JPH02226905A - Piezoelectric vibrator for packaging on surface - Google Patents

Abstract

PURPOSE:To attain sufficient hermetic sealing degree for a container and to improve the reliability by forming an inner electrode and an outer electrode of coil shape opposing to each other to an inner wall and an outer wall of the hermetically sealed container in which a crystal chip in held, connecting electrically an exciting electrode of the crystal chip and the inner electrode, and utilizing the electromagnetic coupling between the inner electrode and the outer electrode to excite the crystal chip. CONSTITUTION:A crystal vibrator is formed by sealing a crystal chip 2 with an exciting electrode 3 and a leadout electrode 4 formed thereto to an hermetically sealed container 1 comprising a base 5 having a projection 7 and a cover 6. Moreover, an inner electrode 9 and an outer electrode 10 wound in coil shape opposite to each other with the base 5 inbetween are formed. A central end of the inner electrode 9 and its outer circumferential end are prolonged respectively up to the projection 7 at both ends. Furthermore, the center end of the outer electrode 10 and the outer peripheral end are prolonged up to the side face opposite to the container 1, respectively. Then the outer circumferential part at both ends of the crystal chip 2 is held on the projection 7 and the center end and the outer circumferential end of each leadout electrode and the inner electrode 9 are connected. Coils L1 and L2 of the inner electrode 9 and the outer electrode 10 are coupled electromagnetically in terms of high frequency and the crystal chip 2 is excited by connecting the outer electrode 10 to the terminal of the oscillation circuit.

Description

[Detailed description of the invention] (Industrial application!!P) The present invention (field of application is a pressure m vibrator for surface mounting),
In particular, the present invention relates to a crystal resonator for surface mounting which is electrically coupled to an external circuit through the capacitance of conductive T1 poles formed on the inner and outer walls of a sealed container.

(Background of the Invention) Crystal resonators are often used as oscillators and filter elements in various electronic devices because of their resonance characteristics. In recent years, surface-mount capacitors such as Chi-Sogo capacitors have been desired.

(Prior Art) FIG. 3 is a diagram of a crystal resonator illustrating a conventional example of this type.

Suito I! The proboscis is placed in a sealed container W4t made of ceramic or the like, for example A.
A T-cut crystal piece 2 is enclosed (consisting of 7 pieces. The crystal piece 2 is, for example, rectangular in shape, and has dynamic vibration electrodes 1ii3 formed on both main surfaces, and extraction electrodes 4 are extended on the outer periphery of both ends. The sealed container 1 is in the form of a flat plate. It consists of a substrate 5 and a cover 6.

A protrusion 7 is formed on the substrate 1° to electrically and mechanically connect and hold the outer periphery of both ends of the crystal piece 2. A metal film 8 is formed on the protrusion 7 and extends from the front surface of the substrate through the side surface and the back surface. The cover 6 is bonded to the substrate using, for example, a glass adhesive. In this type of device, the metal film 8 connected to the excitation electrode 3 of the crystal piece 2 is extended on the side and back surfaces of the substrate 5 without using lead wires.
For example, it facilitates automatic mounting as a surface-mounted element like a chip capacitor or the like.

(Disadvantages of the Prior Art) However, in the crystal resonator having the above configuration, when the substrate 5 and the cover 6 are bonded, the metal film 8 on the substrate and the adhesive do not fit well with each other, resulting in poor sealing at that part. However, there was a problem in that reliability was lowered due to airtight leakage. Also,
There was also a risk that the thickness of the adhesive layer would be increased due to the step difference in the metal film 8, which would reduce the bonding strength.

Note that, for example, there is a structure in which the substrate is a laminated substrate and m poles are extended from the second layer through the side surface to the back surface using through holes, etc., but such a structure has the disadvantage that the processing process is complicated and the cost is high.

(Object of the Invention) An object of the present invention is to provide a highly reliable piezoelectric vibrator for surface mounting with a sufficiently sealed container.

(Solution Means) The present invention forms a coil-shaped opposing inner electrode and outer m-pole on the inner and outer walls of a closed container that holds and accommodates a crystal piece, so that the excitation R electrode and the inner electrode of the crystal piece are connected to each other. The solution is to electrically connect them and to excite the crystal piece using electromagnetic coupling between the inner electrode and the outer W1 pole. An embodiment of the present invention will be described below.

(Example) Fig. 1 is a diagram of a crystal resonator explaining an embodiment of the present invention, in which Fig. 1 (a) is a cross-sectional view, Fig. 1 (b) is a diagram of a substrate, and Fig. 1 (c) is a diagram of a crystal resonator. This is a mock diagram. In addition, the same numbers are given to the same parts as in the previous conventional example diagram, and the explanation thereof will be simplified.

