JP2002076830A - Surface acoustic wave device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface acoustic wave device and its manufacturing method to enhance the workability and stably obtain the product with high quality. SOLUTION: An interdigital electrode 30 and a terminal electrode 31 are formed on one side of a piezoelectric substrate 29 and after the terminal electrode 31 of the piezoelectric substrate 29 and a conductor pattern of a base substrate 33 are connected via a bump 32, the piezoelectric substrate 29 is sealed to the base substrate 33 via a polyamide hot melt resin 35.

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 a frequency filter or the like of a video device such as a television receiver and an improvement of a method of manufacturing the same.

[0002]

2. Description of the Related Art As is well known, a surface acoustic wave device is a comb-shaped electrode (ID) formed of a metal thin film formed on a piezoelectric body.
A device that converts an electric signal into a surface acoustic wave (SAW) and transmits / receives a signal by using an Inter Digital Transducer (T).

[0003] This surface acoustic wave device has been widely used, for example, as a surface acoustic wave filter, a surface acoustic wave element, a delay circuit, and the like. Particularly, in recent years, there is an advantage that it can be made thinner and smaller. Therefore, surface acoustic wave filters have been widely used in the field of video equipment such as television receivers.

Meanwhile, a surface acoustic wave filter in this field has conventionally been provided with a SIP (Singing) using a lead frame.
le Inline Package) and the like, which are inserted and mounted on a circuit board, have become mainstream.

On the other hand, in the case of video equipment, introduction of a double-sided circuit board has been studied in order to reduce the size and cost, and accordingly, a circuit as a surface acoustic wave filter has been developed. A type that is surface-mounted on a substrate is desired.

As a modification of the conventional type using a lead frame, there is a structure in which a leg of a DIP (Double Inline Package) is bent to form a J-lead. However, this cannot reduce the thickness of the package. There is a disadvantage that.

[0007] In short, the surface acoustic wave device aims to have a thickness that can be accommodated in the card in the future.
This type of goal is difficult to achieve with surface mount types.

Therefore, at present, a surface acoustic wave element formed by forming a comb-shaped electrode on a piezoelectric substrate is face-down bonded to a flat base substrate, and this is covered by a protective member. So-called flip-chip mounting has been performed to further reduce the thickness of the surface acoustic wave device.

FIGS. 3A to 3F show a method of manufacturing a surface acoustic wave device by this flip chip mounting. First, as shown in FIG. 3A, a comb-shaped electrode 12 and a terminal electrode 13 are formed on one surface of a piezoelectric substrate 11 by using a thin metal film such as aluminum (Al), and then, as shown in FIG. As shown in b), a bump 14 is attached on the terminal electrode 13.

Then, as shown in FIG. 3C, the surface of the piezoelectric substrate 11 on which the comb electrodes 12 and the terminal electrodes 13 are formed is opposed to the base substrate 15, and FIG.
As shown in FIG. 2, the bumps 14 are connected to conductive patterns (not shown) formed on the base substrate 15 to form a surface acoustic wave element 16.

Thereafter, as shown in FIG. 3 (e), an adhesive 18 is applied to the opening of the cap 17 formed in a substantially box shape, and as shown in FIG. The piezoelectric substrate 11 is adhered to the base substrate 15 so as to accommodate the piezoelectric substrate 11, and the piezoelectric substrate 11 is hermetically sealed by the base substrate 15 and the cap 17.

FIGS. 4A to 4G show another method of manufacturing a surface acoustic wave device by flip-chip mounting. First, as shown in FIG. 4A, after a comb-shaped electrode 20 and a terminal electrode 21 are formed on one surface of a piezoelectric substrate 19, as shown in FIG. Substrate 1
An annular dam 22 is formed so as to surround the comb-tooth electrode 20 and the terminal electrode 21 along the outer periphery of 9.

Then, as shown in FIG. 4 (c), a bump 23 is attached on the terminal electrode 21, and as shown in FIG. 4 (d), the comb-shaped electrode 20 and the terminal electrode 21 of the piezoelectric substrate 19 are formed.
Is formed to face the base substrate 24,
As shown in FIG. 4E, the bump 23 and the base substrate 24
Is connected to a conductive pattern (not shown) formed on the surface of the substrate to form a surface acoustic wave element 25.

