JP6133609B2 - Piezoelectric parts - Google Patents

Description

  The present invention relates to a piezoelectric component that requires high reliability and highly accurate frequency characteristics.

  Conventionally, a support substrate, a piezoelectric element mounted on the support substrate, and a cap made of a frame body and a top plate provided on the support substrate so as to cover the piezoelectric element, the bottom portion of the frame body being sealed. A piezoelectric component (resonator) joined by a stopper is known (see Patent Document 1).

Japanese Patent Laid-Open No. 06-037579

  The above-described piezoelectric component has a structure in which the cap is bonded via a sealing material, so that the airtightness in the cap is maintained and the piezoelectric element is protected against an impact from the outside.

  However, when this piezoelectric component is driven for a long period of time, there is a possibility that a gap may be formed between the bottom portion of the cap (frame body) and the sealing material. Furthermore, when moisture or foreign matter in the atmosphere enters from the gap, migration of an electrode forming component (for example, silver) occurs, and the frequency characteristics may change.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a piezoelectric component in which peeling between a bottom portion of a cap (frame body) and a sealing material is suppressed.

The piezoelectric component of the present invention includes a support substrate, a piezoelectric element mounted on the support substrate, and a cap formed of a frame body and a top plate provided on the support substrate so as to cover the piezoelectric element. A piezoelectric component in which a bottom of a body is joined by a sealing material, and the bottom of the frame has a shape with a height difference in a region between an inner wall surface and an outer wall surface, The bottom portion has a shape with a height difference in which the region on the inner wall surface side near the inner wall surface of the frame body is higher than the region on the outer wall surface side near the outer wall surface of the frame body . The capacitor-forming dielectric layer provided on the main surface is arranged from the inside of the frame to a region that is higher on the inner wall surface side of the bottom.

  Moreover, the piezoelectric component according to the present invention is characterized in that, in the above configuration, the bottom of the frame body has a plurality of bonding surfaces bonded to the sealing material.

  Moreover, the piezoelectric component of the present invention is characterized in that, in the above configuration, the bottom portion of the frame body is stepped.

  Further, in the piezoelectric component of the present invention, in the above configuration, in the cross section cut along a plane perpendicular to the main surface of the support substrate so as to cross the bottom portion of the frame body, the entire region of the bottom portion is a sealing material. It has the cross section joined, It is characterized by the above-mentioned.

Moreover, the piezoelectric component of the present invention is characterized in that, in the above-described configuration, a cross section in which the entire region of the bottom of the frame is joined to the sealing material extends over the entire circumference of the frame.

  According to the present invention, the bottom of the frame has a shape with a height difference in the region between the inner wall surface and the outer wall surface, so that the in-plane direction during driving (the same plane as the main surface of the support substrate) Direction), a portion that receives vibrations in directions other than the in-plane direction is formed, so that the vibration is strong against in-plane vibration during driving. As a result, since it is difficult for deviation to occur between the bottom of the cap (frame body) and the sealing material, peeling is suppressed and sealing is maintained, and stable frequency characteristics are obtained.

(A) is a partially omitted schematic plan view showing an example of an embodiment of the piezoelectric component of the present invention, (b) is a schematic cross-sectional view cut along line AA shown in (a), and (c) is (b) It is an enlarged view of the broken-line area | region B shown in FIG. It is a principal part expanded sectional view which shows the other example of embodiment of the piezoelectric component of this invention. (A) And (b) is a principal part expanded sectional view which shows the other example of embodiment of the piezoelectric component of this invention. Partially omitted schematic plan view showing another example of the embodiment of the piezoelectric component of the present invention

  An example of an embodiment of a piezoelectric component of the present invention will be described in detail with reference to the drawings.

  1A is a partially omitted schematic plan view showing an example of an embodiment of a piezoelectric component according to the present invention, FIG. 1B is a schematic cross-sectional view cut along line AA shown in FIG. FIG.1 (c) is an enlarged view of the broken-line area | region B shown in FIG.1 (b).

  The piezoelectric component shown in FIG. 1 includes a support substrate 1, a piezoelectric element 2 mounted on the support substrate 1, and a frame body 41 and a top plate 42 provided on the support substrate 1 so as to cover the piezoelectric element 2. The piezoelectric component includes a cap 4 and a bottom portion 411 of a frame body 41 joined by a sealing material 5, and the bottom portion 411 of the frame body 41 has a height difference in a region between an inner wall surface and an outer wall surface. It has a shape.

  The support substrate 1 includes, for example, a support substrate body 11 formed as a rectangular flat plate having a length of 2.5 mm to 7.5 mm, a width of 1.0 mm to 3.0 mm, and a thickness of 0.1 mm to 1 mm. It is out. As the support substrate body 11, a ceramic material such as alumina and a resin material such as glass epoxy can be used.

  A pair of signal terminals 121 and 122 and a ground terminal 13 are provided on the lower surface of the support substrate body 11 constituting the support substrate 1. Further, wiring conductors 141 and 142 are provided on the upper surface of the support substrate body 11 so as to be electrically connected to the signal terminals 121 and 122. These are formed by printing and sintering a conductive paste containing metal powder such as gold, silver, copper, aluminum, tungsten, or the like. Moreover, what formed plating, such as Ni / Au and Ni / Sn, may be used as needed.

  On the support substrate 1, the piezoelectric element 2 is mounted so that both ends are fixed. Specifically, both ends of the piezoelectric element 2 are fixed on the support substrate 1 by the conductive bonding material 3 so as to vibrate.

