JP2005094243A - Multiplex mode piezo-electric filter element, surface-mounting filter, piezo-electric oscillation element, and surface mounting piezo-electric oscillation element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiplex mode piezo-electric filter element, a surface mounting filter, a piezo-electric oscillation element, and a surface mounting piezo-electric vibrator which can reduce an adverse influence due to a strain generated when a metal cover is fixed to a package to a minimum limit, in a piezo-electric device of the type accommodating the piezo-electric element in the package by using a polyimide conductive adhesive. <P>SOLUTION: The multiplex mode piezo-electric filter element includes opposed electrodes 3, 4 and 5 adhered and formed to both opposed surfaces of a rectangular piezo-electric substrate 2. Lead terminals 3a, 4a extended from the split electrodes 3, 4 are terminated at the corners 2A, 2B of the piezo-electric substrate on a diagonal line, and a lead terminal 5a extended from the ground electrode 5 is terminated at the other one corner 2C of the piezo-electric substrate. The lead terminal extended from each split electrode is extended and formed at each corner along an edge, and arrived at one edge corresponding to the piezo-electric substrate and then bent, and a slit 6 is formed in parallel with the lead terminal at the piezo-electric substrate adjacent to the lead terminal extended to the corner along the edge. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is capable of solving the problems that have occurred in the past when a lead terminal portion of a piezoelectric element housed in a surface mounting package is fixed to an electrode in the package using a polyimide-based conductive adhesive. The present invention relates to a multimode piezoelectric filter element, a piezoelectric vibration element, and a surface mounting piezoelectric device using these piezoelectric elements.

Examples of the piezoelectric element in which an excitation electrode, an earth electrode, and the like are formed on a piezoelectric substrate include a multimode piezoelectric filter element and a piezoelectric vibration element.
With recent miniaturization of electronic devices, portable communication devices, etc., miniaturization is also required for piezoelectric elements such as piezoelectric filter elements and piezoelectric vibration elements used in these devices.
FIG. 3 is a plan view of a main part showing the configuration of a high frequency multimode filter (MCF) of 300 MHz or higher. The multimode filter 100 is provided in a recess 102 of a ceramic package 101 for surface mounting. Is provided. The ceramic package 101 has a vertical and horizontal dimension of 2.0 mm × 2.5 mm, and the multimode filter element 105 has a vertical and horizontal dimension of 0.8 mm × 1.2 mm and a thickness of 5 μm.
The filter element 105 has a configuration in which a ground electrode 107 and input / output divided electrodes 108 and 109 are attached to both surfaces of a rectangular piezoelectric substrate 106 made of a piezoelectric material such as quartz. The lead terminal 107a from the ground electrode 107 extends to one corner of the piezoelectric substrate 106, and the lead electrodes 108a and 109a from the divided electrodes 108 and 109 respectively extend to two corners on one diagonal line. Yes.
The terminal portions of the lead terminals 107 a, 108 a, and 109 a are electrically and mechanically connected and fixed on the three internal electrodes 103 provided on the inner bottom surface of the package 101 using the conductive adhesive 104.

By the way, as the conductive adhesive 104, a silicon-based adhesive that retains flexibility even after curing is often used, but the silicon-based conductive adhesive has a drawback that aging is poor. In other words, the silicon-based adhesive easily releases gas over time, and when gas particles adhere to the filter element substrate or electrode in the hermetic space of the package, the frequency deteriorates due to mass addition (aging). )cause.
For this reason, it is conceivable to use a polyimide-based conductive adhesive with good aging, but since the polyimide system has high hardness when cured, the frequency fluctuates by about 200 to 500 ppm when the package is sealed. To provoke. That is, when the metal lid is fixed to the metal portion provided on the upper surface of the outer frame of the package 101 by seam welding and hermetically sealed, the package is distorted. The distortion is transmitted to the filter element 105 through the conductive adhesive. The frequency fluctuates due to distortion caused by this external force.
In this way, when a polyimide conductive adhesive is used as a means for adhering a filter element having a conventional structure in a package, distortion generated when a metal lid is fixed to the package propagates distortion to the filter element. There is a defect that it causes frequency fluctuation.
On the other hand, a silicon-based conductive adhesive having a problem in terms of aging has an advantage of reducing the influence of distortion generated when a metal lid is fixed to a package because of low hardness at the time of curing.
Therefore, in order to give priority to the prevention of frequency fluctuation due to distortion over the solution of the problem of aging deterioration, a silicon-based conductive adhesive has to be used.
Such a problem occurs not only in the filter but also in other piezoelectric devices such as a piezoelectric vibrator.
JP-A-6-85599

