JPH1131940A - Surface mount type crystal vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mount type crystal vibrator which securely obtains electric conduction and mechanical holding by applying a conductive adhesive only once and is therefore reduced in variance of electric characteristics and improved in process yield. SOLUTION: This vibrator is constituted by forming a holding electrode 13 which conducts electrically to a mounted electrode 12 formed on the outside bottom surface in a container 11. Further, a crystal piece 16 having exciting electrodes 19, formed on the top and reverse plate surfaces, led out to plate surface end in the mutually opposite directions to the holding electrode is fixed with the conductive adhesive 20. The exciting electrode 19 is connected to a through hole electrode 18 provided at the end part of the crystal piece. Preferably, the crystal piece 16 is adhered directly to the holding electrode 13 with the conductive adhesive 20 and also electrically connected, and the through hole electrode 18 has an electrode film formed by sputtering by boring a through hole in the end part of the crystal piece 16.

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 crystal unit which has little variation in characteristics and is suitable for mass production.

[0002]

2. Description of the Related Art In recent years, various electronic devices have frequently used surface-mounted electronic components in order to reduce the size and weight and to automate the assembly process. For this reason, a surface-mount type crystal resonator used as a reference for time and frequency tends to be used.

FIGS. 6 and 7 are a side sectional view and a plan view showing an example of a conventional surface mount type crystal unit. Reference numeral 1 denotes a box-shaped ceramic container having an opening on the upper surface, for example. On the outer bottom surface of the container 1, a mounting electrode 2 for mounting on a conductive pattern of a printed board (not shown) is formed. Then, the holding electrode 3 is formed in the container 1 by being electrically connected to the mounting electrode 2.

[0004] A conductive adhesive is applied to the holding electrode 3, and the crystal blank 4 is placed and fixed thereon. Then, a conductive adhesive is applied over the lead-out end of the electrode of the crystal blank 4 to electrically connect the lead-out end of the upper electrode to the holding electrode. The crystal blank 4 is formed by cutting artificial quartz at a predetermined angle into a plate shape, polishing the thickness in accordance with a desired frequency, for example, and forming the excitation electrode 5 facing the front and back plate surfaces. .

Then, the excitation electrodes 5 are led out in opposite directions to the end of the plate surface, and a conductive adhesive 6 is applied to the lead ends to hold the crystal blank 4 with the holding electrodes 3 and to hold the excitation electrodes 5
Is electrically connected to the mounting electrode 2 via the holding electrode 3. The opening on the upper surface of the container 1 is hermetically sealed by a lid 7.

However, in such a device, it is necessary to apply a conductive adhesive to the holding electrode, place a crystal blank thereon, and then apply the conductive adhesive from above. The agent must be applied twice. For this reason, it is difficult to make the application amount and the application area of the conductive adhesive uniform, thereby causing a problem that the electrical characteristics vary and the yield decreases. Further, there is a problem that the process yield is reduced because the conductive adhesive is applied twice.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and electric conduction and mechanical holding can be reliably performed by only applying a conductive adhesive once. Accordingly, it is an object of the present invention to provide a surface-mount type crystal unit that has less variation in electrical characteristics and can improve a process yield.

[0008]

According to a first aspect of the present invention, a holding electrode is formed in a container to be electrically connected to a mounting electrode formed on an outer bottom surface, and excitation electrodes formed on front and back plate surfaces are arranged in opposite directions. In a surface-mount type crystal unit in which a crystal piece led to an edge of a plate surface is fixed to the holding electrode with a conductive adhesive, the excitation electrode is connected to a through-hole electrode provided at an end of the crystal piece. According to a second aspect of the present invention, in the second aspect, the quartz piece is directly bonded to the holding electrode by a conductive adhesive, and According to a third aspect of the present invention, there is provided a surface-mount type crystal resonator, wherein the through-hole electrode formed at the end of the crystal blank is connected to the end of the crystal blank. Drill a through hole in the electrode by sputtering To the formation of the a surface mount type crystal resonator according to claim.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a side sectional view shown in FIG. 1 and FIG.
An embodiment of the present invention will be described with reference to a plan view shown in FIG. A mounting electrode 12 for mounting on a conductive pattern of a printed circuit board (not shown) is formed on the outer bottom surface of a ceramic container 11 having an opening on the upper surface and molded in a substantially box shape.

