JPH0766672A - Surface mount type piezoelectric components - Google Patents

Abstract

PURPOSE:To surely and easily make electric connections between external electrodes and lead-out electrodes by eliminating the addition of a special process only by altering a mask pattern which is used when an adhesive is applied. CONSTITUTION:Excitation electrodes 4 and 5 are formed in both the surfaces of the center part of a crystal element plate 19 and led out to end parts of the crystal element plate 19, and electrodes 6 and 7 are extended. The peripheral edge parts of protection substrates 2 and 3 are coated with an adhesive 10 and the substrates 2 and 3 are fixed so as to protect the electrodes 4 and 5 formed on both the surfaces of the element plate 19 and vibration areas nearby them with constant clearances, but the adhesive 10 is applied to positions behind the end parts of the substrates 2 and 3 in the center direction nearby the electrodes 6 and 7. Thus, the electrodes 6 and 7 are made wide in exposure area and electric connections of the electrodes 6 and 7 to base electrodes 11 and 12, and further external electrodes 13 and 14 are securely and easily made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component used as a piezoelectric filter, an oscillator or the like. In particular, the present invention relates to a surface-mounted piezoelectric component having a laminated structure in which protective substrates are fixed on both sides of a piezoelectric substrate with an adhesive.

[0002]

2. Description of the Related Art Conventionally, it has been general practice to fix a piezoelectric substrate to a holding jig installed upright on a base, enclose and seal them in a can case. In recent years, along with the miniaturization of electronic devices and the like, miniaturization and surface mounting of piezoelectric components are also required. For example, surface mounting type piezoelectric components in which a piezoelectric substrate is housed in a flat ceramic package are widely used.

Further, in order to realize further miniaturization, FIG.
As shown in (a) and (b), a thin piezoelectric component in which the piezoelectric substrate 1 is sandwiched between two protective substrates 2 and 3 has been proposed and put into practical use. Incidentally, (a) is an external perspective view of the piezoelectric component, and (b) is an AA cross-sectional view. The piezoelectric substrate 1 has excitation electrodes 4 and 5 on both sides of the central portion of the substrate, and extraction electrodes 6 and 7 extending from the excitation electrodes 4 and 5 to the ends of the piezoelectric substrate 1.
Are formed. In order to protect the excitation electrodes 4 and 5 of the piezoelectric substrate 1 and the vibrating regions in the vicinity thereof with predetermined clearances 8 and 9, the protective substrates 2 and 3 are attached to the protective substrate 2 and 3 via an adhesive 10 applied to the peripheral portions thereof. Fixed on both sides to form a substrate stack. The space volume of the clearances 8 and 9 is defined by the thickness of the adhesive layer 10 that fixes the piezoelectric substrate 1 and the protective substrates 2 and 3. Further sputtering,
The base electrodes 11, 1 are formed on both ends of the substrate laminate by vapor deposition or the like.
After forming 2, the external electrodes 13 and 14 are formed by plating or coating with a metal paste and are electrically connected to the lead electrodes 6 and 7, respectively.

In the piezoelectric component having the above-described structure, the extraction electrodes 6 and 7 are generally formed integrally with the excitation electrodes 4 and 5 simultaneously with the excitation electrodes 4 and 5 by a thin film forming technique such as sputtering or vacuum deposition. 7 and 7 are extremely thin (generally 1 μm or less), like the excitation electrodes 8 and 9. That is, in the conventional piezoelectric component, the contact area between the end portions of the lead-out electrodes 6 and 7 exposed from the end face of the substrate laminated body and the base electrodes 11 and 12 is extremely small, so that the manufacturing yield is lowered due to defective conduction. Also, there is a problem that the wire is likely to be broken due to external stress.

