JPH09266429A - Manufacture of surface acoustic wave device and surface acoustic wave device and information device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability by fixing a small piece of a piezoelectric substrate to a package with an adhesives and heating the element under an environment of including ozone gas while irradiating with an ultraviolet ray before covering process so as to prevent a secular change in a frequency or the like especially in characteristics as a device due to deposition of an organic material. SOLUTION: At first, a required amount of an adhesives 1 is applied to a package 2. Then a small piece 3 of a piezoelectric substrate on which a surface acoustic wave element is formed is fixed onto the adhesives 1. Then electrodes used to stimulate, intercept and reflect a surface acoustic wave and lead wires of the package with a wire 4 electrically. Then the element is heated while irradiating with an ultraviolet ray under an environment of including ozone gas. In this process, the adhesives 1 protruding from the small piece 3 of the piezoelectric substrate forming a surface acoustic wave is removed. Thus, a fixed area by the adhesives 1 is easily controlled and the stress by the adhesives 3 is delivered to the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed and a change in the frequency due to a temperature change or the like is simply prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a surface acoustic wave device used in a communication device such as a mobile phone and a pager, or an information device such as a computer, and a surface acoustic wave device obtained by the manufacturing method. Also, the present invention relates to an information device having the surface acoustic wave device.

[0002]

2. Description of the Related Art As a conventional technique, after applying an adhesive to a package, a small piece of a piezoelectric substrate on which a surface acoustic wave element is formed is attached, and if the adhesive is an ultraviolet light curing adhesive, an ultraviolet light is used. And was cured by heating. If it was a temperature-curing type, it was heat-cured. Then, steps such as wire bonding were performed as needed to cover the package lid.

Further, when the adhesive application area is made smaller than the small piece of the piezoelectric substrate on the surface of which the electrodes for exciting / intercepting / reflecting the surface acoustic wave are made smaller, the actual flat surface 4-447.
As shown in FIG. 1 of Japanese Patent Laid-Open No. 32, a protrusion is provided on the package and an adhesive is applied to the protrusion.

[0004]

As in the prior art described above, a small piece of a piezoelectric substrate having electrodes for exciting, intercepting, and reflecting surface acoustic waves formed on its surface is fixed to a package with an adhesive, and then the lid is closed. When completed by covering, the organic substance adheres on the surface acoustic wave element in the process from the application of the adhesive to the encapsulation by covering the package lid, and the characteristics as a device,
In particular, there is a problem that the frequency and the like change with time. In addition, if the adhesive for fixing the small piece of the piezoelectric substrate on the surface of which the electrodes that excite, intercept, and reflect the surface acoustic wave is detached and adheres to the surface acoustic wave element, the The change over time was extremely large, which was a major cause of deterioration in device reliability.

In the prior art, surface acoustic waves are excited and
Protect the piezoelectric substrate on the surface of which the electrodes that intercept and reflect are protected by an organic film such as photoresist, and cut it with a dicing device into small pieces of the substrate, and wash the organic films one by one. It was peeled off and adhered to the package. However, if the protective film is peeled off and then adhered to the package, dust or the like is often attached when the small pieces of the substrate are mounted on the package, and when mounting, a device such as a transfer device is often used. Since the pattern of the surface acoustic wave element is scratched, it is effective to mount it with the protective film attached. However, an organic solvent must be used in order to remove the protective film after mounting, which has the adverse effect of also degrading the adhesive. In the case of removing by dry etching, there is a problem that the package cannot be used because it is also etched.

Further, when the adhesive application area is made smaller than the small piece of the piezoelectric substrate on the surface of which the electrodes for exciting, intercepting and reflecting surface acoustic waves are formed, a protrusion is provided on the package and Although the adhesive was applied, there was a problem that the cost was high because the protrusion was provided on the package. Further, there is a problem that the substrate is tilted when the wire wire is pressure-bonded in the wire connecting step.

