JPH114137A - Piezoelectric parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a connection process, to recognize a connection situation and to limit a connection area within the range of conduction parts by inserting a piezoelectric element into the recessed part of a holding part so that the electrode face is almost vertical to the surface of a substrate and connecting the electrodes on the surface/back to the first and second conduction parts of the holding stand. SOLUTION: The first and second electrodes 11 and 12 are formed on the upper face of the substrate 10. The holding stand 13 of an almost recessed form is fixed on the inner end part (11b) 12b of the electrodes 11 and 12. The holding stand 13 has the first and second conduction parts conducted with the inner end part (11b) 12b on both sides. The piezoelectric element 20 is inserted into the recessed part of the holding stand 3 so that it becomes almost vertical to the surface of the substrate 10. The electrodes 22 and 23 on the surface/back of the piezoelectric element 20 are fixed with the first and second conduction parts of the holding stand 13 by solder 24. The mechanical fixing and the electric connection of the piezoelectric element 20 can be executed only by solder 24 and the work process can be simplified. Since connection parts are exposed to both sides, the connection situation can easily be recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric component using a piezoelectric element utilizing area vibration, and more particularly to a piezoelectric component suitable as a filter or an oscillator in the kHz band.

[0002]

2. Description of the Related Art Conventionally, as this kind of piezoelectric component, a surface mount type piezoelectric component as shown in FIG. 1 has been proposed. This piezoelectric component includes a piezoelectric element 4 using an area vibration mode such as a length vibration and a spread vibration, and electrodes 4a and 4b are formed on the front and back surfaces. Electrodes 2 and 3 are pattern-formed on a substrate 1 on which the piezoelectric element 4 is mounted, and a back electrode 4 b of the piezoelectric element 4 is connected and fixed on one of the electrodes 2 by a conductive adhesive 5. The front electrode 4 a of the piezoelectric element 4 is connected to the other electrode 3 by a wire 6. On the substrate 1, a metal cap 7 covering the piezoelectric element 4 is adhesively sealed with an adhesive 8, and the electrodes 2,
An insulating layer 9 is formed on the upper surface of the substrate 1 so that the cap 3 and the cap 7 do not conduct.

[0003]

In the case of the above-mentioned piezoelectric component, the back electrode 4b of the piezoelectric element 4 is bonded to the electrode 2 of the substrate 1 with a conductive adhesive 5, and the front electrode 4a of the piezoelectric element 4 is formed. And the electrode 3 must be connected by wire bonding. That is, since it is necessary to perform two processes of completely different types, there is a disadvantage that the working process is complicated and the cost is increased. The back electrode 4 of the piezoelectric element 4
When b is bonded to the electrode 2 of the substrate 1, the piezoelectric element 4 is slightly pressed. However, since the bonded portion cannot be visually observed from the outside, the connection state cannot be confirmed, and the vibration characteristics of the piezoelectric element 4 are adversely affected. There was a risk that the adhesive 5 would spread too much to the effect.

Further, when wire bonding the front side electrode 4a of the piezoelectric element 4 and the electrode 3 of the substrate 1, an impact force is applied to the piezoelectric element 4, so that the piezoelectric element 4 may be damaged. Further, since it is necessary to secure a wiring space for the wires 6 on the substrate 1, the substrate 1 becomes large, and there is a disadvantage that the piezoelectric component as a whole becomes large. for that reason,
It was difficult to arrange a plurality of piezoelectric elements 4 on the substrate 1.

Accordingly, an object of the present invention is to provide a piezoelectric component which can solve the above-mentioned conventional disadvantages.

[0006]

The above object is achieved by the present invention. That is, the piezoelectric component of the present invention has electrodes on the front and back surfaces, a piezoelectric element using area vibration, an insulating substrate having first and second electrodes formed on the front surface, and fixed on the substrate. And a holding table having first and second conductive portions that are electrically connected to the first and second electrodes, respectively, and having a concave portion between the conductive portions, wherein the electrode surface of the piezoelectric element is a surface of a substrate. The vicinity of the node of the piezoelectric element is inserted into the concave portion of the holding table so that the lower surface of the piezoelectric element is kept away from the surface of the substrate, and the vicinity of the node of the front and back electrodes is substantially perpendicular to the electrode. Are connected to the first and second conductive portions, respectively.