Crystal 1! ! The mover has an excitation T1 pole 3 and a drawer 1/t in a sealed container 1 consisting of a substrate 5 having a protrusion 7 and a cover 6.
ri111!4 (D form a satL ta water M+ piece 2
r l't? I) (see Figure 3 (b) j) is enclosed. , the inner and outer walls 1ζ of the substrate 5 form an inner electrode 9 and an outer electrode 10 which are wound in a coil shape and are opposed to each other with the substrate 5 sandwiched therebetween. The center end and outer peripheral end of the inner electrode 9 extend to the projections 7 on both end sides, respectively. Further, the center end and the outer peripheral end of the outer m-pole 10 extend to opposite sides of the container 1, respectively. Then, the outer periphery of both ends of the crystal piece 2 is held on the protrusion 7, and each lead-out j7M pole is connected to the center end and outer periphery of the inner electrode 9 [Fig. 1 (a) (b) J .

In such a device, an inner electrode 9 and an outer electrode 10 in opposing coil shapes are connected at high frequency by electromagnetic coupling of the coil 1 and L8.

Therefore, if the outer m-pole 10 is connected to the terminal (conducting TFI path) of the oscillation circuit on the circuit board (not shown), the electromagnetic coupling (
From this, the crystal piece 2 can be shaken 1717 times.

So? ), unlike in the past, there is no need to lead out the Ti electrode from the inside of the customer equipment to the outside (ζ, for example, through the metal film 8).
The reliability of R@J child can be improved.

Moreover, since it is only necessary to form the inner and outer rt poles that face the inside and outside of the closed passenger device 1 and electromagnetically couple them, manufacturing is facilitated and productivity is improved.

(Iya's 'JJt\) In addition, in the above 'J example, the substrate (sealed container) 5 is the cellar 2.
However, it is preferable to use a material with good magnetic permeability, such as barium ferrite, because it will strengthen the electromagnetic coupling. The thickness of the portion may be made as small as possible, or the opposing area may be increased by using not only the bottom surface (substrate 5) but also the entire side surface and top surface of the closed container 1.

Further, the sealed container W41 was formed from the substrate 5 and the cover 6, and the crystal piece 2 was held on the support stand 9 on the substrate 5. For example, as shown in FIG. 11
The crystal piece 2 may be formed from a lid body 12 and held in the stepped portion of the container body 1, and the present invention is not dependent on the manner in which the sealed container 1 or the crystal piece 2 is held.

In addition, in the present invention, not only is it effective for surface mounting and 17, but also the apparent impedance of the piezoelectric vibrator can be changed upward by changing the coupling ratio of the coils I, L, and Ll. It is possible to arbitrarily match the impedance of It can be used as a trap element by inserting it into the

In this case, the parallel resonance frequency can be set arbitrarily (ζ
Since it can be set, not only narrowband but also wideband towing/sobbing can be configured, and a wide range of applications can be expected. Furthermore, a plurality of piezoelectric vibrators can be enclosed.

(Effects of the Invention) The present invention forms coil-shaped opposing inner and outer electrodes on the inner and outer walls of an airtight container that holds and accommodates a crystal piece, and electrically connects the excitation electrode and the inner electrode of the crystal piece. The piezoelectric resonator LEM is a highly reliable piezoelectric vibrator for surface mounting, which connects the inner and outer electrodes and makes use of the electromagnetic coupling between the inner and outer electrodes. I can provide it.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a crystal resonator illustrating an embodiment of the present invention, in which (+1) is a sectional view, FIG. 1(b) is a diagram of a substrate, and FIG. 1(c) is a simulated diagram. FIG. 2 is a sectional view of a crystal resonator explaining another embodiment of the present invention. Figure 3 is a diagram of a crystal resonator to explain a conventional example.
) is a cross-sectional view of a crystal resonator, and FIG. 2(b) is a diagram of a crystal piece. 1...Airtight container,...Drawer 17F 4 poles, Raised, 8...Metal membrane, 1...? Main body, 1...Crystal piece, 3 Substrate, 6 Inner electrode, 1 - Lid. Excitation T1 pole, cover 7 0...outer electrode, 1st construction Fig. 3

Claims (1)

[Claims] Coiled inner and outer electrodes are formed on the inner and outer walls of a sealed container that holds and accommodates a crystal piece, and the excitation electrode of the crystal piece and the inner electrode are electrically connected, and the inner and outer electrodes are electrically connected to each other. A piezoelectric vibrator for surface mounting, characterized in that the crystal piece is excited using electromagnetic coupling with an outer electrode.