As a method for solving the above-mentioned problem, for example, as disclosed in Japanese Utility Model Laid-Open No. 3-426, the thickness of the extraction electrodes 6, 7 at the end of the piezoelectric substrate 1 is made thicker than the thickness of the excitation electrodes 4, 5. Then, sputtering, vapor deposition, plating, metal paste coating, etc. are applied to predetermined portions of the extraction electrodes 6, 7 to increase the exposed area of the extraction electrodes 6, 7 from the end face of the substrate laminate, and the extraction electrodes 6, 7 and the base electrode 11 are formed. ,
It has been proposed to widen the connection area with 12 to prevent disconnection due to external stress between the extraction electrodes 6 and 7 and the base electrodes 11 and 12.

However, in order to thicken only the predetermined portions of the extraction electrodes 6 and 7, in the case of sputtering or vapor deposition, the excitation electrodes 4 and 5 are formed, and then the vacuum evacuation step is performed again, and in the case of plating, the plating step is performed using a metal paste. In the case of applying, since each step of drying and hardening the metal paste is required, there is a defect that the manufacturing is complicated and the cost is increased.

Further, as disclosed in, for example, JP-A-55-34575, as shown in FIG.
It is known that notches 15, 16, 17, and 18 are provided at the ends of the lead electrodes to expose the extraction electrodes 6 and 7.

However, the notch 1 is formed in the protective substrates 2 and 3.
In order to provide 5, 16, 17, and 18, the protective substrate 2,
Since 3 requires machining, there is a defect that it leads to cost increase. There is also a defect that the piezoelectric substrate 1 in the vicinity of the cutouts of the protective substrates 2 and 3 is exposed, so that the end portion of the piezoelectric substrate 1 is likely to be damaged.

[0009]

An object of the present invention is to eliminate the defects of the conventional piezoelectric component as described above, and to increase the film thickness of a predetermined portion of the extraction electrode of the piezoelectric substrate or to machine the protective substrate. An object of the present invention is to provide a structure of a piezoelectric component in which electrical connection between a lead electrode and an external electrode is ensured and facilitated without performing the process.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, a structure of a surface mount type piezoelectric component according to the present invention is such that an excitation electrode and an extraction electrode extending from the excitation electrode to an end portion of the piezoelectric substrate are formed on both surfaces of the piezoelectric substrate. In order to protect the vibration area of the excitation electrode and the surrounding vibration area with a predetermined clearance so as not to interfere with the vibration area, a protective substrate is fixed on both sides of the piezoelectric substrate with an adhesive applied to the peripheral portion of the protection substrate and hermetically sealed. In the surface mount type piezoelectric component, the external electrode that is electrically connected to the extraction electrode is provided on the end face of the substrate laminated body, and the external electrode is electrically connected to the wiring pattern on the circuit board. In the vicinity of the extraction electrode, the adhesive is applied to a position retracted from the peripheral portion of the protective substrate toward the center of the substrate laminate to form the extraction electrode and the external electrode. One in which accounted if ease of care connections.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the drawings showing the embodiments. 1A and 1B are a plan view and a cross-sectional view, respectively, showing a configuration of an embodiment of the present invention, which is a crystal resonator using an AT-cut crystal element plate as a piezoelectric substrate. In FIG. 1A, the protective substrate is omitted in order to clarify the structure of the adhesive.

Excitation electrodes 4 and 5 are formed on both sides of the central portion of the quartz crystal plate 19, and lead electrodes 6 and 7 are extended from the excitation electrodes 4 and 5 to the ends of the quartz crystal plate 19. Adhesive 10 is applied to the peripheral portions of the protective substrates 2 and 3 so that the excitation electrodes 4 and 5 formed on both sides of the quartz crystal plate 19 and the vibrating regions in the vicinity thereof are protected by constant clearances 8 and 9. In a substrate laminated body in which the protective substrates 2 and 3 are fixed on both sides of the quartz crystal plate 19, respectively, the adhesive 10 is applied to the protective substrate 2 in the vicinity of the extraction electrodes 6 and 7 at the end of the quartz crystal plate 19. It is applied at a position retracted from the three ends toward the center.

By forming the substrate laminated body as described above, the exposed areas of the extraction electrodes 6, 7 are enlarged, and the electrical connection between the extraction electrodes 6, 7 and the base electrodes 11, 12 and by extension the external electrodes 13, 14 is achieved. Is reliable and easy.

