JPS644367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an airtight container for a piezoelectric vibrator and an improvement in a manufacturing method thereof.

In order to maintain stable oscillation of the piezoelectric vibrator, this type of airtight container is used with Chitsuso gas sealed inside or in a vacuum, so its airtightness is strictly required. .

In response to this demand, airtight containers made by soldering, resistance welding, and cold pressure welding have appeared, and although the airtightness is mostly satisfied, all of these are cheaper products due to cost issues. I had reached the limit of my pursuit.

On the other hand, there is a technique for bonding resins together by high-temperature heating to create a relatively inexpensive airtight container, but this method cannot sufficiently withstand high-temperature, high-humidity tests, and problems remain in terms of airtightness.

A first object of the present invention is to provide an airtight container for a piezoelectric vibrator with improved airtightness.
A second object is to provide an airtight container for a piezoelectric vibrator that enables automation of piezoelectric vibrator assembly work and reduces the cost of the piezoelectric vibrator.

In order to achieve such an object, the present invention interposes a ferromagnetic ring between a base made of thermoplastic resin and a lid, and melts and fixes the base and lid in contact with the ferromagnetic ring. There is.

FIG. 1 is an embodiment diagram showing the main part of the present invention.

The base 1 and the lid 2 are made of thermoplastic resin having good cohesive strength, adhesive strength, flexibility, and compatibility with other resins, such as ethylene-vinyl acetate copolymer (EVA).
From polyethylene, atactic polypropylene (APP), ethylene-ethyl acrylate copolymer (EEA), polyamide, polyester, polycarbonate, polyphenylene sulfide (PPS), polyphenylene oxide (PPO), polybutylene terephthalate (PBT), etc. Molded. As shown in Fig. 1A, the base 1 has a structure with a small circular bottom inside a disk, that is, the cross section is formed in the shape of a recess, and a ring-shaped structure is formed so as to go around the upper surface 3 of the recess. A ferromagnetic ring 4 made of iron, nickel, or an alloy thereof is installed. At this time, a part of the ferromagnetic ring 4 is buried in the groove of the upper surface 3 of the recess, and the remaining part protrudes from the upper surface 3 of the recess. Next, the lid 2 is a circular plate having a convex cross section, which is thinner in the portion facing the upper surface 3 of the recess of the base 1 and thicker in the portion facing the inner diameter of the recess.

Therefore, as shown in the cross-sectional view in Fig. 1B, the base 1 and the lid 2 are pressurized in the direction of the arrow with a pressure of about 1 to 20 kg/cm, and the ferromagnetic ring 4 is heated using high-frequency induction heating 5 (high-frequency induction heating 5). By applying a current of 10 to 1000 mA, the ferromagnetic ring 4 is heated,
The parts of base 1 and lid 2 that are in contact with it melt,
This melted portion protrudes into the gap between the upper surface 3 of the concave portion of the base 1 formed by the protruding portion of the ferromagnetic ring 4 and the portion of the lid 2 that faces it, and is shown in detail in FIG. As shown in , the base 1 and the portion 6 of the lid 2 that are in contact with the ferromagnetic material are joined in a molten state. This joint portion 6 is fixed by removing the pressure and high-frequency induction heating and leaving it at room temperature. As a result, complete airtightness can be achieved between the base 1 and the lid 2. In this example, the ferromagnetic ring 4 is buried on the top surface 3 of the recess of the base 1, but the ferromagnetic ring 4 is buried on the top surface 7 of the lid 2, which is opposite to the top surface 3 of the recess.
It may be buried on the side. In addition, in high frequency induction heating,
The object to be heated is heated using eddy current loss and hysteresis loss due to high frequency waves. In the case of eddy current loss, the object to be heated only needs to be a conductor, and metals are mainly used. If a ferromagnetic material is used, heat generation due to hysteresis loss will increase,
It can be heated most efficiently.

FIG. 2 is an embodiment of an airtight container containing a crystal resonator, and a base 8 and a lid 9 correspond to the base 1 and lid 2 of the previous embodiment, respectively. base 8
As shown in the perspective view in FIG. 2A, the plan view with the lid 9 removed in FIG. 2C, and the sectional view in FIG. Extracting electrodes 13, 1 of the crystal plate 10 to be described later
and small chambers 82, 83, 84, 85 for applying conductive adhesives 23, 24, 25, 26 between strip parts 17, 18 connecting metal terminals 19, 20, 21, 22 to be described later. is formed. The crystal plate 10 is an AT-cut disk, and an excitation electrode 1 to be vibrated by thickness shear is centered on both main surfaces of the crystal plate 10.
1, 12, and the crystal plate 10 from each excitation electrode.
Extracting electrodes 13, 14 extending in an arc shape along the periphery of the electrodes are arranged and formed by vacuum evaporation. Note that the circular arc portion of the extraction electrode 14 extends from the surface where the excitation electrode 12 is arranged, through the side surface (thickness surface) of the crystal plate 10, to the same side as the surface where the extraction electrode 13 is arranged.

