JP2005286896A - Piezoelectric vibrator and its fabricating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact piezoelectric vibrator in which a piezoelectric elemental plate is supported by means of bumps and an electrically conductive adhesive on an electrically conductive pad in a cantilevered state to be hermetically sealed thereon, and to provide its fabricating method. <P>SOLUTION: There is provided a fabricating method of a structure in which the piezoelectric elemental plate is supported through a connection electrode on the electrically conductive pad upon an insulation substrate inside a piezoelectric vibrator container in the cantilevered state to be hermetically sealed thereon, and is provided its piezoelectric vibrator. The fabricating method includes a process where the bumps are formed on the electrically conductive pad, that where the piezoelectric elemental plate is arranged and the bumps are connected by welding to the piezoelectric elemental plate by means of supersonic vibration and that where the electrically conductive pad and an external terminal of the piezoelectric elemental plate are adhered together by the electrically conductive adhesive. A vibrating electrode formed on front and back sides of the piezoelectric elemental plate is allowed to conduct to the external terminal through the connection electrode by means of the electrically conductive adhesive applied so as to range from the bumps formed on the electrically conductive pad and the electrically conductive pad to the piezoelectric elemental plate. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

        The present invention relates to a small piezoelectric vibrator in which a piezoelectric element plate is supported in a cantilever state on a conductive pad by a bump and a conductive adhesive and hermetically sealed, and a method for manufacturing the same.

        In recent years, it has become common for piezoelectric vibrators to have a structure in which a piezoelectric base plate is cantilevered inside a piezoelectric vibrator and is hermetically sealed. This is because both ends of the piezoelectric element plate are fixed when the piezoelectric element plate is supported on a conductive pad formed on the insulating substrate of the piezoelectric vibrator in a state where both ends are supported, and this adversely affects characteristics such as frequency characteristics. It is because there is a possibility of giving.

        On the other hand, the recent trend is centered on transmission systems in the communication field, etc., and there is a demand for extremely small and low profile from the market, as well as weight reduction and price reduction. However, for this purpose, a piezoelectric vibrator capable of making the outer shape smaller and thinner is formed by hermetically sealing the previous piezoelectric element plate with a support structure in a cantilevered support state inside the container of the piezoelectric vibrator. Manufacturing has become common.

An example of a method for manufacturing a piezoelectric vibrator is that there are two conductive materials at one end in the length direction of the bottom of a recess formed in an insulating material such as ceramics and provided for a surface-mounted container. Pads are formed, and metal bumps (hereinafter referred to as bumps) made of gold or the like are formed at arbitrary positions on these conductive pads, and excitation electrodes and external connection electrodes are formed on the main surface and the back surface thereof. While placing the base plate and holding it with a holder such as a collet, the holder is ultrasonically vibrated in the length direction of the container while applying a load to the bottom surface of the concave portion of the piezoelectric vibrator container, The external connection electrode and the bump are melt-bonded by frictional heat, and then the holder is removed from the previous piezoelectric element plate, and a metal lid is placed over the recess of the piezoelectric vibrator container to cover the recess in the container. Piezoelectric vibrator is formed by hermetically sealing To.
JP 2001-345664 A

        In addition, the applicant did not find 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, as described above, as the outer shape of the piezoelectric vibrator becomes smaller and the inner volume thereof becomes smaller, the open end of the piezoelectric element plate facing the end of the piezoelectric element plate held by the conductive adhesive and The distance from the inner wall including the lid of the piezoelectric vibrator becomes smaller, and as a result, when deformation occurs in a substrate of a device or the like on which the piezoelectric vibrator is mounted, the piezoelectric vibrator container in which the piezoelectric element plate is mounted inside Therefore, the open end of the above-mentioned piezoelectric element plate mounted inside the piezoelectric vibrator is the inner wall of the piezoelectric vibrator, particularly the substrate inside the piezoelectric vibrator below the piezoelectric element plate, and the upper side of the piezoelectric element plate. There is a problem in that there is a risk of coming into contact with the inner surface of the lid mounted on the.

        Here, when the open end of the piezoelectric element plate facing the end of the piezoelectric element plate held by the conductive adhesive comes into contact with the inner wall of the piezoelectric vibrator container, the contact stress is generated in the piezoelectric element plate, and As a result, it causes a frequency shift.

        The above-mentioned piezoelectric vibrator that causes a frequency shift cannot naturally be a product, and as a result, the production yield of the product may be lowered, and the reliability of the piezoelectric vibrator may be lowered. At the manufacturing stage, various ideas have been made to secure a gap between the open end of the piezoelectric element plate inside the piezoelectric vibrator and the inner wall of the piezoelectric vibrator, but a reliable method has not yet been found. There was no actual situation.

        In addition, in the cantilever support on the conductive pad only by the conductive adhesive not using the bump instead of the cantilever support of the piezoelectric element plate on the conductive pad by the bump described above, after the application of the conductive adhesive, Piezoelectric vibrators have a risk that the position accuracy of the piezoelectric element plate may be deteriorated, such that the piezoelectric element plate is pulled due to the curing and shrinkage of the conductive adhesive, and as a result, the open end of the piezoelectric element plate is displaced. There is a problem that it becomes difficult to manage the amount of the conductive adhesive as the size is reduced.