  The present invention has been made in view of the above, and in a piezoelectric device of a type in which a piezoelectric element is housed in a package using a polyimide-based conductive adhesive, an adverse effect due to distortion generated when a metal lid is fixed to the package. An object of the present invention is to provide a multi-mode piezoelectric filter element, a surface-mounting filter, a piezoelectric vibration element, and a surface-mounting piezoelectric vibrator capable of reducing the above to a minimum.

In order to solve the above-mentioned problem, the invention of claim 1 is an input / output division in which a counter electrode is attached and formed on each of both opposing surfaces of a rectangular piezoelectric substrate, and the counter electrodes on one side are arranged at a predetermined interval. A multimode piezoelectric filter element in which a counter electrode on the other surface side is a ground electrode and lead terminals of each electrode are extended to different corners of the piezoelectric substrate, and leads extending from the divided electrodes Each of the divided electrodes has a terminal terminated at a corner corner on the diagonal line of the piezoelectric substrate, and a lead terminal extending from the ground electrode is terminated at another corner corner of the piezoelectric substrate. The lead terminals extending from the lead terminals are bent after reaching the corresponding one end edge of the piezoelectric substrate, and are extended to the respective corners along the end edges, and the lead terminals extending to the corners along the end edges. Pressure adjacent to the terminal part The substrate portion wherein the slits in parallel with the lead terminal portion is formed.
According to a second aspect of the present invention, the multi-mode piezoelectric filter element according to the first aspect is hermetically sealed in a surface mounting package, and lead terminals extending from the ground electrode and the divided electrode are polyimide conductive adhesives. It is characterized by being adhered to the internal electrode in the package.
According to a third aspect of the present invention, there is provided a piezoelectric vibration element in which counter electrodes are attached and formed on both opposing surfaces of a rectangular piezoelectric substrate, and lead terminals of the respective counter electrodes are formed to extend at different corners of the piezoelectric substrate.
Each lead terminal extending from each counter electrode is bent after reaching a corresponding one end edge of the piezoelectric substrate, and is extended to each corner along the end edge. In the piezoelectric substrate portion adjacent to the lead terminal portion extending to the portion, a slit is formed in parallel with the lead terminal portion.
According to a fourth aspect of the present invention, the piezoelectric vibration element according to the third aspect is hermetically sealed in a surface mounting package, and lead terminals extending from the respective counter electrodes are formed inside the package by a polyimide-based conductive adhesive. It is characterized by being bonded to the electrode.

