JP2000049561A - Structure of piezoelectric vibrator and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the structure of a piezoelectric vibrator which solves the problem that connecting to a lead electrode on the opposite side from a pad side becomes troublesome at the time of connecting and fixing the lead electrode to the pad in a surface mounted package because the lead electrode extending from exciting electrodes formed on both principal planes of respective vibrators must terminate on each principal plane at the time of manufacturing respective small pieces of vibrator from a large wafer by means of batch processing and to provide its manufacturing method. SOLUTION: In a piezoelectric element which is provided with exciting electrodes 13 on both principal planes of a piezoelectric element plate 12 and respectively extends lead electrodes 14 toward the same edge of the piezoelectric element plate or two different edges from each exciting electrode, a recessed- shaped through hole 17 that comes into contact at least with either of the lead electrodes is formed at the edge of the element plate and a conductor film 16 in the through hole is electrically connected to the lead electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a piezoelectric vibrator and a method of manufacturing the same. More particularly, the present invention relates to a method of manufacturing individual vibrator small pieces from a large wafer by batch processing. Since the lead electrode extending from the formed excitation electrode is terminated on each main surface, when the lead electrode is connected and fixed to the pad in the surface mount package, the lead electrode is connected to the lead electrode on the side opposite to the pad side. The present invention relates to a structure of a piezoelectric vibrator capable of solving a problem that connection is troublesome and a method of manufacturing the same.

[0002]

2. Description of the Related Art Products in which electrodes are formed on a piezoelectric element such as a quartz element, such as a tuning fork type crystal element for a watch and an HFF element using an AT-cut sheet crystal, are manufactured by batch processing a large wafer. By applying photolithography technology and etching technology, electrodes are formed on both sides of the base plate and the base plate is formed (split grooves and the like are formed) to produce a plurality of connected vibrator pieces (chips), and then cut. Thereby, individual vibrator pieces are obtained. Since the electrodes formed on both surfaces of the vibrator piece are formed collectively by performing evaporation using a mask on both surfaces of the large wafer, each electrode formed on both surfaces of an individual piece after being cut and separated is used. The structure cannot be such that the lead electrode extending from the excitation electrode reaches the opposite side. When such a vibrator piece is mounted in a package for surface mounting, a conductive adhesive, solder, or the like is used in a state where an electrode on one side of the vibrator piece is in contact with a pad formed on the bottom surface of the package. The binder is fixed by a binder, but the electrodes on the other side (upper side) are usually coated twice with an adhesive or the like to ensure conduction with the pads in the package. Here, the double coating is to realize the connection between the two by applying an adhesive twice to fill the distance between the pad and the upper lead electrode, thereby increasing the usage amount. But the adhesive
The work of re-coating is complicated and increases the number of works, so that improvement in this point has been demanded. In addition, since the amount of the applied adhesive is increased by applying the adhesive twice, there is a problem that the adhesive drips and adheres to an unnecessary portion. This is illustrated and described. As shown in FIG. 9, the excitation electrodes 2 and 2 and the lead electrodes extending from the excitation electrodes to the opposite edge of the substrate, respectively, are provided on the front and back surfaces of the piezoelectric element 1 made of quartz or the like. Although the lead electrodes 3 and 3 are formed, each of the lead electrodes 3 and 3 terminates on the main surface where they are formed and does not reach the opposite side surface. This is because it is impossible to form a lead electrode so as to reach the opposite side because the electrode is formed in a state of a large wafer. Therefore, when mounting on the pad in the package as described above, it is difficult to connect the lead electrode located on the opposite side of the pad to the pad, resulting in a decrease in productivity and an increase in cost.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excitation electrode formed on both main surfaces of an individual vibrator when manufacturing individual vibrator pieces from a large wafer by batch processing. When the lead electrode is connected to the pad in the surface mount package and fixed, the connection with the lead electrode on the side opposite to the pad side must be terminated. The present invention relates to a structure of a piezoelectric vibrator capable of solving a trouble of troublesomeness and a method of manufacturing the same. That is, in the present invention, when forming a crystal resonator by batch processing, a concave portion and a hole are formed on the base plate surface in contact with the lead electrode so as to penetrate the front and back, and the concave portion and the hole are formed as through holes. The conductive film extending to the opposite side is connected to the lead electrode. As a result,
The conductors connected to the excitation electrodes on both surfaces are located on the surface on the pad side, which facilitates connection with the lead electrode on the opposite side from the pad side.

