JP2003078388A - Elastic wave device and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In an electronic component using a bare chip type elastic wave element, an extraction electrode is corroded by humidity, oxygen, or the like. An acoustic wave device comprising: a piezoelectric substrate; an excitation electrode; an extraction electrode connected to the excitation electrode; and a protruding electrode formed on the extraction electrode. The acoustic wave device is characterized in that the entire surface of each of the excitation electrode 2, the extraction electrode 3, and the projection electrode 4 is covered with an insulating protective film 5 so that the tip shape of the projection electrode 4 is formed.

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 filter used for mobile communication devices, televisions, VTRs, etc., a delay line, an acoustic wave device preferably used for a transmitter, etc. is there.

[0002]

2. Description of the Related Art In recent years, electronic parts equipped with many acoustic wave elements as elements such as filters, delay lines, transmitters, etc., of electronic equipment such as mobile communication equipment, televisions, and VTRs that use radio waves (hereinafter, referred to as Elastic wave device) is used. Electronic devices are being made smaller and lighter, so that electronic components used in the electronic devices are required to be smaller and lighter.

Since the current acoustic wave device is mounted on a package for use, the size of the acoustic wave device is considerably larger than that of the acoustic wave device that actually functions. Therefore, the development of a bare chip type acoustic wave device that can be used without being mounted in a package is underway.

FIG. 5 is a sectional view showing an example of such a bare chip type acoustic wave device. In FIG. 5, the excitation electrode 42 and the extraction electrode 43 are formed on the upper surface of the piezoelectric substrate 41. Excitation electrode 42 and extraction electrode 43 are covered with protective film 45 except for a part 46 of extraction electrode 43. Bumps 44 are formed on the region 46 of the extraction electrode 43 without the protective film 45.

In the above-mentioned bare-chip type acoustic wave device, the protective film 45 is not formed on a part of the extraction electrode 43.
Furthermore, since the bump 44 does not have the protective film 45 at all, these portions exposed from the protective film 45 are exposed to moisture,
There is a problem that it cannot be used as an electronic component because it may be corroded by oxygen or the like, or dust or moisture may electrically short-circuit between the extraction electrodes 43.

Therefore, the present invention has been made in view of the above-mentioned problems of the related art, and an object thereof is to cover all the excitation electrodes and the extraction electrodes with a protective film and also to provide the protruding electrodes in a bare chip type acoustic wave device. An acoustic wave device that can be mounted on a circuit board easily and reliably without being housed in a package by covering the entire surface with a protective film, or by covering with a protective film except for a part where electrical connection is made, and its It is to provide a manufacturing method.

[0007]

The elastic wave device of the present invention comprises:
(1): An elastic wave device comprising an excitation electrode, an extraction electrode connected to the excitation electrode, and a protruding electrode formed on the extraction electrode on a piezoelectric substrate, the excitation electrode comprising:
The entire surface of each of the extraction electrode and the protruding electrode is covered with an insulating protective film so that the tip shape of the protruding electrode is formed.

(2): An elastic wave device comprising an excitation electrode, an extraction electrode connected to the excitation electrode, and a protruding electrode formed on the extraction electrode on a piezoelectric substrate, Each surface of the excitation electrode, the extraction electrode, and the protruding electrode is covered with an insulating protective film so that the tip of the protruding electrode is exposed.

Further, (3): the piezoelectric substrate is provided with an excitation electrode, an extraction electrode connected to the excitation electrode, and a projection electrode formed on the extraction electrode, and the projection electrode is a dielectric substrate. It is characterized in that it is connected to an external extraction electrode formed above, and each surface of the excitation electrode, the extraction electrode, and the projection electrode is covered with an insulating protective film. Elastic wave device.

Particularly, in the elastic wave device of (4) :( 2), the surface of the protruding electrode exposed from the protective film is flat.

(5): In the acoustic wave device according to any one of (1) to (4), the excitation electrode, the extraction electrode, and the protruding electrode are arranged on one main surface of the piezoelectric substrate. In addition, a reinforcing substrate is attached to the other main surface of the piezoelectric substrate.

(6): In the method for manufacturing an acoustic wave device according to any one of (1) to (5), the protective film is formed after the excitation electrode, the extraction electrode, and the protruding electrode are formed. Is formed.