The piezoelectric element is inserted into the concave portion of the holder so that the electrode surface is substantially perpendicular to the surface of the substrate, and is supported so that the lower surface of the piezoelectric element does not contact the surface of the substrate. Then, the front and back electrodes are connected to the first and second conductive portions of the holding table using solder, a conductive adhesive, or the like. As described above, the present invention does not require two different connection processes in the related art, and simplifies the operation process. In addition, since the connection portion is exposed on both sides, the connection status can be confirmed, and the connection region is limited to the range of the conductive portion, so that it does not expand more than necessary. Further, since wire bonding can be eliminated, there is no risk of damaging the piezoelectric element, and there is no need to secure a wiring space for wires on the substrate, so that the piezoelectric component can be miniaturized.

The piezoelectric element according to the present invention utilizes area vibration, and the area vibration includes a length vibration mode and a spread vibration mode. This type of element has a node point at the center of the front and back surfaces, so if the vicinity of the center of the piezoelectric element is connected to the conductive part with a conductive material such as solder or conductive adhesive, it will be retained. Since the portion is in the vicinity of the node point, that is, a non-vibration portion, the vibration of the piezoelectric element is not hindered and the electrical characteristics thereof are not impaired. Further, since the lower surface of the piezoelectric element is supported in a state separated from the surface of the substrate, vibration is not damped, and deterioration of characteristics can be prevented.

When the piezoelectric element is inserted between the conductive parts, the lower surface of the piezoelectric element is not always supported in a state where it is separated from the surface of the substrate. Therefore, it is desirable to form an insulating portion lower than the conductive portion on the substrate surface between the first and second conductive portions, and to support the lower surface of the piezoelectric element with the insulating portion. In this case, the lower surface of the piezoelectric element comes into contact with the insulating portion, but since this portion is near the node portion, the vibration characteristics are not adversely affected. Further, by forming an insulating portion between the conductive portions, there is an effect that a short circuit between the conductive portions can be prevented. For the same purpose, a step for supporting the lower surface of the piezoelectric element may be formed on the inner surfaces of the first and second conductive portions. In this case, the lower surface of the piezoelectric element can be supported with a certain distance from the surface of the substrate.

In the present invention, since a piezoelectric element is arranged between a pair of conductive parts, if a plurality of pairs of conductive parts are arranged in series on a substrate, a plurality of piezoelectric elements can be arranged in parallel. Can easily be configured. In this case, if the adjacent conductive portions are shared, further miniaturization is possible.

[0011]

2 and 3 show an example of a piezoelectric component according to the present invention. This embodiment shows an example of a surface mount type oscillator in the kHz band. This oscillator basically corresponds to the substrate 10
And a piezoelectric element 20 and a lid 30.

The substrate 10 is a rectangular thin plate made of an insulating material such as alumina ceramics and heat resistant resin.
The first and second electrodes 11 and 12 are formed on the upper surface of 0 by a known method such as sputtering, vapor deposition, plating, and printing. Outer end portions 11a and 12a of the electrodes 11 and 12 are drawn out to both end portions of the substrate 10 to serve as external terminal electrodes. In this embodiment, the outer ends 11 of the electrodes 11 and 12 are used.
Although a and 12a are drawn only to the upper surfaces of both ends of the substrate 10, the outer ends 11a and 12a may be drawn to the back surface via the side end surfaces of the substrate 10. The inner ends 11b, 12b of the electrodes 11, 12 are close to each other in the short side direction at the center of the substrate 10, and a substantially concave holding table 13 is fixed on the inner ends 11b, 12b. Holder 13
As shown in FIG. 3, the inner ends 11b, 12b
And the first and second conductive portions 14 and 15 that are electrically connected to the conductive portions 14 and 15 respectively. The insulating portion 16 that is lower than the conductive portions 14 and 15 is provided at the center portion. A recess 17 is formed. The width W of the recess 17 is set slightly larger than the thickness of the piezoelectric element 20.
Is desirably set to a dimension that minimizes vibration damping of the piezoelectric element 20 and provides a predetermined holding strength. Further, it is desirable that the depth D of the concave portion 17 is set shorter than the width dimension of the piezoelectric element 20.

