Surface acoustic wave device
First Claim
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1. A surface acoustic wave device comprising:
- a substrate having a piezoelectric outer surface on one side, said substrate having on said one side a recessed portion extending part-way through said substrate to define a recess with a piezoelectric floor on which a pair of spaced excitation portions are applied, each excitation portion having excitation transducer electrodes formed on the piezoelectric surface of said recess floor and a propagating portion between said excitation portions;
taking-out electrodes applied upon said substrate and extending from each of said transducer electrodes to the surface of said substrate outside of said recessed portion;
a plate-shaped covering body covering said recessed portion, said recessed portion being sufficiently deep that an air gap remains on the inner side of said covering body over said exciting portions and said propagating portion;
an encapsulation body sealingly covering at least the outer surfaces of said covering body; and
leads connected to said take-out electrodes and projecting beyond said encapsulation body to make connection to an external circuit.
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Abstract
A surface acoustic wave device according to the present invention can be molded surely with resin, leaving a free space over exciting portions and a propagating portion by disposing a recess portion formed over the exciting portions and the propagating portion on a piezoelectric substrate without using any metallic package.
19 Citations
13 Claims
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1. A surface acoustic wave device comprising:
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a substrate having a piezoelectric outer surface on one side, said substrate having on said one side a recessed portion extending part-way through said substrate to define a recess with a piezoelectric floor on which a pair of spaced excitation portions are applied, each excitation portion having excitation transducer electrodes formed on the piezoelectric surface of said recess floor and a propagating portion between said excitation portions; taking-out electrodes applied upon said substrate and extending from each of said transducer electrodes to the surface of said substrate outside of said recessed portion; a plate-shaped covering body covering said recessed portion, said recessed portion being sufficiently deep that an air gap remains on the inner side of said covering body over said exciting portions and said propagating portion; an encapsulation body sealingly covering at least the outer surfaces of said covering body; and leads connected to said take-out electrodes and projecting beyond said encapsulation body to make connection to an external circuit. - View Dependent Claims (2, 3, 5, 6, 11, 12, 13)
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4. A surface acoustic wave device comprising:
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a layered substrate including at least an insulating base and a piezoelectric thin film disposed on said base, said base and piezoelectric film having a recessed portion formed thereon having a pair of spaced acoustic wave excitation portions formed on said piezoelectric film and each having excitation transducer electrodes formed thereon and a propagating portion between said excitation portions and a conductive area formed on said propagating portion; taking-out electrodes on said piezoelectric film extending from each of said transducer electrodes and conductive area to the surface of said substrate outside of said recessed portion; a covering body comprising a plate covering said recessed portion, said recessed portion being sufficiently deep that an air gap remains on the inner side of said covering body over said exciting portions and said propagating portion; an encapsulation body sealingly covering at least the outer surfaces of said plate; and leads connected to said take-out electrodes and projecting beyond said encapsulation body to make connection to an external circuit.
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7. A surface acoustic wave device comprising:
a substrate, one side of said substrate having opposite end surfaces interconnected by side surfaces, said end and side surfaces defining the margins of a recess extending part way through said substrate and having a piezoelectric surface floor, said substrate having conductive acoustic wave excitation portions disposed on the piezoelectric floor of said recess, spaced conductive pads on said one side of the substrate, conductive areas applied to said substrate surfaces and to the defining walls of said recess for interconnecting said conductive pads and excitation portions, a covering body adhesively secured over said recess along the margins of said recess and defining an air gap in said recess between said recess floor and covering body, conductive leads conductively secured to said pads, and an encapsulation body applied over the outer surfaces of said covering body and substrate, with said leads projecting from said encapsulating body. - View Dependent Claims (8, 9, 10)
Specification