JP2002050940A - Piezoelectric resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric resonator which eliminates connection failure by setting a cylindrical wall member 5b at the inside bottom surface of an enclosure form case of a piezo-resonator to prevent air bubble generation in the member 5b when electrical contact is made by applying a conductive paste to an exposed part 5a which is exposed at the inside bottom surface. SOLUTION: A piezoelectric resonator which is composed of an enclosure form case 4, and a lead terminal 5 which is embedded in the bottom surface of the case 4 and has a part 5a which is partially exposed on the inside of the case 4, and a material 5b which is formed at the bottom surface of the case 4 and encloses the part 5a of the terminal 5, and a conductive bond material 7 which fills in the internal part of the material 5b, and a piezo-resonator device 1. The piezo-resonator is constructed of the device 1 placed on the upper side of the member 5b, and the electrode of the device 1 which is connected to the terminal 5 through the member 7, and slits 5c which are formed in the member 5b in the direction of its wall thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mountable piezoelectric resonator which can be stably bonded on a printed wiring board.

[0002]

2. Description of the Related Art Conventionally, microcomputers and the like have been frequently used for communication equipment and electronic equipment, and a clock oscillation circuit and the like have been connected to such microcomputers.

In this oscillation circuit, as shown in an equivalent circuit diagram of FIG. 6, input / output capacitance components C1 and C2 are connected between both ends of a piezoelectric resonator R and a ground potential. The feedback resistance component r and the inverter I were connected between them. In order to easily achieve this oscillation circuit, the two capacitance components C1 and C2 described above are constituted by one capacitor element as shown by the dotted line in the figure, and the capacitor element and the piezoelectric resonator are shown by the one-dot chain line. The one with R is a built-in capacitance type piezoelectric resonator.

The built-in capacitance type piezoelectric resonator mainly includes a piezoelectric resonator having vibration electrodes formed on at least both main surfaces of a piezoelectric substrate and a capacitor element having two capacitance components. The structure shown in the external perspective view of FIG. 5 has already been proposed as a structure that can be surface-mounted with such a built-in capacitance type piezoelectric resonator. FIG. 2 is a longitudinal sectional view for explaining the present invention. Since the structure is the same as the conventional structure, the conventional example will be described below with reference to FIG.

[0005] As shown in the sectional view of FIG.
Two lead terminals 5 are attached to the case 4. The lead terminal 5 has a central portion embedded in the bottom of the housing case and exposed to the inside of the housing case to expose an exposed portion 5a.
Are formed, and both ends of the lead terminal are bent along the side surface from the bottom surface of the case and led out to the outer surface of the case to form a lead terminal for connecting a circuit board.

[0006] A piezoelectric resonance element 1 is provided in a housing case 4.
And a component in which the capacitor element 2 is integrated. The capacitor element 2 is provided with three connection electrodes 23 to 25 on the lower surface of the dielectric substrate 20, and is connected to the exposed portion 5 a of the housing case 4 by a conductive adhesive member 7. The upper surface of the dielectric substrate 20 has electrodes 21 and 22 extending from both ends toward the center, and forms two capacitance components with the connection electrodes 23 to 25 on the lower surface. Piezoelectric resonance element 1
Are oscillating electrodes 11 and 12 on both main surfaces of a rectangular piezoelectric substrate 10.
Formed at both ends of the lower surface and the capacitor element 2
The both ends of the upper electrodes 21 and 22 are electrically conductively bonded 15,
At 16 they are electrically connected and integrated.

Here, the exposed portion 5a is coated with a conductive paste and connected to the connection electrodes 23 to 25 on the lower surface of the capacitor element to form the conductive adhesive member 7, but the conductive paste stops around the exposed portion 5a, It is necessary to prevent short-circuit with other connection electrodes. For this reason, the exposed portion 5a is formed integrally with the housing-shaped case so as to be one step higher than the bottom surface of the housing-shaped case, and the exposed portion 5a extending from the lead terminal 5 is exposed at the bottom. In shape.

The lead terminals 5 are fixed to the bottom surface of the case-like case 4 as in FIG. 3 and are continuously provided by a lead frame. After cutting along the dashed line shown in FIG. Along the side surface of the case 4, the case 4 is bent at a position where the bottom surface and the side surface intersect. After applying the sealing resin material 3 to the opening of the housing-like case, the opening is fixed with a metal cover 6 thereon.