Further, (7): when manufacturing the elastic wave device of (2) or (4) from the elastic wave device of (1), it is preferable to remove the protective film covering the tip portion of the protruding electrode. Characterize.

Further, (8): in the method of manufacturing an elastic wave device according to (3), the tip of the protruding electrode of the elastic wave device according to (1) is attached to the external extraction electrode formed on the dielectric substrate. By heating the coated protective film while pressing it, the protective film in contact with the external extraction electrode is removed, and the external extraction electrode and the protruding electrode are connected.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings schematically showing.

FIG. 1 is a sectional view showing an example of the elastic wave device of (1). In FIG. 1, an excitation electrode 2 for generating an elastic wave and an extraction electrode 3 electrically connected to the excitation electrode 2 are formed on an upper surface which is one main surface of the piezoelectric substrate 1.
On the extraction electrode 3, the protruding electrode 4 and the tip portion 4a are formed in a steeple shape. Further, a protective film 5 is coated on the entire surfaces of the excitation electrode 2, the extraction electrode 3, and the protruding electrode 4 so that the tip shape of the protruding electrode 4 is formed. Particularly, the portion where the protruding electrode 4 is present is confirmed by the protruding portion 5a of the protective film 5.

According to this acoustic wave device, the excitation electrode 2 and
By covering the extraction electrode 3 and the protruding electrode 4 with the insulating protective film 5, it is possible to prevent corrosion of these parts due to moisture, oxygen or the like as much as possible. Further, although signals cannot be input / output in this state, it is easy to remove a part of the protective film (protruding portion 5a) of the tip portion 4a of the protruding electrode 4 by physical etching, destruction, or chemical etching. It is possible to input and output signals.

FIG. 2 is a sectional view showing an example of the elastic wave device of the above (2) and (4). In FIG. 2, the excitation electrode 12 and the extraction electrode 13 electrically connected to the excitation electrode 12 are formed on the upper surface of the piezoelectric substrate 11. A protruding electrode 14 is formed on the extraction electrode 13. In addition, the tip of the bump electrode 14 is exposed on the surface 14 exposed from the protective film 15.
a is formed in a planar shape. Except for the exposed portion, the acoustic wave element 12, the extraction electrode 13, and the protruding electrode 14 are covered with a protective film 15.

According to the elastic wave device of (2), the excitation electrode 12, the extraction electrode 13 connected to the excitation electrode 12, and the protruding electrode 14 formed on the extraction electrode 13 are provided on the piezoelectric substrate 11. An acoustic wave device including at least an excitation electrode 12, an extraction electrode 13, and a protruding electrode 1
4 is covered with an insulating protective film 15 and at least a part of the protruding electrode 14 is exposed from the protective film 15, so that the lead-out electrode 13 on the piezoelectric substrate 11 is protected by the protective film 15.
Can be completely covered with and the signal can be taken out from the outside through the protruding electrode 14. As a result,
Since the excitation electrode 12 and the take-out electrode 13 are not completely exposed, these parts are not corroded by moisture, oxygen, etc., and the take-out electrodes are not electrically short-circuited due to dust or moisture, and are stably used as electronic parts. can do.

According to the elastic wave device of the above (4),
The portion where the protruding electrode 14 is exposed from the protective film 15 is the tip of the protruding electrode 14, and by making the exposed surface 14a flat, a circuit board on which the acoustic wave device is mounted can be
By forming a commonly used flat type electrode pad, the acoustic wave device can be easily mounted on the circuit board. Further, by mounting the acoustic wave device on a flat electrode pad, since only the exposed surface of the protruding electrode 14 of the acoustic wave device is covered with the electrode pad, the acoustic wave device is exposed to moisture, oxygen, or the like. Corrosion can be suppressed as much as possible.

FIG. 3 is a sectional view showing an example of the elastic wave device of the above (5). In FIG. 3, the excitation electrode 22 and the extraction electrode 23 electrically connected to the excitation electrode 22 are formed on the upper surface, which is one main surface of the piezoelectric substrate 21. A protruding electrode 24 is formed on the extraction electrode 23. The entire surface of these electrodes is covered with a protective film 25 as in FIG. In addition, reference numeral 24 a in the drawing denotes a tip portion of the protruding electrode 24. A reinforcing substrate 27 for reinforcing the acoustic wave device is attached to the lower surface that is the other main surface of the piezoelectric substrate 21.

