JPH07336186A - Surface mounting type surface acoustic wave element - Google Patents

Abstract

PURPOSE:To prevent characteristic deterioration even when the back of a sur face acoustic wave element is rough, by coating resin to the back of a piezoelec tric substrate so as to absorb the reflection of unnecessary wave which can cause characteristic deterioration by means of resin. CONSTITUTION:The surface acoustic wave element 1 consists of a holder base 2 and a lid 3 like before and a terminal part 5 is electrically connected to a bump 6. At this time the bump 6 is not satisfactory for supporting the element 1 by itself, resin 8 is used for adhering and fixing like before. But the back surface of the element 1 is usually rough so that resin 9 is coated to the back surface so as to seal the opening face of the base 2 with the lid 3 after adhesion. Then, resin 8 and 9 can be the same resin and in order to adhere/fix the element 1, it is desirable to cover the whole back surface of the piezoelectric substrate by resin 8. The reflection of the unnecessary waves is absorbed by resin like this.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type surface acoustic wave element used as a filter or an oscillator.

[0002]

2. Description of the Related Art In recent years, surface acoustic wave devices have also been surface-mounted on a printed circuit board in order to increase the mounting density.

A conventional surface mount type surface acoustic wave device will be described below. FIG. 2 is a cross-sectional view of a conventional surface mount surface acoustic wave device. In FIG. 2, 1 is a surface acoustic wave element, 2 is a cage base made of ceramics or the like,
3 is a lid. The surface acoustic wave element 1 has a comb-shaped electrode 4 and a terminal portion 5 formed on the surface thereof. The terminal portion 5 is electrically connected to the bump 6, and the bump 6 is electrically connected to the conductive member 7. As a result, it is possible to input and output electric signals to and from the surface acoustic wave element 1. Since it is insufficient to support the surface acoustic wave element 1 only with the bumps 6, the surface acoustic wave element 1 is adhesively fixed with the resin 8. Further, the opening surface of the cage base 2 is sealed with the lid 3 to obtain a surface mount type surface acoustic wave element. Further, the back surface of the surface acoustic wave element 1 is roughened in order to suppress reflection of an unnecessary wave (bulk wave) that deteriorates the characteristics.

[0004]

In the above-mentioned conventional structure, even if the back surface of the surface acoustic wave element 1 is roughened, the reflection of the unwanted wave cannot be suppressed sufficiently, so that the characteristics are deteriorated. Had.

An object of the present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a surface mount type surface acoustic wave element capable of suppressing deterioration of characteristics due to reflection of an unnecessary wave.

[0006]

In order to achieve this object, the surface mount type surface acoustic wave element of the present invention is one in which resin is applied to the back surface of a piezoelectric substrate.

[0007]

With this structure, the resin can prevent the deterioration of the characteristics by absorbing the unwanted wave.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Since the surface mount type surface acoustic wave element of the present invention is an improvement of the conventional structure, the same components as those of the conventional element shown in FIG. 2 will be described using the same names. FIG. 1 is a structural sectional view of a surface acoustic wave device according to an embodiment of the present invention. Figure 1
In, 1 is a surface acoustic wave element, 2 is a cage base, 3
Are lids, which are the same parts as the conventional ones. As in the conventional case, the terminal portion 5 is electrically connected to the bump 6, and the bump 6 is electrically connected to the conductive member 7. Since the surface acoustic wave device 1 is insufficient to be supported only by the bumps 6,
It is adhesively fixed by the resin 8 as in the conventional case. The back surface of the surface acoustic wave element 1 is rough as in the conventional case, and the resin 9 is applied in this embodiment. After the mounting, the opening surface of the cage base 2 is sealed with the lid 3 to obtain a surface mounting type surface acoustic wave element.

In this embodiment, the resin 8 and the resin 9 are distinguished from each other, but they may be the same, and when the surface acoustic wave element 1 is bonded and fixed, the resin 8 covers the entire back surface of the piezoelectric substrate. It may be fixed by adhesion.

[0010]

As described above, according to the present invention, by applying the resin to the back surface of the piezoelectric substrate, the resin can absorb the reflection of the unwanted wave which causes the deterioration of the characteristics. The surface wave element can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a surface-mounted surface acoustic wave device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional surface mount surface acoustic wave device.

[Explanation of symbols]

 1 surface acoustic wave element 2 cage base 3 lid 4 interdigital electrode 5 terminal portion 6 bump 7 conductive member 9 resin

Claims (1)

[Claims] 1. A surface mount type surface acoustic wave element in which an electrode is provided on the surface side to be surface mounted and a resin is applied to the surface.