JP2005217810A - Method of manufacturing piezoelectric transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the tip of a dispenser discharging a conductive adhesive is difficult to be disposed at a position on an electrode pad where the conductive adhesive is applied and adhered in the dispenser capable of applying the viscous conductive adhesive, because the progress of miniaturization of a piezoelectric transducer causes extreme reduction in an area of an electrode pad formed on the concave portion internal bottom surface of a package and distance between the concave portion side surface and the electrode pad. <P>SOLUTION: A method of manufacturing a piezoelectric transducer is provided with a step in which a conductive adhesive is first applied to only one main surface facing the upper part of an external connection electrode film formed on the end of a longitudinal direction of the piezoelectric transducer plate held with a holding tool, a step in which the piezoelectric transducer plate changes the attitude so that the external connection electrode film applied with the conductive adhesive, a step in which the piezoelectric transducer plate is inserted into a concave portion of the package to join and fix the electrode pad formed in the concave portion of the package with the conductive adhesive faces downward, and a step in which the holding tool is separated from the piezoelectric transducer plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a piezoelectric vibrator, and more particularly to a method for manufacturing a small and thin piezoelectric vibrator.

  In recent years, with the remarkable miniaturization of devices such as mobile communication devices, electronic components such as piezoelectric vibrators used in these devices are required to be further miniaturized and thinned. In particular, a piezoelectric vibrator having a shape corresponding to surface mounting is remarkably reduced in size and thickness. Piezoelectric vibrators having an outer size of 5 mm or less in the length direction and a thickness of 2 mm or less have been developed, and miniaturization and thinning in units of μm are progressing.

  FIG. 3 discloses a cross-sectional view of an embodiment of a piezoelectric vibrator produced by a conventional manufacturing method. As a conventional manufacturing method, a concave portion 32 for mounting a piezoelectric diaphragm 30 to be described later is formed in a package 31 having a shape corresponding to surface mounting formed of an insulating material such as ceramics. Two electrode pads 33 are formed on the bottom surface in the recess 32 on one end side or both end sides in the package length direction.

  As a method of mounting the piezoelectric diaphragm 30 on such a package 31 to form a piezoelectric vibrator, first, the side surface of the external connection electrode film formed on one or both ends of the piezoelectric diaphragm 30 held by a holder. A conductive adhesive is applied so as to adhere to both the front and back main surface portions.

  Next, the piezoelectric diaphragm 30 in which the conductive adhesive is applied to the external connection electrode film while being held by the holder, the conductive adhesive 34 on the external connection electrode film is placed on the electrode pad 33 of the package. Move to place. In order to more securely connect the piezoelectric diaphragm 30 and the electrode pad 33 with the conductive adhesive 34, a step of applying the conductive adhesive on the electrode pad 33 is also provided.

  Next, the holder is lowered toward the bottom surface of the recess 32 in the package 31 to join the electrode pad 33 or the conductive adhesive applied on the electrode pad 33 and the conductive adhesive formed on the external connection electrode film, A conductive adhesive 34 formed between the electrode pad 33 and the piezoelectric diaphragm is fixed.

  Thereafter, the holder is removed from the piezoelectric diaphragm 30, a metal lid that covers the opening of the recess 32 of the package 31 is covered, and the recess in the package is hermetically sealed to form a piezoelectric vibrator.

  As a method for applying the conductive adhesive in the conventional manufacturing method, in addition to the above method, after applying the conductive adhesive on the electrode pad of the package using a dispenser, mounting the piezoelectric diaphragm, and then In the dispenser, a new conductive adhesive is applied so that the conductive adhesive applied in the previous step and the external connection electrode film formed on the upper main surface of the piezoelectric diaphragm are bonded. It is used.

  The following documents are disclosed regarding the piezoelectric vibrator as described above.