        In other words, a surface-mount type piezoelectric vibrator is generally used by a reflow method for mounting the device on the substrate. Therefore, considering the heat resistance of the piezoelectric vibrator, a silicon-based This silicon-based adhesive is familiar with gold (Au), which is a common surface material for connection electrodes formed on conductive pads on the substrate inside the piezoelectric vibrator. There is a problem that the electrical connection between the external connection electrode of the piezoelectric element plate and the connection electrode formed on the previous conductive pad may not be ensured. .

        The present invention has been made under the technical background as described above. Accordingly, the object of the present invention is to have a piezoelectric element plate cantilevered on a conductive pad by a bump and a conductive adhesive. And a method for manufacturing the piezoelectric vibrator.

        In order to achieve the above-described object, the present invention provides a hermetic seal in which a piezoelectric element plate is supported in a cantilever state via a connection electrode on a conductive pad on an insulating substrate inside a piezoelectric vibrator container. In the method of manufacturing a piezoelectric vibrator having the structure described above, the step of forming a bump on the conductive pad, the placement of the piezoelectric element plate on the bump, and the fusion bonding of the bump to the piezoelectric element plate by ultrasonic vibration are performed. And a step of adhering the conductive pad and the external connection terminal of the piezoelectric base plate using a conductive adhesive.

        In the piezoelectric vibrator having a structure in which the piezoelectric element plate is hermetically sealed by being supported in a cantilever manner on a conductive pad on an insulating substrate inside the piezoelectric vibrator container with a connection electrode interposed therebetween, Excitation electrodes formed on the front and back of the main surface of the plate are connected to the bumps formed on the previous conductive pad and a conductive adhesive attached to the piezoelectric element plate from the conductive pad via the connection electrode. The piezoelectric element plate is supported by being electrically connected to the external connection terminal.

        According to the method of manufacturing a piezoelectric vibrator of the present invention, the open end of the piezoelectric element plate mounted inside the piezoelectric vibrator is the inner wall of the piezoelectric vibrator, particularly the substrate inside the piezoelectric vibrator below the piezoelectric element plate, There is no possibility of coming into contact with the inner surface of the lid mounted above the piezoelectric element plate, and the manufacturing yield of the piezoelectric vibrator can be significantly increased.

        In addition, according to the method for manufacturing a piezoelectric vibrator of the present invention, since the positional accuracy of the piezoelectric element plate is increased by using the bump, the possibility of contact of the piezoelectric element plate with the inner wall including the lid of the piezoelectric vibrator is possible. The gap between the piezoelectric element plate inside the manufactured piezoelectric vibrator and the inner wall can be reliably maintained, and in addition, reliability such as ensuring conduction between the piezoelectric element plate and the conductive pad inside the piezoelectric vibrator can be ensured. It can be increased.

        In addition, in the method of manufacturing a piezoelectric vibrator of the present invention that uses not only bumps but also conductive adhesive, it is applied to a piezoelectric element plate such as a quartz element plate by fixing the piezoelectric element plate to the conductive pad only by the bumps. It is possible to remarkably reduce the damage to the piezoelectric element plate and the deterioration of the piezoelectric vibrator characteristics due to the strength of the bump strength.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In addition, the same code | symbol in each figure shall show the same object.

        FIG. 1 is a process diagram of a method for manufacturing a piezoelectric vibrator 2 in which a piezoelectric element plate 1 is supported on a conductive pad 5 in a cantilevered state by a bump 9 and a conductive adhesive 10 according to the present invention. That is, first, a step of forming bumps 9 on the conductive pads 5 (S101) is performed, and then the piezoelectric element plate 1 is disposed on the bumps 9 using a holder of the piezoelectric element plate 1, and then ultrasonic waves are applied. A step of melting and bonding the bump 9 to the piezoelectric base plate 1 by generating frictional heat between the bump 9 and the piezoelectric base plate 1 by vibration (S102) is performed, and finally the conductive pad 5 by the conductive adhesive 10 is used. And the external connection terminal 11 of the piezoelectric element plate 1 are bonded (S103). According to the method of manufacturing the piezoelectric vibrator 2 of the present invention, first, the inclination of the open end of the piezoelectric element 1 is determined by fusion bonding of the bump 9 to the piezoelectric element 1, and the piezoelectric of the main surface of the piezoelectric element 1 is determined. By accurately determining the parallelism and position with respect to the bottom insulating substrate 4 in the vibrator 2 container, and then bonding between the conductive pad 5 and the external connection terminal 11 of the piezoelectric base plate 1 using the conductive adhesive 10, Electrical continuity can be ensured. According to the method of manufacturing the piezoelectric vibrator 2 of the present invention using the conductive adhesive 10 together, the piezoelectric element plate 1 such as a crystal element plate 1 is applied by fixing the piezoelectric element plate 1 to the conductive pad 5 only by the bumps 9. There is an effect that the damage of the piezoelectric base plate 1 due to the strength of the bump 9 and the deterioration of the characteristics of the piezoelectric vibrator 2 can be remarkably reduced.

