JP2010028683A - Piezoelectric device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive piezoelectric device has a good conductivity between a wiring pattern on a substrate and an exciting electrode on the surface of a piezoelectric element, and also a method of manufacturing the piezoelectric device. <P>SOLUTION: The piezoelectric element 2 is directly mounted on a wiring pattern 11 provided on a substrate 1 without any conductive member such as a conductive adhesive provided between the wiring pattern 11 and an exciting electrode 2a on the surface of the piezoelectric element 2. The wiring pattern 11 on the substrate 1 is mechanically and electrically connected to the exciting electrode 2a on the piezoelectric element 2 by a means for enabling direct junction, e.g., by welding. With such an arrangement, since a conductive member, which has been provided between the wiring pattern 11 and the exciting electrode 2a, is eliminated, its material cost is correspondingly reduced and a conductivity between both is increased. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric device and a manufacturing method thereof.

  Conventionally, a piezoelectric device in which a piezoelectric element such as a crystal piece is mounted on a conductive pattern formed on a substrate via a conductive member such as a conductive adhesive is known. (For example, see Patent Documents 1 to 3)

  6A and 6B are diagrams showing a conventional piezoelectric device, where FIG. 6A is a top view and FIG. 6B is a cross-sectional view taken along line AA in FIG. In the top view (a), a part of the configuration is not shown in order to make the internal configuration easy to understand. The conventional piezoelectric device shown here includes a box-shaped insulating substrate 1 (hereinafter simply referred to as a substrate) having a concave portion 1a having a rectangular shape in plan view, a plate-like piezoelectric element 2 housed inside the concave portion 1a, The plate-shaped lid member 3 joined to the upper end of the substrate 1 is roughly configured, and the piezoelectric element 2 is hermetically sealed in a space formed by the substrate 1 and the lid member 3.

  A step portion 1b having a predetermined drop is formed on a part of the bottom surface of the recess 1a of the substrate 1, and two wiring patterns 4 made of a conductive material such as metal are laid on the top surface, and Ag is formed thereon. The piezoelectric element 2 is mounted in a cantilever state via a UV curable conductive adhesive 5 containing conductive particles (nanofiller) such as (silver).

  Two excitation electrodes 2 a having different electrical polarities for driving the piezoelectric element 2 are provided on the front and back surfaces of the piezoelectric element 2, and they are the same surface (back surface) on one end side in the longitudinal direction of the piezoelectric element 2. ) And mechanically and electrically connected to the two wiring patterns 4 on the stepped portion 1b and the conductive adhesive 5 respectively.

  The two wiring patterns 4 on the step portion 1b are electrically connected to two external connection terminals 6 formed on the lower surface of the substrate 1 through a through wiring (not shown) provided in the thick portion of the substrate 1. Through this, electric signals are input / output to / from the piezoelectric element 2.

In the piezoelectric device described above, the conductive adhesive 5 interposed between the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 4 on the stepped portion 1b serves to fix the piezoelectric element 2 on the substrate 1 and to excite it. The electrode 2a and the wiring pattern 4 also serve to conduct each other. The material used is not limited to a conductive adhesive, and various materials such as solder can be appropriately selected.
JP 2007-267101 A JP 2007-195138 A JP 2008-85469 A

  However, in the conventional piezoelectric device, the wiring pattern on the substrate and the excitation electrode on the surface of the piezoelectric element are electrically connected to each other through a conductive member (conductive adhesive, solder, etc.). There is a problem that the material cost is increased, and the electrical conductivity of the piezoelectric element may be affected due to a decrease in mutual conductivity due to the presence of the conductive member between the wiring pattern and the excitation electrode. . In particular, when the piezoelectric device is downsized, the application area of the conductive member is limited accordingly, and the total amount of the conductive material is reduced, so that the conductivity is further lowered.

  The present invention has been made in view of the above problems, and provides an inexpensive piezoelectric device having a good electrical connection between the wiring pattern on the substrate and the excitation electrode on the surface of the piezoelectric element, and a method for manufacturing the piezoelectric device. Objective.

  And at least a substrate, a wiring pattern formed on the substrate, and a piezoelectric element having an excitation electrode formed on a surface thereof, and the piezoelectric element is in a state where the excitation electrode and the wiring pattern are in contact with each other. A piezoelectric device is mounted directly on the wiring pattern without using a conductive member.

