JPH031607A - Piezoelectric resonator element - Google Patents

Abstract

PURPOSE:To decrease the dispersion in the external size and to improve the electric performance and the mechanical performance by containing a piezoelectric resonator and a capacitor to a hollow comprising a resin made frame provided with an earth terminal and a lead terminal and a retainer cover. CONSTITUTION:A piezoelectric resonator 6 is contained in a hollow part of the closed state formed by a resin-made frame and a retainer cover 8 and capacitors 7, 7 are contained to the hollow formed with a resin made frame and an earth electrode plate 9. A lead terminal 3 and the piezoelectric resonator 6, a lead terminal 4 and the piezoelectric resonator 6, the lead terminal and a capacitor 7, and the lead terminal 4 and the capacitor 7 are connected electrically with press contact. Moreover, the capacitor 7 and the earth electrode 9, and the earth terminal 5 and the earth electrode plate 9 are fixed via solder or conductive paste and connected electrically. Then the components except each terminal are molded by a resin-made package 18.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a piezoelectric resonant element, for example a piezoelectric resonant element used in an oscillation circuit.

As a piezoelectric resonant element of this type, for example, a piezoelectric resonant element including one piezoelectric resonator 20 and one capacitor 30 shown in FIG. 5 has been known. The piezoelectric resonator 20 is of an energy trap type in which vibrating electrodes 22 and 23 are provided on the front and back surfaces of a piezoelectric substrate 21, and is fully supported by upper cup portions of a pair of terminals 25 and 26.

A capacitor 30 has a common electrode 32 on the surface of a dielectric substrate 31.
A pair of opposing electrodes (not shown) are provided on the back surface, and the opposing electrodes are soldered to the outside of the upper cup portion of the terminals 25 and 26.

Further, a ground terminal 33 is soldered to the center portion of the common electrode 32. The capacitor 30 has two capacitive parts CI, a common electrode 32 and a pair of counter electrodes (not shown).
It will have C2.

After applying paraffin, etc. for forming a hollow part to the vibrating part of this piezoelectric resonant element, the entire element is dipped in molten exterior resin to adhere the exterior resin, and then heated and hardened to dissolve the paraffin. It was common for the resin to be absorbed into the exterior resin to form a hollow structure.

Although the piezoelectric resonant element with this structure has the advantages of low material cost and simple manufacturing equipment, it has the following drawbacks (1).
) to (5).

(1) Since the piezoelectric resonant element is dipped with exterior resin, the amount of resin deposited is not constant, and the external dimensions after curing vary widely, so the amount of resin deposited is inevitably large.
It is difficult to miniaturize the device.

(2) It is difficult to set bake hardening conditions that dissolve and absorb paraffin.

(3) Since the exterior resin with the function of absorbing paraffin has many pores, its mechanical strength is weak and its reliability is poor.

(4) When the exterior resin attached to the piezoelectric resonant element by dipping is cured by heating over a period of 3 to 6 hours, resin shrinkage occurs, internal stress remains in the piezoelectric resonant element, and electrical performance changes.

(5) When thick metal terminals, which are necessary for automatic insertion parts, are used, stress increases due to differences in thermal expansion coefficients and thermal contraction coefficients of each member, so cracks are likely to occur in piezoelectric resonators and the like.

Therefore, an object of the present invention is to provide a 74% type piezoelectric resonant element with less variation in external dimensions and excellent electrical and mechanical performance.

Means for Solving the Problems In order to solve the problems above, the piezoelectric resonant element according to the present invention includes: (a) a resin frame to which a ground terminal and a pair of lead terminals are assembled; (b) a presser lid attached to one opening of the frame; (C) a ground electrode plate attached to the other opening of the frame in a state connected to the ground terminal; and (d) the frame. and (8) a piezoelectric resonator housed in a sealed hollow part formed by the holding lid and connected to the pair of lead terminals; (8) a hollow part formed by the frame body and the ground electrode plate. a pair of capacitors housed in the housing and connected to the pair of lead terminals and the ground electrode plate; It is characterized by having a body.

Press the lid and ground '7 on the working opening! The piezoelectric resonator and the pair of capacitors are housed in the hollow formed by the resin frame fitted with the electrode plate, so that the resin shrinkage when the resin exterior hardens and the subsequent temperature and humidity Protects the piezoelectric resonator and a pair of capacitors from resin expansion.

In addition, a resin molding method is selected in which the resin exterior body can be completely molded due to the hollow portion formed by the frame regardless of the formation of the hollow portion, and there is little variation in resin thickness.

Furthermore, since the ground terminal and lead terminal are separate from the presser cover and the ground electrode plate, it is difficult to select materials suitable for their respective functions.