[0004]

In order to solve the above-mentioned problems, the invention of claim 1 comprises excitation electrodes on both main surfaces of a piezoelectric element, and the same edge of the piezoelectric element from each excitation electrode;
Alternatively, in a piezoelectric vibrator having a structure in which lead electrodes are respectively extended toward two different edges, a recessed through hole in contact with at least one of the lead electrodes is formed at an edge of the base plate, and the through hole is formed. The inner conductive film is electrically connected to the lead electrode. According to the invention of claim 2, the excitation electrodes are provided on both main surfaces of the piezoelectric element, and the lead electrodes extend from each excitation electrode toward the same edge of the piezoelectric element or two different edges. In the piezoelectric vibrator having the structure, a hole-shaped through-hole in contact with at least one of the lead electrodes is formed on the base plate surface, and the conductor film in the through-hole is electrically connected to the lead electrode. I do. According to a third aspect of the present invention, a concave portion is formed on one main surface of the piezoelectric element plate, a conductor film is formed on the concave portion side, and an excitation electrode and a lead electrode are formed on the other main surface, respectively. A recessed or hole-shaped through-hole in contact with the lead plate is formed on the edge of the base plate or on the surface of the base plate, and the conductor film in the through-hole is electrically connected to the lead electrode. According to a fourth aspect of the present invention, when the piezoelectric vibrator is connected to a pad provided in a recess of a package, a binder is filled in the through-hole with the through-hole placed on the pad. Features. The invention according to claim 5 is a step of forming through holes as through holes at positions corresponding to the respective small pieces on the front and back surfaces of the large wafer to which the small pieces serving as the piezoelectric element plates are connected, and exciting electrodes on both the front and back faces of each small piece portion And forming a conductive film to be a lead electrode, forming a conductive film in the through hole, and dividing the large wafer into small pieces. The invention of claim 6 is characterized in that the step of forming the excitation electrode and the lead electrode and the step of forming a conductor film in the through hole are performed simultaneously. The invention according to claim 7 is characterized in that the piezoelectric vibrator is an AT cut quartz crystal vibrator. The invention according to claim 8 is characterized in that, when the piezoelectric vibrator is an AT-cut quartz vibrator, a through hole is formed by etching from both sides of the piezoelectric element plate.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 is a perspective view of an AT-cut quartz oscillator as an example of the piezoelectric oscillator of the present invention. The quartz oscillator 11 is excited on both main surfaces of a rectangular flat plate 12 so as to be symmetrical with each other. Electrode 13 and lead electrode 14
And a notch 15 formed at the edge of the base plate from which one lead electrode 14 extends.
Has a configuration in which a conductive film 16 that is continuous with the lead electrode 14 is formed on the inner wall. The conductor film 16 extends to the opposite main surface on the extension of the lead electrode 14. That is, the upper lead electrode 14 is extended to the vicinity of the lower surface by making the recess 15 a through hole 17. By providing a recess 15 ′ shown by a dotted line on the opposite side of the recess 15 to form a through hole 17 ′ so that the lead electrode 14 on the lower surface extends to the upper surface, the crystal resonator 11 When mounting in a package, there is no longer any up-down direction, so that connection can be made regardless of which side is faced down, and workability is improved. The illustrated position of the through hole 17 is merely an example, and it goes without saying that the position of the through hole 17 can be variously changed according to the extending direction of the lead electrode.