Japanese Patent Laid-Open No. 11-163653 Japanese Patent No. 2583866

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  However, in the piezoelectric vibrator using the conventional manufacturing method, when the piezoelectric diaphragm is mounted inside the package, the conductive adhesive applied to the external connection electrode films formed on both the main surface and the side surface of the piezoelectric diaphragm. May adhere to the inner wall surface of the concave portion of the package at the time of mounting, and it may not be possible to form a conductive adhesive in an amount that satisfies the adhesion of the piezoelectric diaphragm between the external connection electrode film and the electrode pad. For this reason, it is necessary to widen the space between the inner surface of the recess and the electrode pad so that the conductive adhesive does not adhere to the inner surface of the recess of the package, which may hinder the miniaturization of the piezoelectric vibrator. .

  In the prior art, since the conductive adhesive is also applied on the external connection electrode film formed on the upper main surface side of the piezoelectric diaphragm, the upper main surface of the piezoelectric diaphragm and the lid are A space is required to prevent the conductive adhesive from adhering to the lid or the like, which also hinders the reduction in size and thickness of the piezoelectric vibrator.

  Further, as the piezoelectric vibrator is further downsized, the area of the electrode pad formed on the bottom surface of the concave portion of the package is very small and the distance between the side surface of the concave portion and the electrode pad is narrowed. In a syringe-type dispenser that can apply a conductive adhesive, it is difficult to place the tip of the dispenser at a position where the conductive adhesive on the electrode pad is applied and attached to the syringe-type dispenser from which the conductive adhesive is discharged. Even when conductive adhesive is applied, it may adhere to places where conductive adhesive should not adhere, such as side surfaces of recesses, and on the electrode pad formed on the piezoelectric vibrator package that has been miniaturized. It is becoming impossible to apply a conductive adhesive with a syringe-type dispenser. Inkjet dispensers cannot be used for applying a conductive adhesive because the viscosity of the conductive adhesive is too high.

  In particular, in the case of a piezoelectric vibrator using a so-called cantilever type piezoelectric diaphragm support configuration in which a signal excited by the piezoelectric diaphragm is drawn out from one end in the length direction of the piezoelectric diaphragm, the length direction of the bottom surface inside the package recess Two electrode pads must be formed side by side at one end of the electrode, and as the miniaturization progresses, the distance between the electrode pads becomes very narrow. For this reason, when a conductive adhesive is applied to the electrode pads, there is a possibility that a short circuit occurs between the electrode pads.

The present invention has been made to solve the above-described problems, and a recess is provided inside a package formed of an insulating material, and an electrode pad is formed at the end in the length direction of the bottom of the recess. In this recess, an excitation electrode film and an external connection electrode film electrically connected to the excitation electrode film are formed on the front and back main surfaces at the end in the length direction, and the external connection electrode In a method of manufacturing a piezoelectric vibrator in which a piezoelectric diaphragm coated with a conductive adhesive is inserted on a film, and the conductive adhesive of the piezoelectric diaphragm and an electrode pad of a package are bonded and fixed.
First, a process of applying a conductive adhesive only on one main surface facing upward of the electrode film for external connection formed at the end in the length direction of the piezoelectric diaphragm held by the holder, and this Rotating the holder and changing the posture of the piezoelectric diaphragm so that the external connection electrode film coated with conductive adhesive faces downward, and lowering the holder and inserting the piezoelectric diaphragm into the recess of the package And a step of bonding and fixing the electrode pad formed in the concave portion of the package and the conductive adhesive, and a step of separating the holder from the piezoelectric vibration plate. Is the method.

  By using the method for manufacturing a piezoelectric vibrator according to the present invention, there is no need to apply a conductive adhesive or the like on an electrode pad formed on the package, and a piezoelectric diaphragm coated with a conductive adhesive is packaged. When mounting in the recess, the conductive adhesive does not adhere to the side wall surface or the like in the recess, so that it resembles the desired planar shape of the piezoelectric diaphragm, and the inner bottom surface, the lid and the piezoelectric It is possible to mount the piezoelectric diaphragm with the conductive adhesive in the amount applied first on the package with the recesses with the narrowest gap that does not adversely affect the vibration characteristics of the piezoelectric diaphragm. It can function.