The present invention is not limited to the structure as described above, and as shown in FIG. 2, the extraction electrodes 6 and 7 of the quartz crystal plate 19 are provided.
By removing the adhesive application side ridges 20 at the ends of the protective substrates 2 and 3 in the vicinity, the space between the lead electrodes 6 and 7 and the protective substrates 2 and 3 is widened, and the base electrodes of the external electrodes 13 and 14 are formed. When forming 11 and 12 by sputtering or vapor deposition, it is also possible to perform sputtering or vapor deposition in an oblique direction to further ensure the electrical connection between the extraction electrodes 6 and 7 and the external electrodes 13 and 14.

Further, as shown in FIG. 3, the adhesive 10 does not have to be retracted toward the center of the quartz crystal plate 19 on the surface of the periphery of the quartz crystal plate 19 where the extraction electrodes 6 or 7 are not formed. Thereby, the mechanical strength is increased, the possibility that the end portion of the quartz crystal plate 19 is damaged is reduced, and the handling at the time of manufacturing is facilitated.

The protective substrates 2 and 3 are made of a quartz substrate similar to the quartz plate 19, so that the thermal strain generated in the quartz plate 19 due to the temperature change is reduced and the frequency is stable. Can be realized.

Although the present invention has been described above by taking as an example the one applied to a crystal resonator using an AT-cut crystal blank, the present invention is not limited to this, and the crystal having a cut angle other than AT-cut is used. It may be applied to a resonator such as a crystal oscillator using a base plate or a piezoelectric base plate other than crystal or a dual mode filter having a structure in which a partial electrode is divided into two.

[0018]

EFFECTS OF THE INVENTION Since the present invention is configured as described above, the external electrode and the extraction electrode can be formed by only changing the mask pattern when applying the adhesive and without adding a special step. The electrical connection becomes reliable and easy, and it exerts a remarkable effect in reducing the price of the piezoelectric component.

[0019]

[Brief description of drawings]

1A and 1B are a plan view and a cross-sectional view showing the configuration of an embodiment of a crystal resonator according to the present invention.

FIG. 2 is a sectional view showing the configuration of a second embodiment of the crystal unit according to the present invention.

FIG. 3 is a sectional view showing a configuration of a third embodiment of the crystal unit according to the invention.

4A and 4B are a perspective view and a sectional view showing a configuration of a conventional piezoelectric component.

FIG. 5 is a perspective view showing a configuration of a conventional piezoelectric component in which a protective substrate is provided with a notch.

[Explanation of symbols]

 1 ... Piezoelectric substrate 2, 3 ... Protective substrate 4, 5 ... Excitation electrode 6, 7 ... Extraction electrode 10 ... Adhesive 11, 12, ... Underlying substrate 13, 14 ... External electrode 19 --- Quartz crystal plate 20 --- Protective substrate adhesive application side ridge deletion part

Claims (3)

[Claims] 1. A protective substrate is formed on both surfaces of a piezoelectric substrate to form an excitation electrode and an extraction electrode extending from the excitation electrode to an end of the piezoelectric substrate, and to protect the excitation electrode and a vibrating region around the excitation electrode with a predetermined clearance. In a surface-mounted piezoelectric component, which constitutes a substrate laminate fixed to both surfaces of a piezoelectric substrate via an adhesive applied to its peripheral portion, and which has an external electrode electrically connected to the extraction electrode on an end face of the substrate laminate, A surface mount type piezoelectric component characterized in that the adhesive is applied to a position retracted from the peripheral edge of the protective substrate toward the center of the substrate laminate in the vicinity of the extraction electrode. 2. The surface mount type piezoelectric component according to claim 1, wherein the piezoelectric substrate and the protective substrate are made of the same piezoelectric material. 3. The surface mount type piezoelectric component according to claim 1, wherein an edge of the protective substrate on which the adhesive is applied is removed in the vicinity of the lead electrode.