The metal terminals 19, 20, 21, and 22 are external connection terminals of the crystal resonator, and their material is preferably a metal whose coefficient of thermal expansion is approximately equal to that of the resin of the base 8 and lid 9. The material is polycarbonate resin (coefficient of thermal expansion: 2-3
×10 ^-5 /deg), brass (1.8 to 2.3 × 10 ^-5 /deg) is selected as the material for the metal terminal. These metal terminals are connected by arc-shaped strip portions 17 and 18 installed in parallel on the bottom surface of the storage chamber 81 of the base 8.
8 is arranged so that the exposed portion in the storage chamber 81 corresponds to the arc-shaped extraction electrodes 13 and 14 of the crystal plate 10, and the remaining portion is buried in the base 8.

Because of this structure, the crystal resonator of this example is assembled by placing the crystal plate 10 in the housing chamber 8 of the base 8.
1, and the extraction electrode 13 is inserted into the small chambers 82, 8.
3, the strip-shaped portion 17 of the metal terminal and the extraction electrode 14
Conductive adhesives 23, 24, 25, 26 are applied to the strip-shaped portions 18 of the metal terminals in the small chambers 84, 85, respectively.
Finish by applying. Then, a part of the iron ferromagnetic ring 27 is embedded in a circular groove formed on the top surface of the concave portion of the base 8, the remaining portion is left to protrude from the top surface of the concave portion, and the lid 9 is covered so as to be in contact with the protruding surface. Cover. The lid 9 is provided with a recess 15 that occupies the opening of the storage chamber 81 of the base 8, as shown in FIG. 2B. The base 8 and the lid 9 are melted and fixed at the portions 28 of the base and the lid that are in contact with the ferromagnetic ring 27 using the same pressure and high-frequency induction heating as in the previous embodiment. In this example as well, the ferromagnetic ring 27 is buried in the portion 1 of the lid 9 facing the upper surface of the recess of the base 8.
A groove may be formed in 6.

In the above embodiments, a crystal resonator is used as the piezoelectric resonator, but the piezoelectric resonator is not limited to this, and may be a resonator made of lithium tantalate, lithium niobate, piezoelectric ceramic, etc. It is not limited to a plate, but may be oval or rectangular. If such a shape is used, the shapes of the base, lid, ferromagnetic ring, and metal terminal strip may be appropriately designed to correspond to the shape of the diaphragm.

Since the present invention has the above configuration, it was able to sufficiently pass the so-called boiling test in which the airtightness of an airtight container is tested by placing the container in water heated to 100°C. In addition, since the piezoelectric vibrator can be assembled by dropping it, the assembly process can be automated, and it can be manufactured without using particularly expensive materials, significantly reducing the cost of the piezoelectric vibrator. There are advantages to being able to do so.

[Brief explanation of drawings]

Figure 1 is an embodiment diagram showing the main part of the present invention, in which Figure A is a perspective view of an airtight container, Figure B is a cross-sectional view thereof, Figure C is a detailed cross-sectional view, and Figure D is an after-melting fixation. FIG. Fig. 2 is an example diagram in which a crystal resonator is housed, and Fig. 2A is a perspective view;
Figure B is a perspective view of the back of the lid, Figure C is a plan view with the lid removed, and Figure D is A-A in Figure C.
FIG. 1, 8...base, 2,9...lid, 10...
Crystal plate, 4, 27... ferromagnetic ring.

Claims (1)

[Claims] 1. A piezoelectric vibrator is housed inside a container consisting of a base having a concave cross section and a lid that covers the top surface of the concave portion, and the base and the lid are molded from thermoplastic resin, and the base A ferromagnetic metal ring that goes around the upper surface of the recess or the upper surface portion of the lid opposite thereto is interposed between the base and the lid, and a portion of the base in contact with the ferromagnetic metal ring and the An airtight container for a piezoelectric vibrator, characterized in that the lid is fixed by melting. 2. A piezoelectric vibrator is housed inside a container consisting of a base having a concave cross section and a lid that covers the top surface of the concave portion, and the base and the lid are molded from thermoplastic resin, and the top surface of the concave portion of the base or the lid is molded from thermoplastic resin. A part of the ferromagnetic metal ring is buried in the upper surface of the lid facing the lid, and with the remaining part of the ferromagnetic metal ring protruding, the lid and the base are pressurized, and the ferromagnetic metal ring is A method for manufacturing a piezoelectric vibrator container, characterized in that the base and the lid in contact with the ferromagnetic metal ring are melted and fixed by applying high-frequency induction heating to the magnetic metal ring.