JPS59128809A - Production of elastic surface wave element - Google Patents

Abstract

PURPOSE:To fix effectively a piezoelectric substrate onto a stem with an adhesive by carving a processed part having a recessing/projecting rough surface on the main surface of a stem header which adheres fixedly the piezoelectric substrate by means of a marking press metal mold. CONSTITUTION:A processed part 11 having a recessing/projecting rough surface is carved into meshes, for example, at the approximately center part on a main surface of a stem header 1 by means of a marking press metal mold. A V-shape, a U-shape, a trapezoidal shape or a waveform shape is available for the section shape of the part 11, and the recessing/projecting parts are carved in a single direction or rectangularly to each other. Then nickel is electroplated to the header 1 after forming a prescribed number of hole parts 9. A glass button 2 and a conductive lead 3 are implanted to the header 1 and then burnt and sealed. Thus a stem 4 is produced. Then an adhesive 5 is applied at the approximately center part on the header main surface of the stem 4, and a piezoelectric substrate 6 is put on the header. Thus the substrate 6 is adhered fixedly to the stem 4. A bonding wire 7 is connected to the input and output electrodes of the substrate 6, and a shell 8 is welded and sealed airtightly. In such a way, a piezoelectric substrate can be fixed effectively onto a stem.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a surface acoustic wave device, and in particular to a method for manufacturing a surface acoustic wave device, in particular a method for effectively mounting and fixing a piezoelectric substrate on which input electrodes and output electrodes are formed on a stem using an adhesive. The present invention relates to a method of manufacturing a surface acoustic wave device that can be used.

"Technical Background of the Invention" Generally, as a method for manufacturing a surface acoustic wave device, a method as shown in FIGS. 1 to 7 is used.

That is, FIG. 2 shows a top view, and FIG. 3 shows a vertical cross-sectional view taken along the line X-X in FIG. A conductive lead bottle 3, shown in a perspective view in FIG. 5, is implanted through the hole 9 of 1 through the crow button 2, shown in a perspective view in FIG.
In this state, the stem 4 is produced by firing and sealing at about 1050° C. to about 1080° C.

An epoxy adhesive or the like is applied as an adhesive 5 approximately at the center of the flat header main surface of the stem 4 in an area (approximately 90%) smaller than the bottom area of the piezoelectric substrate 6, as shown in FIG. 6 in a vertical cross-sectional view. As shown in the longitudinal cross-sectional view of FIG. It is made of Ta03, LiNbO3, ceramics, etc., and has an input electrode on its main surface, a shield IT connected to this input electrode, an output electrode and a sound absorbing member arranged opposite to the input electrode via this shield electrode. A piezoelectric substrate 6 on which a layer is formed and the other main surface is roughened is placed and heated at 120° C. to 140° C. for about 1.5 to 2 hours to harden the adhesive 5. Piezoelectric substrate 6
is glued and fixed on the permanent surface of stem 4.

From the conductive lead bin 3 of the stem 4 thus created, bonding wires 7 are connected to each terminal of the input electrode and output electrode provided on the main surface of the piezoelectric substrate 6, as shown in the vertical cross-sectional view in FIG. The shell 8 is welded to the outer peripheral surface of the stem 4 and hermetically sealed, thereby producing a surface acoustic wave element.

In addition, in the step of heating and curing the adhesive 5 and adhesively fixing the piezoelectric substrate 6 onto the main surface of the stem 4, the thickness of the adhesive layer between the piezoelectric substrate 6 and the main surface of the stem 4 is kept constant and uniform. Usually, methods are used to suppress the reflection of bulk waves and to make the distributed capacitance between the piezoelectric substrate 6 and the stem 4 uniform.
During this process, the adhesive 5 often protrudes from the side surface of the piezoelectric substrate 6 due to its own weight, climbs up onto the main surface of the piezoelectric substrate 6, and adheres to the input electrodes and output electrodes, thereby forming a surface acoustic wave element. Poor characteristics may occur, or cracks may occur in the piezoelectric substrate 6 due to mechanical shock or thermal shock. Also,
The adhesive 5 extruded on the side surface of the piezoelectric substrate 6 flows on the glass on the main surface side of the stem 4 and creeps up and adheres to the post of the conductive lead bin 3 to which bonding is performed, resulting in defects such as open bonding. Was.

Furthermore, in the step of applying the adhesive 5 onto the stem 4 shown in FIG. 6, the main surface of the stem 4 where the piezoelectric substrate 6 is adhesively bonded is flat, and the wettability with the adhesive 5 is poor. After the heat curing process, parts where no adhesive is present between the back surface of the piezoelectric substrate 6 and the main surface of the stem 4, uneven coating film thickness, etc. occur, resulting in defects in element electrode capacitance and in the bulk wave suppression effect. Due to deterioration, surface acoustic wave element characteristic defects such as trap attenuation defects and ripple defects occurred.

In order to prevent the occurrence of such characteristic defects of the surface acoustic wave element, as shown in the vertical cross-sectional view in FIG. A method is also used in which the surface is honed using an abrasive powder such as carborundum to form the roughened surface portion 10 having concavities and convexities.