The piezoelectric element 20 is, for example, a piezoelectric vibrator utilizing a length vibration mode, and is formed in a rectangular shape shorter than the long side of the substrate 10. The piezoelectric element 20 has electrodes 22 and 23 formed on the entire front and back surfaces of a piezoelectric ceramic substrate 21, and is inserted into the recess 17 so that the front and back surfaces are substantially perpendicular to the front surface of the substrate 10. Are connected and fixed to the conductive portions 14 and 15 by conductive materials 24 such as solder and conductive adhesive, respectively. At this time, the lower surface of the central portion of the piezoelectric element 20 is in contact with the insulating portion 16, and both ends (the vibrating portion) of the piezoelectric element 20.
Is supported in a state of floating above the surface of the substrate 10.

The lid 30 is made of the same insulating material as the substrate 10 and is adhered and fixed on the substrate 10 so as to cover the element 20. In addition, a metal cap may be used as the lid 30, but in this case, the lid 30 and the electrode 11 of the substrate 10 may be used.
It is desirable to form an insulating layer on the bonding portion of the substrate 10 in order to prevent conduction with the substrate 12.

As described above, the holding table 1 is placed on the piezoelectric element 20 so that its electrode surface is substantially perpendicular to the surface of the substrate 10.
3 of the piezoelectric element 20 and
Since the conductive members 2 and 23 are connected and fixed to the conductive portions 14 and 15 of the holding table 13 by solder 24 or the like, the mechanical fixing and the electrical connection of the piezoelectric element 20 can be performed only by the solder 24, and the working process is simplified. Be transformed into Further, since the connection portions are exposed on both sides, the connection status can be easily confirmed.
In addition, since it is not necessary to press the solder 24 or the like at the time of connection, the solder 24 does not spread more than necessary and does not adversely affect the vibration characteristics of the piezoelectric element 20. Although the above embodiment has been described with respect to an example in which the piezoelectric element 20 is mechanically fixed and electrically connected only by the solder 24,
May be used only for electrical connection, and the piezoelectric element 20 may be mechanically fixed using another insulating adhesive. In this case, the adhesive is preferably applied to the insulating portion 16.

Here, a method of forming the holding table 13 is shown in FIG.
It will be described according to. FIG. 4A shows electrodes 11 and 1 on the surface.
2 shows a substrate 10 on which No. 2 is formed. (B) of FIG.
1 shows a state in which an insulating portion 16 is formed between inner end portions 11b and 12b of the first and second inner ends 11b and 12b. The insulating portion 16 can be easily formed by screen-printing, for example, an insulating resin or the like. Next, as shown in FIG. 4C, conductive portions 14 and 15 are provided on both sides of the insulating portion 16 so as to be electrically connected to the electrodes 11 and 12.
To form These conductive portions 14 and 15 can be easily formed, for example, by screen-printing a conductive paste. It is desirable that the thickness of the conductive portions 14 and 15 be substantially the same as the thickness of the insulating portion 16. Next, as shown in FIG. 4D, a slit 17 is formed in the insulating portion 16 using a dicer or the like to form a recess 17. At this time, the formation of the conductive portions 14 and 15 may be performed simultaneously. FIG. 4 shows an example in which the holding base 13 is formed for each of the substrates 10.
The electrodes 11 and 12 are formed continuously, and a large number of holding tables 13 are formed. Thereafter, the mother substrate may be cut into the substrate 10.

FIG. 5 shows a second embodiment of the holding table. The holding table 40 has conductive portions 41 and 42 on both sides, and an insulating portion 43 lower than the conductive portions 41 and 42 between the conductive portions 41 and 42. A concave portion 44 is formed by the conductive portions 41 and 42 and the insulating portion 43. I have. Outwardly open guide surfaces 41a and 42a are formed in the upper end openings of the conductive portions 41 and 42, so that the piezoelectric element can be smoothly inserted into the concave portion 44. Also, the insulating part 43
A ridge line portion 43a extending in the direction opposite to the conductive portions 41 and 42 is formed at the center of the piezoelectric element to reduce the contact area with the lower surface of the piezoelectric element.

