JPH0432817Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a piezoelectric device, particularly an interdigital transducer electrode formed on a piezoelectric substrate, to generate waves (hereinafter referred to as
A holding structure for a piezoelectric osmotic device that uses waves excited in the bulk (hereinafter referred to as SAW) or waves excited in the bulk (hereinafter referred to as BSW).

(Prior Art) Conventionally, in the piezoelectric device as described above, as shown in FIG. is electrically bonded to the lead 5 passing through the base 2 in an airtight manner using a bonding wire, and then a sealing lid (not shown) is fitted to the flange 6 extending around the outer periphery of the base 2 to make contact with a voltage to block outside air. It was common practice to store and secure them as shown in the figure.

However, when the piezoelectric device is fixed to the base using such a method, the adhesive spreads over the entire surface facing the back surface of the piezoelectric device substrate and the piezoelectric device support surface due to capillary action, so that the adhesive is spread between the substrate and the base. There was a defect in that the piezoelectric substrate was distorted due to the difference in coefficient of thermal expansion between the piezoelectric substrate and the stress applied to the base when the sealing lid was connected to a voltage, causing a change in its resonant frequency.

Furthermore, in Japanese Utility Model Application Publication No. 56-19925, four protrusions of equal height are provided on a stem supporting a piezoelectric substrate, and adhesive is applied to a thickness sufficient to cover these protrusions. A configuration is disclosed in which the piezoelectric substrate is placed on the adhesive to prevent the adhesive from spreading laterally and causing various problems when the piezoelectric substrate is placed on the adhesive before solidification. However, the technology described in this publication uses an adhesive filled between the bottom surface of the piezoelectric substrate supported on the protrusion and the stem to bond the entire bottom surface of the piezoelectric substrate. It is not possible to resolve the problems that occur.

(Purpose of the invention) The present invention was made in order to eliminate the above-mentioned defects of the conventional piezoelectric device holder. It is an object of the present invention to provide a piezoelectric device holder having a structure that does not substantially cause fluctuations in resonance frequency after packaging is completed.

(Summary of the invention) In order to achieve the above-mentioned object, the present invention provides a piezoelectric device that utilizes waves excited in the surface or bulk of a piezoelectric substrate by an interdigital transducer electrode formed on one surface of the piezoelectric substrate. On the substrate support surface of the holder that adhesively fixes the surface of the device substrate on which no electrode is formed, a portion of the holder that corresponds to approximately the center of the electrode that determines the resonance frequency of the piezoelectric device substrate comes into contact with the holder. A land of a minute area is projected on the substrate support surface, and a required number of protrusions are provided at appropriate positions on the substrate support surface that the peripheral edge of the piezoelectric substrate comes into contact with to support the peripheral edge in a non-adhesive state.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 is a diagram illustrating the stress applied to the base and the resulting deformation of the base when the sealing lid is brought into contact with the piezoelectric device holder.

That is, when the sealing lid is fitted to the base 2 and the flange portion 6 of the base is connected to the base 2, the force applied to the base by the welding electrode has a vertical component.
Since not only F _N but also a component F _H parallel to the piezoelectric device support surface 3 of the base 2 is included, the base 2 is bent as shown in an exaggerated dashed line in FIG. 2, and this bending is caused by the welding electrode It is thought that it remains even after it is removed.

For this reason, in the piezoelectric device 1 completely adhesively fixed to the piezoelectric device support surface 3 of the base 2, the interval between the electrode fingers of the interdigital transducer electrodes is expanded, and the resonant frequency is lowered than the desired value. .

In order to solve this problem, in the present invention, the shape of the base is improved so that the piezoelectric device can be bonded to the base only at a portion of as small an area as possible, which corresponds to the vicinity of the center of the electrode.

That is, as shown in FIGS. 1a and 1b, the base 2
A land 7 with a small area is projected from approximately the center of the piezoelectric device support surface, and projections 8, 8 for supporting both edges of the piezoelectric device (piezoelectric substrate) 1 in a non-adhesive state are formed by press working. .

By doing so, all excess adhesive flows out around the land 7, and the piezoelectric device is fixed to the base only at a position corresponding to approximately the center of the electrode, which determines its resonance frequency. It is extremely unlikely to be affected by residual distortion in the base. Furthermore, since the piezoelectric device 1 is kept substantially parallel to the base plane 3 by the protrusions 8, 8, it is possible to limit the area of the land 7. Note that the land 7 and the protrusions 8, 8 do not necessarily have to be linear as shown in FIG. 1b, but may each have a dotted area.

(Effect of the invention) Since the invention is constructed as explained above,
When a SAW or BSW resonator, filter, etc. is housed and fixed on the holding surface using adhesive, not only is the distortion of the base caused by press-fitting the sealing lid hardly transmitted to the piezoelectric device, but also the distortion between the base and the piezoelectric substrate is reduced. The influence of the difference in the coefficient of thermal expansion of
It exhibits a remarkable effect in stabilizing the resonance frequency and reducing its dispersion.

[Brief explanation of the drawing]

FIG. 1a is a cross-sectional view of the base of the piezoelectric device holding structure according to the present invention, FIG. 1b is a plan view thereof, and FIG. FIG. 3 is a schematic diagram for explaining the force applied to the base and the resulting deformation of the base when the sealing lid is pressed against the base. 1...Piezoelectric substrate (piezoelectric vibration device), 2...
Cage (base), 3...Substrate support surface, 7...Land, 8...Piezoelectric vibration device substrate periphery support protrusion.

Claims (1)

[Scope of utility model registration request] A holder that adhesively fixes the surface of a piezoelectric device substrate on which no electrode is formed, which utilizes waves excited in the surface or bulk of the electric substrate by an interdigital transducer electrode formed on one surface of the piezoelectric substrate. On the substrate supporting surface of the holder, a land of a minute area is protruded onto the substrate supporting surface of the holder, which is in contact with a portion corresponding to approximately the center of the electrode that determines the resonant frequency of the piezoelectric device substrate. 1. A holding structure for a piezoelectric device, characterized in that a required number of protrusions are provided at appropriate positions on a substrate support surface with which the peripheral edge comes into contact, the protrusions supporting the peripheral edge in a non-adhesive state.