JPH0120804B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a support structure for a piezoelectric vibrator, and more specifically, a lead terminal is disposed in a recess formed in an insulating substrate, and a piezoelectric diaphragm is mounted on the lead terminal. This paper relates to improvements to support structures for piezoelectric vibrators that are fixed in place.

In this type of support structure, conductive adhesive is applied to the piezoelectric diaphragm and lead terminals at multiple locations in order to obtain mechanical strength, but this adhesive strength is strengthened to improve vibration and shock resistance. If this is done, it will be affected by the temperature characteristics of the insulating substrate that is the main body of the support system.

This effect appears as a disadvantage in that the original frequency-temperature characteristics of the piezoelectric vibrator is deformed or the bonded portions are peeled off. Peeling of the bonded area is
Since the adhesive generally serves not only as a mechanical connection to support the piezoelectric vibrator main body but also as an electrical connection to the excitation electrode, it may lead to failure of the electrical connection and stop oscillation.

The object of the present invention is to provide a piezoelectric vibrator that eliminates the above-mentioned drawbacks, improves mechanical strength, eliminates the influence of temperature characteristics on the piezoelectric vibrator of the support system, and facilitates assembly work. It is to provide a supporting structure for the child.

In order to achieve such an objective, the present invention
A feature is that in the lead terminal portion exposed at the bottom surface of the insulating substrate with the recess, a notch is formed between the conductive bonding point with the piezoelectric diaphragm and the penetration fixing point of the insulating substrate.

FIG. 1 shows an embodiment in which the present invention is applied to a disk-shaped crystal resonator.

As shown in the front view of FIG. 1A and the A-A sectional view of FIG. Excitation electrodes 101 and 102 to be subjected to thickness-shear vibration are placed facing each other near the center of the oscillator, and extraction electrodes 103 and 104 are placed in opposite directions from the excitation electrodes 101 and 102 to the periphery of the crystal diaphragm 100 so as not to face each other. It is placed. Extracting electrode 10
The peripheral end portions 105 and 106 of 3 and 104 are extended in an arc shape along the circumference of the crystal diaphragm 100. Note that the extraction electrode 104 is connected to the crystal diaphragm 10.
0 from the back surface to the side surface and the peripheral edge portion 106 of the front surface.
It has been extended to The above electrodes are deposited by vacuum deposition of metals such as gold and silver using a deposition mask.

The lead terminal frame 200 is integrally formed by press working as shown in the front view of FIG.
metal, in this example brass (α=1.8~2.3×
10 ^-5 /deg). This lead terminal frame 200 has two lead terminals 201 and 202 connected by common holding parts 203 and 204 at both ends (the two common holding parts are removed when completed), and the lead terminals 201 and 202 are In the part where the crystal diaphragm 100 described above is mounted, similarly to the crystal diaphragm 100, there are arcuate portions 205, 206, and cuts 207, 20 near both ends of the arcuate portions 205, 206.
8, 209, 210 and an insulating substrate 300 to be described later
The stopper 211, 2 is inserted into the
12, 213, and 214 are formed. Note that the holes 21 made in the common holding parts 203 and 204
5, 216 is used for positioning the lead terminal frame 200.

As shown in the front view of FIG. 1D and the BB sectional view of FIG.
The lead terminals 201 and 20 described above are located on the bottom surface of the
Lead terminals 201, 2 are exposed from one side to the other.
02 stoppers 211, 212, 213, 21
4 is embedded and fixed through the hole. Insulating substrate 300
The material is a thermoplastic resin with characteristics such as cohesive strength, adhesive strength, flexibility, and compatibility with other resins. In this example, polycarbonate (thermal expansion coefficient α
= 2 to 3 x 10 ^-5 /deg). Recess 3
Inside the 01, stepped surfaces 302 and 303 on which a lid 500 (described later) is placed are connected to lead terminals 201 and 20.
Cut 2 in the arcuate portions 205 and 206 of 2
07, 208, 209, and 210, and this end is fixed. Above the recess 301 of the insulating substrate 300, the recess 301
A groove 304 is formed inside near the outer peripheral edge along the circumference of the groove 304, and between this groove 304 and the inner surface of the recess 301, a groove 304 is formed that protrudes higher than the top surface 305 of the recess 301 from the bottom surface of the groove 304 toward the tip. Thinner convex portion 3
06 is formed. As a modified example of the convex portion 306, it may be a protruding portion having a constant thickness, but the thickness is preferably about 1 to 2 mm.