Therefore, the present invention is intended to solve the above problems, and an object of the present invention is to reduce the characteristics as a device due to the adhesion of organic substances, in particular, the frequency and other changes over time, and to reduce the cost and reliability. An object of the present invention is to provide a method of manufacturing a surface acoustic wave device that can be improved.

[0008]

According to the method of manufacturing a surface acoustic wave device of the present invention, (1) a small piece of a piezoelectric substrate having electrodes for exciting, intercepting and reflecting surface acoustic waves formed on its surface is packaged. The method is characterized in that after fixing with an adhesive and before covering with the lid, heating is performed while irradiating with ultraviolet light in an atmosphere containing ozone gas.

(2) A small piece of the piezoelectric substrate is protected by an organic film, fixed to the package with an adhesive, and heated while irradiating with ultraviolet light in an atmosphere containing ozone gas before the step of covering with a lid. Then, the organic film on the small piece of the piezoelectric substrate is removed.

(3) The adhesive is an ultraviolet light curing adhesive.

(4) The organic film is a protective film when the piezoelectric substrate is cut and divided into small pieces of the piezoelectric substrate.

(5) The application area of the adhesive is smaller than that of a small piece of a piezoelectric substrate having electrodes for exciting, intercepting, and reflecting surface acoustic waves formed on the surface thereof.

(6) After the step of heating while irradiating with ultraviolet light in the atmosphere containing the ozone gas, after the step of connecting the electrode for exciting / intercepting / reflecting the surface acoustic wave and the electrode of the package with a wire line Is characterized in that.

(7) The small piece of the piezoelectric substrate is protected by a photoresist, and the surface acoustic wave that connects the electrode that excites, intercepts, and reflects the surface acoustic wave by development and the electrode of the package is excited and intercepted. The photoresist is exposed so that the reflective electrode portion is removed, and after development, a small piece of the piezoelectric substrate on which the electrode for exciting, intercepting, and reflecting the surface acoustic wave is formed is fixed to the package with an adhesive, After the wire connection process, heating is performed while irradiating with ultraviolet light in an atmosphere containing ozone gas, and the remaining photoresist is removed while the adhesive application area is the surface where the electrode that excites, intercepts, and reflects surface acoustic waves is the surface. It is characterized in that it is made smaller than a small piece of the piezoelectric substrate formed in 1.

Further, the surface acoustic wave device of the present invention is (8) characterized by being obtained by any one of the above manufacturing methods.

Further, the information equipment of the present invention is characterized by (9) having the surface acoustic wave device.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred example of a method of manufacturing a surface acoustic wave device according to the present invention will be described in detail.

FIG. 1 is a process chart showing a method of manufacturing a surface acoustic wave device according to an embodiment of the present invention. First, the required amount of the adhesive 1 is applied to the package 2 (FIG. 1A). The adhesive 1 may be applied by dropping it with a dispenser or the like. Next, as shown in FIG. 1B, the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed is fixed on the adhesive 1.
The fixing may be temporary fixing such that the small pieces 3 of the piezoelectric substrate on which the surface acoustic wave element is formed are not displaced and adhered during the wire connecting step which is the next step, or even if the adhesive 1 is completely cured. I don't care. This is because the adhesive can be completely cured by applying temperature for a desired time in the step of irradiating with ultraviolet light while heating in an atmosphere containing ozone gas. When the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed is pressed onto the adhesive 1, the adhesive 1
May spread slightly, and in some cases, it may stick out from the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed, or the adhesive 1 may adhere to the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed. The adhesive protruding in this manner is released after curing, and the frequency of the surface acoustic wave element is changed.

The next step is a wire connection step in which the electrodes for exciting / intercepting / reflecting surface acoustic waves are electrically connected to the lead wires of the package by wire wires 4 (FIG. 1 (c)).

