JP2003087078A - Crystal vibrator structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of many variations being generated in the value of wiring resistance and wiring being disconnected, if worst comes to worst because portions of discontinued metal film or thin metal film are formed, due to an etching residue inside a through-hole, when making the through-hole on a case made of a crystal to establish continuity between the inner and outer portions. SOLUTION: The through-hole is made into a polygonal, form and respective inner side faces constituting the polygon of the through-hole are made to be perpendicular with respect to X-axis of the crystal. Since etching rate is smaller in an X-axis than in a Z-axis, the etching progresses mostly in the X-axis, and a shape having no etching residues can be obtained. Thus, the variations in the resistance value of wiring can be reduced, and disconnections can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator structure in which a crystal oscillator used as a reference signal source for a timepiece or a mobile communication device is housed. More specifically, the present invention relates to a crystal unit structure in which a housing for storing a crystal unit is made of crystal, and the body has a through hole for establishing electrical continuity between the crystal unit and the outside. .

[0002]

2. Description of the Related Art A so-called tuning fork type crystal oscillator having two vibrating legs is widely used as a reference signal source for a timepiece and a mobile communication device. The performance of such a crystal oscillator deteriorates due to friction with air due to vibration, and thus it is necessary to use it in a vacuum atmosphere and used in a state where it is housed in a hermetically sealed case. Figure 1 is the most widely used
6 is a cylindrical crystal resonator structure 31 in which the casing shown in 6 is made of a metal cylinder. Conduction between the crystal unit inside and the outside is performed through the lead wire 33 provided on the bottom surface. The lead wire 33 penetrates at the bottom of the housing, and electrically connects the inside and the outside of the housing. The penetrating part is filled with glass, and at the same time airtightness is maintained while achieving insulation. Such a cylindrical crystal oscillator structure 31 is used such that the lead wire 33 is connected to the circuit board 35 and then laid down sideways as shown in FIG. Due to the demand for miniaturization and thinning of watches and mobile communication devices, the quartz crystal structure is also required to be thin.
In the above cylindrical shape, the height of the component is determined by the diameter of the cylinder and cannot be made smaller than that. Although various proposals have been made for this problem, in Japanese Patent Laid-Open No. 56-44213, a frame surrounding the crystal unit (hereinafter, referred to as the crystal unit frame plate 1) is manufactured and shown in FIG. As described above, a technique for obtaining a crystal resonator structure by sandwiching the crystal resonator frame plate 1 between the separately manufactured upper housing 9 and lower housing 11 is disclosed. According to this structure, the crystal resonator structure can be thinned. In this publication, the electrodes of the internal crystal unit, that is, the internal electrodes and the external electrodes 23 which are outside the housing and are used for connecting to the circuit board are electrically connected by the through holes 3 formed in the housing. Although there is no detailed description on the method of forming the metal film inside the through hole 3 in this publication,
Actually, it is formed by vacuum evaporation. Further, this publication does not have a detailed description of the shape of the through hole 3 and the like, and only the circular shape is shown in the drawing. The publication describes the use of quartz as one of the materials for the housing.

[0003]

However, in the above-mentioned conventional technique, when the case is made of quartz, due to the anisotropy, even if the etching mask is circular, the inside of the through hole is not circular due to the difference of crystal planes. As a result, a residue is formed inside the through hole, a shadowed portion appears during vapor deposition, and a portion where the metal film is not continuous or a thin portion is generated. There was a problem of breaking the wire. Further, if the through hole is small and deep, it is difficult for the etching solution to enter.Therefore, the etching of the through hole does not end even after the etching of the outer shape of the housing is completed, and an etching residue is generated inside the through hole. There is a problem that the metal film has a discontinuous portion or a thin portion, the wiring resistance value varies widely, and in the worst case, the metal film is cut and broken.

In order to solve the above-mentioned problems, an object of the present invention is to eliminate etching residues inside the through holes provided in the housing, to prevent the metal film from forming a discontinuous portion or a thin portion,
It is an object of the present invention to provide a crystal resonator structure in which variations in wiring resistance values are small and disconnection does not occur.

