JPH11261124A - Piezoelectric device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric device which can be reduced in thickness, and at the same time for which the management of metallized layers formed as holding electrodes and of the condition of the seepage, etc., at the metallizing of printing can be dispensed with. SOLUTION: A piezoelectric device is provided with a piezoelectric element 22 having vibrating electrodes 24a and 24b and terminal electrodes 25a and 25b, respectively connected to one ends of the electrodes 24a and 24b on both surfaces of a piezoelectric substrate 23, a case 21 for sealing the element 22, and at least a pair of holding electrodes 29a and 29b, which are provided on the bottom of the case 21a and hold the piezoelectric element 22 by the portions of the terminal electrodes 25a and 25b. The piezoelectric element 22 is held in such a state that the element 22 is inclined with respect to the bottom plate 26 of the main body 21a of the case 21, by forming a recessed section having a slope 26a into the bottom plate 26 and arranging the holding electrodes 29a and 29b on the slope 26a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric device and a method for manufacturing the piezoelectric device, and more particularly, to a piezoelectric device characterized by a structure for holding a piezoelectric element and a method for manufacturing the piezoelectric device.

[0002]

2. Description of the Related Art In a conventional piezoelectric device, a shelf is formed in a case for sealing the piezoelectric element so that vibration of the piezoelectric element is not hindered, and one end of the piezoelectric element is fixed to the shelf. And one in which a metallized layer is thickly printed on the bottom surface of the case and one end of the piezoelectric element is fixed to the metallized layer.

FIG. 4 (a) is a cross-sectional view schematically showing an example of a conventional piezoelectric device, FIG. 4 (b) is a plan view without a cover, and FIG. 4 (c) is a cover and a piezoelectric element. FIG. FIG. 5A is a perspective view of the piezoelectric element, and FIGS. 5B and 5C are a plan view and a bottom view, respectively.

[0004] In the figure, reference numeral 3 denotes a piezoelectric substrate. Vibration electrodes 4a and 4b are formed on both surfaces of the piezoelectric substrate 3, respectively, and terminal electrodes 5a and 5b are connected to one ends of the vibration electrodes 4a and 4b. These piezoelectric substrates 3,
The piezoelectric element 2 includes the vibration electrodes 4a and 4b and the terminal electrodes 5a and 5b.

The piezoelectric element 2 comprises a bottom plate 6 and frames 7 and 8.
The terminal electrodes 5a and 5b are accommodated in a case 1 including a case base 1a made of
a and 10b are electrically connected via a conductive adhesive (not shown), and the piezoelectric element 2 is held by the case base 1a at the holding electrodes 10a and 10b. On the lower surface of the bottom plate 6, for example, connection electrodes 11 connected to the holding electrodes 10a and 10b via through holes (not shown) provided at the ends.
a and 11b are formed. Further, a lid 9 for sealing the piezoelectric element 2 is adhered on the frame 8.

FIG. 6A is a cross-sectional view schematically showing another conventional piezoelectric device, FIG. 6B is a plan view without the cover, and FIG. 6C is a plan view without the cover and the piezoelectric element. FIG. Components having the same functions as those of the piezoelectric device shown in FIG. 4 are denoted by the same reference numerals, and description thereof will be omitted.

The piezoelectric element 2 is housed in a case 12 including a case base 12a comprising a bottom plate 13 and a frame 14, and a lid 15. Terminal electrodes 5a and 5b are formed on the upper surface of the bottom plate 13. The piezoelectric elements 2 are electrically connected to the holding electrodes 16a and 16b via a conductive adhesive (not shown), and the piezoelectric element 2 is connected to the case base 12 at the holding electrodes 16a and 16b.
a. On the lower surface of the bottom plate 13, for example, the holding electrode 1 is inserted through a through hole (not shown) provided at the end.
Connection electrodes 17a and 17b connected to 6a and 16b are formed. Further, a lid 15 for sealing the piezoelectric element 2 is adhered on the case base 12a.