  By this action, the present invention has an effect of providing a piezoelectric vibrator that has high reliability such as the fixing strength of the piezoelectric diaphragm and can be reduced in size and thickness.

Hereinafter, an embodiment of a method for manufacturing a surface-mount type crystal resonator according to the present invention using a quartz crystal which is one of piezoelectric materials will be described with reference to the drawings.
FIG. 1 is a plan view showing a form in which a conductive adhesive is formed on a crystal diaphragm used in a surface-mounted crystal resonator according to the present invention.
FIG. 2 is a process diagram disclosed by using a sectional view when the process of mounting the crystal diaphragm disclosed in FIG. 1 on a package is cut at the position of the cutting line A1-A2 illustrated in FIG.
In each figure, a part of the structure is not shown for the sake of clarity. Each dimension is also partially exaggerated, and the thickness dimension of each part is particularly exaggerated.

  That is, in the quartz crystal plate 10 disclosed in FIG. 1, on both the front and back main surfaces of the rectangular crystal base plate 11, a multi-layer made of gold and chrome is located at the center of the main surface of the crystal base plate 11 facing the front and back. An excitation electrode film 12 having a structure is formed, and an extraction electrode film 13 extends from the excitation electrode film 12 formed on the front and back main surfaces toward one end in the length direction of the quartz base plate 11. Further, an external connection electrode film 14 that is fixedly connected to an electrode pad 23 formed in a recess 22 of the package 21 described later is formed on the tip of the crystal vibrating plate 10. The external connection electrode film 14 is connected to an external connection electrode film having substantially the same shape formed on the opposite main surface through an electrode film formed on the side surface of the piezoelectric element plate 11. 1 is electrically conductive on the external connection electrode film 14 formed on the main surface side opposite to the electrode pad 23 when the crystal diaphragm 10 disclosed in FIG. The adhesive 15 is applied.

  FIG. 2 discloses a process of mounting the crystal diaphragm 10 disclosed in FIG. 1 on the package 21 to form a crystal resonator that is one of piezoelectric resonators. First, the collet 24 that holds the crystal diaphragm 10 is attached to the main surface on the lower side of the crystal diaphragm 10. At this time, a hole is formed in the surface of the portion of the collet 24 that is in contact with the crystal diaphragm 10 (not shown), and the pressure inside the hole is made lower than the external pressure, so that the crystal diaphragm 10 is connected to the collet 24. It is adsorbed and held on the holding surface. The collet 24 is connected to a mechanism for moving the piezoelectric diaphragm to a desired position.

  Next, on the external connection electrode film 14 formed on the main surface opposite to the main surface on which the collet 24 of the crystal diaphragm 10 is mounted, the conductive material is prevented from flowing out to the side surface of the crystal diaphragm 10. Adhesive 15 is applied by a dispenser (not shown). Since there is nothing in the space around the external connection electrode film 14 that obstructs the arrangement of the tip of the dispenser, it is easy to apply the conductive adhesive 15 on the external connection electrode film 14 by the dispenser.

  Next, the collet 24 holding the quartz vibrating plate 10 coated with the conductive adhesive 15 is rotated, and the main surface of the quartz vibrating plate 10 facing upward is coated downward. Turn to. After that, the conductive adhesive 15 formed on the quartz crystal plate 10 whose posture is reversed is opposed to the electrode pad 23 formed in the recess 22 of the package 21 arranged at a predetermined position, and the inner surface of the recess 22 When the crystal diaphragm 10 is moved to a position where the crystal diaphragm 10 is not in contact with the collet 24 by a mechanism connected to the collet 24 and the crystal diaphragm 10 is disposed at a desired position, the crystal diaphragm 10 is lowered together with the collet 24 The collet 24 is fixed at a position where the conductive adhesive 15 is joined to the electrode pad 23. At this time, since the conductive adhesive 15 is applied only in the region on the external connection electrode film formed on one main surface of the quartz vibrating plate 10, the conductive adhesive 15 is conductive to the side wall surface in the recess 22 at the time of insertion. The adhesive 15 does not adhere.