[0005]

In order to achieve the above object, a crystal resonator structure according to the present invention is a crystal composed of a crystal resonator and a casing for housing the crystal resonator therein and hermetically sealing it. A vibrator structure, wherein the housing is made of crystal,
There is a through hole that connects the inside and the outside of the housing, and the cross-sectional shape of the through hole is a substantially polygonal shape, and each of the inner side surfaces forming the polygonal shape is substantially with respect to the X axis of the crystal axis of quartz. It is characterized by being vertical.

In the crystal resonator structure according to the present invention, the polygonal shape is a substantially triangular shape, the through hole has three inner side surfaces forming the triangle, and a crystal of quartz crystal orthogonal to each of the inner side surfaces. The X-axis of the shaft is characterized in that the inside of the through hole is negative and the outside is positive.

The crystal unit structure according to the present invention is characterized in that the polygon is substantially hexagonal.

The crystal resonator structure according to the present invention is characterized in that an opening area of the through hole is larger in a portion in contact with the outside of the casing than in a portion in contact with the inside of the casing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 to 3 are views showing a form of a crystal resonator structure according to the present invention. FIG. 1 is a perspective view of a crystal resonator structure according to the present invention. FIG. 2 is a perspective view of a crystal unit frame plate 1 which is one of the components constituting the crystal unit structure according to the present invention. FIG. 3 is a sectional view through the through hole 3 of the crystal unit structure according to the present invention. The crystal unit structure according to the present invention includes a crystal unit frame plate 1 and a crystal unit frame plate 1 each including a crystal unit 5 and a frame portion 7 supporting the crystal unit 5.
It is composed of an upper casing 9 and a lower casing 11 which sandwich the frame 7 with the frame 7. In FIG. 1, the upper housing 9 is drawn below and the lower housing 11 is drawn above so that the through hole 3 can be easily seen. Actually, the lower housing side is attached to the circuit board side for mounting.

The crystal resonator frame plate 1, the upper casing 9 and the lower casing 11 are each made of quartz and are formed by etching using a liquid in which hydrofluoric acid and an ammonium fluoride aqueous solution are mixed. Crystal oscillator frame plate 1 of the present invention,
The upper housing 9 and the lower housing 11 are made of quartz having the same crystal orientation. This is to reduce the influence of thermal expansion on the joint 13. In the crystal resonator structure of the present invention, the width direction of the legs of the crystal resonator 5 coincides with the X-axis direction of the crystal axis of the crystal. The direction in which the legs extend and the thickness direction,
The directions are rotated by an angle θ with the X axis as the axis of rotation from the state in which they are aligned with the Y axis and the Z axis of the crystal axis of the crystal.
θ is 0 to 5 °. The crystal oscillator frame plate 1 is composed of the crystal oscillator and the frame portion 7 supporting the crystal oscillator as described above. The frame 7 and the crystal unit 5 are connected at the base of the crystal unit 5. The crystal unit 5 and the frame 7 are integrated, and are formed by etching from a single crystal plate. The crystal oscillator 5 has electrodes for exciting vibration, that is, the internal electrode 1
5 are provided. The frame portion 7 is provided with a sealing metal film 17 and is used for joining the upper casing 9 and the lower casing 11 and hermetically sealing them. The lower housing 11 is provided with two through holes 3 for guiding the internal electrodes 15 of the crystal unit 5 to the outside of the housing. A connection electrode 21 made of a metal film is formed on the inner side surface 19 of the through hole 3 by vacuum deposition or the like, and is formed outside the inner electrode 15 provided on the crystal unit 5 inside the housing and the lower housing 11. External electrode 2
3 and 3 are conducted. FIG. 4 is an enlarged view of the vicinity of the through hole 3 of the lower housing 11. The shape of the through hole 3 is a substantially triangular shape,
Each side of the triangle is substantially perpendicular to the X axis of the crystal axis of quartz. The reason why the shape of the through hole 3 is set as described above is as follows.