[0008]

In the piezoelectric device shown in FIG. 4, a shelf 7a is formed so as not to hinder the vibration of the piezoelectric element 2, and one end of the piezoelectric element 2 is held by the shelf 7a. Therefore, the cost of the mold for forming the shelf 7a is high, the cost is high, and the number of steps is increased in the manufacturing process.
In recent years, the thickness of the piezoelectric device has been reduced. However, the piezoelectric device shown in FIG. 3, which has a three-layer structure having a shelf 7a, is not suitable for thinning.

On the other hand, in the piezoelectric device shown in FIG. 6, the piezoelectric element 2 is floated by the thickness of the holding electrodes 16a and 16b formed on the bottom surface (the upper surface of the bottom plate 13) of the case by metallization printing or the like and the adhesive. Therefore, it can be said that it is more suitable for thinning than the piezoelectric device shown in FIG.

However, when the case base 12a is warped, there is a problem that the piezoelectric element 2 comes into contact with the case base 12a, and in order to float the piezoelectric element 2, the metallization layer is adjusted to an appropriate thickness to perform the printing process. It is necessary to strictly consider the conditions of the thickness, the condition of bleeding at the time of printing, and the like, and there is a problem that the condition management becomes very difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to reduce the thickness, and it is not necessary to manage conditions such as the thickness of a metallized layer as a holding electrode and bleeding during metallized printing. It is an object of the present invention to provide a piezoelectric device.

[0012]

In order to achieve the above object, a piezoelectric device (1) according to the present invention has vibration electrodes on both sides of a piezoelectric substrate and one end of each of these vibration electrodes. A piezoelectric device comprising: a piezoelectric element having a terminal electrode; a case for sealing the piezoelectric element; and at least one pair of holding electrodes provided on a bottom surface of the case and holding the piezoelectric element at the terminal electrode portion. , A concave portion having an inclined surface is formed on the bottom surface, the holding electrode is provided on the inclined surface, and the piezoelectric element is held in a state of being inclined with respect to the bottom surface.

According to the piezoelectric device (1), since one end of the piezoelectric element is fixed to the inclined surface provided on the bottom surface of the case, the other end is in a floating state,
Mechanical vibration and a piezoelectric effect can be obtained. Therefore,
Unlike the conventional case, there is no need to provide a shelf on the bottom surface or to consider the thickness condition of the holding electrode (metallized layer) and the like, so that the manufacturing cost can be greatly reduced.

Further, in the piezoelectric device (2) according to the present invention, in the piezoelectric device (1), the distance between the inner surface of the top plate of the case and the upper surface of the free end of the piezoelectric element is determined by the displacement amount at the free end. It is characterized in that it is set to a value that is suppressed to a predetermined value or less.

According to the piezoelectric device (2), even if a stress such as an impact or vibration acts, the displacement at the free end is suppressed to a predetermined value or less. Damage to the bonded portion on the end side can be prevented, and vibration and impact resistance can be improved.

The method (1) for manufacturing a piezoelectric device according to the present invention is the method for manufacturing the piezoelectric device (1) or (2), wherein the recess is formed by pressing the bottom surface and having an inclined surface. And a step of performing a metallized printing process for the holding electrode on the formed inclined surface.

A method (2) for manufacturing a piezoelectric device according to the present invention is a method for manufacturing the piezoelectric device (1) or (2), wherein a metallized printing process for the holding electrode is performed on the bottom surface. And press forming the metallized bottom surface to form a concave portion having the inclined surface.

