JPH09162694A - Surface acoustic wave device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the short circuit that occurs between the input and output electrodes by providing a cover on a piezoelectric substrate via a support part to cover the upper part of plural pairs of input and output interdigital electrodes which are provided to the piezoelectric substrate. SOLUTION: Plural pairs of input and output interdigital electrodes 12 which excite or detect the surface acoustic waves are provided on the surface of a piezoelectric substrate 11 together with the grating reflectors 13 which reflect the surface acoustic waves. A support part 14 using an adhesive is applied at an end part of the substrate 11, and a cover 15 made of a thin glass sheet etc., is fixed on the part 14. Thus the comb-line electrodes 12 are covered with the cover 15. In such a constitution, the short circuit never occurs between the electrodes 12 even if the metallic scraps caused when a metallic cap is welded, the plating scraps of the metallic cap, etc., drop onto the electrodes 12. Thus the reliability is improved for a surface acoustic wave device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device used for video equipment, communication equipment and the like.

[0002]

2. Description of the Related Art In recent years, surface acoustic wave devices have changed from the VHF band to U.
As a compact and highly reliable signal processing device that operates in the frequency band up to the HF band, cordless phones, mobile phones,
Widely used in communication devices such as pagers.

Conventionally, this type of surface acoustic wave device has a structure as shown in FIGS. In FIGS. 3 and 4, 1 is a piezoelectric substrate, 2 is a comb-shaped input / output electrode, 3 is a bonding pad, and 4 is a grating reflector.
Was adhered and fixed to the stem, electrically connected by wire bonding or the like, and hermetically sealed with a metal cap.

[0004]

However, in such a conventional structure, since the input and output electrodes 2 formed on the piezoelectric substrate 1 are in a bare state, metal scraps generated during metal cap welding and metal There was a problem that plating scraps and the like of the cap entered and dropped and adhered onto the output electrode 2, resulting in a short circuit between the input and the output.

The present invention is intended to solve such a problem and provides a highly reliable surface acoustic wave device by preventing a short circuit between input and output.

[0006]

In order to solve this problem, in the surface acoustic wave device of the present invention, a cover for covering the upper portions of the plurality of pairs of input / output electrodes is provided on the piezoelectric substrate via a supporting portion. To achieve the intended purpose.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION With the constitution of claim 1 of the present invention,
It is possible to prevent metal waste generated from the metal cap for sealing the piezoelectric substrate from directly entering and dropping onto the output electrode, and it is possible to prevent an electrical short circuit between the input and output electrodes. .

An embodiment of the present invention will be described in detail below with reference to the drawings. 1 and 2 are structural views of a surface acoustic wave device according to an embodiment of the present invention. In FIGS. 1 and 2, reference numeral 11 denotes a piezoelectric substrate, on the surface of which a comb-shaped input / output electrode 12, a grating reflector is provided. 13 are respectively configured. A support portion 14 made of an adhesive is applied to an end portion of the piezoelectric substrate 11, and a cover 15 made of thin glass is formed on the support portion 14.
Is fixed. 16 is a bonding pad portion,
An electrical connection can be established with an external terminal by wire bonding. Since the comb-shaped input / output electrode 12 portion is covered with the cover 15 made of glass, even if metal scraps fall from the upper portion, they do not enter, adhere to the output electrode 12, and are not short-circuited. Although the cover 15 is formed of glass in the present embodiment, any material that does not generate conductive fine dust, for example, a ceramic material such as alumina or an insulating material such as a heat-resistant resin material can be used.

[0009]

As described above, according to the present invention, by providing the cover for covering the upper portions of the plurality of pairs of input / output electrodes on the piezoelectric substrate through the support, the metal scrap generated during the metal cap welding. Also, it is possible to provide a highly reliable surface acoustic wave device in which plating scraps or the like of the metal cap do not directly enter and fall and adhere onto the output electrode to cause a short circuit.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a sectional view of a conventional example.

FIG. 4 is a plan view of FIG. 3;

[Explanation of symbols]

 11 Piezoelectric Substrate 12 Input / Output Electrode 14 Support 15 Cover

Claims (1)

[Claims] 1. A plurality of pairs of interdigitated input and output electrodes for exciting or detecting surface acoustic waves, and a grating reflector for reflecting surface acoustic waves are provided on a piezoelectric substrate, and the plurality of pairs are provided. A surface acoustic wave device, characterized in that a cover for covering the upper and lower portions of the input and output electrodes is provided on the piezoelectric substrate via a support portion.