JPH04367111A - Plezoelectric oscillator and production of the same - Google Patents

Abstract

PURPOSE:To obtain a piezoelectric oscillator and its producing method with good productivity by accurately connecting a supporting body to the prescribed position of a ceramic substrate without damaging the spring action of the supporting body using a joining material. CONSTITUTION:The piezoelectric oscillator is composed of a ceramic substrate 1 with metal wirings 21 and 22, at least two metallic supporting bodies 31 and 32 having the junction part with the metallic wire and the mounting part of a piezoelectric diaphragm, a piezoelectric oscillating plate 4 in which the exciting electrodes are formed on the surface, and a cap 5 covering the piezoelectric oscillating plate etc. The junction between the metallic wiring and the supporting body is performed by laser beam welding. As the method for production, a pair of supporting bodies are integrated, continuous lead frames are prepared, and plural ceramic substrate with metallic wiring are arranged while keeping an equal space with a pair of supporting bodies. The supporting body and the metallic wiring are jointed by the laser beam, and the junction between the supporting body and the frame is disconnected.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator and a method for manufacturing the same.

0002

2. Description of the Related Art A conventional support structure for a piezoelectric resonator will be explained using a surface-mounted crystal resonator as an example, with reference to a schematic side view of FIG. Metal wirings 62 and 63 are formed on the surface of a ceramic substrate 61 made of alumina or the like by metallization or the like. This metal wiring consists of two support joint parts and a wiring lead-out part for electrically drawing out each joint part to the outside. A conductive bonding material 66 is applied to the joints of these supports, a pair of supports 64 and 65 are mounted on this, and the conductive bonding material is cured by heating and drying to establish an electrical and mechanical connection between the two. conduct. Then, a crystal diaphragm 67 on which excitation electrodes are formed is mounted on these supports, and the crystal diaphragm and the like are covered with a cap 68 and hermetically sealed.

0003

[Problems to be Solved by the Invention] However, the above method for joining supports has the following problems. ■． Until the conductive bonding material dries and hardens,
When a vibration impact is applied to the ceramic substrate or the support, the support is displaced from a predetermined position on the ceramic substrate or tilted. ■． A crystal diaphragm (piezoelectric diaphragm) cannot be mounted on the support until after the conductive bonding material has hardened. Generally, it takes a relatively long time for the bonding material to harden. ■． The conductive bonding material before hardening spreads between the support and the metal wiring or ceramic substrate due to capillary action, and in some cases, this may impair the springiness of the support and reduce the ability of the support to buffer against shock, which is the original role of the support. Deterioration occurs. ■． Due to variations in the amount and position of the conductive bonding material applied, variations in adhesive strength occur. ■． Symmetry is likely to be lost because a pair of supports are mounted individually. In particular, if the position of the support is not fixed correctly, stress strain may be applied to the piezoelectric diaphragm mounted on the support, which greatly affects the reliability of the piezoelectric vibrator.

The present invention has been made to solve the above-mentioned problems, and it is possible to accurately connect a support to a predetermined position on a ceramic substrate, without impairing the springiness of the support with a bonding material, and furthermore, It is an object of the present invention to provide a piezoelectric vibrator with good workability during manufacturing and a method for manufacturing the same.

[0005]

[Means for Solving the Problems] In order to solve the above problems, a piezoelectric vibrator according to the present invention is provided with a ceramic substrate provided with metal wiring, mounted at a predetermined position of the metal wiring, at least two metal supports having a joint portion with the support body and a mounting portion of the piezoelectric diaphragm, a piezoelectric diaphragm installed between the mounting portions of the supports and having an excitation electrode formed on its surface, and a piezoelectric diaphragm. The piezoelectric vibrator is characterized in that the metal wiring and the support are joined by laser beam welding. Laser beam welding may be performed at one point or at multiple points at the joint of the support.

[0006] Note that if one or more small holes are provided in the joint portion of the support and a laser beam is irradiated mainly around the small holes, the metal wiring and the support can be joined more efficiently. Furthermore, the reliability of the bonding can be further improved by supplementarily bonding the support and the metal wiring with a small amount of bonding material after laser beam welding. In this case, one or more small holes may be provided in the joint portion to improve the joint strength of the joint material.

[0007] In addition, as a manufacturing method, a pair of supports are integrated with a frame frame, a lead frame in which these are continuously connected is prepared, and a ceramic substrate on which metal wiring is applied is placed at an interval between the pair of supports. The joint part of the support body is brought into contact with the joint pad of the metal wiring, and both the joint parts of the support body and the metal wiring are joined by laser beam welding, and the support body and the frame are There is a manufacturing method characterized in that the connecting portion with the frame is also cut using a laser beam. Of course, the required number of supports varies depending on the electrode lead-out form, and three or more supports may be used.

[0008]

[Operation] Since the metal wiring on the ceramic substrate and the support body are joined by laser beam welding, metal-to-metal joining is performed between the two without the presence of foreign substances, and the joining is reliable. In addition, the various disadvantages of using a bonding material (for example, the curing time is long, the springiness of the support may be impaired, etc.) are eliminated.

Furthermore, according to the manufacturing method described in claim 2, the distance and position between the supports can be determined correctly, and the positioning of the supports with respect to the bonding pads of the metal wiring is extremely easy, and the reliability of the connection is high. .