The above-described piezoelectric device manufacturing method (1) or (2)
According to the method, the piezoelectric element is held in a state of being obliquely inclined with respect to the bottom surface by fixing one end of the piezoelectric element to a recess formed on the bottom surface of the case and having the inclined surface. The device can be manufactured. Therefore, it is possible to manufacture a piezoelectric device that does not need to manage conditions such as thickness conditions and bleeding conditions during metallization printing.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the piezoelectric device according to the present invention will be described below with reference to the drawings. 1A is a cross-sectional view schematically showing a piezoelectric device according to an embodiment, FIG. 1B is a plan view excluding a lid, and FIG. 1C is a plan view excluding a lid and a piezoelectric element. FIG. Further, the structure of the piezoelectric element here is the same as the structure of the piezoelectric element 2 shown in FIG.

In the drawing, reference numeral 23 denotes a piezoelectric substrate. Vibration electrodes 24a and 24b are respectively formed on both surfaces of the piezoelectric substrate 23, and terminal electrodes 25a and 25b are connected to one end of the vibration electrodes 24a and 24b. The piezoelectric element 22 includes the piezoelectric substrate 23, the vibration electrodes 24a and 24b, and the terminal electrodes 25a and 25b.

The piezoelectric element 22 includes a bottom plate 26 and a frame 2.
The bottom plate 26 is housed in a case 21 that includes a case base 21 a made of a resin 7 and a lid 28, and a recess having an inclined surface 26 a is formed on the upper surface of the bottom plate 26. The terminal electrodes 25a and 25b are electrically connected to the holding electrodes 29a and 29b formed on the inclined surface 26a via a conductive adhesive (not shown), and the piezoelectric element 22 is connected to the holding electrodes 29a and 29b.
The portion b is held by the case base 21a. Bottom plate 26
For example, connection electrodes 30a and 30b connected to the holding electrodes 29a and 29b via through holes (not shown) provided at the ends are formed on the lower surface of the. Further, a lid 28 for sealing the piezoelectric element 22 is adhered on the case base 21a.

According to the piezoelectric device of the above embodiment,
Since one end of the piezoelectric element 22 is fixed to the inclined surface 26 a provided on the upper surface of the bottom plate 26, the other end (the free end 2
2a) is in a floating state, and mechanical vibration and a piezoelectric effect can be obtained. Therefore, there is no need to provide a shelf on the bottom surface of the case or to consider the thickness conditions of the holding electrode (metallized layer) as in the conventional case, so that the manufacturing cost can be greatly reduced.

Further, the inner surface of the top plate of the lid 28 and the piezoelectric element 2
2 is set to a value that suppresses the amount of displacement at the free end 22a to a predetermined value or less, so that even if a stress such as an impact or vibration is applied, the piezoelectric element 2
2 can prevent damage to the bonded portion on the fixed end side, and can improve vibration resistance and impact resistance.

Since the free end 22a and the bottom surface (bottom plate 26) of the case base 21a are sufficiently separated, the piezoelectric element 22 and the case base 21 are warped by the case base 21a.
a can be eliminated.

Next, a method (1) for manufacturing the piezoelectric device according to the above embodiment will be described with reference to the flowchart shown in FIG. First Step One side of a green sheet formed into a substantially rectangular plate is pressed to form a recess having an inclined surface 26a. ● Second Step A metallized printing process is performed to form a paste layer for forming a pair of holding electrodes 29a and 29b on the inclined surface 26a.
Examples of a material for forming the green sheet include a material obtained by adding a resin and a solvent to an insulating material such as ceramic or glass ceramic. Third step The green sheet is fired, plated, and then cut into individual chips.

Fourth step: The inclined surface 26a on which the holding electrodes 29a and 29b are formed is
The terminal electrodes 25a and 25b formed on the piezoelectric element 22 are fixed with a conductive adhesive or the like. Fifth Step A lid 28 made of ceramic or the like is placed on the case base 21a having a concave cross-sectional shape, and hermetically sealed with glass, resin, brazing, or the like.