Then, heating is performed while irradiating with ultraviolet light in an atmosphere containing ozone gas (FIG. 1 (d)). By this process, the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed.
The adhesive 1 that protrudes further is removed. Further, the adhesive 1 to be removed changes depending on the heating temperature and the processing time. In this example, the treatment is performed until the adhesive 1 on the edge side of the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed is slightly scraped. However, the treatment is performed until the area of the adhesive 1 reaches a desired area. Should be done. By doing this, 4-44
The structure shown in FIG. 1 can be realized without providing a protrusion on the package as shown in FIG. By this method,
The fixing area with the adhesive 1 can be easily controlled, and the stress from the adhesive 1 can be easily transmitted to the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed, and the frequency can be easily changed due to temperature change. Can be prevented.

If an ultraviolet light curable adhesive is used as the adhesive 1, the adhesive is adhered in this step without separately irradiating it with ultraviolet light by heating it while irradiating it in an atmosphere containing ozone gas. It is possible to completely cure Agent 1.

FIG. 1E is a process diagram for welding the package lid 5 to complete the package.

The purpose of the contents described above with reference to FIG. 1 is to fix the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed with the adhesive 1 and then heat it while irradiating it with ultraviolet light in an atmosphere containing ozone gas. That is, the wire connecting step of FIG. 1C may be performed after the heating process while irradiating with ultraviolet light in an atmosphere containing ozone gas. But,
This treatment can protect the surface acoustic wave element from the contamination of organic substances if it is performed as soon as possible before the step of covering the package lid 5.

FIG. 2 is a process chart showing a method of manufacturing a surface acoustic wave device according to a second preferred embodiment of the present invention.

The difference between this embodiment and FIG. 1 is that FIG.
That is, the organic film 6 is present on the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed. Then, in FIG. 2C, the organic film 6 is removed by heating in an atmosphere containing ozone gas while irradiating with ultraviolet light. 2 (a), 2 (d) and 2 (e) are the same as those in FIGS.

As described above, since the small piece 3 of the piezoelectric substrate on which the surface acoustic wave element is formed can be mounted while being protected by the organic film 6, when the organic film 6 is cut into the small pieces by cutting the piezoelectric substrate. By using the step also serving as the protective film, it is possible to simplify the step and prevent scratches from being formed during the step.

In particular, the organic film 6 is made of, for example, O produced by Tokyo Ohka Co.
When an organic film having many unsaturated carbon bonds such as MR-83 negative photoresist is used, it can be removed in a short time by heating while irradiating with ultraviolet light in an atmosphere containing ozone gas. This is because when a novolac resin such as a positive resist is used for the protective film 6, it takes a long time to peel off because the unsaturated carbon bond is small. In this example, a photoresist is used for the organic film 6, but the organic film 6 does not need to be a photosensitive material at all, and it is simply available as a semiconductor material, and the surface acoustic wave is excited, intercepted, and intercepted. This is because it is a material that can be applied without melting or damaging the reflective electrode.

Next, when the protective film is a photosensitive resin,
After the wire connection process, heating is performed in an atmosphere containing ozone gas while irradiating with ultraviolet light, and the adhesive application area excites, intercepts, and reflects surface acoustic waves, rather than a small piece of piezoelectric substrate with electrodes formed on the surface. A method of reducing the size will be described with reference to FIGS. 3 and 4 which are views showing a method of manufacturing a surface acoustic wave device according to a third preferred embodiment of the present invention.

FIG. 3A shows a piezoelectric substrate 7 on which electrodes 8 for exciting, intercepting, and reflecting a plurality of surface acoustic waves are formed. That is, a large number of surface acoustic wave elements are formed on the piezoelectric substrate 7, which is before the piezoelectric substrate 7 is cut and divided into small pieces. In this state, a photoresist 9 is applied as an organic protective film (FIG. 3 (b)). Here, as the photoresist 9, a positive photoresist is taken as an example. Of course, the photoresist 9 is baked and hardened. The baking at this time is performed at a temperature and for a time such that the function as the photoresist is not lost because the exposure and development are performed later.

Next, exposure is performed (FIG. 3 (c)). Since we consider the organic protective film as a positive photoresist,
The portion of the photoresist 9 to be removed must be irradiated with light. The portion irradiated with this light is the portion 10 removed by developing the photoresist shown in FIG. Portion 10 removed by development of photoresist
Is a part of an electrode that excites, intercepts, and reflects a surface acoustic wave necessary for connecting a wire line in a wire line connecting step later.

