JP2577339Y2 - Surface mount type piezoelectric vibrator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator used for communication equipment and the like, and more particularly to a surface mount type structure.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 6 is a plan view of a surface mount type crystal filter, and FIG. 7 is a sectional view of FIG.

The quartz plate 5 is an AT-cut quartz plate, on the surface of which an input electrode 51 and an output electrode 52 are provided by thin film forming means such as a vacuum evaporation method, and on the back surface, a common electrode 53 is provided by similar means. Is provided. The case 6 is made of ceramic and has lead terminals 61, 62, 63, 64 implanted therein. A quartz plate 5 is mounted on the inner portions of the four lead terminals so that the respective extraction electrodes match with each other, and is electrically and mechanically joined by a conductive joining material (not shown). The lead terminals 61 and 63 are an input terminal and an output terminal, and the lead terminals 62 and 64 are a ground terminal. Although not shown, the case is hermetically sealed with a lid plate.

[0004]

As described above, the above-mentioned piezoelectric vibrator generally has a piezoelectric material bonded to a support and then a metal material is added to the electrode portion by means of a vacuum deposition method or the like to finely adjust the frequency. . In particular, in the case of a quartz filter, it is common to make fine adjustments by vapor deposition on both the front and back surfaces.However, the surface mount type quartz filter shown in the conventional example cannot perform vapor deposition on the back surface due to its structure, making it extremely suitable for vapor deposition work. There was a drawback that accuracy was required and man-hours increased. Also, in the vapor deposition operation, there is a disadvantage that the attachment / detachment of the vapor deposition mask is complicated and the workability is not excellent.

Further, in the structure of the prior art, since the quartz plate is directly attached to the lead terminals, thermal and mechanical strains are directly applied to the quartz plate, and the electrical characteristics of the piezoelectric vibrator may be impaired. Was.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a surface mount type piezoelectric vibrator which facilitates frequency adjustment and has improved thermal and mechanical shock resistance. And

[0007]

In order to solve the above-mentioned problems, a surface mount type piezoelectric vibrator according to the present invention has a piezoelectric plate having electrodes formed on the front and back surfaces, and a planar mounting of the piezoelectric plate. A substrate having a support also serving as an electrical connection, a case containing the substrate and having lead terminals electrically connected to the support, and a lid plate hermetically sealing the case; Wherein the substrate has a structure in which an insulating coating film is formed on at least the front and back surfaces of an elastic metal plate, and corresponds to a part of electrodes on the piezoelectric plate of the substrate. A frequency adjusting window is provided in a portion to be adjusted.

Further, at least a portion of the support for connecting the substrate and the case may have a buffer structure, or a frequency adjustment window may be provided on the substrate,
An insulating plate having a frequency adjusting window corresponding to the electrode provided on the upper surface of the piezoelectric plate may be provided close to the piezoelectric plate.

[0009]

Since the piezoelectric plate is mounted on the substrate having the support, thermal mechanical strain is not directly transmitted to the piezoelectric plate.
In particular, since a substrate having a structure in which an insulating coating film is formed on an elastic metal plate is used as the substrate, the substrate itself has a buffering action. In addition, the frequency adjustment window provided on the substrate allows the frequency adjustment work on the back surface after the piezoelectric plate is attached to the substrate, and the frequency adjustment can be easily performed with high accuracy.

Further, as described in claim 2 of the present invention, at least a portion of the support connecting the substrate and the case has a buffer structure, so that a thermal mechanical Distortion is further reduced, and adverse effects on the vibration characteristics of the piezoelectric plate can be eliminated as much as possible.

Further, as described in claim 3 of the utility model registration, by providing a frequency adjusting window also on the upper part of the piezoelectric plate, it is possible to mount the support on the piezoelectric plate,
The frequency can be adjusted for each electrode.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings, taking a surface mount type crystal filter as an example. FIG. 1 is an exploded perspective view showing a first embodiment of the present invention, FIG. 2 is a plan view in which components in FIG. 1 are incorporated, FIG. 3 is a cross-sectional view of FIG. ing. The surface mount type crystal filter includes a crystal plate 1 on which electrodes are formed, a substrate 2 on which the crystal plate 1 is mounted, a case 3 for housing the substrate, and a lid plate 4 for hermetically sealing the case.

The quartz plate 1 is an AT-cut quartz plate, and is processed into a substantially circular shape. An input electrode 11 and an output electrode 12 are provided on the surface, and extraction electrodes 11a and 12a are extended from the respective electrodes to the end face of the quartz plate. A common electrode 13 corresponding to the input / output electrodes 11 and 12 is provided on the back surface, and an extraction electrode 13a is also extended from the common electrode to the end face of the quartz plate.

The substrate 2 has a structure in which an insulating coating film 72 of polyimide or the like is formed on at least the front and back surfaces of a metal plate 71 (for example, aluminum, copper, etc.) rich in elasticity. It has a square shape. In addition, a frequency adjusting window 2a is provided substantially at the center of the substrate at a position facing a common electrode formed on a quartz plate (piezoelectric plate). The position, size and shape of the adjustment window are determined by the position, size and shape of the common electrode.

In the vicinity of the four corners of the substrate 2, supports 21, 22, 23, 24 made of a metal plate are attached by means such as brazing. These supports partially protrude from the substrate to the outside.