[0009]

However, in the above-described structure, conduction between the exposed portion 5a on the inner bottom surface of the casing-like case 4 and the three connection electrodes 23 to 25 on the lower surface of the strip-shaped dielectric substrate 20 is conductive. When the conductive paste is applied to the concave portion of the cylindrical wall member 5b of the exposed portion 5a, the conductive adhesive is applied between the lead exposed portion in the concave portion, the wall of the cylindrical wall member 5b, and the conductive paste. A case where air bubbles are bitten occurs. In such a case, the connection between the connection electrode of the capacitor element and the exposed portion of the lead in the exposed portion may not be established properly, or even if the connection is made, the internal bubbles may expand due to a change in ambient temperature or the like. It shrinks, and the conductive adhesive member made of the conductive paste is peeled off, thereby causing a failure such as disconnection or unstable conduction. That is, a defective product in which electrical continuity cannot be established between the lead terminal embedded in the housing-like case 4 and the laminated body of the piezoelectric resonance element and the capacitor element inserted therein, or connection is lost in the initial stage. Even if it does, it will come off during use and cause a defect in reliability. The present invention
It was devised to solve the above problems,
The purpose is to ensure that the conductive paste that serves as a conductive adhesive member that connects between the exposed part of the lead terminal and the connection electrode of the capacitor element is applied stably, and that the electrical and mechanical connection between them is ensured. It is an object of the present invention to provide a piezoelectric resonator with a built-in capacitor.

[0010]

According to the present invention, there is provided a case-like case, and a lead terminal having an exposed portion which is embedded in the bottom of the case and partially exposed to the inside of the case.
A cylindrical wall member formed on the bottom surface of the case and surrounding the exposed portion of the lead terminal; a conductive adhesive member filled in the wall member; and a piezoelectric resonance element, In the piezoelectric resonator in which the piezoelectric resonance element is mounted on the upper surface side and the electrodes of the piezoelectric resonance element are connected to the lead terminals via the conductive adhesive member, the wall member has a slit formed in the thickness direction. A piezoelectric resonator is provided.

According to the present invention, when the conductive paste is injected into the wall member during the manufacturing process, the conductive paste spreads inside the wall member and air existing inside the wall member is pushed out of the slit. Thus, the conductive paste can be easily and quickly filled with the conductive paste to form the conductive adhesive member. Thereby, the conductive adhesive member is reliably connected to the exposed portion of the lead terminal without bubbles, and the mechanical and electrical bonding strength with the electrode of the piezoelectric resonance element mounted thereon is enhanced. be able to.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a piezoelectric resonator according to the present invention will be described in detail with reference to the drawings. 1 and 2 are views for explaining the internal structure of a built-in capacitance type piezoelectric resonator. FIG. 1 is a longitudinal sectional view.
FIG. 2 is a cross-sectional view.

In the figures, 1 is a piezoelectric resonance element, 2 is a capacitor element, 4 is a housing-like case, 5 is a lead terminal embedded in the bottom of the case 4, 6 is a metal cover, and 7 is a conductive adhesive member. Reference numeral 3 denotes a sealing member.

The piezoelectric resonance element 1 includes PT (lead titanate),
It comprises a rectangular piezoelectric substrate 10 made of a piezoelectric ceramic material such as PZT (lead zirconate titanate), a single crystal material such as quartz, lithium tantalate, lithium niobate, and vibrating electrodes 11 and 12. The vibrating electrodes 11 and 12 are formed so as to face each other near the center of both main surfaces of the piezoelectric substrate 10 such as PT. The vibration electrode 11 is formed on the upper surface of the piezoelectric substrate 10 and extends to the other end. The vibrating electrode 12 is formed on the lower surface of the piezoelectric substrate and extends to one end. Vibrating electrodes 11 and 12
Is formed of, for example, a thin film conductor film mainly composed of an Ag-based material.

The capacitor element 2 is made of PT (lead titanate), PZT (lead zirconate titanate), BaTiO ₃
It comprises a strip-shaped dielectric substrate 20 made of a dielectric ceramic material such as (barium titanate) and a plurality of capacitance electrodes for forming two capacitance components on both upper and lower main surfaces of the dielectric substrate 20. ing. Note that the planar shape of the dielectric substrate 20 is the same as the planar shape of the piezoelectric substrate 10 described above.

In the figure, two electrodes 21 and 22 are formed on the main surface of the upper surface of the dielectric substrate 20.
At the same time as the formation of the capacitance component on the lower surface of 0, connection electrodes (simply called electrodes) 23, 24, and 25 for achieving connection with the outside (three lead terminals 5) are formed. The upper electrode 21 and the lower electrode 23 are connected via a conductor film on one end surface or side surface of the dielectric substrate 20, and the upper electrode 22 and the lower electrode 24 are
They are connected via a conductor film on the other end face or side face of the dielectric substrate 20.