[0010] The holding electrode 13 is formed in the container 11 by being electrically connected to the mounting electrode 12. The mounting electrode 12 and the holding electrode 13 may be formed by embedding and embedding a thin metal plate, or may be formed by performing a metallizing process on the surface of ceramic.

Then, for example, as shown in FIG. 3, a resist 15 is applied to a quartz plate 14 polished to a desired thickness.
Only the resist corresponding to the shape of each crystal blank 16 is left, and the surface of the crystal plate is exposed. 4 and 5 are cross-sectional views of the quartz plate 14 whose thickness is exaggerated. Further, the resist is also removed from the through holes 17 formed at both ends of each crystal blank 16 to expose the plate surface.

Then, the crystal plate 14 is immersed in an etching solution and etched for an appropriate time to divide the crystal plate 16 into respective crystal blanks 16. As shown in FIG. A through hole is formed. The diameter of the through hole may be, for example, 20 microns or more.

An excitation electrode is formed on the front and back surfaces of the crystal blank 15 by sputtering, and a metal thin film is formed on the inner wall of the through hole 17 to form the through hole electrode 1.
8 is formed. The main purpose of the etching is to form the through holes 17, and the individual crystal blanks 16 may be divided using a dicing saw or the like. The main purpose of sputtering is to form a through-hole electrode 18 formed by depositing a metal thin film on the inner wall of the through-hole 17, so that the excitation electrode is formed by using conventional evaporation or by evaporation alone. Needless to say, this may be done.

Therefore, for example, after the resist is removed from the quartz plate 14, individual quartz pieces 16 having a predetermined outer shape are formed.
May be cut. The crystal blank 16 forms an excitation electrode 19 on the front and back plate surfaces, and the excitation electrode 1
9 are led out in opposite directions to the end of the plate surface, and connected to the through-hole electrode 17 at the end of the plate surface. And container 1
A conductive adhesive 20 is applied to the holding electrode 13 in 1, a crystal blank 14 is placed and fixed thereon, and each excitation electrode 19 is electrically connected to the holding electrode 13. The opening of the container 11 is hermetically sealed with the lid 21.

In this way, since each of the excitation electrodes 19 is electrically connected to both side surfaces at the end of the crystal blank,
By applying a conductive adhesive 20 to the substrate and placing the crystal blank 16 thereon, the excitation electrode 19 and the holding electrode 13 can be electrically connected to each other. Therefore, the work of applying the conductive adhesive only needs to be performed once, and even if the amount of the conductive adhesive applied is relatively small, conduction can be reliably obtained. Further, the process can be simplified, and variations in vibration characteristics can be reduced.

[0016]

The present invention is embodied in the form described above and has the following effects.

The operation of applying the conductive adhesive may be performed only once, and the holding and conduction can be reliably achieved with a relatively small amount of application. Therefore, variation in vibration characteristics is small, and process defects can be reduced. Further, when a through hole is formed by etching and divided into individual crystal pieces, a large amount of crystal pieces can be obtained efficiently.

[Brief description of the drawings]

FIG. 1 is a side sectional view of one embodiment of the present invention.

FIG. 2 is a plan view of the crystal resonator shown in FIG. 1 with a lid removed.

FIG. 3 is a plan view of a quartz plate having a large number of quartz pieces and through holes according to the present invention.

FIG. 4 is a cross-sectional view illustrating a photo-etching process of the present invention.

FIG. 5 is a cross-sectional view illustrating a photoetching process of the present invention.

FIG. 6 is a side sectional view showing an example of a conventional crystal unit.

FIG. 7 is a plan view showing an example of a conventional crystal unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Container 12 Mounting electrode 13 Holding electrode 16 Quartz piece 18 Through-hole electrode 19 Excitation electrode 20 Conductive adhesive

Claims (3)

[Claims] 1. A holding electrode, which is formed on the outer bottom surface and is electrically connected to a mounting electrode, is formed in a container, and the excitation electrode formed on the front and back plate surfaces is led out to the end of the plate surface in opposite directions to the holding electrode. A surface-mount type crystal unit, wherein said excitation electrodes are respectively connected to through-hole electrodes provided at both ends of a crystal piece, respectively. 2. A surface-mount type crystal unit according to claim 1, wherein said crystal blank is directly bonded to said holding electrode by a conductive adhesive and electrically connected thereto. 3. A through-hole electrode formed at an end of a crystal blank according to claim 1, wherein a through-hole is formed at an end of the crystal blank to form an electrode film by sputtering. Surface mount type crystal unit.