  The package 21 used at this time has a shape corresponding to the surface mounting formed of an insulating material such as ceramics, and a recess 22 is formed. Two electrode pads 23 are formed on the bottom surface of the recess 22 on one end side in the length direction of the package. The electrode pads 23 are fixedly connected to other substrates formed on the outer peripheral bottom surface of the package 21. The external connection electrode pads 24 are electrically connected to each other.

  The shape of the recess 22 formed in the package 21 is similar to the length and width direction of the quartz crystal plate 10 in the length and width direction of the recess 22, and the length and width direction of the recess 22. When the crystal diaphragm 10 is inserted into the recess 22, there is a minimum distance at which the entire inner surface of the recess 22 does not contact the crystal diaphragm and does not adversely affect the vibration characteristics of the crystal diaphragm. It is formed with such dimensions.

  Next, the collet 24 is removed from the crystal diaphragm 10, and then the conductive adhesive 15 bonded to the electrode pad 23 is heated and solidified to fix the crystal diaphragm to the electrode pad. A metal lid (not shown) that covers the opening of the recess 22 is disposed on the metallized layer on the top of the side wall of the package 21. At this time, in the present invention, since the conductive adhesive 15 is not applied on the upper main surface of the crystal diaphragm 10 mounted in the recess, the side wall that minimizes the distance between the crystal diaphragm 10 and the lid. By using the package 21 having the height of the part, it is possible to reduce the thickness of the crystal resonator. After that, the atmosphere in the recess 22 is replaced with nitrogen or evacuated to vacuum, and then hermetically sealed, thereby forming a crystal resonator.

  In this embodiment, the case where quartz is used as the piezoelectric material constituting the piezoelectric diaphragm is exemplified. However, since the effect in the present invention does not change depending on the material of the piezoelectric material, other piezoelectric materials are used. Even when used for materials such as ceramics and lithium tantalate, the same effects as the present embodiment can be obtained. Moreover, although the case where a collet is used as a holder for holding the piezoelectric diaphragm has been disclosed in this embodiment, this is also the case where the effect of the present invention is not achieved due to the difference in the holder, Other holders may be used.

FIG. 1 is a plan view of a quartz crystal plate mounted on a piezoelectric vibrator according to the present invention as seen from the main surface on the fixing side. FIG. 2 is a process diagram shown in a schematic cross-sectional view when the process of mounting the crystal diaphragm disclosed in FIG. 1 on the package is cut at the position of the cutting line A1-A2 shown in FIG. FIG. 3 is a cross-sectional view of an embodiment of a piezoelectric vibrator produced by a conventional manufacturing method.

Explanation of symbols

10. Piezoelectric diaphragm (crystal diaphragm)
12, excitation electrode film 14, external connection electrode film 15, conductive adhesive 21, package 22, recess 23, electrode pad 24, holder (collet)

Claims (1)

A recess is provided inside the package formed of an insulating material, and an electrode pad is formed at the end in the length direction of the bottom surface of the recess. In the recess, an excitation electrode film on both the front and back main surfaces and An external connection electrode film electrically connected to the excitation electrode film is formed at the end in the length direction, and a piezoelectric diaphragm coated with a conductive adhesive is inserted on the external connection electrode film, and the piezoelectric In the method of manufacturing a piezoelectric vibrator in which the conductive adhesive of the diaphragm and the electrode pad of the package are bonded and fixed,
Applying a conductive adhesive only on one main surface facing upward of the external connection electrode film formed at the end in the length direction of the piezoelectric diaphragm held by the holder;
Rotating the holder and changing the piezoelectric diaphragm to a posture in which the external connection electrode film coated with the conductive adhesive faces downward;
Lowering the holder, inserting the piezoelectric diaphragm into the recess of the package, and bonding and fixing the electrode pad and the conductive adhesive formed in the recess of the package;
Separating the holder from the piezoelectric diaphragm, and a method for manufacturing the piezoelectric vibrator.

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