Embodiments Hereinafter, embodiments of the piezoelectric resonant element according to the present invention will be described with reference to FIGS. 1 to 4.

This embodiment is a hollow structure piezoelectric resonant element 1 including one piezoelectric resonator and two capacitors.

The piezoelectric resonator 6 and capacitor 7.7 are pressed into contact with the lead terminals 3 and 4 assembled on the resin frame 2, and these parts are placed in the hollow formed by the presser M8, the ground electrode plate 9, and the frame 2. is housed therein, and a resin exterior body 18 is completely formed on its outer periphery.

The resin frame 2 is a synthetic resin molded product with open upper and lower surfaces, and is composed of a partition wall portion 28 and a side wall portion 2b. Frame body 2
The lead terminals 3 and 4 are connected to the external reading portion 3g on the side wall portion 2b of the
The insert is finished with 4a protruding. The internal connections L'1 (3b, , ab) of the lead terminals 3 and 4 partition the internal space of the frame 2 into upper and lower parts together with the partition wall 2a.

The ground terminal 5 is embedded in the lower surface of the partition wall 2a. The lead terminal 3.4 and the ground terminal 5 are integrally provided on the tie bar T, and are bridged between the tie bars 1. The external connection portion 5a of the ground terminal 5 is bent and has a structure applicable to an insertion mounting type.

The piezoelectric resonator 6 has lead terminals 3 formed in this way,
The internal connecting portions 3b and 4b of 4 are pressed into contact with each other by a pressing lid 8 parallel to the thickness direction, and are electrically connected. The piezoelectric resonator 6 has vibrating electrodes 11a and llb provided on the front and back surfaces of a ceramic piezoelectric substrate 10 by means of metal vapor deposition, etc., and energy trapping thickness shear vibration occurs at the opposing portions of the vibrating electrodes 11a and llb. Do this. The vibrating electrode 11a extends around the edge of the substrate 10 to the opposing surface.

The holding lid 8 is made of synthetic resin or metal, and is completely attached to the upper opening of the frame 2. The presser lid 8 is composed of a lid portion 8a and a spring portion 8b, and the lid portion 8a and the frame 2
A sealed hollow part is formed, and the piezoelectric resonator 6 is housed in the hollow part.

On the other hand, the spring portion 8b has an arcuate shape and presses the piezoelectric resonator 6 with its bending elastic force to electrically connect the lead terminals 3, 4 and the vibrating electrodes 11a, llb.

A pair of capacitors 7.7 are electrically connected to the lower sides of the internal connecting portions 3b and 4b of the lead terminals 3 and 4, respectively, by the ground electrode plate 9 in parallel with the thickness direction. A pair of capacitors 7.7 is a ceramic dielectric substrate 1
2. Capacitive electrodes 13a, 13a, 13 on the front and back surfaces of 12
b, 13b is provided by metal vapor deposition, metal paste coating/baking, etc.

The ground electrode plate 9 is made of a conductive metal and is completely attached to the lower opening of the frame 2. A capacitor 7.degree. 7 is housed in a hollow space formed by the ground electrode plate 9 and the frame 2. Moreover, the ground electrode plate 9 has tongues 9a, 9a shaped by punching, and its bending elastic force presses the capacitor 7.7, thereby connecting the node terminals 3, 4 and the capacitor electrode 1.
3a, 13a are electrically connected, and the tongue parts 9a, 9
a itself is electrically connected to the capacitor electrodes 13b, 13b. Furthermore, this ground electrode plate 9 is fixed to the lower side of the ground terminal 5 via solder or conductive paste, and is electrically connected to the ground terminal 5.

The piezoelectric resonant element 1 having the above configuration has external connection portions 3a, 4 of each terminal 3, 4.5 in a mold cavity (not shown).
A and 5a are sandwiched between molds and set in a supported state, and the outer periphery is molded with exterior resin, for example, PPS resin, leaving the external connection parts 3a, 4a, and 5a, and the tree JJ is formed.
An exterior body 18 made of W is formed. After molding, each terminal 3.4
．． Cut 5 and separate it from the tie bar T.

At this time, if the ground terminal 5 and the lead terminals 3 and 4 are cut in the same direction as shown in FIG. 2, an insertion-mount type piezoelectric resonant element can be obtained. vice versa,
If the ground terminal 5 and the lead terminals 3, 4 are cut in opposite directions as shown in Figure 3, each terminal 3, 4.5 can be bent after cutting to form a surface mount type. .