FIG. 2A is a perspective view showing a state in which the crystal unit 11 is mounted in a package body 20, and FIG. 2B is a sectional view taken along the line AA. Package body 20
When each lead electrode 14 is connected to the pad 23 formed on the step 22 on the inner bottom surface of the recess 21 formed on the upper surface of the lower electrode, the lower lead electrode 14 is mounted on one pad 23. Place a conductive adhesive or solder (binder)
The connection is made at 25, and the upper lead electrode 14 is connected to the conductor film 16 in the through hole 17 and the other pad 23 with a small amount of conductive adhesive 25 or the like. That is, the work of connecting the upper and lower lead electrodes 14 to the respective pads 23 can be completed by applying the conductive adhesive 25 once, respectively, and the productivity can be improved. Further, by pouring the conductive adhesive or the like into the through-hole 17, the conductive adhesive or the like is bonded to the three inner wall surfaces of the through-hole, so that the bonding strength is increased and only a small amount of the adhesive is required. Further, since the adhesive or the like accumulates in the through-hole, the problem of flowing out to the outside is eliminated. As a result of using less adhesive, the mechanical strain after solidification is reduced, the influence on the frequency of the vibrator is reduced, and the generation of gas is reduced, so the crystal resonator is hermetically sealed in the package. In this case, it is possible to avoid the adverse effect of the gas when the gas flows. Next, FIG. 3 shows a case where a quartz oscillator 11 of a type in which through holes 17 are formed at opposite end edges of the piezoelectric element
FIG. 3 is a cross-sectional view showing a state where the semiconductor device is mounted on the semiconductor device 3. In this case, a conductive adhesive or the like 25 is applied so as to connect the conductive film 16 in the recesses 15 located at both ends and each pad 23. Thus, both lead electrodes 14 can be connected to each pad 23.

FIG. 4A is a perspective view showing the structure of a crystal unit according to another embodiment of the present invention.
1 is different from the other embodiments in that the quartz crystal plate 12 is not a flat plate but has a configuration in which a concave portion 30 is formed on one surface (a lower surface in this example). Also, the recess 30
The conductive film 31 is formed on the bottom surface (the vibrating portion 37), its inner wall, and a part of the outer frame 38, and the excitation electrode 32 and the lead electrode 33 are formed on a flat surface (the surface side of the vibrating portion 37). Form. Further, the lead electrode 33 is connected to the through hole 34 formed at the side edge by bending 90 degrees to the side. The through hole 34 includes a recess 35 and a conductor film 36 formed on the inner wall of the recess, and the lead electrode 33 extends to the opposite side via the conductor film 36. Further, another through hole 34 ′ is provided at the edge opposite to the edge where the through hole 34 is formed, and this through hole 34 ′ is connected to a lead electrode (not shown) extending from the conductor film 36. As shown in FIGS. 4 (b) and 4 (c), this type of crystal resonator 11 is mounted on a pad 23 on the inner bottom surface of a package 20, and a conductive adhesive (binder) 2 is provided in each recess 35.
5 is mounted by connecting each conductor film 36 to each pad 23 by filling the space 5. In this embodiment, two through holes 34 each including a recess 35 and a conductor film 36 are provided. However, only the through hole 34 connected to the upper lead electrode 33 is provided, and the lower conductor film 36 is formed. May be directly connected to the other pad 23.

[0008] The crystal resonator of this embodiment also has the same effect as the above embodiment. That is, the operation of connecting both the lead electrodes 33 to the respective pads 23 can be completed by one application of the conductive adhesive 25 or the like, respectively.
Productivity can be improved. Also, through hole 3
By pouring a conductive adhesive or the like into 4, the conductive adhesive or the like adheres to the three inner wall surfaces of the through hole.
Adhesive strength is increased, and less adhesive is required. Further, since the adhesive or the like accumulates in the through holes, the problem of flowing to the outside is eliminated. As a result of using less adhesive, the mechanical strain after solidification is reduced, the influence on the frequency of the vibrator is reduced, and the generation of gas is reduced, so the crystal resonator is hermetically sealed in the package. In this case, it is possible to avoid the adverse effect of the gas when the gas flows.