According to this elastic wave device, the excitation electrode 22
The lead electrode 23 and the protruding electrode 24 are formed on the same piezoelectric substrate 21 surface (one main surface), and the reinforcing substrate 26 for increasing the strength of the acoustic wave device is provided on the back surface which is the other main surface of the piezoelectric substrate 21. By being attached, the mechanical strength of the entire acoustic wave device is increased, the main body is not damaged when the acoustic wave device is gripped by the mounting machine, and the acoustic wave device can be mounted on the circuit board without damage. it can.

FIG. 4 is a sectional view for explaining an example of the elastic wave device of (3) and an example of a method of manufacturing the elastic wave device of (8). In FIG. 4, an excitation electrode 32 and an extraction electrode 33 electrically connected to the excitation electrode 32 are formed on the lower surface of the piezoelectric substrate 31. A protruding electrode 34 is formed on the extraction electrode 33. Excitation electrode 32 and extraction electrode 33 except for a part 36 of protruding electrode 34.
The protective film 35 covers the protruding electrodes 34.

A part 36 of the protruding electrode 34 is formed on the dielectric substrate 3
7 is mechanically and electrically connected to the extraction electrode 38 of the dielectric substrate 37 formed on the upper surface of 7. According to this acoustic wave device and the method of manufacturing the same, the excitation electrode 32, the extraction electrode 33, and the protruding electrode 34 are formed, and then the protective film 35 is formed. It can be completely covered with the protective film 35. In the step of peeling off a part of the protective layer of the bump electrode 34, the shape of the bump electrode portion to which the peeled protective layer is attached may be changed.

Further, according to the method (6) for manufacturing an acoustic wave device, it is possible to provide an acoustic wave device having a complete protective structure very simply and surely.

According to the method of manufacturing an elastic wave device of the above (7), in the elastic wave device of the above (1), by pressing the protruding electrode and the rigid body, the protective film laminated on the tip of the protruding electrode. By removing the above, the protective film on the tip of the protruding electrode can be removed and the tip of the protruding electrode can be made flat, and the structure of the acoustic wave device of (2) and (4) can be formed.

According to the method of manufacturing an elastic wave device of (8), in the elastic wave device of (1), the protruding electrode and the extraction electrode stacked on the dielectric substrate are pressed to push the protruding electrode. By destroying the protective film laminated on the tip of the at the same time, by electrically connecting the protruding electrode and the extraction electrode laminated on the dielectric substrate,
The elastic wave device (1) can be easily mounted on the circuit board in one step.

[0028]

EXAMPLES Next, specific examples of the elastic wave device of the present invention will be described. [Embodiment 1] An embodiment of the present invention shown in FIG. 1 will be described.

As the piezoelectric material substrate, lithium tantalate having a thickness of 0.35 mm and a dielectric constant of 43 was used. The acoustic wave device on the piezoelectric material substrate was formed by forming an aluminum-copper alloy film by a sputtering method and then processing it by a photoresist process.
The thickness of the excitation electrode is 0.2 μm. The extraction electrode was produced by laminating 0.6 μm aluminum on a 0.2 μm aluminum-copper alloy. The protruding electrode was produced by taking out a gold wire having a spherical tip and pressing it against the electrode surface, and then tearing the wire off. The protruding electrode was formed by applying ultrasonic waves and heat. The formation conditions are an ultrasonic frequency of 60 KHz, a load of 294 mN, and a temperature of 150 ° C. After the bump electrodes were formed, a SiO2 film was laminated by 0.02 μm by CVD.

In the conventional method, the protective film on the take-out electrode is partially removed after the protective film is laminated, and then the protruding electrode is formed. Since the part was exposed to the outside air, it was a cause of corrosion of the take-out electrode. However, as in claim 5 of the present invention, by forming the protruding electrode and then stacking the protective film, the extraction electrode below the protruding electrode does not come into contact with the outside air. Was able to make up.

