JPH02278910A - Manufacture of connection terminal for surface acoustic wave element - Google Patents

Abstract

PURPOSE:To avoid poor continuity due to the destruction of the film caused by a wire bonding pressure by providing a thick film electrode on a piezoelectric substrate and an interdigital electrode coated with the thick film electrode. CONSTITUTION:An electrode such as an aluminum film being a thick film electrode 22 is vapor-deposited on a piezoelectric substrate 21, a photo resist pattern 25 is formed and the thickness film electrode 22 is formed by the photo etching method, the thick film electrode 22 is etched to form the smooth electrode. Then the aluminum thin film being an interdigital electrode 23 is vapor- deposited, a photo resist pattern 25 is formed and the interdigital electrode 23 is formed by the photo etching method to form a wire bonding structure to the interdigital electrode 23 by coating the thick film electrode 22. Since the thick electrode is overlaid on the thin interdigital electrode and poor continuity due to the destruction of the film under the bonding pressure is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a surface acoustic wave device, and in particular to a surface acoustic wave device with an improved structure of a wire bonding pad portion connected to a cross-finger electrode and an external terminal. The present invention relates to a method of manufacturing a connection terminal for use in a computer.

[Conventional technology]

Conventionally, in this type of surface acoustic wave device, as shown in FIG. 3, when a high frequency voltage is applied to interdigital electrodes 33 arranged in a planar structure on a piezoelectric substrate 31, the electric field generated between the electrodes causes the Surface waves are excited. Surface waves are propagated in both directions of the electrodes, and a surface acoustic wave filter device is constructed by arranging receiving interdigital electrodes in the direction of propagation.

[Problem to be solved by the invention]

In the above-mentioned conventional surface acoustic wave device, external connections are made to the interdigital electrode portions by wire bonding, but when the operating band frequency becomes, for example, about 1 GHz, the electrode portions become thin, at 300 to 400 A. Therefore, there is a drawback that the membrane is destroyed by the wire-pounding pressure, resulting in poor conductivity.

[Means to solve the problem]

The method of manufacturing a connection terminal for a surface acoustic wave device according to the present invention includes a curved thick film electrode provided on a piezoelectric substrate in a planar structure using a photolithography method, and a curved thick film electrode having a larger area than the thick film electrode. and interdigital electrodes covering the thick film electrodes.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

Fig. 1 is an enlarged perspective view of an embodiment of the present invention, Fig. 2(a)
to f) are perspective views sequentially showing the structural steps of this embodiment.

This embodiment consists of a piezoelectric substrate 1, a thick film electrode 2, an interdigital electrode 3, and a wire 4, and a bloody thick film electrode 2 provided on the piezoelectric substrate 1 in a brainer structure by photolithography method; The structure is such that an interdigital electrode 3 having a larger area than the thick film electrode 2 and covering the thick film electrode 2 and a wire 4 are bonded onto the interdigital electrode 3.

The manufacturing process will be specifically explained in the order of FIGS. 2(a) to 2(f). First, as shown in FIG. 2(a), an aluminum film, for example, which will become the thick film electrode 22, is deposited on the piezoelectric substrate 21, and a photoresist pattern 25 is formed. Next, the thick film electrode 2 is etched using a photoetching method as shown in FIG.
form 2. The end face of the electrode at this time is an acute angle. Next, the thick film electrode 22 formed in the previous step is immersed in an etching solution. For example, by immersing an aluminum electrode with a thickness of 1.5 .mu.fn in a phosphoric acid solution for 60 seconds, a bloody thick film electrode 22 as shown in FIG. 3(C) can be formed. Next, as shown in FIG. 3(d), a thin film of aluminum, for example, which will become the interdigital electrode 23, is deposited. Next, as shown in the figure (e), a photoresist pattern 25 of the interdigitated electrodes 23 is formed, and after this, as shown in the same figure (e), an aluminum thin film is formed by photoetching to form the interdigitated An electrode 23 is formed and the thick film electrode 22 is covered to form a wire bonding structure in the interdigital electrode 23 portion.

In this embodiment, aluminum is used for the electrode, but it goes without saying that other conductive metal materials can also be used.

〔Effect of the invention〕

As explained above, in the present invention, by overlapping the thin interdigital electrode portion with the thick film electrode, there is no conduction failure due to film destruction due to bonding pressure. Furthermore, by providing blood flow on the thick film electrode, there is an effect of preventing breakage when thin interdigital electrodes are overlapped.

Although the present invention has been described above with respect to a surface acoustic wave device, the present invention also applies to other devices using thin films as materials.
It can be widely applied.

[Brief explanation of drawings]

FIG. 1 is an enlarged perspective view of one embodiment of the present invention, and FIG.
or fl is a perspective view sequentially showing the manufacturing process of this embodiment, and FIG. 3 is a perspective view of an example of a conventional surface acoustic wave element. 1, 21, 31... Piezoelectric substrate, 2.22... Thick film electrode, 3.23.33... Cross-finger electrode, 4.34
...wire, 25...photoresist pattern. Agent: Patent Attorney Shinkan Uchihara 3 times

Claims (1)

[Claims] It is characterized by comprising: a curved thick film electrode provided on a piezoelectric substrate with a planar structure using a photolithography method; and an interdigital electrode having a larger area than the thick film electrode and covering the thick film electrode. A method for manufacturing a connection terminal for a surface acoustic wave device.