Next, FIGS. 5 (a) and 5 (b) show that the base plate 12 of the crystal unit 11 is not flat, as in the embodiment of FIG.
A concave portion 30 is provided on one side. An electrode film 31 is formed on one surface of the base plate 12 including the recessed portion 30, and an excitation electrode 32, a lead electrode 33, and a through hole 3 are formed on the other flat surface.
4 are formed. The through-hole 34 includes a recess 35 having a cut edge, and a conductor film 36 extending to the other side of the lead electrode 33 formed on the inner wall of the recess 35. The inner bottom surface of the recess 30 has an ultra-thin plate-shaped vibrating portion 3.
7 is provided, and has a configuration in which the vibrating portion 37 is reinforced by the thick outer frame 38. FIG. 5B is a cross-sectional view showing a state in which the crystal unit is mounted in a package. The crystal unit 11 with the concave portion 30 facing down is placed on a pad 23 in a package 20. And then the electrode film 3
Mounting is performed by connecting and fixing the conductive film 36 of the through hole 34 and the other pad 23 between the first pad 23 and the one pad 23 with a conductive adhesive 25 or the like. Also in this case, the conductive film 36 in the through hole and the pad can be connected by one application without applying a conductive adhesive or the like twice when connecting the upper lead electrode 33 to the pad 23. Therefore, workability is greatly improved. The effects of this embodiment are the same as those described in the above embodiments.

Next, FIG. 6A is a perspective view of another embodiment of the crystal unit of the present invention, FIG. 6B is a perspective view of a state of being housed in a package, and FIG. FIG. 3B is a cross-sectional view of the crystal resonator 11. In this crystal resonator 11, an excitation electrode 13 and a lead electrode 14 are formed on both main surfaces of a plate-shaped quartz crystal plate 12 so as to be symmetrical. The lead electrode 14 is extended to the other surface side by forming a through hole 40 (hole 41, conductive film 42) in the shape of a hole in the surface of the base plate located at the position shown in FIG. In this example,
Although the through holes 40 for extending the front and back lead electrodes 14 to the opposite sides are provided respectively, the through holes 40 may be provided only to one of the lead electrodes. When the crystal unit 11 is housed in the package 20, as shown in FIG. 6C, the through hole 40 and one pad 23, and the lead electrode 14 on the lower surface and the other pad 23 are in contact with each other. Each through hole 40 is filled with a required amount of conductive adhesive 25 or the like. Thus, the connection between each pad 23 and each lead electrode 14 is completed. The formation position of the through hole 40 (not shown) is merely an example, and it goes without saying that various changes can be made in accordance with the direction of the lead electrode 14 extending from each excitation electrode 13. The effect obtained by providing the through holes in this embodiment is the same as that described in each of the above embodiments.

Next, FIGS. 7 (a), 7 (b) and 7 (c) show a quartz oscillator according to another embodiment of the present invention. This quartz oscillator 11 is of a cantilever type different from the above-mentioned types. Vibrator. Accordingly, the lead electrodes 14, 14 extending from the excitation electrodes 13, 13 formed on both main surfaces are both extended toward the same edge of the base plate 12. In this embodiment, through-holes 50, 50 are formed at the edges of the raw plate located in the direction in which the lead electrodes 14,
4, 14 extend to the opposite main surface. That is,
The through hole 50 includes a recess 51 and a conductor film 52 formed on the inner wall of the recess 51. The conductor film 52 is electrically connected to each lead electrode 14 and has a surface on which the lead electrode is formed. Extends to near the opposite surface. For this reason, when the crystal unit 11 is fixed in a cantilever state to the pad 57 on the step 56 in the package 55, any surface may be turned upward. By filling the adhesive 25 or the like, each pad 57 and each through hole (each lead electrode 14) can be reliably connected. In the above embodiment, through-holes are provided for each of the lead electrodes 14, 14. However, this is an example, and one of the lead electrodes 14
May be provided only in this case. In this case, the through hole 50 is formed only in the lead electrode 14 on the upper side.
Is provided, the connection between the upper lead electrode and the pad is completed by simply filling the through hole 50 with the conductive adhesive 25 when connecting the crystal oscillator to the pad 57. , Workability is improved. In the above embodiment, two or 1
A plurality of recessed through holes 50 were formed, but a hole-like through hole was formed on the surface of the base plate closer to the center than the edge of the base plate, and the upper side of the upper surface was formed using the conductive film in the through hole. The connection between the lead electrode and the pad may be realized. Note that the crystal resonator having the recessed portions shown in FIGS. 4 and 5 can be of a cantilever type as in the example of FIG. 7, and in this case, one of the crystal blanks 12 is used. 2 along the edge
Would form two through holes. The effect obtained by providing the through holes in this embodiment is the same as that described in each of the above embodiments.