Quartz is an anisotropic single crystal that belongs to the trigonal system, and the etching rate varies significantly depending on the orientation. The etching rate in the Z-axis direction is about 100 times faster than the etching rate in the negative X-axis direction. Therefore, FIG.
As described above, when the quartz plate 25 used in the present invention is etched by forming a mask 27 made of a film on which Au is attached with Cr as a base so as to protect the positive side of the X axis perpendicular to the X axis direction, the etching is There is almost no progress from the negative direction of the axis, and the progress is in the Z-axis direction. As a result, a cross-sectional shape having no debris and a uniform shape in the thickness direction is formed as shown in FIG. Further, the crystal is a three-fold symmetric crystal having the Z axis as the axis of symmetry,
There are three X-axes every 120 ° around the Z-axis and they are equivalent. Therefore, a triangle can be made with a line perpendicular to each of the three X-axes. As shown in FIG. 7, when the triangle 27 is used as the mask 27 and etching is performed with the negative direction of the X-axis being the center side of the through hole 3, the inner surface of the through hole 3 is cut straight in the thickness direction, so there is no residue. Hole 3
Therefore, when the connection electrode 21 is vacuum-deposited on the inner surface of the through hole 3, a discontinuous portion, a thin portion, or a disconnection does not occur.

Since the etching rate from the positive direction of the X-axis is faster than the etching rate from the negative direction of the X-axis, a protrusion 29 as shown in FIG. 8 is formed, but the extent of this difference is different from the etching rate in the Z-axis direction. Since it is smaller than the above, it is possible to set the positive direction of the X-axis to the center side of the through-hole 3, but it is better to form the through-hole 3 with the negative direction of the X-axis toward the center of the through-hole. Is desirable because it can be reduced. For the above reasons, the shape of the through hole 3 is substantially triangular, and each side of the triangle is substantially perpendicular to the X axis of the crystal axis of quartz.

As described above, the etching rate from the negative X-axis direction and the etching rate from the positive X-axis direction are different,
The inner surface of the through hole 3 when the through hole 3 is formed with the negative direction of the X axis being the center side of the through hole 3 and when the through hole 3 is formed with the positive direction of the X axis being the center side of the through hole 3. The shape is different, but the difference is slight. Therefore, as shown in FIG. 9, the through hole 3 in which the negative direction of the X axis is the center side of the through hole 3 and the through hole 3 in which the positive direction of the X axis is the center side of the through hole 3 may be combined. Further, the same through hole 3 may have both an inner side surface with the negative direction of the X axis being the center side of the through hole 3 and an inner side surface with the positive direction of the X axis being the center side of the through hole 3. For example, it may be a hexagon as shown in FIG. 10, a pentagon as shown in FIG. 11, or a quadrangle as shown in FIG. 12 or 13. Of these, the hexagon is the closest to a circle and has good symmetry, so the size of the through hole 3
Is useful when it is necessary to provide.

As described above, in the crystal resonator structure according to the present embodiment, since the protrusion due to the etching residue is not formed on the inner surface of the through hole 3 for establishing the conduction between the inside and the outside of the housing, the disconnection occurs. It is possible to provide a crystal resonator structure that does not have a stable wiring resistance value.

In the present embodiment, an example in which the two through holes 3 are provided in the lower housing 11 has been shown, but the sectional shape of the through holes 3 is important, regardless of the position or number of the through holes 3. It is clear from the above description that the effects of the present invention can be obtained. Therefore, it goes without saying that two through holes 3 may be provided in the upper housing 9 or the through holes 3 may be provided in each of the upper housing 9 and the lower housing 11.

(Embodiment 2) FIGS. 14 and 15 are views showing another embodiment of the present invention, in which the opening area of the through-hole 3 formed in the housing is larger than that of the housing which is in contact with the inside of the housing. This is an example in which the outside is enlarged. 14 is an enlarged view of the vicinity of the through hole 3 of the lower housing 11, and FIG. 15 shows the lower housing 11 in FIG.
It is sectional drawing when it cut | disconnects in a -A position. When the opening areas of the through holes 3 are made different as in the present invention, the etching of the portion in contact with the outside of the housing is large because the through holes 3 are large, so that the etching solution penetrates well and progresses quickly, and etching from inside the housing is prevented. Even at the latest, the etching of the through holes 3 is completed, etching residue does not occur, and the occurrence of disconnection can be prevented.

