Piezoelectric resonator and manufacturing method thereof

Abstract

The quartz resonator (1 and 51) is provided with a structure which is integrally airtight-connected with upper-side and lower-side substrates (3, 4, 53 and 54) which are overlapped on the upper surface and the lower surface of a middle quartz plate (2 and 52) integrally forming a quartz resonator sheet (5 and 55) and a housing (6 and 56). The upper-side and lower-side substrates are respectively provided with a concave part on a surface facing to the middle quartz plate so as to form cavities (16 and 66) for airtight sealing the quartz resonator sheet in a suspension state. The upper and lower connection surface of the middle quartz plate forms a conductive film (9 and 11) after being grinded and processed at the lens surface. Each connection surface of the upper-side and lower-side substrates consists of bare quartz surfaces which are grinded and processed at the lens surface. In another embodiment, a metal film (67 to 69) is formed on each connection surface of the upper-side and lower-side substrates consists of bare quartz surfaces which are grinded and processed at the lens surface. The upper-side and lower-side substrates and the middle quartz plate are all or one by one overlapped with each other and are then pressurized at room temperature (heated optionally) after whose connection surfaces are surface-activated through plasma processes, so as to be airtight-connected with each other, thereby sealing the cavities in a vacuum or idle gas atmosphere.

Description

technical field [0001] The present invention relates to a piezoelectric vibrator in which a tuning-fork type or a thickness-shear vibration mode piezoelectric vibrating piece is hermetically sealed and packaged, and a method for manufacturing the same. Background technique [0002] With the miniaturization and thinning of electronic equipment, further miniaturization / thinning of piezoelectric devices such as quartz oscillators is required. Conventionally, piezoelectric devices are mostly surface-mounted devices suitable for mounting on circuit boards and the like. Generally, surface-mount piezoelectric devices generally use a structure in which a piezoelectric vibrating reed is sealed in a package made of an insulating material such as ceramics. In the conventional package structure, the substrate and the lid are joined by low-melting-point glass or seam welding. Therefore, due to the influence of the gas generated by the low-melting-point glass and the high heat of the seam...

AI Technical Summary

Problems solved by technology

In addition, excessive heating during bonding of the substrates may affect the vibration characteristics of the piezoelectric vibrating reed, resulting in failure to obtain desired performance.

[0013] However, in the conventional method of directly bonding the metal films on the bonding surface as described above, since room temperature bonding is performed at a low temperature from room temperature to 180°C or lower or 100°C or lower, in order to ensure the tuning fork shape or thickness cut There is a problem that it takes a long time to obtain the necessary and sufficient airtight bonding strength of the piezoelectric vibrator with variable vibration mode

Therefore, the productivity is lowered, and it is not suitable for industrial application

On the contrary, in the case of bonding substrates under heating at 300°C as in the above-mentioned prior art, it takes a long time to bring the inside of the package into a sufficient vacuum state, and there is also a problem that it is not suitable for industrial use.

[0014] In addition, as described above, in the conventional piezoelectric vibrator in which the three-layer substrates are directly bonded with the silicon oxide layer interposed therebetween by ultraviolet irradiation, the connecting portion does not have conductivity, so in order to connect the excitation electrodes of the quartz substrates to Leading out to the outside of the package, another wiring structure needs to be set up

Therefore, the structure of the vibrator as a whole becomes complicated, and airtightness may be impaired

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