Next, a method of manufacturing the crystal resonator shown in each of the above embodiments by batch processing will be described with reference to FIG. Here, as an example, a method of manufacturing the crystal resonator shown in FIG. 1 is illustrated and described, but the manufacturing procedure for the crystal resonator shown in other than FIG. 1 is in accordance with the procedure of FIG. First, FIG. 8A shows a step of forming a through-hole 62 to be a through-hole by etching, laser processing, or the like on a large wafer 60 in which a plurality of small pieces 61 are not separated and connected to each other. The position where the through hole 62 is formed is a position determined for each small piece 61. In this example, the position is along the boundary between the small pieces 61. The step of forming the dividing groove 63 for dividing each small piece 61 at a position corresponding to the boundary of each small piece 61 may be performed simultaneously or before or after. The piezoelectric vibrator is A
In the case of a T-cut quartz resonator, the through-hole 62 can be formed by etching from both sides of the piezoelectric element plate. Next, (b) is a process for forming electrodes and the like, and a conductive film 64 constituting a required shape of excitation electrode and lead electrode is formed on both front and back surfaces of each small piece 61 by vapor deposition using a required mask. Simultaneously with or before or after this step, a conductive film is formed at an appropriate position on the inner wall of the through hole 62 to ensure conduction with one of the lead electrodes. (c) shows a step of dividing each small piece 61 from the large wafer 61 along the dividing groove 63, and when the individual small pieces 61 are divided, the crystal resonator shown in FIG. 1 is completed. 6 and 7, the description of the process shown in FIG. 8 is the same as that of the flat type crystal resonator except for the formation position of the through-hole constituting the through-hole and the shape of the electrode. That is true. However, in the case of a crystal resonator having a hole-shaped through hole as shown in FIG. 6, the through hole 62 is formed not at a position along the split groove 63 but at a position closer to the inside of the small piece 61 than the split groove 63. Will be done. On the other hand, in the case of the crystal resonator having the recess shown in FIGS.
In the step (a), a step of forming a recess is performed, and the subsequent steps are similarly performed. In the case of a piezoelectric vibrator such as a crystal vibrator manufactured by the above-described process, a through-hole serving as a through-hole is formed beforehand at an appropriate position on a large wafer, and the through-hole is formed when performing vacuum deposition for forming an electrode. Since the lead electrode extends to the opposite side by forming a conductive film in the inside, when connecting each lead electrode of the crystal unit to the pad in the package, the upper lead electrode Also extends downward through the through-hole, so that only a small amount of binder such as conductive adhesive or solder is filled in the through-hole, making it possible to reliably achieve electrical and mechanical connection. Become.

[0013]

As described above, conventionally, when individual vibrator pieces are manufactured from a large wafer by batch processing, the lead electrodes extending from the excitation electrodes formed on both main surfaces of the individual vibrators are used. Since the lead electrode must be terminated on the surface, when connecting and fixing the lead electrode on the pad in the surface mount package, there is a problem that the connection with the lead electrode on the side opposite to the pad side becomes troublesome. However, in the present invention, when forming a quartz resonator by batch processing, a recess, a hole is formed to penetrate the front and back sides of the base plate surface in contact with the lead electrode,
By making these recesses and holes through holes, the conductor film extending to the opposite side is connected to the lead electrode. As a result, the conductors connected to the excitation electrodes on both surfaces are located on the surface on the pad side, and connection with the lead electrode on the opposite side from the pad side is facilitated.

[Brief description of the drawings]

FIG. 1 is a perspective view of an AT-cut crystal resonator as an example of a piezoelectric resonator according to the present invention.

2A is a perspective view showing a state in which the crystal unit is mounted in a package body, and FIG. 2B is a cross-sectional view taken along the line AA.