  The excitation electrode and the wiring pattern may be a piezoelectric device bonded to each other.

  It may be a piezoelectric device in which an adhesive is interposed between the piezoelectric element and the substrate.

  A piezoelectric device comprising at least a step of forming a wiring pattern on a substrate, a step of placing a piezoelectric element having an excitation electrode on the wiring pattern, and a step of bonding the wiring pattern and the excitation electrode to each other The manufacturing method is as follows.

  The wiring pattern is formed by applying a liquid or paste conductive material on the substrate, the piezoelectric element is placed on the wiring pattern in a state where the wiring pattern is uncured, and the wiring It can be set as the manufacturing method of the piezoelectric device which joins the said wiring pattern and the said excitation electrode mutually by hardening a pattern.

  At least a step of forming a wiring pattern on a substrate, a step of applying a curing shrinkable adhesive on the substrate, and a piezoelectric element having an excitation electrode on the adhesive in a state where the adhesive is uncured The method of manufacturing a piezoelectric device includes: a step of placing the substrate; and a step of curing the adhesive and causing the excitation electrode and the wiring pattern to adhere to each other by curing shrinkage.

  According to the present invention, the wiring pattern on the substrate and the excitation electrode on the surface of the piezoelectric element are electrically connected to each other without using the conductive member, so that the electrical connection between the wiring pattern and the excitation electrode is increased, and Cost reduction is achieved by reducing material costs.

  At least a substrate, a wiring pattern formed on the substrate, and a piezoelectric element having an excitation electrode formed on the surface, and the piezoelectric element is electrically conductive on the wiring pattern in a state where the excitation electrode and the wiring pattern are in contact with each other. It is a piezoelectric device that is directly mounted without using a sex member.

  1A and 1B are diagrams showing an embodiment of a piezoelectric device according to the present invention. FIG. 1A is a top view, FIG. 1B is an AA cross-sectional view of FIG. In the top view (a), a part of the configuration is not shown in order to make the internal configuration easy to understand. The piezoelectric device of the present invention shown here has a flat plate shape made of a box-shaped insulating substrate 1 (hereinafter simply referred to as a substrate) having a concave portion 1a having a rectangular shape in plan view, and a crystal housed in the concave portion 1a. The piezoelectric element 2 and the flat lid member 3 made of metal or the like bonded to the upper end of the substrate 1 are generally configured. The piezoelectric element 2 is hermetically sealed in the space formed by the substrate 1 and the lid member 3. It is in a stopped state.

  A step portion 1b having a predetermined drop is provided on a part of the bottom surface of the concave portion 1a of the substrate 1, and two wiring patterns 11 having a rectangular shape in a plan view made of a conductive material are formed on the upper surface. The piezoelectric element 2 is directly mounted on the top without a conductive member such as a conductive adhesive.

  Two excitation electrodes 2 a having different electrical polarities for driving the piezoelectric element 2 are formed on the front and back surfaces of the piezoelectric element 2, and they are the same surface (back surface) on one end side in the longitudinal direction of the piezoelectric element 2. ) And mechanically connected (joined) to the corresponding wiring pattern 11 out of the two wiring patterns 11 on the stepped portion 1b, and the piezoelectric element 2 itself is connected to the wiring pattern by the mechanical coupling force. 11 is fixed on the substrate 1 through 11.

  In the above configuration, between the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern on the stepped portion 1b, a conductive member (conductive adhesive, solder, etc.) for conducting both of them as in a conventional piezoelectric device. Etc.), the conductivity between the excitation electrode 2a and the wiring pattern 4 is improved, and the conductive material itself is omitted, thereby reducing the material cost.

  The two wiring patterns 11 on the stepped portion 1b are electrically connected to two external connection terminals 6 formed on the lower surface of the substrate 1 through a through wiring (not shown) provided in the thick portion of the substrate 1, respectively. An electric signal is input / output to / from the piezoelectric element 2 through this.

  2 is a cross-sectional view showing a method of manufacturing the piezoelectric device of the present invention shown in FIG. When manufacturing the piezoelectric device of the present invention shown in FIG. 1, first, as shown in FIG. 2 (a), the step of the substrate 1 in which a concave portion 1a having a rectangular shape in plan view is formed in advance on one main surface side. Two wiring patterns 11 for mounting the piezoelectric element 2 are formed on the part 1b using a liquid or paste conductive material adjusted to a predetermined viscosity.