Further, the electrode 2 on the upper surface of the dielectric substrate 20
Some of the electrodes 1 and 22 face the electrode 25 on the lower surface side of the dielectric substrate 20. That is, when viewing the lower surface 25 of the dielectric substrate 20 as a center, a predetermined capacitance component C1 is formed between the dielectric substrate 20 and the electrode 21 on the upper surface via the thickness of the dielectric substrate 20, and between the upper surface 22 and the predetermined capacitance component C1. A predetermined capacitance component C2 is formed.

The electrodes 21 to 25 are formed on the upper and lower main surfaces of the dielectric substrate 20 by selective printing and baking of a conductive paste mainly containing Ag or the like. still,
23 to 25 formed on the lower surface of the dielectric substrate 20 are electrodes for connecting to the lead terminals 5, respectively, and are referred to as connection electrodes in the present invention.

The above-described piezoelectric resonance element 1 and capacitor element 2
Is mechanically joined at predetermined intervals between the two substrates and electrically connected to each other by conductive bondings 15 and 16 interposed in the vicinity of both ends on the contact surface side of both substrates.

The conductive laminations 15 and 16 are made of a conductive adhesive sheet or a conductive resin paste having a predetermined thickness. The distance between the piezoelectric resonance element 1 and the capacitor element 2 can be controlled by the thickness of the conductive adhesive sheet, the number of sheets to be laminated, the amount of conductive paste printed, and the number of times of overprinting. Can be controlled.

The conductive bonding 15 is, for example, a piezoelectric resonance element 1 which is led out through one end of a piezoelectric substrate.
Vibrating electrode 11 and dielectric substrate 2 as capacitor element 2
0 is electrically connected to the upper surface side 21 (furthermore, the electrode 23 through one end of the dielectric substrate 20), and the conductive bonding 16 is formed by the vibration electrode 12 of the piezoelectric resonance element 1 and the capacitor element 2. It is electrically connected to an upper surface side electrode 22 of a certain dielectric substrate 20 (and a connection 24 via the other end of the dielectric substrate 20).

It is to be noted that the above-mentioned electrical connection is ensured,
In order to ensure the mechanical connection between the piezoelectric resonance element 1 and the capacitor element 2, the two elements 1 and 2 are
It is preferable to continuously arrange conductive adhesives and the like on the end faces 1 and 2 to perform joining.

The case-like case 4 is made of a resin material having excellent heat resistance such as polyetheretherketone (PEEK), has an opening 41 on its upper surface, and has a laminated body storage area (internal space) 40 therein. Are formed.

The inner space 40 of the case 4 has a shape substantially sufficient to accommodate a laminated body in which the piezoelectric resonance element 1 and the capacitor element 2 are stacked, and the area of the opening 41 is
The inner space 40 has a shape that slightly widens from the area of the bottom surface, so that the stacked body of the piezoelectric resonance element 1 and the capacitor element 2 can be easily housed and arranged in the inner space 40.

The inner side surface of the case 4 is formed in an inclined shape so that the stacked body of the housed piezoelectric resonance element 1 and capacitor element 2 can be easily positioned at the center of the case.

Further, on the bottom of the case 4,
One end of the lead terminal 5 made of a metallic member made of nickel-white or the like is integrally molded, and it is desirable that the linear expansion coefficient of these metals is close to the linear expansion coefficient of the case 4.

As shown in FIG. 3, the lead terminal 5 integrally formed with the case 4 is divided into two parts so as to spread from the bottom surface of the case 4 in both side directions. The corners are bent, and the two other ends extend to the side surfaces of the case 4. Specifically, a metal hoop material (opened state before cutting and bending) serving as the lead terminal 5 is fixed to the bottom surface of the case 4 by resin molding when the case 4 is molded, and cut into a predetermined length. In addition, it is configured to bend along the side surface of the case 4. The central portion of the fixed lead terminal 5 is exposed on the inner bottom surface of the case to form an exposed portion 5a.

FIG. 4 shows details of the exposed portion 5a. A tubular wall member (wall member) 5b is provided so as to be one step higher than the inner bottom surface of the housing-like case 4, and a part of the lead terminal 5 is exposed at the bottom thereof to an exposed portion (exposed portion). Is formed. A slit 5c is formed through the center of the cylindrical wall member 5b. The width of the slit is 0.1
The depth is from the upper surface of the cylindrical wall member to the lead terminal surface. Actually, it is 0.1 to 0.3 mm.

While the cylindrical wall member 5b has a function of holding the conductive paste, the slit 5c allows the conductive paste to be exposed.
When the conductive paste is supplied to the central portion of a, the conductive paste spreads over the inner surface of the tubular wall member 5b due to surface tension, and a part of the paste spreads outside the tubular wall member 5b via the slit 5c.