This sample was tested at a temperature of 60 ° C. and a humidity of 90 to 9
It was left to stand in a 5% atmosphere for 1000 hours. Subsequent samples had no change in the surface of both the acoustic wave device and the extraction electrode, and the corrosion of the extraction electrode could be prevented. [Embodiment 2] An embodiment of the present invention shown in FIG. 2 will be described.

As the piezoelectric material substrate, lithium tantalate having a thickness of 0.35 mm and a dielectric constant of 43 was used. The acoustic wave device on the piezoelectric material substrate was formed by forming an aluminum-copper alloy film by a sputtering method and then processing it by a photoresist process.
The thickness of the excitation electrode is 0.2 μm. The extraction electrode was produced by laminating 0.6 μm aluminum on a 0.2 μm aluminum-copper alloy. The protruding electrode was produced by taking out a gold wire having a spherical tip and pressing it against the electrode surface, and then tearing the wire off. The protruding electrode was formed by applying ultrasonic waves and heat. The formation conditions are an ultrasonic frequency of 60 KHz, a load of 294 mN, and a temperature of 150 ° C. After the bump electrodes were formed, a SiO2 film was laminated by 0.02 μm by CVD.

Then, the protruding electrode forming surface was pressed against the SUS plate to crush the tip of the protruding electrode forming surface. As a result, the protective film was peeled off at the tip of the bump electrode, and the bump electrode surface was exposed.

As described above, by pressing the protruding electrode and the rigid body as in the elastic wave device shown in (7) above,
The protective film laminated on the tip of the protruding electrode was destroyed and removed, whereby the structure of the acoustic wave device of (2) could be completed. Moreover, the structure according to claim 3 could be completed by pressing the protruding electrode against the SUS plate having a flat surface.

This sample was tested at a temperature of 60 ° C. and a humidity of 90 to 9
It was left to stand in a 5% atmosphere for 1000 hours. Subsequent samples had no change in the surface of both the acoustic wave device and the extraction electrode, and the corrosion of the extraction electrode could be prevented. [Embodiment 3] An embodiment of the present invention shown in FIG. 3 will be described.

As the piezoelectric material substrate, lithium tantalate having a thickness of 0.35 mm and a dielectric constant of 43 was used. The acoustic wave device on the piezoelectric material substrate was formed by forming an aluminum-copper alloy film by a sputtering method and then processing it by a photoresist process.
The thickness of the excitation electrode is 0.2 μm. The extraction electrode was produced by laminating 0.6 μm aluminum on a 0.2 μm aluminum-copper alloy. The protruding electrode was produced by taking out a gold wire having a spherical tip and pressing it against the electrode surface, and then tearing the wire off. The protruding electrode was formed by applying ultrasonic waves and heat. The formation conditions are an ultrasonic frequency of 60 KHz, a load of 294 mN, and a temperature of 150 ° C. After the bump electrodes were formed, a SiO2 film was laminated by 0.02 μm by CVD.

An aluminum oxide substrate having a thickness of 0.3 mm was attached to the surface of the piezoelectric material substrate on which the protruding electrodes were not formed. An epoxy adhesive was used for the bonding.

As a result, when the acoustic wave device is mounted on the circuit board, the back surface is not clogged.

As described above, in the elastic wave device of the above (1), the excitation electrode, the extraction electrode, and the protruding electrode are formed in the same piezoelectric substrate surface, and the electronic component using the excitation electrode on the back surface of the piezoelectric substrate. The structure of the acoustic wave device of the above (4) of the present invention, which is characterized in that a reinforcing substrate for increasing the strength of (1) is attached, can be constructed. [Embodiment 4] An embodiment of the present invention shown in FIG. 4 will be described.

As the piezoelectric material substrate, lithium tantalate having a thickness of 0.35 mm and a dielectric constant of 43 was used. The acoustic wave device on the piezoelectric material substrate was formed by forming an aluminum-copper alloy film by a sputtering method and then processing it by a photoresist process.
The thickness of the excitation electrode is 0.2 μm. The extraction electrode was produced by laminating 0.6 μm aluminum on a 0.2 μm aluminum-copper alloy. The protruding electrode was produced by taking out a gold wire having a spherical tip and pressing it against the electrode surface, and then tearing the wire off. The protruding electrode was formed by applying ultrasonic waves and heat. The formation conditions are an ultrasonic frequency of 60 KHz, a load of 294 mN, and a temperature of 150 ° C. After the bump electrodes were formed, a SiO2 film was laminated by 0.02 μm by CVD.

