Piezoelectric vibrator manufacturing method, piezoelectric vibrator, oscillator, electronic device, and radio-controlled timepiece

A method for manufacturing a plurality of piezoelectric vibrators at a time using a base substrate wafer, a lid substrate wafer, a conductive rivet member having a planar base portion and core portions extending from a rear surface of the base portion, the piezoelectric vibrators each including a base substrate, a lid substrate bonded to the base substrate in a state where a cavity is formed between the base substrate and the lid substrate, a piezoelectric vibrating reed bonded to an upper surface of the base substrate in a state of being received in the cavity, outer electrodes formed on a lower surface of the base substrate, and penetration electrodes formed so as to penetrate through the base substrate in a vertical direction so that the piezoelectric vibrating reed is electrically connected to the outer electrodes, the method comprising:

• at the time of forming the penetration electrodes,
• a penetration hole forming step of forming a plurality of penetration holes on the base substrate wafer so as to penetrate through the base substrate wafer in the vertical direction;
• a core portion insertion step of inserting the core portions of the rivet member into the respective penetration holes from one side of the base substrate wafer;
• a melting step of bringing the rear surface of the base portion of the rivet member into contact with the base substrate wafer so as to close an opening end on the one side of the penetration holes, heating the base substrate wafer while pressing the other side of the base substrate wafer so as to melt a surface portion on the other side of the base substrate wafer to produce a liquid base substrate material, and causing the base substrate material to flow into gaps between inner circumferential walls of the penetration holes and the rivet member from the other side of the penetration holes so as to close the gaps;
• a curing step of cooling and curing the base substrate material poured into the gaps to fix the base substrate wafer and the rivet member to be integral with each other;
• and
• a polishing step of removing the base portion of the rivet member and polishing the base substrate wafer and the rivet member so that the base substrate wafer and the core portion are planarized.