said crystal blank and said IC chip therein, wherein: said hermetic package comprises a ceramic substrate having a substantially rectangular shape and formed with a metal film which makes a round on one main surface thereof, and a concave metal cover having an open end face bonded to said metal film, said ceramic substrate comprises mounting electrodes at corners on the other main surface of said ceramic substrate for use in mounting said crystal oscillator on a wiring board, said IC chip is secured to the one main surface of said ceramic substrate through ultrasonic thermo-compression bonding using bumps, said crystal blank is disposed above said IC chip, and said one main surface of said ceramic substrate is formed as a flat surface, wherein said ceramic substrate comprises a first ceramic layer formed with said mounting electrodes, and a second ceramic layer laminated on said first ceramic layer for securing said IC chip thereto, said first ceramic layer comprises a cutout portion in a central area of each side thereof, said cutout portion having an outer periphery open to said side, an adjustment terminal is formed on a laminated surface of said second ceramic layer exposed by each said cutout portion, and said adjustment terminals include a pair of write surface terminals used to write temperature compensation data into a temperature compensation mechanism within said IC chip, and a pair of crystal test terminals used to measure oscillation characteristics of said crystal blank.