Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1996-07-01
2001-06-26
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S363000
Reexamination Certificate
active
06252337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a piezoelectric resonator and more particularly to a piezoelectric resonator for use in an oscillation circuit, a filter circuit or the like and a piezoelectric component using such a piezoelectric resonator.
2. Description of Related Art
It is well-known to form piezoelectric components in which a piezoelectric resonator is held in place by metal terminals which contact opposite surfaces of the piezoelectric resonator. The piezoelectric resonator includes a piezoelectric substrate having a electrodes formed on its opposing surfaces. The electrodes are normally made from silver. The metal terminals are typically made from a metal plate member, for example a phosphor bronze member, which is coated with silver to improve the electrical contact with the electrodes and lead electrodes.
While silver is advantageous for its excellent conducting characteristics, it has a tendency to self-weld. As a result, welding may occur at positions where the silver coated metal terminals contact the electrodes. If this occurs, the electrodes may be peeled off of the piezoelectric substrate when the piezoelectric substrate vibrates, thus causing inferior electrical conduction between the electrodes and the metal terminals.
Accordingly, it is an object of the present invention to provide a piezoelectric resonator and a piezoelectric component using such a piezoelectric resonator in which the likelihood that the electrodes provided on the surfaces of a piezoelectric substrate will weld with metal terminals whose surface is coated with a silver film is significantly reduced.
SUMMARY OF THE INVENTION
In order to achieve the aforementioned goal, an inventive piezoelectric resonator comprises:
a piezoelectric substrate;
an electrode including silver provided on a surface of said piezoelectric substrate, said electrode having a contact surface adapted to be contacted by a terminal; and
high fusion point metal provided on said contact surface of said electrode.
The high fusion point metal is preferably a high fusion point metal film or a high fusion point fine particle. The high fusion point metal is provided either on the entirety of the contact surface of the electrode or only on the portion of the electrode which is in contact with a silver coated terminal.
In the preferred embodiment, the piezoelectric resonator, comprises:
a piezoelectric substrate having first and second opposed surfaces;
first and second electrodes including silver provided on said first and second opposed surfaces, respectively, said electrodes each having a contact surface adapted to be contacted by a respective terminal; and
first and second high fusion point metals provided on said contact surface of said first and second electrodes, respectively.
Again, the high fusion point metal is preferably a high fusion point metal film or high fusion point particles. The high fusion point metal can be formed on the entire surface of the electrodes or only on the portions which are in contact with the terminals.
The piezoelectric resonator of the present invention can be used in a piezoelectric component in which one or more terminals support the piezoelectric resonator and are in contact with the contact surfaces of the electrodes. The piezoelectric resonator and the terminals are preferably housed in a housing to form a unitary component.
Because the electrode provided on the surface of the piezoelectric substrate contacts the silver film of the metal terminal via the high fusion point metal film, the electrode will not directly contact the silver film, thereby avoiding self-welding of the silver film.
Further, because the electrode provided on the surface of the piezoelectric substrate contacts the silver film of the metal terminal through the intermediary of the high fusion point fine particles, the area where the electrode contacts directly with the silver film is reduced, thus suppressing the self-welding of the silver.
The specific nature of the invention, as well as other objects, uses and advantages thereof, will clearly appear from the description and from the accompanying drawings in which like numerals refer to like or corresponding components.
REFERENCES:
patent: 2556558 (1951-06-01), Silverman
patent: 3317762 (1967-05-01), Corwin et al.
patent: 4259607 (1981-03-01), Noguchi et al.
patent: 4492892 (1985-01-01), Nakatani
patent: 4695756 (1987-09-01), Tanaka
Budd Mark O.
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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