[Problems with the Background Art] However, even if the honing process is performed in this way to form the uneven roughened portion 10 on the whole surface of the stem header 1, the uneven shape of the uneven roughened portion 10 is It was difficult to suppress variations, and the effect of preventing phenomena such as extrusion and flow of the adhesive 5 that occurred in manufacturing methods that did not involve honing was reduced, making it impossible to completely prevent characteristic defects in surface acoustic wave elements. .

Rough honing requires a large number of man-hours to process the unevenness of the stem header 1, which increases the cost of the stem header 1. There was also the drawback that a certain nickel plating film was torn and the steel plate of the stem header 1 was exposed, causing rust.

[Object of the Invention] The present invention has been made in response to such conventional circumstances,
The adhesive coating layer between the main surface of the stem and the back surface of the piezoelectric substrate can be thermally cured in a thick and uniform state, and after the piezoelectric substrate is placed on the adhesive coating and heated and cured, the adhesive coats the piezoelectric substrate. The present invention aims to provide a method for manufacturing a surface acoustic wave element that can prevent the piezoelectric substrate from protruding from the side surface and also can adhesively fix the piezoelectric substrate parallel to the main surface of the stem.

[Summary of the Invention] That is, the present invention manufactures a stem header by press working, implants a glass button and a conductive lead bottle into the stem header, and seals the stem by baking, and then applies an adhesive to the stem. A piezoelectric substrate on which an input N pole and an output electrode are formed is placed on the adhesive, and the piezoelectric substrate is adhesively fixed on the stem by heating and curing the adhesive, and the conductive lead bin and the piezoelectric substrate are bonded and fixed on the stem. In the method for manufacturing a surface acoustic wave device in which electrodes are connected with bonding wires and a shell is mounted on the stem, an engraved press mold is used to press the stem header. This is a method of manufacturing a surface acoustic wave device, which is characterized by carving a surface-processed portion.

"Embodiments of the Invention" Details of the present invention will be described below with reference to FIGS. 9 to 18.

FIG. 9 is a longitudinal cross-sectional view of a surface acoustic wave device manufactured by the method of manufacturing a surface acoustic wave device according to the present invention, and FIG. 10 is a stamping press mold of the method of manufacturing a surface acoustic wave device according to the present invention. FIG. 11, a top view of the pressed stem header 1, is a longitudinal sectional view of the stem header 1 of FIG. 10 taken along the Y-Y line. FIG. 12 and FIG. 13 respectively show a glass button 2 and a
It is a perspective view of the conductive lead bin 3, and FIGS. 14 and 15 are longitudinal sectional views showing a part of the process of the method for manufacturing a surface acoustic wave device according to the present invention. FIGS. 16 to 18 show a roughened surface 11 of the stem header 1 which has been pressed using the stamping press mold of the method for manufacturing a surface acoustic wave device according to the present invention.
It is an enlarged longitudinal cross-sectional view showing C.

Next, a method for manufacturing a surface acoustic wave device according to the present invention will be explained step by step.

First, as shown in FIGS. 10 and 11, by using a stamping press mold, a vertical cross section as shown in FIGS. A roughened surface 11 having concavities and convexities is carved. At this time, the shape of the vertical Da surface of the roughened surface processing portion 11 may be, for example, V-shaped as shown in FIG.
It may be U-shaped or ladder-shaped as shown in FIGS. 7 and 18, respectively. Further, although not shown, other shapes such as a wave shape or a sawtooth shape may be used.

In addition, the approximate dimensions of the uneven shape of the roughened surface processing portion 11 are, for example, in the case shown in FIG. It is appropriate that d is approximately 50 μm, and the number of grooves is 18 in the width direction of the piezoelectric substrate 6 and 82 in the length direction.
Although it is preferable to set the grooves to this degree, the present invention is not limited to these numerical examples. It may be provided only in the vertical or horizontal direction.

In this way, a roughened surface 11 is formed on the whole surface of the stem header 1 using a stamping press mold, and a predetermined number of roughened parts (four in the case of the embodiment shown in FIG. 10) are formed at a predetermined position.
After forming the hole 9, the stem header 1 is electroplated with nickel to a thickness of about 2 μm to 6 μm.

The glass button 2 and the conductive lead bin 3 are implanted in the stem header 1 thus created in the conventional manner, and in this state approximately 1.
The stem 4 is produced by firing and sealing at 050°C to 1080°C. Thereafter, in the same manner as in the conventional manufacturing method of surface acoustic wave elements, as shown in FIG. Apply the adhesive 5 shown in FIG.
A piezoelectric substrate 6 made of Nb 03, ceramics, etc., on which an input electrode, a shield electrode, an output electrode, and a sound absorbing material layer are formed, and whose other main surface is roughened, is mounted and heated to 120°C. The adhesive 5 is cured by heating for about 1.5 hours to 2 hours at 140'C to 140'C, and the piezoelectric substrate 6
is glued and fixed on the permanent surface of stem 4.

In addition, at this time, the average film thickness of the adhesive 5 after thermosetting is 30 um.
It is desirable to have culm.