A quartz plate 1 is bonded to the support of the substrate by a conductive bonding material. In this state, the frequency is finely adjusted by partial vapor deposition. In particular, the back surface of the quartz plate is set through the frequency adjusting window 2a. Then, vapor deposition is performed and the frequency is adjusted to a predetermined frequency. The case 3 is made of ceramics such as alumina, and has a hollow rectangular parallelepiped shape with an open upper surface. The lead terminals 31, 32, 33, and 34 are led out from the vicinity of four corners of the bottom surface. The layer 3a is formed.

The substrate 2 on which the crystal plate has been mounted after the frequency adjustment is completed is housed in the case, and the support members and the lead terminals are electrically and mechanically joined by a conductive joining material. Thereafter, the metallic cover plate 4 and the metallized layer 3a of the case are hermetically sealed by seam welding or the like, thus completing the surface-mounted crystal filter.

As shown in FIG. 4, when a more cushioning effect is required, the supports 25, 26, 27, 28
In this case, a buffer structure may be provided as appropriate, such as reducing the cross-sectional area near the joint with the lead terminals 31, 32, 33, and 34, or adopting a bent structure.

The present invention is not limited to the quartz filter, but can be applied to a piezoelectric resonator having a pair of front and back electrodes.

A second embodiment according to the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view showing a state where the quartz plate is attached to the substrate. Since the structure of the case and the like is the same as that of the first embodiment, the description is omitted.

Input / output electrodes 11 and 12 are provided on the surface of the quartz plate 1.
However, a common electrode 13 is provided on the back surface.
The substrate 2 has a structure in which an insulating coating film is formed on at least the front and back surfaces of a metal plate rich in elasticity, a frequency adjusting window 2a for the common electrode 13 is provided, and supports 22 and 23 are provided. I have.

These supports have thin portions 22a, whose thickness is reduced by half-etching or the like, on the quartz plate mounting portion.
23a are formed, and the positioning of the quartz plate is facilitated by this thin portion. An upper insulating plate 8 having frequency adjusting windows 8a and 8b corresponding to the input electrode 11 and the output electrode 12 is provided on the upper surface of a frame 29 provided near the outer periphery of the substrate.
Is installed.

With the above configuration, it is possible to add mass to each electrode while the support is attached to the quartz plate.
Frequency adjustment can be performed very easily and accurately.

[0024]

[Effect of the Invention] Since a piezoelectric plate is mounted on a substrate having a support, thermal mechanical strain is not directly transmitted to the piezoelectric plate, and the piezoelectric plate has extremely excellent shock resistance and excellent vibration characteristics. A vibrator can be obtained. In addition, the frequency adjustment window provided on the substrate allows the frequency adjustment work on the back surface after the piezoelectric plate is attached to the substrate, and the frequency adjustment, which was conventionally difficult, can be easily performed with high accuracy.

Further, as described in claim 2 of the present invention, at least a portion of the support connecting the substrate and the case has a buffer structure, so that a thermal mechanical The distortion is further reduced, and the impact resistance is further improved. Further, adverse effects on the vibration characteristics of the piezoelectric plate can be eliminated as much as possible.

Further, as described in claim 3 of the utility model registration, a frequency adjusting window is also provided on the upper part of the piezoelectric plate, so that the support is attached to the piezoelectric plate.
The frequency can be adjusted for each electrode, and more accurate frequency adjustment can be performed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a plan view showing a state where each component in FIG. 1 is incorporated.

FIG. 3 is a sectional view of FIG. 2;

FIG. 4 is a plan view showing a modified example of the first embodiment.

FIG. 5 is a plan view showing a second embodiment.

FIG. 6 is a plan view showing a conventional example.

FIG. 7 is a sectional view of FIG. 6;

[Explanation of symbols]

Reference Signs List 1 crystal plate (piezoelectric plate) 11, 51 input electrode 12, 52 output electrode 13, 53 common electrode 2 substrate 2a, 8a, 8b frequency adjustment window 21, 22, 23, 24, 61, 62, 63, 64 support 3, 6 Case 8 Upper insulating plate

Claims (3)

(57) [Scope of request for utility model registration] 1. A piezoelectric plate having electrodes formed on front and back surfaces, a substrate having a support on which the piezoelectric plate is mounted two-dimensionally and also serving as an electrical connection, and a housing for accommodating the substrate and the support A case having lead terminals electrically connected to the piezoelectric vibrator, and a lid plate for hermetically sealing the case, wherein the substrate is provided on at least the front and back surfaces of an elastic metal plate. A surface-mount type piezoelectric vibrator having a structure in which an insulating coating film is formed, and a frequency adjusting window provided in a portion of the substrate corresponding to a part of an electrode on the piezoelectric plate. 2. A surface mount type piezoelectric vibrator according to claim 1, wherein at least a portion of said support body connecting said substrate and said case has a buffer structure. 3. A frequency adjusting window is provided on a substrate, and an insulating plate having a frequency adjusting window corresponding to an electrode provided on an upper surface of the piezoelectric plate is provided close to the piezoelectric plate. 3. The surface mount type piezoelectric vibrator according to claim 1, wherein the utility model is registered.