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings, taking a surface-mounted crystal resonator as an example. FIG. 1 is an exploded perspective view showing an embodiment of the present invention, FIG. 2 is a side sectional view of FIG. 1 with a crystal diaphragm attached and a cap covered, and FIG. 3 is a support integrated into a lead frame. Figure 4 shows a state in which the body is laser beam welded to metal wiring.
FIG. 3 is a diagram showing a state in which the support body is separated from the lead frame. The ceramic substrate 1 is made of alumina, processed into a thin plate shape, and has four notches 1 on its side.
a, 1b, 1c, and 1d are provided. On this ceramic substrate 1 are metal wirings 21 and 2 which have been metallized.
2 is provided. The metal wirings 21 and 22 have bonding pads 21a and 22a with the support, respectively, and lead-out portions 21b and 22b extending from these bonding pads to the notches in the end face of the ceramic substrate. The supports 31 and 32 are made of metal such as nickel silver, and each has a joint 3 with the metal wiring.
It has 1a, 32a, connecting parts 31b, 32b, and mounting parts 31c, 32c for the crystal diaphragm 4. Supports 31, 32
are mounted on the bonding pads 21a and 22a, and the two are bonded by laser beam welding. Crystal diaphragm 4
is made of AT-cut crystal plate, processed into a rectangular shape,
An excitation electrode 41 is on the surface (the back surface is not shown).
is formed by means such as vapor deposition. This crystal diaphragm 4 is suspended between the supports, and is electrically fixed with a conductive bonding material (not shown). Then, these crystal diaphragms, etc. are covered with a cap 5 made of ceramic material or resin material,
Seal hermetically.

Next, a manufacturing method for mass-producing the piezoelectric vibrator described above while ensuring reliability will be explained with reference to FIGS. 3 and 4. The lead frame L includes a pair of supports 31,
32 are arranged facing each other, and these supports are connected to the frame L1 by connecting parts R1, R2, R3, and R4. It has a shape. Note that the bonding pad 21 of the ceramic substrate is located just between the bonding portions of the pair of supports.
The distance is set to the distance between a and 22a. metal wiring 21,
A plurality of ceramic substrates 1 having 22 are successively provided (referred to as a ceramic substrate group) at equal intervals to the intervals at which the supports are installed. The lead frame L is moved onto these ceramic substrate groups, and the bonding pads 21
a, 22a and joint portions 31a, 32a, respectively, are brought into contact with each other. Then, a laser beam focused by a lens C is applied to each of the connection parts at two locations to perform laser beam welding. Next, as shown in FIG. 4, in order to cut the support body from the lead frame, the connecting parts R1, R2, R3,
irradiate it with a laser beam and fuse it. By performing these series of operations one after another, it is possible to provide a piezoelectric vibrator support structure that is highly reliable and mass-producible.

The output of the laser beam must be adjusted in consideration of the materials, thicknesses, etc. of the support and metal wiring to such an extent that they will not be damaged more than necessary. For example, using Al2O3 (alumina) as a ceramic substrate, metallized wiring with a total thickness of 20 μm, which is metalized in the order of a tungsten layer, a nickel layer, and a gold layer, is provided on the surface of the ceramic substrate, and a nickel silver plate with a plate thickness of 50 μm is attached to this metalized wiring. When laser beam welding the support made of the following materials, strong electrical and mechanical bonding could be achieved with an output of 0.12 J. Note that when the support body was separated from the lead frame, it was possible to cut it with an output of 0.13 J.

[0013]

[Effects of the Invention] Since the metal wiring on the ceramic substrate and the support are joined by laser beam welding, metal-to-metal joining is performed without the presence of foreign substances, and the joining is reliable. Additionally, since bonding materials generally take a long time to cure, vibrations and shocks may be applied during curing, which may cause the support to shift or tilt from the specified bonding position, or the amount of bonding material applied may be reduced. In some cases, there is too much, and this impairs the springiness of the support, but these drawbacks can be eliminated and a highly reliable piezoelectric vibrator can be obtained.

Furthermore, by using the manufacturing method shown in the present invention, a plurality of supports are integrated into a lead frame, ceramic substrates are arranged at equal intervals to the arrangement intervals of the supports, and laser beam welding or cutting is performed. This makes it extremely suitable for mass production. In addition, the symmetry of the opposing supports is ensured, making positioning of the supports extremely easy and reliable connection, even when a piezoelectric diaphragm is installed.
There is no occurrence of stress or strain due to inappropriate connection positions of the support, and the electrical characteristics of the piezoelectric vibrator are less likely to change over time.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment according to the present invention.

FIG. 2 is a cross-sectional view of FIG. 1.

FIG. 3 is a diagram illustrating a method of manufacturing a piezoelectric vibrator.

FIG. 4 is a diagram illustrating a method for manufacturing a piezoelectric vibrator.

FIG. 5 is a diagram showing a conventional example.

[Explanation of symbols]

1 Ceramic substrate 21, 22 Metal wiring 31, 32 Support 4 Crystal diaphragm (piezoelectric diaphragm) 5 Cap L lead frame

Claims (2)

[Claims] 1. A ceramic substrate provided with metal wiring, and at least two metal supports mounted at predetermined positions of the metal wiring and having a joint portion with the metal wiring and a mounting portion for a piezoelectric diaphragm. In the piezoelectric vibrator, the piezoelectric vibrator is constructed of a piezoelectric diaphragm installed between the mounting portions of the support and having an excitation electrode formed on its surface, and a cap covering the piezoelectric diaphragm, etc., in which the metal wiring and the support are connected. A piezoelectric vibrator characterized by joining by laser beam welding. 2. A pair of supports are integrated with a frame frame, a lead frame is prepared in which these are continuously connected, and a ceramic substrate on which metal wiring is applied is arranged at equal intervals to the spacing between the pair of supports. A plurality of pieces are arranged, the joint part of the support body is brought into contact with the joint pad of the metal wiring, and both the joint parts of the support body and the metal wiring are joined by laser beam welding, and the connection part between the support body and the frame frame is A method for manufacturing a piezoelectric vibrator, characterized in that the piezoelectric vibrator is cut using a laser beam.