As shown in the front view in FIG. 1 and the CC sectional view in FIG.
06, with the peripheral end portions 105, 106 of the extraction electrodes 103, 105 aligned, and the conductive adhesives 401, 402, 403, 40
4 is applied to both ends of the circumferential end portions 105, 106 and the arcuate portions 205, 206 of the lead terminals 201, 202 near both ends of the crystal diaphragm 100. It is electrically and mechanically bonded. This adhesive point 40
1,402,403,404 are lead terminals 20
These cuts 207, 2
08, 209, 210 are the aforementioned insulating substrates 30
Penetration fixing points of lead terminals 201, 202 and bonding points 401, 40 of crystal diaphragm 100 in 0
It is between 2,403,404.

As shown in the front view of FIG. 1H and the DD sectional view of FIG.
It is processed to have a circular plane shape that fits into the inner surface of the recess 301 of No. 00, and the material thereof is molded from polycarbonate resin like the insulating substrate 300. and,
A groove 501 symmetrical to the groove 304 of the insulating substrate 300 is formed along the circumference of the lid 500 near the outer periphery, and a convex portion 306 of the insulating substrate 300 is formed between the groove 501 and the outer surface of the lid 500. Similarly, groove 50
A convex portion 503 is formed that protrudes higher than the top surface 502 of the lid 500 from the bottom surface of the lid 500 and becomes thinner toward the tip.

Next, as shown in the front view of FIG.
By placing it on the stepped surfaces 302 and 303 in the recess 301 of the insulating substrate 300, the inner surface of the protrusion 306 of the insulating substrate 300 and the outer surface of the protrusion 503 of the lid 500 come into contact with each other, and heat is applied to the mutually contacting portion from the upper surface. Heat the plate 600 (the heating temperature is the temperature between the insulating substrate 30 and the lid 5).
The temperature is preferably 30 to 100 degrees higher than the melting point of 00,
In this example, it is 300°C. ), both protrusions 306,5
Melt 03. At this time, since the tip of the convex portions 306, 503 has a tapered structure or a modified example thereof, a relatively thin thickness structure, the heat capacity of the tip portion is relatively small and can be easily melted. When melting begins, the convex portions 306 and 503 of the next layer (lower layer) act to melt one after another, as shown in the front view in Figure 1E and the FF cross-sectional view in Figure 1W. Melting part 700
Expand. This melted portion 700 is
It is fixed by releasing it from 0 and leaving it at room temperature. In addition, in order to prevent sticking to the hot plate 600 during melting, it is effective to coat the abutting portion of the hot plate 600 with Teflon or to interpose a heat-resistant non-adhesive sheet such as Teflon between the two. be.

FIG. 2 shows another embodiment in which the present invention is applied to a rectangular plate crystal resonator.
Components having the same functions as those shown in the previous embodiment are replaced by the same symbols. In addition, Figure 2 A is a front view showing the crystal diaphragm, and Figure 2 B is a front view showing the crystal diaphragm.
- A sectional view, C is a front view showing the lead terminal frame, D is a front view showing the insulating board fixed through the lead terminal frame, E is a sectional view taken along line B-B in the previous figure,
Figure F is a front view showing the state in which the crystal diaphragm is placed on the lead terminal and conductively bonded, and Figure G is a front view showing the state in which the crystal diaphragm is placed on the lead terminal and conductively bonded.
C is a sectional view, C is a front view of the lid, R is a sectional view taken along line D-D in the previous figure, N is a front view of the lid placed on the stepped surface of the insulating substrate, and C is a front view of the lid. 1 is a sectional view taken along the line E-E in the previous figure, O is a front view showing a state in which the lid and the convex portion of the insulating substrate are melted, and Wa is a sectional view taken along the line FF in the previous figure.

