JP2010263258A - Manufacturing method of tuning fork crystal unit - Google Patents

Abstract

A tuning fork resonator is provided which facilitates the formation of a trapezoidal crystal holding terminal.
A pair of lead terminals (ab) provided on one main surface of a tuning fork base 2a in electrical connection with an excitation electrode 7 formed on a pair of tuning fork arms 2b of a tuning fork crystal piece 2, In the manufacturing method of a tuning fork type crystal resonator, which is provided on the inner wall of the container body 1 and is fixed to the crystal holding terminal 5 (ab) of the divided inner wall step portion independent by the central groove 4 by the conductive adhesive 9, the crystal holding terminal 5 (ab) is formed by simultaneously dividing the metal film formed on the continuous inner wall step portion before formation of the divided step portion together with the divided step portion by the central groove 4, and the crystal holding terminal 5 (ab) The opposite side sides are asymmetric with respect to the center line that bisects the bottom side, and at least the upper end of the crystal holding terminal 5 (ab) and one end of the bottom side that is closer to the outer surface of the tuning fork base 2a One side connected to the base 0 ° and smaller than an acute angle of the inclined line and configuration.
[Selection] Figure 1

Description

  The present invention has, for example, a manufacturing method of a tuning fork crystal resonator (hereinafter referred to as a tuning fork resonator) for surface mounting, in particular, a crystal holding terminal (bump, to which a tuning fork base portion of a tuning fork crystal piece is fixed). The present invention relates to a method for manufacturing a terminal protrusion.

(Background of the Invention)
Tuning fork vibrators are built into various electronic devices having a clock function such as a wristwatch. In recent years, a surface mount type in which a tuning fork crystal piece is accommodated in a ceramic container and hermetically sealed is the mainstream. The tuning fork crystal pieces are mass-produced by obtaining a large number of tuning fork crystal pieces from a crystal wafer using photolithographic or etching techniques.

(Example of conventional technology)
FIG. 5 (ab) is a diagram for explaining a tuning fork vibrator according to a conventional example (see Patent Document 1). FIG. 5 (a) is a cross-sectional view of the tuning fork vibrator in the long side direction, and FIG. FIG. 4 is a cross-sectional view in the short side (width) direction.

  The tuning fork vibrator accommodates a tuning fork crystal piece 2 in a concave container body 1 made of laminated ceramic, and a metal cover 3 is joined to the opening end face so as to hermetically enclose the tuning fork crystal piece 2. The container body 1 has a three-layer structure including a bottom wall 1a, an intermediate frame 1b, and an upper frame 1c, and has an inner wall stepped portion by the intermediate frame 1b on one end side. The inner wall step portion is a divided step portion divided by the central groove 4. A crystal holding terminal 5 (ab) is provided on the surface of the divided step portion, and is electrically connected to the mounting terminal 6 (ab) on the outer bottom surface by a wiring path including a through electrode (not shown).

  These are the ceramic electrodes (bottom wall sheet, intermediate frame sheet, upper frame sheet) that are the respective layers, by printing tungsten (W) or molybdenum (Mo) on the base electrode of each electrode including the crystal holding terminal 5 (ab). After forming, they are integrally laminated and fired. Then, Ni and Au are sequentially formed by, for example, electroplating. Thereafter, the container body 1 is divided.

  Here, the crystal holding terminals 5 (ab) are trapezoidal with an equal leg, and a base electrode is formed separately on the surface of each divided step portion of the intermediate frame sheet by multilayer coating or the like. However, the crystal holding terminal 5 (ab) has the same effect even when the isosceles trapezoidal biped (side) is curved outward or the upper side is arcuate. " Strictly speaking, the contour line has a staircase shape when formed by multi-layer printing, but here it is a straight line or a curved line.

  The tuning fork-shaped crystal piece 2 has a pair of tuning fork arms 2b extending from the tuning fork base 2a, and the crystal axis (XYZ) is, for example, a Z-cut in which the Z axis is orthogonal to the principal surface. The axis is the thickness direction. Each tuning fork arm 2b has excitation electrodes 7 on both main surfaces and both side surfaces (see FIG. 7), both main surfaces and both side surfaces of each tuning fork arm 2b are connected in common, and each tuning fork arm 2b One main surface and the other both side surfaces are connected in common by one set of wiring paths (not shown). A set of wiring paths extends to both lower ends of one main surface of the tuning fork base portion 2a to form lead terminals 8 (ab).

  In these, a large number of tuning-fork crystal pieces 2 including electrode formation are integrally formed on a crystal wafer (not shown) by using photo-etching or etching technology. Then, the crystal wafer is divided into individual tuning fork crystal pieces 2. Thereafter, the lead terminal 8 (ab) of the tuning fork base 2a is fixed to the trapezoidal crystal holding terminal 5 (ab) by the conductive adhesive 9, and is electrically and mechanically connected.

  The metal cover 3 is seam welded to a seam ring (not shown) provided on the opening end surface of the container body 1 using a pair of roller electrodes, for example, using Kovar as a base material. However, it is not limited to seam welding, and may be an electron beam, glass sealing or resin sealing with a cover made of metal or an insulator, and can be applied as long as the sealing is sufficient.