Next, the piezoelectric substrate 7 is attached to the dicing sheet 1
1 and is cut into small pieces 3 of a piezoelectric substrate on the surface of which electrodes for exciting, intercepting and reflecting surface acoustic waves are formed by a cutting machine called a dicing device (FIG. 3 (d)). The dicing sheet 11 is a sheet-shaped tape with an adhesive for fixing the piezoelectric substrate 7. This can be easily attached when fixed to a dicing machine,
In addition, since it is easy to peel off the small piece 3 of the piezoelectric substrate on the surface of which the electrode for exciting, intercepting, and reflecting the surface acoustic wave is easily peeled off, it is often used in such a cutting process. However, the fixing to the dicing device is not limited to the dicing sheet 11. When the cutting is completed, the cutting waste generated by the cutting is sprayed with pure water or the like to be dropped and washed. Furthermore, the surface of the dicing sheet 11 is excited as it is.
The small piece 3 of the piezoelectric substrate, on the surface of which the electrodes for intercepting and reflecting are formed, is dried. The cutting step of FIG. 3 (d) must be performed under a light so that the photoresist 9 used as the organic protective film is not exposed.

FIG. 3E shows the developing process. As a result, the photoresist 9 is developed and the previously exposed portion is removed. Exciting and intercepting surface acoustic waves
If the small piece 3 of the piezoelectric substrate having the reflecting electrode formed on the surface thereof is attached to the dicing sheet 11 and developed, it can be developed at a time rather than one by one, which is simple. In addition, rinsing and drying are easy because a spin cleaning device / spin drying device can be used.

4A, the small piece 3 of the piezoelectric substrate having the electrodes for exciting / intercepting / reflecting the surface acoustic wave, which is attached to the dicing sheet 11, is peeled off, and the adhesive 1 is used to package the package. It is the figure fixed to 2. The surface of the small piece 3 of the piezoelectric substrate having an electrode for exciting / intercepting / reflecting a surface acoustic wave formed on the surface is covered with a photoresist 9 except for the portion developed in the previous figure. When using the conventional technology, when a small piece of the piezoelectric substrate is peeled off from the dicing sheet, the electrodes that excite, intercept, and reflect the surface acoustic waves may be damaged, or the adhesive on the dicing sheet may be attached. There was a nature. However, in the present invention, such a phenomenon does not occur because it is covered with the photoresist 9.

FIG. 4B shows a wire line connecting step. Since the developed portion of the photoresist is the portion to which the wire line 4 of the electrode that excites, intercepts, and reflects the surface acoustic wave is connected, the other portion can be wire-bonded with the photoresist attached.

FIG. 4C shows a step of heating while irradiating with ultraviolet light in an atmosphere containing ozone gas. Thereby, the adhesive transferred from the photoresist and the dicing sheet 11 can be removed. Also, since the adhesive 1 can be removed, the adhesive application area can be made smaller than the small piece of the piezoelectric substrate on the surface of which the electrode for exciting / intercepting / reflecting the surface acoustic wave is formed. It is possible. Finally, cover the lid 5 of the package and seal it,
Completion (Figure 4 (d)).

By the method of manufacturing the surface acoustic wave device as described above, it is possible to reduce the attachment of dust and scratches to the electrodes that excite, intercept, and reflect the surface acoustic wave as much as possible.

[0037]

EFFECTS OF THE INVENTION According to the present invention, organic substances adhere to the surface acoustic wave element in the process from the application of the adhesive to the encapsulation by covering the package lid, and the characteristics of the device, especially the frequency, etc., change over time. When the adhesive for fixing the small piece of the piezoelectric substrate on the surface of which the electrode that excites, intercepts, and reflects the surface acoustic wave is fixed is detached and adheres to the surface acoustic wave element. However, it can be easily removed by the present invention. Further, it is possible to prevent the adhesive from being detached and changing the frequency during use of the surface acoustic wave device, and the reliability is improved.