According to the first and second aspects of the present invention, the lead terminal extending from the ground electrode is disposed at one corner of the rectangular piezoelectric substrate, and the other corners located on both sides of the corner provided with the ground lead terminal. Lead terminals from the two divided electrodes were drawn out at the corners, and the lead terminals of the divided electrodes were formed on narrow-band-shaped piezoelectric substrate portions formed at the corners. Furthermore, each corner portion where each lead terminal extends was adhered to the internal electrode in the surface mounting package with a polyimide-based conductive adhesive. At this time, the internal electrode corresponding to the corner portion where the ground lead terminal extends is fixed with a sufficient amount of conductive adhesive, and a relatively small amount of conductive is applied to the corner portion where the lead terminal extending from each divided electrode extends. By fixing with the adhesive, it is possible to obtain the same characteristics as when this filter element is supported in a substantially cantilevered state. Therefore, the influence of distortion transmitted from the package can be reduced.
According to the third and fourth aspects of the invention, the above structure can be applied to a piezoelectric vibration element and a piezoelectric vibrator using the same, and the same effect can be obtained.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
FIGS. 1A and 1B are a longitudinal sectional view and a plan view of an essential part showing the structure of a surface mount filter using a multimode piezoelectric filter element according to an embodiment of the present invention.
The multimode piezoelectric filter element 1 is mounted in a recess of a surface mounting package 20 and the opening of the recess is hermetically sealed with a metal lid 25 so that the multimode piezoelectric filter 30 for surface mounting is mounted. Is completed.
The multi-mode piezoelectric filter element 1 has an excitation divided electrode 3 in which a counter electrode is attached and formed on both opposing surfaces of a rectangular piezoelectric substrate 2 made of quartz or the like, and the counter electrodes on one side are arranged at a predetermined interval. 4, the opposite electrode on the other side is the ground electrode 5, and the lead terminals 3 a, 4 a, 5 a of the electrodes 3, 4, 5 are extended to different corners of the piezoelectric substrate 2. ing.
The lead terminals 3a and 4a extending from the divided electrodes 3 and 4 are terminated at corners 2A and 2B on one diagonal line of the piezoelectric substrate 2, respectively, and the lead terminals 5a extending from the ground electrode 5 are Terminate at the other corner 2C. More specifically, the lead terminals 3a and 4a extending from the respective divided electrodes 3 and 4 are bent after reaching the corresponding one end edges 2a and 2b of the piezoelectric substrate, respectively, and are bent at the respective corners along the end edges 2a and 2b. The portions 2A and 2B are extended. That is, each lead terminal 3a, 4a includes a first lead terminal portion 3a-1, 4a-1 extending toward each end edge 2a, 2b and each first lead terminal portion 3a-1, 4a-1. Second lead terminal portions 3a-2 and 4a-2 extending from the end portions toward the respective corners 2A and 2B along the respective end edges 2a and 2b.
On the other hand, each of the second lead terminal portions 3a-2 is adjacent to the second lead terminal portions 3a-2 and 4a-2 that extend to the corner portions 2A and 2B along the edges 2a and 2b. The slit 6 is formed in parallel with 4a-2. Accordingly, the piezoelectric substrate portion on which the second lead terminal portions 3a-2 and 4a-2 are formed has a narrow strip shape.

When the filter element 1 is accommodated in the package 20, the terminal portions (pad portions) of the lead terminals 3a, 4a, and 5a are positioned on the three internal electrodes 21 provided on the inner bottom portion of the package 20. The polyimide conductive adhesive 7 is used for adhesion. At this time, the tip of the lead terminal 5a of the ground electrode 5 and the internal electrode 21 are fixed with a sufficient amount of the conductive adhesive 7, while the other lead terminals 3a and 4a are relatively small in conductivity. Adhesive 7 is used for bonding to such an extent that electrical connection can be secured. As a result, the support structure of the filter element 1 is the same as the case where the filter element 1 is supported at one point by the corner 2C corresponding to the tip of the lead terminal 5a.
For this reason, even if the package is distorted when the metal lid 25 is seam welded to the package 20, the effect of the distortion is exerted on the filter element 1 because the fixing position by the polyimide-based conductive adhesive is one place. The frequency variation amount can be suppressed to 100 ppm or less.

Next, FIGS. 2A and 2B are a longitudinal sectional view and a plan view of an essential part showing a configuration example when the present invention is applied to a piezoelectric vibrator.
The piezoelectric vibration element 41 is mounted in a recess of the surface mounting package 60, and the opening of the recess is hermetically sealed with a metal lid 65, whereby the surface mounting piezoelectric vibrator 70 is completed. .
In the piezoelectric vibration element 41, excitation electrodes 43 and 44 are formed on opposite surfaces of a rectangular piezoelectric substrate 42 made of quartz or the like, and lead terminals 43a and 44a of the excitation electrodes 43 and 44 are arranged at different angles on the piezoelectric substrate 2, respectively. It has a configuration that is extended at the corner.
The lead terminals 43a and 44a extending from the excitation electrodes 43 and 44 are terminated at corners 42A and 42B on one diagonal line of the piezoelectric substrate 42, respectively. More specifically, the lead terminals 43a and 44a extending from the respective excitation electrodes 43 and 44 are bent after reaching the corresponding one end edges 42a and 42b of the piezoelectric substrate, respectively, and are bent along the end edges 42a and 42b. The portions 42A and 42B are extended. That is, the lead terminals 43a and 44a are respectively formed of the first lead terminal portions 43a-1 and 44a-1 extending toward the end edges 42a and 42b, and the first lead terminal portions 43a-1 and 44a-1. The second lead terminal portions 43a-2 and 44a-2 extend from the end portions toward the corner portions 42A and 42B along the end edges 42a and 42b.
On the other hand, a slit 46 is formed in the piezoelectric substrate portion adjacent to the second lead terminal portion 44a-2 extending to the corner portion 42B along the edge 42b in parallel with each second lead terminal portion 44a-2. Yes. Accordingly, the piezoelectric substrate portion on which the second lead terminal portion 44a-2 is formed has a narrow strip shape.

