Piezoelectric vibrator having peripheral notches therein
Provided are a vacuum package and a method for manufacturing the vacuum package having excellent airtightness and capable of improving mounting strength, and a piezoelectric vibrator, an oscillator, an electronic device, and a radio-controlled timepiece. The package includes a base substrate and a lid substrate bonded to each other, a cavity formed between the base substrate and the lid substrate and configured to be capable of sealing a piezoelectric vibrating reed, and penetration electrodes penetrating through the base substrate in the thickness direction so as to make the inner side of the cavity and the outer side conductive. Portions of the base substrate and the lid substrate in the vicinity of the cavity form bonding regions in which the two substrates are bonded. A notch portion through which the bonding surface of the lid substrate is exposed as seen from the thickness direction of the base substrate is formed on the corner portions of the base substrate.
1. A piezoelectric vibrator comprising:
a hermetically closed casing comprising first and second substrates anodically bonded at respective bonding faces thereof and defining a cavity therebetween, wherein the second substrate includes square corner regions and the first substrate includes notches in a thickness direction in a periphery thereof, the notches exposing an associated square corner regions at the bonding face;
a bonding film at the bonding face of the first and second substrates;
a metal film in at least some of the notches and overlying the associated square corner region of the second substrate and abutting the bonding film, the metal film extending over an outer surface of the first substrate and providing external electrodes thereon; and
a piezoelectric vibrating reed secured inside the cavity and electrically coupled to the external electrodes by electrically conductive throuqh-holes in the first substrate.
2. The piezoelectric vibrator according to claim 1 , wherein the first substrate includes corners and the notches are located at some of the corners.
3. The piezoelectric vibrator according to claim 1 , wherein the notches extend through the periphery of the first substrate.
4. The piezoelectric vibrator according to claim 1 , wherein the notches have an arcuate shape.
5. An oscillator comprising the piezoelectric vibrator defined in claim 1 .
6. An electronic device comprising the piezoelectric vibrator defined in claim 1 which is electrically connected to a clock section of the electronic device.
7. A radio-controlled timepiece comprising the piezoelectric vibrator defined in claim 1 which is electrically connected to a filter section of the radio-controlled timepiece.