FIG. 6 shows a third embodiment of the holding table. In the holding table 50, a recess 55 for inserting the piezoelectric element 54 is formed by the conductive parts 51 and 52 and the insulating part 53, and a recess 56 one step lower is formed in the center of the insulating part 53. Also in this case, since the lower surface of the piezoelectric element 54 is supported by the step portions 57 on both sides of the insulating portion 53, the contact area can be reduced.

FIG. 7 shows a fourth embodiment of the holding table. The holding table 60 is configured such that a recessed portion 65 into which the piezoelectric element 64 is inserted is formed by the conductive portions 61 and 62 and the insulating portion 63, and a protrusion 56 is formed at the center of the insulating portion 63. Also in this case, since the lower surface of the piezoelectric element 64 is supported by the protrusion 56,
The contact area can be reduced.

FIG. 8 shows a fifth embodiment of the holding table. The holding table 70 includes conductive portions 71 and 72 fixed at intervals.
Step portions 71 a and 72 a for supporting the lower surface of the piezoelectric element 73 are formed on the inner surfaces of the conductive portions 71 and 72. Also in this case, the contact area with the lower surface of the piezoelectric element 73 can be reduced.

FIGS. 9 to 12 show a ladder-type filter which is a second embodiment of the piezoelectric component according to the present invention. In this embodiment, as shown in FIG. 13, two series resonators and two parallel resonators are provided. And child. This filter includes a substrate 80, four piezoelectric elements 91 to 94, and the like.

The substrate 80 has an input electrode 81 and an output electrode 8
2. An earth electrode 83 and an intermediate electrode 84 are formed, and outer ends of the electrodes 81 to 83 are extended to three outer edges of the substrate 80. One end of the intermediate electrode 84 is located between the inner end of the input electrode 81 and the inner end of the ground electrode 83, and is located between the inner end of the ground electrode 83 and the inner end of the output electrode 82. The other end of the intermediate electrode 84 is located between them. A total of five conductive portions 85 to 89 are fixed in a line and at regular intervals on the inner ends of the input / output electrodes 81 and 82 and the ground electrode 83 and on both ends of the intermediate electrode 84. An insulating part 90 lower than the conductive part is fixed between the conductive parts 85 to 89. The conductive portions 85 to 89 and the insulating portion 90 constitute four continuous holding tables.

The piezoelectric elements 91 to 94 are strip-shaped piezoelectric elements using the same length vibration mode as the piezoelectric element 20 in the first embodiment (see FIG. 2). That is, it is inserted between the conductive portions 85 to 89 so as to be perpendicular to the surface of the substrate 80, and is connected and fixed by a material 95 such as solder or a conductive adhesive. Although a gap is provided between the lower surface of each of the piezoelectric elements 91 to 94 and the insulating section 90 in FIG.
4 may be in contact with the insulating portion 90.

The connection as described above allows the piezoelectric element 9
Reference numerals 1 and 94 are series resonators connected in series between the input electrode 81 and the output electrode 82, and piezoelectric elements 92 and 93 are parallel resonators connected in parallel with the ground electrode 83. Since the lower surfaces of both ends of the piezoelectric elements 91 to 94 are supported in a state of floating above the surface of the substrate 80, the vibration of the piezoelectric elements 91 to 94 is hindered, and the electrodes are
There is no danger of conduction with 84. Note that a lid (not shown) covering the entirety of the piezoelectric elements 91 to 94 is adhered onto the substrate 80, and the inside is sealed.

Since the plurality of piezoelectric elements 91 to 94 can be arranged on one substrate 80 as described above, high density and miniaturization can be realized. In particular, since the piezoelectric elements 91 to 94 are accurately positioned by the holding tables (the conductive parts 85 to 89 and the insulating part 90), there is no possibility that the piezoelectric elements contact each other or cause a positional shift, and a stable quality piezoelectric element is provided. Parts can be obtained. Further, by sharing the adjacent conductive portions 86 to 88, the interval between the piezoelectric elements 91 to 94 can be reduced, and the mounting density of the elements can be further increased.