In this case, the dam 22 is in close contact with the base substrate 24, so that the comb-shaped electrodes 20 and the terminal electrodes 21 of the piezoelectric substrate 19 are connected to the piezoelectric substrate 19 itself, the dam 22 and the base. It is hermetically sealed with the substrate 24.

Thereafter, as shown in FIG. 4F, an epoxy resin 26 is poured from the piezoelectric substrate 19 side, and the piezoelectric substrate 19 and the base substrate 24 are solidified so as to be integrated. In this case, the dam 22 causes the epoxy resin 2
6 is prevented from flowing into the comb-shaped electrode 20 and the terminal electrode 21.

After the epoxy resin 26 is solidified, the protruding portion 27 protruding from the end of the base substrate 24 is formed.
In addition, unnecessary portions 28 and the like that have wrapped around the back surface of the base substrate 24 are removed, and the piezoelectric substrate 19 is hermetically sealed with the base substrate 24 and the epoxy resin 26 as shown in FIG. You.

However, first, in the method of manufacturing the surface acoustic wave device shown in FIG. 3, handling of the cap 17, which is an individual piece, and applying the adhesive 18 to the cap 17 or the base substrate 15 are very troublesome. At the same time, there is a problem that a defective product that is not hermetically sealed is likely to be generated depending on the application state of the adhesive 18.

Further, in the method of manufacturing the surface acoustic wave device shown in FIG.
The number of steps for removing the burrs 27 and the unnecessary portions 28 and the like increase, and it is difficult to balance the height of the dam 22 and the height of the bumps 23, which causes a problem that quality control is difficult.

[0019]

As described above, the conventional method of manufacturing a surface acoustic wave device has a problem that the number of steps is large, the operation is complicated, the workability is poor, and the quality of the product is liable to deteriorate. I have.

Therefore, the present invention has been made in view of the above circumstances, and has an extremely good surface acoustic wave device which can improve workability and can stably obtain a high quality product, and a method of manufacturing the same. The purpose is to provide.

[0021]

A surface acoustic wave device according to the present invention comprises a piezoelectric substrate having a comb-shaped electrode and a terminal electrode formed on one surface, and a bump provided on the terminal electrode of the piezoelectric substrate. A base substrate having a conductive pattern formed thereon and a polyamide hot melt resin for sealing the piezoelectric substrate to the base substrate.

Further, according to a method of manufacturing a surface acoustic wave device according to the present invention, a first step of forming a comb-shaped electrode and a terminal electrode on one surface of a piezoelectric substrate, and after the first step, A second step of connecting the terminal electrodes of the piezoelectric substrate to the conductive patterns of the base substrate via bumps; and, after the second step, the piezoelectric substrate is connected to the base substrate via a polyamide-based hot melt resin. The third step of sealing is performed.

Further, in the method of manufacturing a surface acoustic wave device according to the present invention, a first step of forming a comb-like electrode and a terminal electrode on one surface of a piezoelectric substrate, and after the first step,
A second step of forming a sound absorbing material at a predetermined position on one surface of the piezoelectric substrate, and after the second step, connecting the terminal electrodes of the piezoelectric substrate to the conductive patterns of the base substrate via bumps. The third step and, after the third step, a fourth step of sealing the piezoelectric substrate to the base substrate via a polyamide hot melt resin.

According to the above configuration and method, the piezoelectric substrate is sealed to the base substrate with a polyamide hot melt resin. This polyamide-based hot melt resin 35 is a resin whose fluidity can be controlled by heat. For this reason, for example, when a polyamide-based hot melt resin solidified in a sheet shape is placed on the surface of the piezoelectric substrate on which the comb-shaped electrodes and terminal electrodes are not formed, and melted while controlling the fluidity by heat, The hot melt resin hangs down from the periphery of the piezoelectric substrate onto the base substrate, and is solidified in this state, whereby the piezoelectric substrate and the base substrate can be integrated.

