JP2557761Y2 - 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 surface mount type piezoelectric vibrator, and more particularly, to a piezoelectric plate holding structure for suppressing deflection of a piezoelectric plate using quartz or the like.

[0002]

2. Description of the Related Art With the recent miniaturization of electronic equipment, electronic parts are required to be thin, low, and mounted on a printed wiring board at a high density on the surface thereof. This is not an exception in the field of crystal oscillators, and recently, a thin surface-mount type crystal oscillator has been devised. As shown in FIG. 6, the crystal oscillator is conventionally used on the upper surface of a base substrate 1 made of ceramic. The quartz plate 5 on which the excitation electrode 12 was formed was directly mounted on the upper surface of the electrode pad 3 of the lead terminal formed on the substrate without using the support, and was joined with a conductive bonding material. In addition, a support 4 for eliminating the inclination of the quartz plate in accordance with the thickness of the electrode pad is provided in a portion facing the electrode pad 3. The base substrate 1 and a sealing lid (not shown) are joined using, for example, low-melting glass, and hermetically sealed.

[0003]

However, in the above configuration, since the quartz plate is fixedly supported by a non-elastic supporting member such as an electrode pad and a ceramic laminate, when a shock such as a drop is applied, the structure shown in FIG. As shown in the sectional view, the quartz plate 5 is greatly bent, and the quartz plate 5 is
Was sometimes damaged.

An object of the present invention is to provide a more reliable surface-mount type piezoelectric vibrator which minimizes the bending of a piezoelectric plate such as a crystal due to an external impact and eliminates the damage of the piezoelectric plate due to the bending. It is.

[0005]

Therefore, the surface mount type piezoelectric vibrator of the present invention has a base substrate made of an insulating material on which a lead electrode to the outside is formed, and supports the piezoelectric plate near both ends in the longitudinal direction. A support member having low elasticity is formed, and a piezoelectric plate having excitation electrodes formed on the front and back surfaces is flatly mounted and electrically and mechanically connected to at least one of the support members by a conductive bonding material. In a surface mount type piezoelectric vibrator in which a sealing lid is attached and sealed at an upper portion, at least a portion not in contact with an excitation electrode of the piezoelectric plate in the vicinity of the periphery of the piezoelectric plate, an auxiliary not mechanically joined to the piezoelectric plate. A support member is provided.

[0006]

According to this structure, the bending of the piezoelectric plate caused by supporting the both ends in the longitudinal direction of the piezoelectric plate with the support member having low elasticity is minimized by the auxiliary support member near the periphery of the piezoelectric plate. Further, even if an impact such as a drop is applied, the piezoelectric plate is prevented from being damaged from the supporting portion. Since the auxiliary support member is provided at a portion of the piezoelectric plate that does not contact the excitation electrode, the excitation electrode is not damaged. In addition, since the piezoelectric plate and the auxiliary support member having a different thermal expansion coefficient are not mechanically connected to the piezoelectric plate, they do not interfere with each other, and the difference in the coefficient of thermal expansion between the piezoelectric plate and the auxiliary support member due to a change in temperature is reduced. This does not cause a change in strain on the piezoelectric plate due to the occurrence, and reduces the occurrence of CI value fluctuation and the like.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a piezoelectric vibrator according to the present invention. FIG.
FIG. 1 is a perspective plan view showing a first embodiment of the present invention. FIG.
FIG. 2 is a sectional view taken along line AA in FIG. 1. FIG. 3 is a perspective plan view showing the second embodiment. FIG. 4 is a perspective plan view showing the third embodiment. FIG. 5 is a perspective plan view showing the fourth embodiment. In the first, second, third, and fourth embodiments of the present invention, similar parts are denoted by the same reference numerals. The base substrate 1 and the sealing lid 2 of the surface mount type crystal unit of the present invention are made of ceramic such as alumina. Then, connection terminals 1 a and 1 b as external circuits are provided on the side surface in the longitudinal direction of the base substrate 1, and a crystal plate 5 is provided on the upper surface of the base substrate 1.
Are provided with connection electrodes 3a and 3b for electrical connection with the excitation electrode 12 (the back surface is not shown). In addition, a support 4 for preventing the quartz plate from tilting according to the thickness of the connection electrode is provided at a portion facing the connection electrode. The external connection terminals 1a and 1b and the connection electrodes 3a and 3b are electrically connected to each other by providing extraction electrodes 13a and 13b. Therefore, the width of the extraction electrode 13b is provided so as to be large, and formed so as to overlap around the crystal plate. Also, the connection electrode 3a is formed so as to overlap around the crystal plate almost in the same manner as the extraction electrode 13b. A dummy electrode 13c not connected to the electrode is provided. These electrodes are formed to be slightly thinner than the thicknesses of the connection electrodes 3a, 3b and the support 4 to provide a step. This is, for example, after forming a metallized layer of tungsten on the upper surface of the base substrate 1 and forming a nickel plated layer on the upper surface of the metallized layer of tungsten by electrolytic plating. It is obtained by covering with a mask and further forming a gold plating layer on the upper surfaces of the electrodes other than the extraction electrode 13b and the dummy electrode 13c. Then, the rectangular AT-cut quartz plate 5 on which the excitation electrode 12 is formed (the back surface is not shown) is mounted on the connection electrodes 3a, 3b and 4 and joined with the conductive joining material 6, and thereafter, the base substrate The sealing lid 2 is placed over the upper part 1 and bonded to the bonding part 21 between the sealing lid and the base substrate with the low-melting glass 7 and hermetically sealed. In the surface-mounted crystal resonator thus formed, the extraction electrode 13b and the dummy electrode 13c function as an auxiliary support member.