  Here, in forming the wiring pattern 11, for example, an ink jet method is selected. The ink jet method is a method in which a liquid or pasty material is ejected as droplets from a discharge nozzle at a high speed and adhered to an object. The discharge nozzle is moved horizontally with respect to the object, and the discharge position is gradually changed. By shifting the position, it is possible to accurately draw an arbitrary pattern on the surface of the object.

  In the present embodiment, a conductive material obtained by mixing minute conductive particles (nanofiller) in a solvent is used as a discharge material, and the wiring pattern 11 is discharged by discharging it onto the stepped portion 1b of the substrate 1. Form. At this time, by appropriately adjusting the viscosity of the conductive material in advance, even after the discharged droplets land on the stepped portion 1b of the substrate 1, it does not solidify (harden) for a predetermined time and maintains a constant viscosity. Keep it like that. If it is desired to increase the thickness of the wiring pattern 11, the same process is repeated until a desired thickness is reached at this point, so that the wiring pattern 11 is deposited thickly.

  Next, as shown in FIG. 2B, the piezoelectric element 2 is placed on the uncured wiring pattern 11 in correspondence with the excitation electrode 2a on the surface, and is appropriately pressed from above as necessary. . In this state, the piezoelectric element 2 is held on the wiring pattern 11 by the adhesive force of the conductive material constituting the wiring pattern 11. If there is a possibility that the piezoelectric element 2 may be displaced or tilted, the piezoelectric element 2 is cured. You may make it hold | maintain auxiliary with tools.

  Next, as shown in FIG. 2C, the wiring pattern 11 is cured by heating the entire constituent member or locally heating only the wiring pattern 11. As a result, the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 11 on the step portion 1b are mechanically firmly coupled (bonded), and at the same time, innumerable conductive particles existing inside the wiring pattern 11 are formed. Aggregates and the two become conductive.

  In the above manufacturing process, there is no step of interposing a conductive member such as a conductive adhesive between the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 11 on the stepped portion 1b as in the prior art. Productivity is improving.

  After the piezoelectric element 2 is mounted on the wiring pattern 11, the lid member 3 is joined to the upper end portion of the substrate 1 in a vacuum atmosphere, so that the piezoelectric element 2 is joined to the substrate 1 and the lid member 3 (package). It will be in the state airtightly sealed inside. In the above description, the through wiring, the external connection terminal 6 and the like are preliminarily formed at an arbitrary stage before the piezoelectric element 2 is mounted on the wiring pattern 11.

  In Example 1, the wiring pattern 11 itself is solidified to mechanically and electrically connect the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 11 on the stepped portion 1b. As a configuration having the same operation and effect, it is possible to join the excitation electrode 2a and the wiring pattern 11 by ultrasonic waves, laser, ultraviolet rays, surface activation, and the like after appropriately selecting each other's constituent materials. In either case, the conductive member is not interposed as a separate member between the excitation electrode 2a and the wiring pattern 11, and the problems of the prior art can be solved.

  FIGS. 3A and 3B are diagrams showing another embodiment of the piezoelectric device according to the present invention, in which FIG. 3A is a top view, FIG. 3B is a cross-sectional view taken along line A-A in FIG. In the top view (a), a part of the configuration is not shown in order to make the internal configuration easy to understand. The piezoelectric device of the present invention shown here has the same basic configuration as that of the first embodiment described above, and is characterized in that the excitation electrode on the surface of the piezoelectric element and the wiring pattern on the substrate are not joined to each other.

  In the second embodiment, on the step portion 1b of the substrate 1, there are formed two wiring patterns 12 having a rectangular shape in plan view with a smaller outer size so as to be within the outer region of the piezoelectric element 2. Insulative adhesive 13 is applied to four locations so as not to contact the wiring pattern 12 around the periphery. The piezoelectric element 2 is placed on the wiring pattern 12 in contact with the insulating adhesive 13 so as to correspond to the excitation electrode 2a on the surface, and the excitation electrode 2a and the wiring pattern 12 are in contact with each other, so On the other hand, an adhesive is interposed between the piezoelectric element 2 and the substrate 1, so that the piezoelectric element 2 is fixed on the stepped portion 1 b by its fixing force. Here, the insulating adhesive 13 is a so-called curing / shrinking type adhesive having a property of contracting at the time of curing, and the piezoelectric element 2 is attracted to the substrate 1 side by the contracting force, thereby exciting the surface of the piezoelectric element 2. The electrode 2a is in close contact with the wiring pattern 12 on the step portion 1b.