At this time, by controlling the fluidity of the hot melt resin when it hangs down from the peripheral edge of the piezoelectric substrate onto the base substrate, it is possible to eliminate the need for forming a dam on the piezoelectric substrate as in the conventional case. In addition, the hot melt resin can be prevented from flowing into the comb-shaped electrode and the terminal electrode, and the step of forming a dam is not required. In addition, this polyamide-based hot-melt resin is a process of removing the burrs and unnecessary portions after the solidification, as in a conventional epoxy resin, without generating any burrs or unnecessary portions wrapping around the base substrate. Is no longer necessary.

[0026]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, FIG.
As shown in FIG. 1, after a comb-shaped electrode 30 and a terminal electrode 31 are formed on one surface of a piezoelectric substrate 29, a metal bump is formed on the terminal electrode 31 as shown in FIG. 32 is formed by bonding or screen printing or the like.

Then, as shown in FIG. 1C, the surface of the piezoelectric substrate 29 on which the comb-shaped electrodes 30 and the terminal electrodes 31 are formed is made to face the base substrate 33, and FIG.
As shown in (1), the bump 32 and the conductive pattern (not shown) formed on the base substrate 33 are connected, and the surface acoustic wave element 34 is formed here.

After that, as shown in FIG. 1E, the piezoelectric substrate 2 is
9 and the base substrate 33 are solidified so as to be integrated. This polyamide-based hot melt resin 35 is a resin whose fluidity can be controlled by heat.

In this case, for example, a hot melt resin 35 made of a polyamide solidified in a sheet shape is formed on the piezoelectric substrate 29 in the state shown in FIG. And dissolve it while controlling the fluidity by heat. Then, hot melt resin 3
5 hangs down from the periphery of the piezoelectric substrate 29 onto the base substrate 33 and is solidified in this state.
As shown in (e), the piezoelectric substrate 29 and the base substrate 33
Can be integrated.

At this time, when the hot melt resin 3 hangs down from the peripheral edge of the piezoelectric substrate 29 onto the base substrate 33.
By controlling the fluidity of the piezoelectric element 5 by heat, the hot melt resin 35 is prevented from flowing into the comb-shaped electrode 30 and the terminal electrode 31 even if the dam 22 is not formed on the piezoelectric substrate 19 as in the related art. Therefore, the step of forming the dam 22 is not required.

Also, by using a resin whose fluidity can be controlled by heat, such as the polyamide hot melt resin 35, the conventional epoxy resin 26
After the solidification, the burrs 27 and the unnecessary portions 28 wrapping around the base substrate 24 are not generated, and the step of removing the burrs 27 and the unnecessary portions 28 is not required.

Further, since the polyamide-based hot melt resin 35 has an adhesive effect and a property of low water absorption, the piezoelectric substrate 29 can be sealed and sealed well.

When the piezoelectric substrate 29 is sealed on the base substrate 33, the surface of the piezoelectric substrate 29 on which the comb-shaped electrodes 30 and the terminal electrodes 31 are not formed is entirely made of a polyamide hot melt resin. It is not necessary to cover with 35. That is,
It is sufficient that at least the periphery of the piezoelectric substrate 29 and the base substrate 33 are connected by the hot melt resin 35, and the comb-shaped electrode 30 and the terminal electrode 3 of the piezoelectric substrate 29
The surface where 1 is not formed may be exposed.

FIG. 2 shows a state in which a sound absorbing material 36 for absorbing surface acoustic waves is formed on the outer peripheral portion of the piezoelectric substrate 29. That is, in the conventional method of manufacturing the surface acoustic wave device shown in FIG. 4, the dam 22 is also provided with a surface acoustic wave sound absorbing function. However, the dam 22 has a structure in which the epoxy resin 26 has the electrodes 20 and 21.
Therefore, the piezoelectric substrate 19 needs to be formed in an annular shape along the outer periphery of the piezoelectric substrate 19 because it serves to prevent the piezoelectric substrate 19 from flowing into the piezoelectric substrate 19.