When the piezoelectric vibrator 41 is accommodated in the package 60, the terminal portions (pad portions) of the lead terminals 43a and 44a are positioned on the two internal electrodes 61 provided on the inner bottom portion of the package 60. Bonding is performed with a polyimide-based conductive adhesive 67. At this time, the lead terminal 42b on the slit forming side is fixed to the internal electrode 61 with a sufficient amount of conductive adhesive 67, while the other lead terminal 44a is relatively small in amount. Adhesive 67 is used to adhere to the extent that electrical connection with the internal electrode 61 can be secured. As a result, the support structure of the filter element 41 is the same as that in the case where the filter element 41 is supported at one point by the corner portion 42B corresponding to the tip portion of the lead terminal 42b.
For this reason, even if the package is distorted when the metal lid 65 is seam welded to the package 60, since the fixing position by the polyimide conductive adhesive 67 is one place, the influence of the distortion is applied to the filter element 41. There is no risk of being affected, and the frequency fluctuation amount can be suppressed to 100 ppm or less.

(A) And (b) is a longitudinal cross-sectional view which shows the structure of the filter for surface mounting using the multimode piezoelectric filter element which concerns on one Embodiment of this invention, and a principal part top view. (A) And (b) is a longitudinal cross-sectional view which shows the structural example at the time of applying this invention to a piezoelectric vibrator, and a principal part top view. Explanatory drawing of a prior art example.

Explanation of symbols

  1 Multimode Piezoelectric Filter Element, 2 Piezoelectric Substrate, 2a, 2b Substrate Edge, 2A, 2B, 2C Corner Corner, 3, 4 Divided Electrode, 3a, 4a Lead Terminal, 3a-1, 4a-1 First Lead Terminal portion, 3a-2, 4a-2, 5 ground electrode, 5a lead terminal, 7 polyimide conductive adhesive, 20 package, 21 internal electrode, 25 metal lid, 41 piezoelectric vibration element, 42 piezoelectric substrate, 43, 44 Excitation electrode, 43a, 44a Lead terminal, 42A, 42B Corner corner, 60 package, 61 Internal electrode, 65 Metal lid.

Claims (4)

A counter electrode is attached and formed on each of both opposing surfaces of a rectangular piezoelectric substrate, and a counter electrode on one side is formed as an input / output divided electrode arranged at a predetermined interval, and a counter electrode on the other side is a ground electrode. And a multimode piezoelectric filter element in which lead terminals of each electrode are formed to extend at different corners of the piezoelectric substrate,
A lead terminal extending from each of the divided electrodes is terminated at a corner corner on a diagonal line of the piezoelectric substrate, and a lead terminal extending from the ground electrode is terminated at another corner corner of the piezoelectric substrate. In things,
The lead terminals extending from the respective divided electrodes are bent after reaching the corresponding one end edge of the piezoelectric substrate, and are extended to the respective corners along the end edge, and the corner terminals are extended along the end edge. A multimode piezoelectric filter element characterized in that a slit is formed in the piezoelectric substrate portion adjacent to the lead terminal portion extending to the portion in parallel with the lead terminal portion.   The multi-mode piezoelectric filter element according to claim 1 is hermetically sealed in a surface-mounting package, and lead terminals extending from the ground electrode and the divided electrodes are connected to the internal electrodes in the package by a polyimide-based conductive adhesive. Surface mount filter characterized by being bonded to the surface. In the piezoelectric vibration element in which a counter electrode is attached and formed on each of both opposing surfaces of a rectangular piezoelectric substrate, and lead terminals of each counter electrode are extended to different corners of the piezoelectric substrate,
Each lead terminal extending from each counter electrode is bent after reaching a corresponding one end edge of the piezoelectric substrate, and is extended to each corner along the end edge. A piezoelectric vibration element, wherein a slit is formed in a portion of a piezoelectric substrate adjacent to a lead terminal portion extending to the portion in parallel with the lead terminal portion.   The piezoelectric vibration element according to claim 3 is hermetically sealed in a surface mounting package, and lead terminals extending from the respective counter electrodes are bonded to internal electrodes in the package with a polyimide-based conductive adhesive. Surface mount piezoelectric vibrator.

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