Bonding wires 1'77 are bonded from the conductive lead bin 3 of the stem 4 thus created to each terminal of the input electrode and output electrode on the main surface of the piezoelectric substrate 6, and the shell 8 is placed on the outer peripheral surface of the stem 4. After welding and hermetically sealing, the surface acoustic wave device is completed.

[Effects of the Invention] As described above, according to the method for manufacturing a surface acoustic wave element of the present invention, a roughened surface is formed using a stamping press mold on the main surface of the stem to which the piezoelectric substrate is adhesively fixed. By engraving, it is possible to improve the dimensional accuracy of the roughened surface of the irregularities, and also to shorten the process time for processing the irregularities, thereby improving efficiency when producing stems in large quantities. In addition, since the stem header is nickel plated after roughening, it is possible to prevent the stem header from rusting.

Furthermore, when applying adhesive to the main surface of the stem, the adhesive is trapped in the grooves of the roughened surface, resulting in adhesive repelling and uneven thickness due to poor dripping. It also prevents the adhesive from protruding or creeping up to the side of the piezoelectric substrate after the adhesive is heated and cured, and prevents surface acoustic wave elements from being damaged due to poor bonding at conductive lead bins, input electrodes, output electrodes, etc. It is possible to prevent defective characteristics, the adhesive can be applied with a uniform thickness between the main surface of the stem and the back surface of the piezoelectric substrate, and the piezoelectric substrate can be adhesively fixed parallel to the main surface of the stem, thereby preventing defects in electrode capacitance and elastic surfaces. It can prevent insufficient trap attenuation defects in wave elements, and it can also prevent the occurrence of cracks in the substrate of surface acoustic wave elements due to mechanical and thermal shocks, greatly improving the characteristics of surface acoustic wave elements. There is something.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a surface acoustic wave device manufactured by a conventional surface acoustic wave device manufacturing method, FIG. 2 is a top view of a stem header manufactured by a conventional surface acoustic wave device manufacturing method, and FIG.
The figure is a longitudinal cross-sectional view taken along the line X-X in Figure 2, Figure 4 is a perspective view of a glass button used in the conventional surface acoustic wave device manufacturing method, and Figure 5 is a cross-sectional view of a conventional surface acoustic wave element. A perspective view of a conductive lead bin used in the manufacturing method, FIG. 6 is a vertical cross-sectional view showing one step in a conventional method for manufacturing a surface acoustic wave device, and FIG. 7 shows a step in a conventional method for manufacturing a surface acoustic wave device. 8 is a vertical cross-sectional view of a surface acoustic wave device manufactured by another conventional method for manufacturing a surface acoustic wave device, and FIG. 9 is a vertical cross-sectional view of a surface acoustic wave device manufactured by a method for manufacturing a surface acoustic wave device according to the present invention. FIG. 10 is a longitudinal sectional view of the surface acoustic wave device according to the present invention, and FIG.
Figure 1 is a vertical cross-sectional view taken along the Y-Y line in Figure 10;
13 is a perspective view of a conductive lead bin used in the method of manufacturing a surface acoustic wave device of the present invention, and FIG. 14 is a perspective view of a glass button used in the method of manufacturing a surface acoustic wave device of the present invention. FIG. 15 is a vertical cross-sectional view showing one step in the method for manufacturing a surface acoustic wave device of the present invention, and FIG. 16 is a vertical cross-sectional view showing one step in the method for manufacturing a surface acoustic wave device according to the present invention. FIG. 17 is a vertical cross-sectional view of the roughened surface of the stem header according to the present invention, and FIG. 18 is a vertical cross-sectional view of the roughened surface of the stem header according to the present invention. FIG. 1... Stem header 2...
・・・・・・Glass button 3・・・・・・・・・・・・
・Conductive lead bin 4・・・・・・・・・・・・Stem 5・・・・・・・・・Adhesive 6・・・・・・・・・Piezoelectric substrate 7・・......Bonding wire 8...
・・・・・・・・・・Shell 9・・・・・・・・・・・・Bore 10.11・・・Patent attorney representing the uneven processing department Satoshi Suyama - Figure 1 Figure 2 Figure 3 Yuge Figure 68 Figure 7 Figure 8

Claims (2)

[Claims] (1) A stem header is manufactured by press processing, a glass button and a conductive lead bottle are implanted in the stem header, and adhesive is applied onto the stem created by baking and sealing, and input electrodes are placed on the adhesive. A piezoelectric substrate on which a pressure electrode is formed is placed, the piezoelectric substrate is adhesively fixed on the stem by heating and curing the adhesive, and the conductive lead bin and the electrode on the piezoelectric substrate are connected with a bonding wire, Further, in the method for manufacturing a surface acoustic wave device in which a shell is mounted on the stem, a roughened surface portion having an uneven surface is engraved on the stem header using a stamping press die during press working of the stem header. A method for manufacturing a featured surface acoustic wave device. (2) The uneven surface roughening portion is characterized by carving uneven portions having a V-shaped, U-shaped, ladder-shaped, or wavy cross-sectional shape so as to intersect in one direction or in a substantially right-angled direction. A method for manufacturing a surface acoustic wave device according to claim 1.