On the other hand, by using the polyamide-based hot melt resin 35 and making the dam 22 unnecessary,
It is only necessary to form the sound absorbing material 36 only on a necessary portion on the piezoelectric substrate 29. In such a point, the operation can be simplified and the quality can be improved.

In this case, the sound absorbing material 36 is formed after the comb-shaped electrode 30 and the terminal electrode 31 are formed on the piezoelectric substrate 29 as shown in FIG. 1A, and thereafter, as shown in FIG.
As shown in FIG. 5, a bump 32 is formed on the terminal electrode 31.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified and implemented without departing from the scope of the invention.

[0038]

As described in detail above, according to the present invention,
It is possible to provide a very good surface acoustic wave device which can improve workability and stably obtain a high-quality product, and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a view for explaining an embodiment of a surface acoustic wave device and a method of manufacturing the same according to the present invention.

FIG. 2 is a plan view shown for explaining the arrangement of the sound absorbing material in the embodiment.

FIG. 3 is a view for explaining a method of manufacturing a conventional surface acoustic wave device.

FIG. 4 is a view for explaining another method for manufacturing a conventional surface acoustic wave device.

[Explanation of symbols]

 Reference Signs List 11: piezoelectric substrate, 12: comb-shaped electrode, 13: terminal electrode, 14: bump, 15: base substrate, 16: surface acoustic wave element, 17: cap, 18: adhesive, 19: piezoelectric substrate, 20 ... comb-shaped electrode, 21 ... terminal electrode, 22 ... dam, 23 ... bump, 24 ... base substrate, 25 ... surface acoustic wave element, 26 ... epoxy resin, 27 ... burr, 28 ... unnecessary part, 29 ... piezoelectric Substrate, 30: Comb-shaped electrode, 31: Terminal electrode, 32: Bump, 33: Base substrate, 34: Surface acoustic wave element, 35: Hot melt resin, 36: Sound absorbing material.

Claims (6)

[Claims] A piezoelectric substrate having a comb-shaped electrode and a terminal electrode formed on one surface; a base substrate having a conductive pattern connected to the terminal electrode of the piezoelectric substrate via a bump; A surface acoustic wave device comprising: a polyamide-based hot melt resin for sealing the piezoelectric substrate to the base substrate. 2. The elastic surface according to claim 1, wherein the hot melt resin covers the entire other surface of the piezoelectric substrate, and extends from a peripheral edge of the piezoelectric substrate onto the base substrate. Wave device. 3. A first step of forming a comb-like electrode and a terminal electrode on one surface of a piezoelectric substrate, and after the first step, a terminal pattern of the piezoelectric substrate and a conductive pattern of a base substrate. Through a bump, and after this second step, a third step of sealing the piezoelectric substrate to the base substrate via a polyamide-based hot melt resin. A method for manufacturing a surface acoustic wave device. 4. The third step comprises placing the polyamide-based hot melt resin solidified in a sheet shape on the other surface of the piezoelectric substrate, and melting the hot melt resin while controlling the fluidity by heat. The method of manufacturing a surface acoustic wave device according to claim 3, wherein the hot-melt resin is caused to hang down from a peripheral edge of the piezoelectric substrate onto the base substrate. 5. A first step of forming a comb-like electrode and a terminal electrode on one surface of a piezoelectric substrate, and after the first step, a sound absorption at a predetermined position on one surface of the piezoelectric substrate. A second step of forming a material, a third step of connecting a terminal electrode of the piezoelectric substrate and a conductive pattern of the base substrate via a bump after the second step, and a third step After,
And a fourth step of sealing the piezoelectric substrate to the base substrate via a polyamide-based hot-melt resin. 6. In the fourth step, the polyamide-based hot melt resin solidified into a sheet is placed on the other surface of the piezoelectric substrate, and the hot melt resin is melted while controlling fluidity by heat. The method of manufacturing a surface acoustic wave device according to claim 5, wherein the hot-melt resin is caused to hang down from a peripheral edge of the piezoelectric substrate onto the base substrate.