Further, it is possible to mount the small piece of the piezoelectric substrate on which the surface acoustic wave element is formed with the protective film attached.

By making the adhesive application area smaller than the small piece of the piezoelectric substrate on the surface of which the surface acoustic wave is excited / intercepted / reflected, it becomes possible to provide no protrusion on the package. Therefore, the cost can be suppressed. Further, in the wire connecting step, a small piece of the substrate may be tilted in the past, but in the present invention, an electrode whose adhesive application area excites / intercepts / reflects surface acoustic waves is formed on the surface after the wire connecting step. Since the piezoelectric substrate is made smaller than the small piece, the small piece of the substrate does not tilt.

The present invention makes it possible to obtain an excellent surface acoustic wave device and an information device having the same as described above.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method of manufacturing a surface acoustic wave device according to a preferred embodiment of the present invention.

FIG. 2 is a process drawing showing the manufacturing method of the surface acoustic wave device of the second preferred example of the present invention.

FIG. 3 is a process drawing showing a method of manufacturing a surface acoustic wave device according to a third preferred example of the present invention.

FIG. 4 is a process drawing showing a method of manufacturing a surface acoustic wave device according to a third preferred example of the present invention.

[Explanation of symbols]

 1 Adhesive 2 Package 3 Piece of Piezoelectric Substrate 4 Wire Wire 5 Package Lid 6 Organic Protective Film 7 Piezoelectric Substrate 8 Electrode for Excitation / Interception / Reflection of Surface Acoustic Wave 9 Photoresist 10 Removed by Development of Photoresist Part 11 dicing sheet

Claims (9)

[Claims] 1. An atmosphere containing ozone gas after a small piece of a piezoelectric substrate having electrodes for exciting, intercepting, and reflecting surface acoustic waves formed on the surface thereof is fixed to a package with an adhesive and before the step of covering with a lid. A method of manufacturing a surface acoustic wave device, which comprises heating while irradiating with ultraviolet light. 2. A small piece of the piezoelectric substrate is protected by an organic film, fixed to a package with an adhesive, and then heated while being irradiated with ultraviolet light in an atmosphere containing ozone gas before the step of covering with a lid. The method for manufacturing a surface acoustic wave device according to claim 1, wherein the organic film on the small piece of the piezoelectric substrate is removed. 3. The method for manufacturing a surface acoustic wave device according to claim 1, wherein the adhesive is an ultraviolet light curing adhesive. 4. The method of manufacturing a surface acoustic wave device according to claim 2, wherein the organic film is a protective film when the piezoelectric substrate is cut and divided into small pieces of the piezoelectric substrate. 5. The application area of the adhesive is smaller than that of a small piece of a piezoelectric substrate having electrodes for exciting, intercepting, and reflecting surface acoustic waves formed on the surface thereof. A method for manufacturing the surface acoustic wave device according to any one of claims. 6. The step of heating while irradiating with ultraviolet light in an atmosphere containing ozone gas excites surface acoustic waves.
The method for manufacturing a surface acoustic wave device according to claim 1, which is after the step of connecting the intercepting / reflecting electrode and the package electrode with a wire line. 7. A small piece of the piezoelectric substrate is protected by a photoresist, and a surface acoustic wave is excited / intercepted by development.
An electrode that excites, intercepts, and reflects the surface acoustic wave that connects the reflecting electrode and the package electrode, and exposes the photoresist so that the electrode portion is removed and develops the surface acoustic wave after development. After fixing the small piece of the piezoelectric substrate formed on the surface to the package with an adhesive, after the wire wire connection process, heat while irradiating with ultraviolet light in an atmosphere containing ozone gas, and remove the remaining photoresist. 7. The method of manufacturing a surface acoustic wave device according to claim 6, wherein the adhesive application area is smaller than that of the small piece of the piezoelectric substrate on the surface of which the surface acoustic wave is excited, intercepted, and reflected. 8. A surface acoustic wave device obtained by the manufacturing method according to claim 1. 9. An information device comprising the surface acoustic wave device according to claim 8.