Next, a method (2) of manufacturing the piezoelectric device according to the above embodiment will be described with reference to the flowchart shown in FIG. ● First step One side of a green sheet formed into a substantially rectangular plate shape is subjected to a metallizing printing process to form a pair of holding electrodes 29a and 29b.
A paste layer for forming is formed. Examples of a material for forming the green sheet include a material obtained by adding a resin and a solvent to an insulating material such as ceramic or glass ceramic. ● Second step Pressing the metallized print section creates a slope 2
A recess having 6a is formed. Third step The green sheet is fired, plated, and then cut into individual chips.

[Fourth Step] On the inclined surface 26a on which the holding electrodes 29a and 29b are formed,
The terminal electrodes 25a and 25b formed on the piezoelectric element 22 are fixed with a conductive adhesive or the like. Fifth Step A lid 28 made of ceramic or the like is placed on the case base 21a having a concave cross-sectional shape, and hermetically sealed with glass, resin, brazing, or the like.

The method (1) or (2) for manufacturing the piezoelectric device.
According to this, by fixing one end of the piezoelectric element 22 to the concave portion formed on the bottom plate 26 and having the inclined surface 26a, the piezoelectric element 22 is held in a state of being inclined obliquely with respect to the bottom surface of the case base 21a. Piezoelectric device can be manufactured. Therefore, it is possible to manufacture a piezoelectric device that does not need to manage conditions such as thickness conditions and bleeding conditions during metallization printing.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view schematically showing a piezoelectric device according to an embodiment of the present invention, FIG. 1B is a plan view excluding a lid, and FIG. 1C is a lid. FIG. 2 is a plan view excluding a piezoelectric element.

FIG. 2 is a flowchart showing a method (1) for manufacturing a piezoelectric device according to an embodiment.

FIG. 3 is a flowchart showing a method (2) for manufacturing a piezoelectric device according to an embodiment.

FIG. 4A is a cross-sectional view schematically illustrating an example of a conventional piezoelectric device, FIG. 4B is a plan view excluding a lid, and FIG. It is the top view which removed.

5A is a perspective view schematically showing a piezoelectric element, FIG. 5B is a plan view, and FIG. 5C is a bottom view.

FIG. 6A is a cross-sectional view schematically illustrating another conventional piezoelectric device, and FIG. 6B is a plan view excluding a lid,
(C) is a plan view excluding the lid and the piezoelectric element.

[Explanation of symbols]

1, 12, 21 Case 1a, 12a, 21a Case base 2, 22 Piezoelectric element 3, 23 Piezoelectric substrate 4a, 4b, 24a, 24b Vibration electrode 5a, 5b, 25a, 25b Terminal electrode 6, 13, 26 Bottom plate 7, 8 , 14, 27 Frame 7a Shelf 9, 15, 28 Lid 10a, 10b, 16a, 16b, 29a, 29b Holding electrode 11a, 11b, 17a, 17b, 30a, 30b Connection electrode 22a Free end 26a Inclined surface

Claims (4)

[Claims] A piezoelectric element having vibrating electrodes on both sides of a piezoelectric substrate and terminal electrodes respectively connected to one end of the vibrating electrodes; a case for sealing the piezoelectric element; A piezoelectric device comprising at least a pair of holding electrodes for holding the piezoelectric element at the terminal electrode portion, wherein a concave portion having an inclined surface is formed on the bottom surface, and the holding electrode is provided on the inclined surface. A piezoelectric device, wherein the piezoelectric element is held in a state of being inclined with respect to the bottom surface. 2. A distance between an inner surface of a top plate of the case and an upper surface of a free end of the piezoelectric element is set to a value that suppresses a displacement amount at the free end to a predetermined value or less. 2. The piezoelectric device according to 1. 3. The method for manufacturing a piezoelectric device according to claim 1, wherein the bottom surface is subjected to press working to form the concave portion having an inclined surface, and Performing a metallized printing process for the holding electrode. 4. The method for manufacturing a piezoelectric device according to claim 1, wherein a metallized printing process for the holding electrode is performed on the bottom surface, and a press process is performed on the metalized printed bottom portion. Forming a concave portion having the inclined surface.