The shape of the through hole 3 is substantially polygonal, and each side of the polygon is substantially perpendicular to the X axis of the crystal axis of quartz. The reason for this is as described above.

[0019]

As described above, according to the crystal resonator structure of the present invention, there is no protrusion due to etching residue on the inner surface of the through hole formed in the housing, and the metal film is not continuous. It is possible to obtain a stable wiring resistance at the same time without obtaining a thin portion or disconnection, and at the same time, to obtain a stable wiring capacitance, and to obtain a crystal resonator structure in which the resonance frequency is stable and variation is small. There is an effect.

[0020]

[Brief description of drawings]

FIG. 1 is a perspective view of a crystal unit structure according to the present invention.

FIG. 2 is a perspective view of a crystal unit frame plate, which is one of the components constituting the crystal unit structure according to the present invention.

FIG. 3 is a cross-sectional view through a through hole of a crystal resonator structure according to the present invention.

FIG. 4 is an enlarged view of the vicinity of a through hole of a lower housing in the crystal unit structure according to the present invention.

FIG. 5 is a diagram for explaining anisotropy of etching of a quartz plate.

FIG. 6 is a diagram for explaining the etching anisotropy of the crystal plate, showing the cross-sectional shape when the crystal plate is etched from the negative direction of the X axis.

FIG. 7 is a diagram illustrating a shape of a through hole in the crystal resonator structure of the present invention.

FIG. 8 is a diagram for explaining the anisotropy of etching of the crystal plate, showing the cross-sectional shape when the crystal plate is etched from the positive direction of the X axis.

FIG. 9 is an enlarged view of the vicinity of the through hole of the lower housing in the crystal unit structure according to the present invention.

FIG. 10 is a diagram showing a shape of a through hole of the crystal unit structure according to the present invention.

FIG. 11 is a view showing a shape of a through hole of the crystal unit structure according to the present invention.

FIG. 12 is a view showing a shape of a through hole of the crystal resonator structure according to the present invention.

FIG. 13 is a view showing a shape of a through hole of the crystal unit structure according to the present invention.

FIG. 14 is a view showing another embodiment of the present invention, and is an enlarged view of the vicinity of the through hole of the lower housing.

FIG. 15 is a view showing another embodiment according to the present invention, which is a cross-sectional view near the through hole of the lower housing.

FIG. 16 is a diagram showing a conventional cylindrical crystal unit structure.

FIG. 17 is a view showing a mounted state of a conventional cylindrical crystal unit structure.

FIG. 18 is a diagram showing a conventional crystal resonator structure.

[Explanation of symbols]

1 Crystal oscillator frame plate 3 through holes 5 Crystal unit 7 frame 9 Upper case 11 Lower case 13 joints 15 internal electrodes 17 Metal film for sealing 19 Inside 21 Connection electrode 23 External electrode 25 crystal plate 27 masks 29 Projection 31 Cylindrical crystal unit 33 lead wire

Claims (4)

[Claims] 1. A crystal resonator structure comprising a crystal resonator and a housing for housing the crystal resonator therein and hermetically sealing the crystal resonator, wherein the housing is made of crystal and the inside of the housing is provided. Has a through hole connecting the outside and the outside, and the cross-sectional shape of the through hole is substantially polygonal, and each of the inner side surfaces forming the polygon is substantially perpendicular to the X axis of the crystal axis of quartz. A crystal unit structure characterized by. 2. The polygon is a substantially triangular shape, the through hole has three inner side surfaces forming the triangle, and the direction of the X axis of the crystal axis of the quartz crystal orthogonal to each of the inner side surfaces is ,
The crystal unit structure according to claim 1, wherein the crystal unit structure extends from the inside to the outside of the through hole. 3. The crystal resonator structure according to claim 1, wherein the polygon is a substantially hexagon. 4. The opening area of the through hole on the side facing the outside is
The crystal resonator structure according to any one of claims 1 to 3, wherein the opening area of the through hole on the side facing the crystal resonator is made larger.