  In such a case, since the crystal holding terminal 5 (ab) has a trapezoidal shape, for example, the upper surface of the central tip portion is in close contact with the lead terminal 8 (ab) in a point-like manner, and is spaced from the central portion to the outer peripheral portion. Gradually increases and gradually joins. Thereby, while maintaining the adhesive strength with the conductive adhesive 9, the change of the vibration frequency by stress distortion can be suppressed.

JP 2008-211173 A

(Problems of conventional technology)
However, in the tuning fork resonator having the above-described configuration, as the outer dimension of the tuning fork crystal piece 2 becomes smaller, the crystal holding terminal 5 (ab) of the divided step portion is also shown in FIG. 8 (cross-sectional view in the width direction). Get smaller. For this reason, there is a problem that it becomes difficult to form the center tip of the trapezoidal crystal holding terminal 5 (ab) at a predetermined position where both ends of the tuning fork base 2a are located.

  In these cases, the smaller the outer dimension of the tuning fork crystal piece 2 is, the more the portion from one crystal wafer is increased, and the productivity is improved. Therefore, even when the existing container main body 1 (for example, the planar outer shape is 3.2 × 1.5 mm) is used or when the container main body 1 is made smaller than this as a downsizing of the tuning fork vibrator, the same problem occurs. .

(Object of invention)
An object of the present invention is to provide a method for manufacturing a tuning fork vibrator that facilitates the formation of a trapezoidal crystal holding terminal including an arc shape.

  The present invention is provided on one main surface of a tuning fork base portion in electrical connection with excitation electrodes formed on a pair of tuning fork arms of a tuning fork crystal piece as shown in the claims (Claim 1). In the method for manufacturing a tuning fork type crystal resonator in which a pair of lead terminals are provided on the inner wall of the container main body and fixed to the crystal holding terminal of the divided inner wall stepped portion by a central groove with a conductive adhesive, the crystal holding terminal The metal film formed on the continuous inner wall step portion before the formation of the divided step portion is simultaneously divided together with the divided step portion by the central groove, and the opposite sides of the crystal holding terminal are halved at the bottom. One side that connects at least the upper end of the crystal holding terminal and one end of the bottom that is closer to the outer surface of the tuning fork base is 90 ° to the base. A small sharp slope And it formed.

  In such a configuration, the crystal holding terminal is formed by dividing the holding terminal metal film formed on the continuous inner wall step portion together with the inner wall step portion by the central groove, so that even if the crystal holding terminal becomes small The holding terminal metal film can be formed large. Therefore, it is possible to improve the positional accuracy of the crystal holding terminal obtained by dividing the metal film for holding terminal, rather than forming the crystal holding terminals individually.

  And since the side near the outer surface of the tuning fork base in the crystal holding terminal is an inclined side, the upper end side of the crystal holding terminal is closely attached by the conductive adhesive at the lead-out terminal of the tuning fork base, and the fixing strength is increased. The closer it is, the more gentle it becomes. Therefore, the fixing strength is maintained as in the conventional example, and the change of the vibration frequency due to the stress strain is prevented.

(Embodiment section)
According to a second aspect of the present invention, in the first aspect, the inclined side is curved. As a result, the degree of adhesion from the upper end side can be made gentler than in the case of making it linear, so that the frequency change due to the fixing strength and stress strain can be finely controlled.

It is sectional drawing of the width direction of the tuning fork type | mold vibrator explaining one Embodiment of this invention. It is a typical sectional view of a tuning fork type vibrator showing a manufacturing process of one embodiment of the present invention. It is a top view of the ceramic sheet (intermediate frame layer) explaining the manufacturing process of one Embodiment of this invention. FIG. 10 is a schematic cross-sectional view of a tuning fork vibrator showing another manufacturing process example of the present invention. FIG. 5 is a diagram of a tuning fork type vibrator, FIG. 5 (a) is a cross-sectional view in the long side direction of the tuning fork type vibrator, and FIG. 5 (b) is a diagram in the short side (width) direction. It is sectional drawing. It is sectional drawing of the crystal holding terminal explaining a prior art example. It is a front view of the tuning fork-shaped crystal piece explaining a prior art example. It is sectional drawing of the width direction of the tuning fork type | mold vibrator explaining the problem of a prior art example.

  FIG. 1 (cross-sectional view of a tuning fork vibrator), FIG. 2 (manufacturing process based on the schematic cross-sectional view), and FIG. 3 (plan view of the intermediate frame sheet 1B) are shown in FIG. Will be explained.

  As described above, the tuning fork vibrator extends from the excitation electrode 7 of the pair of tuning fork arms 2b to the crystal holding terminal 5 (ab) of the independent divided step portion by the central groove 4 of the concave container body 1 made of multilayer ceramic. The lead-out terminal 8 (ab) on one main surface of the tuning fork base 2a is fixed with a conductive adhesive 9 and hermetically sealed with a metal cover 3 formed by seam welding (see FIG. 5). As described above, the planar outer shape of the tuning fork vibrator (container body 1) is 3.2 × 1.5 mm, and the outer shape of the tuning fork crystal piece 2 is 2.3 × 0.35 mm, which is much smaller than the container main body 1, thereby improving productivity. It is assumed that it has been raised.

