JPH0548427U - Surface mount crystal unit - Google Patents

Abstract

(57) [Abstract] [Purpose] In an ultra-compact surface-mounted crystal unit that uses a thin, small-sized crystal diaphragm, the substantial vibration area of the crystal diaphragm is increased and it is affected by holding. Provide a difficult and highly reliable mounting structure. [Structure] In a package 1 made of a laminated ceramic material and formed with an extraction electrode to the outside, a recess 1a is provided on the side surface at one end in the longitudinal direction inside the package. One end of a rectangular quartz crystal diaphragm 2 having an excitation electrode formed on the surface is housed in the recess of the package. The housing portion is joined with the conductive joining material 5. The lid plate 3 and the upper portion of the package 1 are joined with a joining material such as low melting point glass.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a crystal oscillator used as a reference oscillation source of communication equipment or a clock source of a microcomputer, and more particularly to a surface mount type crystal oscillator in consideration of holding a crystal diaphragm.

[0002]

[Prior Art]

 With the miniaturization of electronic devices, electronic parts are required to be thin and low and to be mounted on a printed wiring board at a high density on its surface. This is no exception in the field of crystal oscillators, and thin surface mount crystal oscillators such as those shown in FIGS. 4 and 5 have been devised. FIG. 4 is a perspective view, and FIG. 5 is a cross-sectional view in a state of being sealed with a cap. This crystal oscillator is a crystal oscillator in which an excitation electrode is directly formed on the upper surface of a ceramic insulating substrate 61 having a recess for a vibration space, without using a support such as a leaf spring that has been conventionally used. The plate 62 is mounted and bonded with a conductive bonding material. Then, the cap 63 is hermetically sealed. By omitting the support, which has been a bottleneck in the conventional crystal resonators in this way, a thin and compact surface mount crystal resonator was obtained.

[0003]

[Problems to be solved by the device]

 In recent years, such a crystal unit has been further miniaturized as a whole, and accordingly, the external dimensions of the crystal diaphragm contained therein have also been miniaturized. However, in the above configuration, since the quartz crystal diaphragm is held at both ends in the longitudinal direction, this holding part is mechanically and firmly fixed, and thus cannot be an effective vibration area. In such a case, the electrical characteristics such as the high CI value of the crystal unit may be significantly deteriorated.

The present invention has been made to solve the above-mentioned problems, and in an ultra-compact surface-mount type crystal resonator using a thin and small crystal diaphragm, a substantial vibration area of the crystal diaphragm is used. The purpose is to provide a highly reliable mounting structure that is less susceptible to retention.

[0005]

[Means for Solving the Problems]

 In the surface mount type crystal oscillator according to the present invention, a rectangular crystal vibrating plate having excitation electrodes formed on the surface is housed in a package made of a ceramic material and having external extraction electrodes, and hermetically sealed with a lid plate. A concave portion is provided on a side surface at one end in the longitudinal direction inside the package, and one end of the crystal diaphragm is inserted into the concave portion and held by a conductive bonding material.

[0006]

[Action]

 According to the present invention, the crystal diaphragm is inserted into the recess provided in the package, and the inserted portion is bonded with the conductive bonding material, so that the crystal diaphragm can be held in a cantilever manner. There is no need to support the other end, which was required in the past. As a result, even if the crystal diaphragm is the same size as the conventional one, the vibration area can be made large, and the deterioration of the electrical characteristics is small. In addition, since the conductive bonding material is present in the recess, it acts as a buffer material between the crystal resonator and the package.

[0007]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings by taking a crystal resonator using an AT-cut crystal plate as an example. 1 is a perspective view showing a first embodiment of the present invention, FIG. 2 is a perspective view before inserting the crystal vibration plate in FIG. 1, and FIG. 3 is a view showing a state where the crystal vibration plate is inserted into a package. It is sectional drawing which shows a state. The ceramic package 1 is made of alumina, and includes a first layer 11 that forms the lower surface of the package, a second layer 12 that forms a frame portion of the crystal vibration plate 2 having support bases 12a and 12b, and the support. A metallization layer (not shown) formed on the upper surfaces of the bases 12a and 12b, a third layer 13 forming a frame portion having a portion into which the crystal diaphragm 2 is inserted, and a support portion that presses the crystal diaphragm from above. And a fourth layer 14 forming the uppermost frame portion having 14a and 14b. These four layers of green sheets (including a metallized layer) are laminated and sintered to obtain a package having a concave portion 1a on the side surface in the longitudinal direction. The thickness of the third layer 13 is set to be slightly larger than the thickness of the quartz crystal diaphragm 2 to be inserted later. Of course, it is necessary to design considering the shrinkage rate during sintering. The metallized layer (made of, for example, tungsten) is nickel-plated to form connection electrodes 1b and 1c for connecting to the crystal diaphragm, and the connection electrodes 1b and 1c are led out of the package. By adjusting the protrusion dimension d of the support portion of the fourth layer, it is possible to adjust the inclination of the crystal diaphragm 2 held in the recess 1a formed between the second layer and the fourth layer. The crystal vibrating plate 2 is made of a rectangular AT-cut crystal plate, and excitation electrodes 21 and 22 are provided on the front and back surfaces thereof. As shown in FIG. 3, the conductive bonding material 5 is dropped on the connection electrodes 1b 1 and 1c, the crystal diaphragm 2 is lowered from the opening of the package to the inside, and inserted into the recess 1a. The conductive bonding material 5 is pressed into the concave portion 1a and, after being cured, also serves as a buffer material for the crystal diaphragm. Finally, the lid plate 3 and the upper part of the package are joined with a joining material such as low melting point glass, and the quartz crystal diaphragm is hermetically sealed.

[0008]

[Effect of the device]

 According to the present invention, the crystal diaphragm is inserted into the recess provided in the package, and the inserted portion is bonded with the conductive bonding material, so that the crystal diaphragm can be held in a cantilever manner. There is no need to support the other end, which was required in the past. Since the conductive bonding material also serves as a cushioning material, impact resistance is also improved. As a result, even if the crystal diaphragm is as large as the conventional one, it is possible to obtain a large vibration area, and it is possible to obtain a small-sized crystal resonator with little deterioration in electrical characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view showing a surface mount type crystal unit according to an embodiment of the present invention.

FIG. 2 is a perspective view before inserting the crystal diaphragm in FIG.

FIG. 3 is a cross-sectional view showing a state where a crystal diaphragm is inserted into a package.

FIG. 4 is a perspective view showing a conventional example.

5 is a cross-sectional view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package 1a Recesses 1b, 1c Connection electrodes 2 Crystal diaphragms 21 and 22 Excitation electrodes 3 Lid plate 5 Conductive bonding material

Claims (1)

[Scope of utility model registration request] 1. A surface mount type in which a rectangular crystal vibrating plate having an excitation electrode formed on a surface thereof is housed in a package made of a ceramic material and having external extraction electrodes, and hermetically sealed with a cover plate. In the crystal unit, a recess is provided on one side surface in the longitudinal direction inside the package, and one end of the crystal diaphragm is inserted into the recess and held by a conductive bonding material. Crystal oscillator.