       FIG. 2 is a schematic side view showing a state in which the piezoelectric element plate 1 is supported on the conductive pad 5 in a cantilever state by the bump 9 and the conductive adhesive 10 by the method for manufacturing the piezoelectric vibrator 2 of the present invention. It is a schematic diagram. As shown in the figure, in addition to the fusion bonding of the bump 9 to the lower surface main surface of the piezoelectric element plate 1, the upper surface main surface of the cantilever support portion of the piezoelectric element plate 1 is hung on the conductive pad 5 so as to be covered. By applying the conductive adhesive 10, the support of the piezoelectric base plate 1 can be made stronger. The conductive adhesive 10 may be a general silicon-based adhesive.

       FIG. 3 is a schematic top view showing a state in which the piezoelectric element plate 1 is supported on the conductive pad 5 in a cantilever state by the bump 9 and the conductive adhesive 10 by the method for manufacturing the piezoelectric vibrator 2 of the present invention. It is a schematic diagram.

       FIG. 4 shows a method of manufacturing the piezoelectric vibrator 2 according to the present invention. In the state where the piezoelectric element plate 1 is cantilevered by a plurality of bumps 9 and a conductive adhesive 10 on a single conductive pad 5. It is a general | schematic side surface schematic diagram which shows a mode supported by. There may be a plurality of bumps 9 on one conductive pad 5, or two or more bumps as shown in the figure, and these cases are also included in the technical scope of the present invention. Needless to say.

       FIG. 5 shows a state of another embodiment in which the piezoelectric element plate 1 is supported on the conductive pad 5 in a cantilever state by the bump 9 and the nonconductive adhesive by the method of manufacturing the piezoelectric vibrator 2 of the present invention. FIG. As shown in this figure, the bonding strength between the piezoelectric element plate 1 and the conductive pad 5 and the reliability of conduction are improved by fusion bonding with a plurality of bumps 9 formed on one conductive pad 5. The bonding strength between the piezoelectric element plate 1 and the conductive pad 5 can be further reinforced by using a non-conductive adhesive as the adhesive.

       FIG. 6 is a schematic side view showing a state in which the piezoelectric element plate 1 is supported on the conductive pad 5 in a cantilever state only by the conventional conductive adhesive 10.

It is process drawing of the manufacturing method of the piezoelectric vibrator which supports a piezoelectric element board on a conductive pad in the cantilever state with the bump and conductive adhesive of this invention. FIG. 5 is a schematic side view schematically showing a state in which a piezoelectric element plate is supported on a conductive pad in a cantilever state by a bump and a conductive adhesive by the method for manufacturing a piezoelectric vibrator of the present invention. FIG. 4 is a schematic top view schematically showing a state in which a piezoelectric element plate is supported on a conductive pad in a cantilever state by a bump and a conductive adhesive by the method for manufacturing a piezoelectric vibrator of the present invention. Schematic showing a state in which a piezoelectric element plate is supported on a conductive pad in a cantilevered manner by a plurality of bumps and a conductive adhesive on one conductive pad by the method for manufacturing a piezoelectric vibrator of the present invention. It is a side surface schematic diagram. Schematic top view schematically showing a state of another embodiment in which a piezoelectric element plate is supported on a conductive pad in a cantilever state by a bump and a non-conductive adhesive by the method for manufacturing a piezoelectric vibrator of the present invention. It is. It is a schematic side view showing a state in which a piezoelectric element plate is supported on a conductive pad in a cantilever state only by a conventional conductive adhesive.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric base plate 2 Piezoelectric vibrator 3 Piezoelectric vibrator container 4 Insulating substrate 5 Conductive pad 6 Connection electrode 7 Main surface of piezoelectric base plate 8 Excitation electrode 9 Bump 10 Conductive adhesive 11 External connection terminal 12 Lid

Claims (2)

In the method of manufacturing a piezoelectric vibrator in which the piezoelectric element plate is hermetically sealed by being supported in a cantilever state via a connection electrode on a conductive pad on an insulating substrate inside the piezoelectric vibrator container,
Forming bumps on the conductive pads;
Disposing the piezoelectric element plate on the bump and performing fusion bonding of the bump to the piezoelectric element plate by ultrasonic vibration;
A method of manufacturing a piezoelectric vibrator, comprising: a step of bonding the conductive pad and an external connection terminal of the piezoelectric base plate with a conductive adhesive. In the piezoelectric vibrator having a structure in which the piezoelectric element plate is supported and hermetically sealed in a cantilever state via a connection electrode on a conductive pad on an insulating substrate inside the piezoelectric vibrator container,
Excitation electrodes formed on the front and back of the main surface of the piezoelectric base plate are bumps formed on the conductive pad, and a conductive adhesive attached to the piezoelectric base plate from the conductive pad. A piezoelectric vibrator characterized in that the piezoelectric element plate is supported by being electrically connected to an external connection terminal via the connection electrode.

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