  In the above configuration, since the conductive material having fluidity is not used to connect the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 12 on the step portion 1b, the conductive material flows out to the surroundings. Thus, the adjacent conductive patterns 12 are not short-circuited, and when the piezoelectric element 2 is fixed to the substrate 1, an adhesive conductive material is used as an adhesive as in the first embodiment. However, since a material specialized for the adhesive force that does not consider conductivity can be selected, it is possible to increase the fixing force of the piezoelectric element 2 to the substrate 1, and in addition, the insulating adhesive Since it is generally cheaper than a conductive adhesive, the cost is reduced accordingly.

  4 is a cross-sectional view showing a method of manufacturing the piezoelectric device of the present invention shown in FIG. When the piezoelectric device of the present invention shown in FIG. 3 is manufactured, first, as shown in FIG. 4A, a step of the substrate 1 in which a concave portion 1a having a rectangular shape in plan view is formed on one main surface side in advance. On the part 1b, a liquid or paste-like conductive material having a high quick-drying property is discharged by an ink jet method to form two wiring patterns 12 for mounting the piezoelectric element 2. At this time, since the droplets of the conductive material discharged by the ink jet method are dried and solidified immediately after landing on the surface of the stepped portion 1b, the wiring pattern 12 does not have adhesiveness at this time. If it is desired to increase the thickness of the wiring pattern 12, the same process is repeated until a desired thickness is obtained at this point, and the wiring pattern 12 is deposited thickly. Further, the wiring pattern 12 only needs to be solidified in a state having no adhesiveness at this time, and the formation method is not limited to the ink jet method, and a sputtering method or the like can also be adopted.

  Next, as shown in FIG. 4B, a curing shrinkable and ultraviolet curable insulating adhesive 13 (hereinafter simply referred to as an adhesive) is used around the two wiring patterns 12 by using a dispensing method or an inkjet method. ) Is applied. At this time, the adhesive 13 is applied at a position and amount that does not come into contact with the wiring pattern 12 even when the adhesive 13 wets and spreads to the periphery so that the adhesive 13 swells to an appropriate height than the thickness of the wiring pattern 12. When the inkjet method is used to apply the adhesive 13, the same application operation is repeated until the adhesive 13 has a desired height (thickness) and is deposited thickly. At this time, when the adhesive 13 contacts the wiring pattern 12 and the surface thereof is covered with the adhesive 13, the conduction between the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 12 on the step portion 1b is established. There is a risk of being disturbed.

  Next, as shown in FIG. 4C, the piezoelectric element 2 is placed on the adhesive 13 in a state where the excitation electrode 2a on the surface thereof corresponds to the wiring pattern 12, and it is appropriately adjusted from above if necessary. Pressurize. In this state, the piezoelectric element 2 is held by the adhesive force of the adhesive 13, but if there is a possibility that the piezoelectric element 2 may be displaced or tilted, the piezoelectric element 2 should be supplementarily held by a jig or the like. Also good.

  Next, as shown in FIG. 4D, the adhesive 13 is irradiated with ultraviolet rays to be cured, and the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 12 on the step portion 1b are contracted by shrinkage at the time of curing. Adhere to each other. Thereby, the excitation electrode 2a on the surface of the piezoelectric element 2 is surely brought into contact with the wiring pattern 12 on the step portion 1b and is electrically connected to each other, while the piezoelectric element 2 itself is firmly fixed to the substrate 1 by the adhesive 13. Is done.

  In the above manufacturing method, the piezoelectric element 2 is placed on the substrate 1 after the adhesive 13 is applied to the substrate 1. For example, the piezoelectric element 2 is placed on the substrate 1 first and then cured. In this state, the adhesive 13 is applied near the boundary between the outer periphery of the piezoelectric element 2 and the substrate 1, or the adhesive 3 is permeated into the gap between the piezoelectric element 2 and the substrate 1. It may be.

