JP2002299995A - Piezoelectric resonator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a connection defect by preventing air bubbles from being generated on a cylindrical wall member 5b when taking an electric connection by providing the cylindrical wall member on the inner bottom of the casing- like case of a piezoelectric resonator and applying conductive paste to an exposed part 5a exposed on that bottom surface. SOLUTION: The piezoelectric resonator is composed of a casing-like case 4, a lead terminal 5 embedded and formed on the base of the case 4 while having an exposed part 5a partially exposed on the inside of the case, a cylindrical wall member 5b formed on the bottom of the case 4 while surrounding the exposed part 5a of the lead terminal 5, a conductive adhesive material 7 charged into the wall member 5b and a piezoelectric resonance element 1, the piezoelectric resonance element 1 is placed on the upper surface of the wall member 5b, and the electrode of the piezoelectric resonance element 1 is connected through the conductive adhesive material 7 to the lead terminal. In such a piezoelectric resonator, an inclined part 5c is formed on the inner surface of the wall member 5b.

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.

A 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. 1 is a longitudinal sectional view for explaining the present invention. Since the structure is the same as that of the conventional structure, the conventional example will be described below with reference to FIG.

As shown in the cross-sectional view of FIG. 1, an opening 41 is formed on the upper surface, and a three-dimensional structure is arranged on the bottom surface in parallel in the length direction.
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.

[0007] In the case-like case 4, the piezoelectric resonance element 1 is provided.
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 terminal 5 is fixed to the bottom surface of the case-like case 4 and is continuously provided by a lead frame as in FIG. 3, and is cut along a 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.

[0010]

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 paste 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. The bubble expands and contracts, 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 has been devised to solve the above-mentioned problems, and an object thereof is to provide a conductive adhesive member that connects between an exposed portion of a lead terminal and a connection electrode of a capacitor element. An object of the present invention is to provide a piezoelectric resonator with a built-in capacitor, in which a conductive paste is stably applied and an electrical and mechanical connection therebetween can be reliably established.

[0013]

According to the present invention, there is provided a housing-like case, a lead terminal buried in a bottom surface of the case, and a part of the lead terminal is exposed on the bottom surface of the case. It comprises a cylindrical wall member surrounding the exposed portion of the terminal, and a piezoelectric resonance element having a plurality of electrodes. The piezoelectric resonance element is mounted on the upper surface of the wall member, and the electrodes of the piezoelectric resonance element are electrically conductive. In the piezoelectric resonator connected to the lead terminal via the adhesive member, the inner peripheral surface of the wall member is formed with an inclined portion having a smaller opening from above the wall member to the exposed portion. And a piezoelectric resonator characterized by the following.

In the present invention, when the conductive paste is injected into the wall member during the manufacturing process, bubbles are generated at the corner formed by the inner wall and the bottom surface of the cylindrical wall member. However, due to the inclination, the conductive paste spreads inside the slope of the inner periphery of the wall member, and the air existing at the corners inside the wall member is pushed out along the inclined portion, and the conductive paste is easily and easily converted. It can be quickly filled to form a 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.

[0015]

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 figure, 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 vibrating 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 that is led out through one end of the 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 should 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 housing case 4 is made of a heat-resistant resin material such as polyetheretherketone (PEEK) or the like, has an opening 41 on its upper surface, and has a laminated body storage area (internal space) 40 inside. Are formed.

The internal space 40 of the case 4 has a shape which is 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 stored 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 the details of the exposed portion 5a. A cylindrical wall member 5b is provided so as to be one step higher than the inner bottom surface of the housing case 4, and a part of the lead terminal 5 is exposed at the bottom to form an exposed portion 5a. The inner wall of the cylindrical wall member 5b is formed with an inclined surface 5c whose opening decreases as the upper opening reaches the circular exposed portion 5a. The inclined surface 5c has an inclination of 20 to 60 degrees with respect to the diameter of the exposed portion 5a of 0.2 to 0.4 mm. The height from the exposed portion 5a to the upper surface of the wall member 5b is 0.1 to
0.3 mm.