  Here, as described in the claims (Claim 1), the crystal holding terminal 5 (ab) of the divided step portion has an asymmetric shape with respect to the center line that bisects the base. In this example, an isosceles trapezoid is divided into two trapezoids in the vertical direction (FIG. 1). In other words, one side near the outer periphery of the tuning fork base 2a is a trapezoid with an acute angle smaller than 90 ° with respect to the bottom, and the other side near the central groove 4 is a trapezoid.

  In these, the holding terminal metal film 5 ′ having an isosceles trapezoidal shape is formed on the continuous inner wall step portion before the central groove 4 is formed (FIG. 2 (a)). Then, a central groove 4 extending from the surface of the holding terminal metal film 5 'to the lower surface of the inner wall step portion is provided, and the crystal holding terminal 5 (b) is formed together with the divided step portion (FIG. 2 (b)).

  More specifically, as shown in FIG. 3, first, the base layer of the holding terminal metal film 5 ′ is printed on the intermediate frame sheet 1B which is a flat plate of a ceramic sheet to be a divided step portion (inner wall step portion). Electrodes (W and Mo) are formed. Then, the opening frame 10 having the central groove 4 is provided by a punching rod including the holding terminal metal film 5 '.

  Next, a bottom wall sheet and an upper frame sheet (not shown) are laminated and fired, and Ni and Au are sequentially plated on the base electrode exposed on the surface in an electrolytic solution. Finally, for example, a metal ring for seam welding is provided on the opening end face, and is divided into individual container bodies 1 along vertical and horizontal cutting lines (AA, BB).

  With such a configuration, as described in the effect column, the crystal holding terminal 5 (ab) is a holding terminal metal film 5 ′ formed on a continuous inner wall step, that is, a flat intermediate frame sheet 1B. Are divided together with the inner wall step by the central groove 4. Therefore, with the downsizing of the outer shape of the tuning-fork crystal piece 2 due to, for example, improvement in productivity, the holding terminal metal film 5 ′ can be formed larger even if the crystal holding terminal 5 (ab) is reduced. Thereby, the positional accuracy of the crystal holding terminal 5 (ab) obtained by dividing the holding terminal metal film 5 ′ can be improved as compared with the case where the crystal holding terminals 5 (ab) are individually formed.

  One side of the crystal holding terminal 5 (ab) that is closer to the outer surface of the tuning fork base 2a is an inclined side. Therefore, the upper end side of the crystal holding terminal 5 (ab) is brought into close contact with the conductive adhesive 9 at the lead-out terminal 8 (ab) of the tuning fork base portion 2a, and the fixing strength is increased. Thus, the fixing strength is maintained as in the conventional example, and the change of the vibration frequency due to the stress strain is prevented.

(Other matters)
In the above embodiment, the crystal holding terminal 5 (ab) has been described as a trapezoidal shape. For example, as shown in FIG. 4, an arc-shaped holding terminal metal film 5 ′ is provided on a continuous inner wall step, and a central groove is formed. 4 may be divided together with the inner wall step. In this case, each crystal holding terminal 5 (ab) has a curved surface shape that gradually decreases in thickness from the upper end side. Thereby, since the conductive adhesive 9 continuously increases in thickness with the upper end side being the minimum thickness, the same effect as in the case of the trapezoidal shape is obtained.

  In addition, the case where the size of the container main body 1 is improved as an example of the existing external shape (3.2 × 1.5 mm) has been described as an example, but the tuning fork-shaped vibrator (that is, the container main body 1) is reduced in size as the tuning fork vibrator (ie, the container main body 1) is downsized. Of course, the same applies even when the crystal piece 2 becomes smaller.

  DESCRIPTION OF SYMBOLS 1 Container main body, 2 Tuning fork crystal piece, 3 Cover, 4 Central groove, 5 Crystal holding terminal, 6 Mounting terminal, 7 Excitation electrode, 8 Lead-out terminal, 9 Conductive adhesive, 10 Opening part.

Claims (2)

A pair of lead terminals provided on one main surface of the tuning fork base and electrically connected to excitation electrodes formed on a pair of tuning fork arms of the tuning fork crystal piece are provided on the inner wall of the container body and are independent by a central groove. In the manufacturing method of the tuning fork type crystal resonator fixed to the crystal holding terminal of the divided inner wall stepped portion by the conductive adhesive,
The crystal holding terminal is formed by simultaneously dividing the metal film formed on the continuous inner wall step portion before the formation of the divided step portion together with the divided step portion by the central groove,
The crystal holding terminal is asymmetric with respect to a center line in which both opposite sides bisect the bottom,
One of the side edges connecting at least the upper end of the crystal holding terminal and one end of the base near the outer surface of the tuning fork base is an acute inclined line of less than 90 ° with respect to the base. A method for manufacturing a tuning fork crystal unit.   2. The method of manufacturing a tuning fork type crystal resonator according to claim 1, wherein the inclined side is curved.