Thereafter, the protruding electrode surface was pressed against the extraction electrode (gold / nickel / tungsten) surface laminated on the dielectric substrate (aluminum oxide) of the circuit board. At this time, ultrasonic waves and heating were simultaneously applied. Mounting conditions are load 3920mN, ultrasonic frequency 63.5KHz, temperature 15
It was set to 0 ° C. As a result, the acoustic wave device and the dielectric substrate were mechanically and electrically connected.

As in the method (8) for manufacturing an acoustic wave device, the protective film laminated on the tip of the projecting electrode by pressing the projecting electrode and the extraction electrode laminated on the dielectric substrate. The acoustic wave device of (1) can be easily mounted on a circuit board in one step by electrically connecting the protruding electrode and the extraction electrode laminated on the dielectric substrate at the same time as destroying I was able to. Comparative Example As a comparative example to the present invention, a comparative example of the present invention shown in FIG. 5 will be described.

As the piezoelectric material substrate, lithium tantalate having a thickness of 0.35 mm and a dielectric constant of 43 was used. The acoustic wave device on the piezoelectric material substrate was formed by forming an aluminum-copper alloy film by a sputtering method and then processing it by a photoresist process.
The thickness of the excitation electrode is 0.2 μm. The extraction electrode was produced by laminating 0.6 μm aluminum on a 0.2 μm aluminum-copper alloy. Then, a SiO 2 film was deposited thereon by 0.02 μm as a protective film by CVD. After that, a part of the protective film on the extraction electrode was removed by a photoresist process, and a protruding electrode was formed on the extraction electrode in the groove. The protruding electrode was produced by taking out a gold wire having a spherical tip and pressing it against the electrode surface, and then tearing the wire off.
The protruding electrode was formed by applying ultrasonic waves and heat. The formation conditions are ultrasonic frequency 60 KHz, load 294 mN, temperature 15
It is 0 ° C.

This sample was tested at a temperature of 60 ° C. and a humidity of 90 to 9
It was left to stand in a 5% atmosphere for 1000 hours. In the subsequent samples, the surface of the excitation electrode did not change, but SiO2
In the extraction electrode portion not covered with the, the metallic luster on the surface became dull and the color was slightly changed to white. in this way,
The conventional technique cannot suppress the corrosion (oxidation) of the extraction electrode.

It should be noted that the above is merely an example of the embodiments of the present invention, and the present invention is not limited to these, and various modifications and improvements may be made without departing from the scope of the present invention. It doesn't matter.

For example, the piezoelectric substrate may be any lithium niobate single crystal, lithium tetraborate single crystal, or the like as long as it exhibits piezoelectric characteristics, in addition to the lithium tantalate single crystal.

Dielectric substrate materials include mullite (3Al2O3 · 2SiO2), forsterite (2MgO · SiO2), and steatite (Mg) in addition to aluminum oxide.
O.SiO2), cordierite (2MgO.2Al2O)
3.5 SiO2) Various ceramic materials such as aluminum nitride, zirconium oxide, silicon carbide and silicon nitride, and dielectrics such as organic materials can be applied.

Also in the materials of the excitation electrode and the extraction electrode, aluminum-copper alloy, gold in addition to aluminum,
Silver, copper, platinum, aluminum, chromium, titanium, tungsten, etc., or a composite laminate of these, etc. are applicable, and are not particularly limited by the present invention.

The wire material used for the protruding electrode is
Gold or a gold alloy, which is the most stable against temperature and humidity, is preferable, but any metal that can adhere to the extraction electrode, such as aluminum, can be applied.

Further, the protruding electrode may be formed by printing solder or applying a metal-containing paste, instead of forming it based on the wire, and it does not particularly depend on the forming method and material.

Further, as the material of the adhesive for joining the piezoelectric substrate and the reinforcing substrate, other than epoxy adhesive, urethane adhesive, polyimide adhesive, silicone adhesive, etc. can be applied as long as they have an adhesive effect. There is no particular limitation.

An electronic component using the acoustic wave device of the present invention is
Although it is most effective to mount it on a circuit board as a bare chip type, it may be housed in a package and its use is not particularly limited.