FIG. 3 is a cross-sectional view showing a state where a crystal unit of a type in which through holes are formed at opposing ends of a base plate is mounted on a pad in a package.

FIG. 4A is a perspective view of a crystal unit according to another embodiment of the present invention, FIG. 4B is a perspective view showing a state where the crystal unit is mounted in a package,
(c) is a sectional view showing a mounted state.

FIGS. 5A and 5B are a perspective view and a sectional view showing a state of being housed in a package, respectively, of a crystal unit according to another embodiment of the present invention.

FIGS. 6 (a), (b) and (c) are perspective views of a crystal unit according to another embodiment of the present invention, a perspective view showing a state of being housed in a package,
And BB sectional drawing.

7 (a), (b) and (c) are perspective views of a crystal unit according to another embodiment of the present invention, a perspective view showing a storage state in a package,
And CC sectional drawing.

8 (a), (b) and (c) are views for explaining a procedure for manufacturing an example of the piezoelectric vibrator of the present invention.

FIG. 9 is a perspective view of a conventional crystal unit.

[Description of Signs] 11 quartz oscillator, 12 piezoelectric element, 13 excitation electrode,
14 lead electrode, 15, 15 'recess, 16 conductor film, 17 through hole, 20 package body, 21
Recess, 22 step, 23 pad, 25 conductive adhesive or solder (binder), 30 recess, 34, 3
4 'through hole, 36 conductor film, 37 vibrating part, 38
Outer frame, 40 through hole, 41 hole, 42 conductor film, 50 through hole, 51 recess, 52 conductor film,
55 packages, 56 steps, 57 pads, 60
Large wafer, 61 small pieces, 62 through holes, 63 split grooves, 64 conductor film.

Claims (8)

[Claims] 1. A structure in which excitation electrodes are provided on both main surfaces of a piezoelectric element plate and lead electrodes extend from each excitation electrode toward the same edge or two different edges of the piezoelectric element, respectively. In the piezoelectric vibrator, a recessed through hole in contact with at least one of the lead electrodes is formed at an edge of the base plate, and a conductive film in the through hole is electrically connected to the lead electrode. Structure of the piezoelectric vibrator. 2. A structure in which excitation electrodes are provided on both main surfaces of a piezoelectric element plate and lead electrodes extend from each excitation electrode toward the same edge or two different edges of the piezoelectric element, respectively. A piezoelectric vibrator, wherein a hole-shaped through hole in contact with at least one of the lead electrodes is formed in the base plate surface, and a conductive film in the through hole is electrically connected to the lead electrode. Vibrator structure. 3. A concave portion is formed on one main surface of the piezoelectric element plate, a conductor film is formed on the concave portion side, and an excitation electrode and a lead electrode are formed on the other main surface, respectively, and are in contact with the lead electrode. A structure of a piezoelectric vibrator, wherein a recessed or hole-shaped through hole is formed at an edge or a surface of a base plate, and a conductor film in the through hole is electrically connected to the lead electrode. 4. When connecting the piezoelectric vibrator to a pad provided in a recess of a package, the through hole is filled with a binder in a state where the through hole is placed on the pad. The method for connecting a piezoelectric vibrator according to claim 1, 2, or 3. 5. A step of forming through holes serving as through holes at positions corresponding to the small pieces on both front and back surfaces of a large wafer to which small pieces serving as piezoelectric element plates are connected, and exciting electrodes and leads on both front and back faces of each small piece portion. A method for manufacturing a piezoelectric vibrator, comprising: a step of forming a conductor film serving as an electrode; a step of forming a conductor film in the through hole; and a step of dividing the large wafer into small pieces. 6. The method according to claim 5, wherein the step of forming the excitation electrode and the lead electrode and the step of forming a conductor film in the through hole are performed simultaneously. 7. The piezoelectric vibrator according to claim 1, wherein the piezoelectric vibrator is an AT-cut quartz crystal vibrator. 8. When the piezoelectric vibrator is an AT-cut quartz vibrator, a through-hole is formed by etching from both sides of a piezoelectric element plate.
A manufacturing method of the piezoelectric vibrator according to the above.