  In addition, in order to increase the reliability of conduction by bringing the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 12 on the stepped portion 1b into close contact with each other, it is preferable that the adhesive used is a curing shrink type, It is not limited to that as long as conduction is ensured, and it may be a thermosetting type instead of an ultraviolet curable type.

  FIG. 5 is a top view showing a wiring pattern for mounting a piezoelectric element and an adhesive applied around the wiring pattern. Regarding the configuration of the second embodiment described above, referring to the shape of the wiring pattern 12 for mounting the piezoelectric element 2 and the application position of the adhesive 13, for example, as shown in FIG. In the plan view cross shape, the adhesive 13 is applied to the four blank areas around it, and as shown in FIG. 5 (b), the wiring pattern 12 is formed in an intermittent arc shape in plan view, and the center of the arc is formed. Adhesive 13 may be applied.

  In particular, in the configuration shown in FIG. 5A, the areas of the wiring pattern 12 and the adhesive 13 can be efficiently secured in a limited space, and in the configuration shown in FIG. Since there is a gap between the wiring patterns 12 adjacent to each other, even if gas is generated when the adhesive 13 is cured, the gas is released to the outside through the gap between the individual patterns. The region surrounded by the pattern 12 does not stagnate, and the position of the piezoelectric element 2 is not shifted by the gas pressure.

  The relationship between the shape of the wiring pattern 12 and the application position of the adhesive 13 is not limited to these, and various other types can be selected as appropriate without departing from the spirit of the present invention.

  The configurations of the first and second embodiments described above can be implemented in combination with each other. For example, in the configuration of the first embodiment, the configuration shown in the second embodiment between the piezoelectric element 2 and the stepped portion 1b is shown. The hardening shrinkable adhesive 13 is interposed to improve the fixing strength of the piezoelectric element 2 to the substrate 1 and the adhesion between the excitation electrode 2a on the surface of the piezoelectric element 2 and the wiring pattern 12 on the step portion 1b. May be.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows one Embodiment of the piezoelectric device by this invention, (a) Top view, (b) AA sectional drawing of (a), and its principal part enlarged view (Example 1). Sectional drawing which shows the manufacturing method of the piezoelectric device of this invention shown in FIG. 1 (Example 1) It is a figure which shows other embodiment of the piezoelectric device by this invention, (a) Top view, (b) AA sectional drawing of (a), and its principal part enlarged view (Example 2). Sectional drawing which shows the manufacturing method of the piezoelectric device of this invention shown in FIG. 3 (Example 2) Top view showing wiring pattern for mounting piezoelectric element and adhesive applied around it It is a figure which shows the conventional piezoelectric device, (a) Top view, (b) AA sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 1a Concave part 1b Step part 2 Piezoelectric element 2a Excitation electrode 3 Cover member 4 Wiring pattern 5 Conductive adhesive 6 External connection terminal 11 Wiring pattern 12 Wiring pattern 13 Insulating adhesive

Claims (6)

  And at least a substrate, a wiring pattern formed on the substrate, and a piezoelectric element having an excitation electrode formed on a surface thereof, and the piezoelectric element is in a state where the excitation electrode and the wiring pattern are in contact with each other. A piezoelectric device which is directly mounted on a wiring pattern without a conductive member.   The piezoelectric device according to claim 1, wherein the excitation electrode and the wiring pattern are bonded to each other.   The piezoelectric device according to claim 1, wherein an adhesive is interposed between the piezoelectric element and the substrate. at least,
Forming a wiring pattern on the substrate;
Placing a piezoelectric element having an excitation electrode on the wiring pattern;
A method for manufacturing a piezoelectric device comprising the step of bonding the wiring pattern and the excitation electrode to each other.   The wiring pattern is formed by applying a liquid or paste conductive material on the substrate, the piezoelectric element is placed on the wiring pattern in a state where the wiring pattern is uncured, and the wiring The method for manufacturing a piezoelectric device according to claim 4, wherein the wiring pattern and the excitation electrode are bonded to each other by curing the pattern. at least,
Forming a wiring pattern on the substrate;
Applying a curing shrinkable adhesive on the substrate;
Placing a piezoelectric element having an excitation electrode on the adhesive in an uncured state of the adhesive;
A method of manufacturing a piezoelectric device, comprising: a step of curing the adhesive and causing the excitation electrode and the wiring pattern to adhere to each other by curing shrinkage thereof.

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