The thickness of the protective film is 0.01 μm to 10 μm.
The range of is desirable. This is because if the thickness is 0.01 μm or less, the moisture permeability becomes large and the electrodes may corrode, and if it is 10 μm or more, the loss of the acoustic wave element becomes large, which is not preferable.

[0054]

As described above, according to the electronic component using the acoustic wave device of the present invention, the excitation electrode, the extraction electrode connected to the excitation electrode, and the extraction electrode are formed on the piezoelectric substrate. An acoustic wave device including at least a protruding electrode, wherein all of the excitation electrodes and all of the extraction electrodes are
Part or all of the protruding electrode was covered with an insulating protective film. As a result, even in the bare-chip type acoustic wave device, it is possible to prevent the excitation electrode and the extraction electrode from being corroded by moisture, oxygen, etc. as much as possible. In addition, it is possible to provide an excellent acoustic wave device that can be easily realized and highly easily mounted on a circuit board, and a method for manufacturing the same.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically illustrating an embodiment of an acoustic wave device according to the present invention.

FIG. 2 is a cross-sectional view schematically illustrating another embodiment of the acoustic wave device according to the present invention.

FIG. 3 is a cross-sectional view schematically illustrating another embodiment of the acoustic wave device according to the present invention.

FIG. 4 is a cross-sectional view schematically illustrating another embodiment of the acoustic wave device according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional acoustic wave device.

[Explanation of symbols]

1, 11, 21, 31, 41: Piezoelectric substrate 2, 12, 22: Excitation electrodes 3, 13, 23: Extraction electrode with protective film 4, 14, 24: protruding electrodes 5, 15, 25: protective film 16, 36: Extraction electrode without some protective film 26: Reinforcing board 37: Dielectric substrate 38: Extraction electrode of dielectric substrate

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) // H01L 21/60 H01L 21/92 604J

Claims (8)

[Claims] 1. An elastic wave device comprising a piezoelectric substrate, an excitation electrode, an extraction electrode connected to the excitation electrode, and a protruding electrode formed on the extraction electrode, the excitation electrode comprising: An acoustic wave device, characterized in that the entire surface of each of the extraction electrode and the protruding electrode is covered with an insulating protective film so that the tip shape of the protruding electrode is formed. 2. An acoustic wave device comprising a piezoelectric substrate, an excitation electrode, an extraction electrode connected to the excitation electrode, and a protruding electrode formed on the extraction electrode, wherein the excitation electrode, An acoustic wave device characterized in that each surface of the extraction electrode and the protruding electrode is covered with an insulating protective film so that a tip portion of the protruding electrode is exposed. 3. A piezoelectric substrate is provided with an excitation electrode, an extraction electrode connected to the excitation electrode, and a projection electrode formed on the extraction electrode, and the projection electrode is formed on a dielectric substrate. An elastic wave device, which is connected to an external extraction electrode, and each surface of the excitation electrode, the extraction electrode, and the protruding electrode is covered with an insulating protective film. 4. The acoustic wave device according to claim 2, wherein the surface of the protruding electrode exposed from the protective film is planar. 5. The excitation electrode, the lead-out electrode, and the protruding electrode are provided on one main surface of the piezoelectric substrate, and a reinforcing substrate is attached to the other main surface of the piezoelectric substrate. The elastic wave device according to any one of claims 1 to 4, wherein. 6. The method of manufacturing an acoustic wave device according to claim 1, wherein after forming the excitation electrode, the extraction electrode, and the protruding electrode on the piezoelectric substrate. A method for manufacturing an acoustic wave device, characterized in that the surfaces of these electrodes are covered with the protective film. 7. A method of manufacturing the acoustic wave device according to claim 2 or 4 from the acoustic wave device according to claim 1, wherein the protective film covering the tip of the protruding electrode is removed. A method for manufacturing a characteristic acoustic wave device. 8. The method of manufacturing an acoustic wave device according to claim 3, wherein the tip of the protruding electrode of the acoustic wave device according to claim 1 is attached to an external extraction electrode formed on the dielectric substrate. By heating the protective film covering the portion while pressing it, the protective film in contact with the external extraction electrode is removed, and the external extraction electrode and the projecting electrode are connected to each other. Production method.