The cylindrical wall member 5b has a function of holding the conductive paste. The conductive paste is supplied to the central portion of the exposed portion 5a so as to swell higher than the wall member 5b, and the lower surface of the strip-shaped dielectric substrate 20 is pressed, whereby the conductive paste is extruded into the cylindrical wall member. spread. Looking at the movement of the conductive paste at this time, the boundary of the conductive paste continuously extends from the exposed portion 5a along the inclined portion 5c of the wall member. That is, the inclined portion 5c of the wall member
Is inclined at an appropriate angle θ, the extruded conductive paste does not reach the upper portion of the cylindrical wall member 5b before spreading on the inclined surface, and no entrapment of bubbles occurs. .

Although the inclination of the inclined portion 5c is related to the fluidity of the conductive paste, for example, when a conductive paste having a viscosity of 11 Pa · S is used, by setting θ to 30 to 45 degrees, no bubbles are trapped. An assembly process can be achieved.

The conductive paste has a low viscosity of 5 to 10 Pa
In the case of S, θ can be about 60 degrees. Conversely, when the viscosity is high and 10 to 20 Pa · S, θ = 15 to 4
It is desirable to take 0 degrees.

It is desirable that the inclined portion is formed in a shape extending in four directions. However, when the interval between adjacent connection electrodes cannot be sufficiently obtained, the inclined portion may be formed only in the width direction. An inclined portion may not be formed in the direction of the adjacent connection electrode, but may be upright as shown in FIG. Although an elliptical inclined portion is shown in FIG. 3, a rectangular inclined portion having a long side in the width direction may be used. The effects are equivalent.

When the conductive paste is dropped, the inclined portion 5c does not cause air bubbles to be trapped on the inner surface of the cylindrical wall member 5b, so that poor conduction does not occur. In addition, even if the amount of the conductive paste applied is excessive, the conductive paste is absorbed in the concave portion formed by the inclined portion, so that the conductive paste wraps between adjacent connection electrodes to cause a short circuit failure. To prevent that.

FIG. 4 shows a structure in which a groove 42 is further provided on 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.

As a result, the conductive electrode 7 connected to the connection electrode 23 allows the vibration electrode 11 of the piezoelectric
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 cover 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, as shown in FIG. 4, an inclined portion 5c is provided on a cylindrical wall member 5b of a lead terminal 5a exposed inside a case 4. Due to this inclined portion, when the conductive paste is applied by a dispenser or transferred to an application pin and then the capacitor element is pressed, the conductive paste is pushed out from below, and bubbles are trapped inside the inclined portion 5c. The lead terminals and the capacitor element are reliably electrically connected by the conductive paste, and the reliability is improved.

[0043]

As described above, according to the present invention, since the inclined portion is formed on the inner surface of the cylindrical wall member surrounding the exposed portion of the lead terminal in the housing case, the conductive portion is formed during the assembly process. When the paste is applied to the inside of the wall member and the capacitor element is pressed, the conductive paste spreads from below the sloped wall member, and the air existing inside the wall member is pushed out from the sloped portion, so that the conductive paste can be easily and easily removed. It can be quickly filled to form a conductive adhesive member. 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 ... Housing-shaped case 5 ... Lead terminal 5a ... Exposed part 5b ... Cylindrical wall member 5c ... Sloped part 7 ... Conductive adhesive member

Claims (1)

[Claims] 1. A case-like case, a lead terminal buried in a bottom surface of the case and partially exposed to the case bottom surface, and a cylindrical shape opening upward and surrounding an exposed portion of the lead terminal. A wall member, and a piezoelectric resonance element having a plurality of electrodes. The piezoelectric resonance element is mounted on the upper surface of the wall member, and the electrode of the piezoelectric resonance element is connected to a lead terminal via a conductive adhesive member. The piezoelectric resonator according to claim 1, wherein an inner peripheral surface of the wall member is formed with an inclined portion having a smaller opening from above the wall member to the exposed portion.