As shown in FIG. 3, electrodes serving as auxiliary support members are provided at both ends in the longitudinal direction of the quartz plate.
And the extraction electrode 13d and the dummy electrodes 13e and 13f are formed so as to overlap with each other, or as shown in FIG.
The electrode as the auxiliary support member may be formed so that the quartz plate 5 and the extraction electrode 13g and the dummy electrode 13h overlap near the center of the quartz plate in the longitudinal direction.

In the embodiment of the present invention, the auxiliary support member is formed by forming an electrode. However, as shown in FIG. 4, ceramic is laminated on the base substrate 1 in advance, and the auxiliary support member is partially formed on the base substrate. 11a and 11b may be formed. In the present invention, since the auxiliary support member is made of the same electrode material as the lead electrode formed on the base substrate, or the same ceramic material as the base substrate, the electrode is formed or the base substrate is molded. Because they can be made at the same time, they can be manufactured extremely efficiently and precisely.

In the embodiment of the present invention, only the surface-mount type piezoelectric vibrator having the support structure for holding the quartz plate in a cantilever manner has been described. Needless to say, this can also be applied. The thickness of the auxiliary member may be equal to or smaller than the thickness of the support member.However, if the thickness of the auxiliary support member is too small, the distance between the crystal plate and the auxiliary support member increases, and the Since the quartz plate may be bent, the thickness of the auxiliary support member needs to be designed to have a certain thickness so that the distance between the quartz plate and the auxiliary support member is set short.

[0011]

According to the first aspect of the present invention, the deflection of the piezoelectric plate caused by supporting both ends in the longitudinal direction of the piezoelectric plate with the support member having low elasticity is minimized by the auxiliary support member near the periphery of the piezoelectric plate. Can be Further, even if an impact such as a drop is applied, the piezoelectric plate is prevented from being damaged from the supporting portion. Since the auxiliary support member is provided at a portion of the piezoelectric plate that does not contact the excitation electrode, the excitation electrode is not damaged. In addition, since the piezoelectric plate and the auxiliary support member having a different thermal expansion coefficient are not mechanically connected to the piezoelectric plate, they do not interfere with each other, and the difference in the coefficient of thermal expansion between the piezoelectric plate and the auxiliary support member due to a change in temperature is reduced. This does not cause a change in strain on the piezoelectric plate due to the occurrence, and reduces the occurrence of CI value fluctuation and the like. As described above, it is possible to provide an extremely practical crystal oscillator that can provide an even more reliable crystal oscillator in terms of impact resistance and environmental characteristics in which electrical characteristics do not change due to changes in temperature. It is.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective plan view showing a second embodiment.

FIG. 4 is a perspective plan view showing a third embodiment.

FIG. 5 is a perspective plan view showing a fourth embodiment.

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

FIG. 7 is a cross-sectional view showing a bending structure of a conventional quartz plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base board 1a, 1b ... Connection terminal 2 ... Sealing lid 3 ... Electrode pad 3a, 3b ... Connection electrode 4 ... Support base 5 ... Quartz plate 12: Excitation electrodes 13a, 13b, 13d: Lead electrodes 13c, 13e, 13f: Dummy electrodes

Claims (1)

(57) [Scope of request for utility model registration] 1. A base substrate made of an insulating material on which an extraction electrode to the outside is formed, a support member having low elasticity for supporting a piezoelectric plate is formed near both ends in the longitudinal direction, and excitation electrodes of the excitation electrode are formed on the front and back surfaces. A surface-mounted piezoelectric plate in which the formed piezoelectric plate is mounted flat, electrically and mechanically connected to at least one of the supporting members by a conductive bonding material, and a sealing lid is attached to an upper portion of the base substrate. In the vibrator, an auxiliary support member that is not mechanically joined to the piezoelectric plate is provided on at least a portion of the vibrator that is not in contact with an excitation electrode of the piezoelectric plate near the periphery of the piezoelectric plate. Vibrator.