Temperature compensated crystal oscillator and method of manufacturing same

A method of manufacturing a temperature compensated crystal oscillator comprising a package body formed with a first and a second recess respectively in a first and a second principal surface opposing each other, a crystal blank hermetically sealed in said first recess, and an IC chip integrating an oscillation circuit electrically connected to said crystal blank, and a temperature compensating mechanism for compensating said crystal blank for a frequency-temperature characteristic, said IC chip having external write terminals formed on a principal surface thereof, which is not a circuit formation surface, for writing temperature compensation data into said temperature compensating mechanism, said method comprising the steps of:

• hermetically sealing said crystal blank in said first recess to make up a crystal unit, and securing said circuit formation surface of said IC chip to a bottom face of said second recess through ultrasonic thermo-compression bonding using bumps to build a crystal oscillator assembly;
• operating said crystal oscillator assembly to oscillate to measure a frequency-temperature characteristic thereof;
• and
• writing temperature compensation data found from the measured frequency-temperature characteristic into said temperature compensating mechanism through said external write terminals.