The present invention is based on the structure shown in the above embodiments, and in particular, a notch is formed in the lead terminal on which the crystal diaphragm is placed, and the position of the notch is located between the penetration fixing point of the insulating substrate and the bonding point of the crystal diaphragm. Since it is between
Thermal expansion coefficient α of the insulating substrate ^{is larger than ×10 -5 /} deg. Stress can be released at the cut point. Therefore, according to the present invention, even if the crystal diaphragm is firmly bonded to the lead terminal, the influence of the temperature characteristics of the support system is eliminated, and the conductive bonded parts are prevented from peeling, and the original frequency of the crystal oscillator is It is possible to make temperature characteristics appear. Additionally, the assembly of the crystal diaphragm onto the insulating substrate is extremely easy and can be automated, as it can be completed by simply placing it in the recess and applying conductive adhesive. . Furthermore, thermoplastic resin such as polycarbonate is used as the material for the insulating substrate and the lid, and the grooves and protrusions described above are formed on the top surface, and the protrusions at the joints are melted to ensure airtightness. can be secured.
Regarding this airtightness, it has fully passed the so-called boiling test, which is tested by immersing it in water heated to 100 degrees Celsius. Other examples of thermoplastic resin materials include:
Ethylene-vinyl acetate copolymer (EVA), polyethylene-atactic polypropylene (APP),
Examples include ethylene-ethyl acrylate copolymer (EEA), polyamide, polyester, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), and polybutylene terephthalate (PBT).

Although a crystal diaphragm was used as the piezoelectric diaphragm in the above embodiments, other materials such as lithium tantalate, lithium niobate, and piezoelectric ceramics may also be used, and a slit-like shape was mentioned as the shape of the notch. In addition, it may be a semicircle, a triangle, a quadrilateral, or any other arbitrary shape.

[Brief explanation of drawings]

FIG. 1 shows an embodiment in which the present invention is applied to a disk-shaped crystal oscillator. FIG. is a front view showing the lead terminal frame, D is a front view showing the insulating substrate fixed through the lead terminal frame, E is a cross-sectional view taken along line B-B in the previous figure, and F is a front view showing the lead terminal of the crystal diaphragm. A front view showing the state where it is placed on and conductively bonded,
In the same figure, G is a cross-sectional view taken along the line C-C in the previous figure, C is a front view showing the lid, L is a cross-sectional view taken along D-D in the previous figure, and N in the same figure shows the lid placed on the stepped surface of the insulating substrate. Figure 1 is a front view showing the state in which the lid and the insulating substrate have been melted. FIG. Second
The figure shows another embodiment in which the present invention is applied to a rectangular plate crystal oscillator, where A is a front view of the crystal diaphragm, B is a sectional view taken along line A-A in the previous figure, and FIG. C is a front view showing the lead terminal frame, D is a front view showing the insulating board fixed through the lead terminal frame, E is a sectional view taken along line B-B in the previous figure, and F is a lead on the crystal diaphragm. A front view showing the state in which it is placed on the terminal and conductively bonded.D is a sectional view taken along the line C-C in the previous figure. , N in the same figure is a front view showing the state in which the lid is placed on the stepped surface of the insulating substrate, L in the same figure is a sectional view taken along line E-E in the previous figure, and O in the same figure is a state in which the convex parts of the lid and the insulating substrate are melted. A front view showing the same and a sectional view taken along line F-F in the previous figure. 100... Crystal diaphragm, 205, 206... Exposed portion of lead terminal, 207, 208, 209,
210...notch, 300...insulating substrate, 301
... recess, 401, 402, 403, 404...
conductive adhesive.

Claims (1)

[Claims] 1 An insulating substrate having a recessed cross section, a lead terminal is partially exposed at the bottom of the recess of the insulating substrate, and is fixed through the insulating substrate from one side surface to the other side, and the piezoelectric diaphragm is fixed to the insulating substrate. placed on the exposed portion of the lead terminal, conductively bonded to the lead terminal, and forming a cut in the exposed portion of the lead terminal between the conductive bonded portion and the through-fixed portion of the insulating substrate; A support structure for a piezoelectric vibrator.