The piezoelectric resonant element 1 thus obtained is as shown in FIG.
A piezoelectric resonator 6 is housed in a sealed hollow space formed by the frame body 2 and the holding lid 8, and a capacitor 7.7 is housed in a hollow space formed by the frame body 2 and the ground electrode plate 9. .

The lead terminals 3 and the piezoelectric resonator 6, the lead terminals 4 and the piezoelectric resonator 6, the lead terminals 3 and the capacitor 7, and the lead terminals 4 and the capacitor 7 are electrically connected by pressure contact. Further, the capacitor 7 and the ground electrode plate 9 and the ground terminal 5 and the ground electrode plate 9 are fixed and electrically connected through solder or conductive paste.

Examples of the present invention will be described using more specific numerical values.

The piezoelectric resonator 6 has a length of 6.7 mm, a width of 1.2 mm,
A capacitor 6.6 with a length of 1.5 mm, a width of 1.5 mm, and a thickness of 0.5 mm is used. A piezoelectric resonant element 1 of the example was manufactured. As a result, the volume ratio, height, and thickness were reduced by 273 cm, and the occupied area was reduced by 273 cm compared to the conventional model.

It should be noted that the piezoelectric resonant element according to the present invention is not limited to the embodiments described above, and can be variously modified within the scope of the gist.

For example, the holding lid 8 may be made of a conductive material and may function as a terminal for one electrode of the piezoelectric resonator 6.

Furthermore, the piezoelectric resonator 6 may utilize a thickness longitudinal vibration mode in addition to the thickness shear vibration mode.

A resin frame with a presser cover and a ground electrode plate attached to the opening of the pot forms a hollow structure containing a piezoelectric resonator and a pair of capacitors, so paraffin, etc., which were conventionally used, are used. is no longer necessary, and the restriction on exterior resins that was limited to resins that have the ability to absorb paraffin etc. has been removed.
In addition to expanding the range of resin selection, the resin exterior can be formed using a molding method that can stably obtain a desired molding thickness, so a piezoelectric resonator element with small dimensions and less variation in finished dimensions can be obtained.

In addition, since the piezoelectric resonator and the pair of capacitors are protected from the resin casing by the holding lid, ground electrode plate, and frame, the resin shrinkage when the casing hardens, and the subsequent effects of temperature and humidity As a result, it is possible to provide a piezoelectric resonant element whose electrical characteristics are stabilized without being affected by changes in electrical performance due to resin expansion.

In addition, after molding the piezoelectric resonant element with resin, it is possible to make it into a surface mount type by cutting the terminals.
Compatible with both insertion mount type and surface mount type.

In this case, since the terminal portion is separate from the presser cover and the ground electrode plate, materials suitable for each can be selected.

For example, when a piezoelectric resonant element is used as an automatic insertion mounting type element, the terminal part has a thick wall (approximately 0.4 to 0.6
If a thinner material is used for the holding lid and ground electrode plate, the terminal will be able to withstand the mechanical stress during automatic insertion, and the piezoelectric resonator will not crack. An element with no In addition, when used as a surface mount type element, the terminal part should have a thin wall (approximately 0.
If a material with a thickness of 0.05 to 0.2 mm is used and a thicker material is used for the holding lid and the ground electrode plate, the mechanical stress during bending of the terminal will be small and the pressing force of the piezoelectric resonator etc. will be reduced. Sufficient elements can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing a piezoelectric resonant element according to an embodiment of the present invention, and FIGS. 2 and 3 are views showing the appearance of the piezoelectric resonant element shown in FIG. FIG. 2 is a perspective view of an insertion mount type, and FIG. 3 is a perspective view of a surface mount type. FIG. 4 is a sectional view taken along line xx' of the piezoelectric resonant element shown in FIG. 3. FIG. 5 is a perspective view of a conventional piezoelectric resonant element. DESCRIPTION OF SYMBOLS 1... Piezoelectric resonance element, 2... Resin frame, 3, 4...
... Node terminal, 5... Earth terminal, 6... Piezoelectric resonator, 7... Capacitor, 8... Holder lid, 9...
- Earth electrode plate, 18...resin exterior body. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. a resin frame to which a ground terminal and a pair of lead terminals are assembled; a presser lid attached to one opening of the frame; and a connection to the ground terminal to the other opening of the frame. a piezoelectric resonator housed in a sealed hollow formed by the frame and the holding lid and connected to the pair of lead terminals; and the frame and a pair of capacitors housed in a hollow formed by the earth electrode plate and connected to the pair of lead terminals and the earth electrode plate; and the frame body equipped with the holding lid and the earth electrode plate. A piezoelectric resonant element characterized by comprising: a resin exterior covering an outer peripheral portion.