When the conductive paste is dropped, the slits 5c do not cause air bubbles to be trapped on the inner surface of the cylindrical wall member 5b, so that poor conduction does not occur. Although the case-shaped case is made of heat-resistant plastic such as PEEK, the adhesiveness with the conductive paste is relatively low, and it is easy to peel off by vibration or impact. The contact area with the housing case can be increased, and the adhesive strength can be doubled.

The application amount of the conductive paste is controlled so as to be constant, but often varies. In particular, when the amount of application is too large, it is led out through this slit and can be taken to a place where no problem occurs even if it spreads.

FIG. 4 shows a structure in which a groove 5d is further provided in the inner bottom surface of the housing-like resin case (not shown in FIG. 1). This groove serves as a dam for preventing the paste from spreading to another exposed portion 5a and causing a short circuit when a large amount of the conductive paste is applied.

A conductive paste such as Ag is applied and supplied to an exposed portion 5 a which is a lead terminal exposed on the inner bottom surface of the case 4 to form a conductive adhesive member 7. In the exposed portion 5 a, the connection electrodes 23, 24, 25 on the lower surface of the laminate including the piezoelectric element 1 and the capacitor element 2 in the case 4 and a part of the lead terminal 5 are mechanically and electrically connected.

Thus, the conductive electrode 7 connected to the connection electrode 23 allows the vibration electrode 11 of the piezoelectric resonance
And the electrode 21 on the upper surface of the capacitor element 2 is led out,
Further, the conductive adhesive member 7 connected to the connection electrode 24 of the capacitor element 2 allows the vibration electrode 12 of the piezoelectric resonance element 1 to be connected.
And the electrode 22 on the upper surface of the capacitor element 2 is led out,
Further, the conductive adhesive member 7 connected to the connection electrode 25 of the capacitor element 2 allows one of the two capacitance components C1 and C2 of the capacitor element 2 to be commonly led to the outside so as to have the ground potential.

The opening 41 of the case 4 is hermetically sealed by the metal lid 6 and the sealing resin material 3 formed in a concave shape. The sealing resin material 3 is applied to the inside of the concave-shaped metal lid and then cured together with the opening 41 of the case 4.

According to the above structure, the number of assembly parts is
A housing-like case 4 in which lead terminals 5 are integrated, a laminate in which the piezoelectric resonance element 1 and the capacitor element 2 are integrated, a sealing resin material 3, a metal lid 6, and a conductive adhesive member 7 The configuration reduces the number of parts and simplifies the manufacturing process.

A feature of the present invention is that a slit 5c is provided in the cylindrical wall member 5b of the lead terminal 5a exposed inside the case 4, as shown in FIG. When the conductive paste is applied with a dispenser or transferred to an application pin by this slit, the air bubbles trapped inside are pushed out from the slit, and the lead terminal and the capacitor element are reliably connected to each other by the conductive paste. , Reliability is improved.

[0038]

As described above, according to the present invention, the slit is formed on the upper surface of the cylindrical wall member surrounding the exposed portion of the lead terminal in the housing case and in the entire thickness direction. When the conductive paste is injected into the wall member during the manufacturing process, the conductive paste spreads inside the wall member, and the air present inside the wall member is pushed out of the slit,
The conductive paste can be formed easily and quickly by filling the conductive paste. This ensures that there is no air bubbles in the conductive adhesive member and the exposed portion of the lead terminal is electrically connected, and the mechanical and electrical bonding strength with the electrode of the piezoelectric resonance element mounted thereon is increased. Reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an internal structure of a piezoelectric resonator of the present invention.

FIG. 2 is a cross-sectional view taken along line aa of FIG.

FIG. 3 is a view for explaining that lead terminals are integrally formed on the bottom surface of a housing-like case of the piezoelectric resonator of the present invention.

FIG. 4 is an enlarged view of an exposed portion of the piezoelectric resonator of the present invention.

FIG. 5 is an external perspective view of the piezoelectric resonator of the present invention.

FIG. 6 is an oscillation circuit diagram of the piezoelectric resonator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric resonance element 2 ... Capacitor element 3 ... Sealing resin material 4 ... Casing case 5 ... Lead terminal 5a ... Exposed part 5b ... Cylindrical wall member 5c ... Slit 7 ... Conductive adhesive

Claims (1)

[Claims] 1. A case-like case, a lead terminal buried in the bottom surface of the case, and having an exposed part partially exposed to the inside of the case, and a lead terminal formed on the bottom surface of the case to expose the lead terminal. A cylindrical wall member surrounding the portion, a conductive adhesive member filled in the wall member, and a piezoelectric resonance element. The piezoelectric resonance element is mounted on the upper surface of the wall member, and the piezoelectric resonance element is mounted on the wall member. A piezoelectric resonator in which an electrode of a resonance element is connected to a lead terminal via a conductive adhesive member, wherein the wall member has a slit formed in a thickness direction thereof.