The present invention is not limited to the above embodiment, but can be variously modified. The piezoelectric component according to the present invention is not limited to the surface mount type, but can be configured as a leaded piezoelectric component by fixing an external connection terminal to a substrate. In addition, the holding table shown in FIGS.
Of course, it can be applied to the piezoelectric component of the second embodiment (see FIGS. 2 and 9). Further, in the above embodiment, the conductive portion can be formed of an elastic conductive material such as conductive silicon. In this case, by making the interval between the conductive portions slightly smaller than the thickness of the piezoelectric element, the electrode surface of the piezoelectric element can be elastically held, and temporary holding is possible. Further, the piezoelectric element according to the present invention is not limited to a two-terminal type piezoelectric element, but may be applied to a three-terminal or more piezoelectric element having a plurality of electrodes divided on one surface by vertical grooves. In this case, it is necessary to form one of the conductive portions vertically in a plurality of stages.

[0027]

As is apparent from the above description, according to the present invention, the piezoelectric element is inserted into the concave portion of the holder so that the electrode surface is substantially perpendicular to the surface of the substrate, and While holding the lower surface so that it does not touch the surface of the board,
Since the front and back electrodes are connected and fixed to the first and second conductive portions of the holding table, only one type of connection process is required, and the operation process is simplified. In addition, since the connection portion is exposed on both sides, the connection state can be confirmed, and the connection portion is limited to the node portion, so that good vibration characteristics of the piezoelectric element can be secured. Also, since the wire bonding step can be eliminated, there is no risk of damaging the piezoelectric element, and there is no need to secure a wiring space for wires on the substrate, so that the piezoelectric component can be miniaturized. Furthermore, even when a large number of elements are mounted on a substrate, the elements can be arranged close to each other, so that high-density mounting is possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of an example of a conventional piezoelectric component.

FIG. 2 is a perspective view of a first embodiment of the piezoelectric component according to the present invention.

FIG. 3 is an enlarged perspective view of a part of the piezoelectric component of FIG. 2;

FIG. 4 is a process chart showing a manufacturing order of the substrate of FIG. 2;

FIG. 5 is a perspective view of a second embodiment of the holding table.

FIG. 6 is a side view of a third embodiment of the holding table.

FIG. 7 is a side view of a fourth embodiment of the holding table.

FIG. 8 is a side view of a fifth embodiment of the holding table.

FIG. 9 is a plan view of a second embodiment of the piezoelectric component according to the present invention.

FIG. 10 is a front view of the piezoelectric component of FIG. 9;

FIG. 11 is a plan view of the substrate of FIG. 9;

FIG. 12 is a front view of the substrate of FIG. 9;

FIG. 13 is a circuit diagram of the piezoelectric component of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Substrate 11, 12 Electrode 13 Holder 14, 15 Conductive part 16 Insulating part 17 Depression 20 Piezoelectric element 22, 23 Electrode 30 Cover

Claims (4)

[Claims] A piezoelectric element having electrodes on the front and back surfaces and utilizing area vibration; an insulating substrate having first and second electrodes formed on the front surface; A holding table having first and second conductive portions each electrically connected to the second electrode and having a recess between the conductive portions, wherein the electrode surface of the piezoelectric element is substantially In order to be vertical, the vicinity of the node of the piezoelectric element is inserted into the recess of the holding table, the lower surface of the piezoelectric element is held in a state separated from the surface of the substrate, and the vicinity of the node of the front and back electrodes is the first and the first. A piezoelectric component being connected to each of the second conductive portions. 2. An insulating portion lower than the conductive portion is formed between the first and second conductive portions on the substrate surface, and the lower surface of the piezoelectric element is supported by the insulating portion. The piezoelectric component according to claim 1, wherein: 3. The piezoelectric component according to claim 1, wherein a step for supporting a lower surface of the piezoelectric element is formed on an inner surface of each of the first and second conductive portions. 4. The semiconductor device according to claim 1, wherein a plurality of pairs of first and second conductive portions are formed in series on the substrate, and adjacent conductive portions are shared. A piezoelectric component according to any of the above.