  The piezoelectric body 21 constituting the piezoelectric element 2 is formed, for example, as a rectangular flat plate having a length of 1.0 mm to 4.0 mm, a width of 0.2 mm to 2 mm, and a thickness of 40 μm to 1 mm. The material is polarized in the thickness direction. The piezoelectric body 21 is made of, for example, piezoelectric ceramics based on lead titanate, lead zirconate titanate, sodium niobate, potassium niobate, a bismuth layered compound, etc., or a piezoelectric single unit such as lithium tantalate or lithium niobate. It can be formed using crystals.

  In addition, the piezoelectric element 2 includes electrodes (excitation electrodes 22 and 23) arranged so as to have regions facing each other on one main surface and the other main surface of the piezoelectric body 21. The excitation electrode 22 provided on the upper main surface of the piezoelectric body 21 is provided so as to extend from one end portion toward the other end portion, and is provided on the lower main surface of the piezoelectric body 21. The excitation electrode 23 is provided so as to extend from the other end toward the one end, and has regions facing each other. The excitation electrodes 22 and 23 can be made of metal such as gold, silver, copper, and aluminum, and are applied to the surface of the piezoelectric body 21 to a thickness of, for example, 0.1 μm to 3 μm. The excitation electrode 22 of the piezoelectric element 2 is electrically connected to the wiring conductor 141 via the conductive bonding material 3, and the excitation electrode 23 of the piezoelectric element 2 is connected to the wiring conductor 142 via the conductive bonding material 3. And are electrically connected.

  Here, the conductive bonding material 3 also has a function of ensuring a predetermined space (gap) between the upper surface of the support substrate 1 and the lower surface of the piezoelectric element 2. As such a conductive bonding material 3, for example, solder, a conductive adhesive, or the like is used. As long as the solder is used, a lead-free material such as copper, tin, or silver can be used. If it is an adhesive agent, the epoxy-type conductive resin or silicone-type resin containing 75-95 mass% of electroconductive particles, such as silver, copper, and nickel, can be used.

  In such a piezoelectric element 2, when a voltage is applied between the excitation electrode 22 and the excitation electrode 23 from both ends, thickness longitudinal vibration or thickness slip occurs at a specific frequency in a region where the excitation electrode 22 and the excitation electrode 23 face each other. The piezoelectric vibration is generated.

  A cap 4 is provided on the support substrate 1 so as to cover the piezoelectric element 2. The cap 4 includes a frame body 41 and a top plate 42 having a thickness of 250 to 300 μm, for example, and a bottom portion 411 of the frame body 41 is joined to a peripheral edge portion of the upper surface of the support substrate 1 by a sealing material 5. Thereby, the function of protecting the piezoelectric element 2 accommodated in the space formed with the support substrate 1 from the physical and chemical influences from the outside, water into the space formed with the support substrate 1, etc. It has a hermetic sealing function to prevent the entry of foreign matter.

  As a material of the cap 4, for example, a metal such as SUS, ceramics such as alumina, resin, glass, or the like can be used. Further, an insulating resin material such as an epoxy resin may contain an inorganic filler in a proportion of 25 to 80% by mass so as to reduce the difference in thermal expansion coefficient with the support substrate 1.

  Examples of the material for the sealing material 5 include epoxy-based, epoxy acrylate-based, and silicone-based adhesives.

  And the bottom part 411 of the frame 41 is a shape with a difference in height in the area | region between an inner wall surface and an outer wall surface.

The bottom portion 411 of the frame body 41 has a shape having a height difference in the region between the inner wall surface and the outer wall surface, so that the in-plane direction during driving (the same plane direction as the main surface of the support substrate 1) can be obtained. Since there is a portion that receives vibration in a direction other than the in-plane direction with respect to vibration, it is strong against in-plane vibration during driving. As a result, since it is difficult for deviation to occur between the bottom 411 of the cap 4 (frame body 41) and the sealing material 5, peeling is suppressed and sealing is maintained, and stable frequency characteristics are obtained.

  The difference in height here means the difference between the highest point and the lowest point (height H shown in the figure). In the form shown in FIG. The point of intersection with the wall surface is the highest, and the horizontal plane at the bottom 411 is the lowest. The height difference H is preferably a difference of 25 to 75 μm, for example, from the viewpoint of having the above-described effect while maintaining the strength of the cap 4.

Here, FIG. 1 (c), the as shown in FIG. 2, the bottom of the frame body 41 411 is preferably a region of the inner wall surface side from the outer wall surface area is higher. In FIG. 1C and FIG. 2, the position of the bottom 411 is high, and the side where the thickness of the sealing material 5 is thick is the region on the inner wall surface side. According to this configuration, since a large amount of the sealing material 5 is present below the region on the inner wall surface side of the bottom 411 of the frame body 41, the internal pressure is reduced with respect to changes in the internal pressure during driving. Can play a role. As a result, it is possible to maintain sealing performance against changes in internal pressure.

  Further, as shown in FIGS. 1C, 2, and 3, it is preferable that the bottom portion 411 of the frame body 41 has a plurality of bonding surfaces bonded to the sealing material 5. The term “joint surface” as used herein means a flat surface, and includes both horizontal and inclined surfaces. According to this configuration, the bonding area is increased and the adhesion (sealing property) is improved. Specifically, the number of interfaces between the sealing material 5 and the bottom portion 411 of the cap 4 (frame body 41) increases, and the structure is bent between adjacent interfaces, and microcracks formed at the interfaces Can stop progress.

  Moreover, as shown in FIG. 3, it is preferable that the bottom part 411 of the frame 41 is stepped. According to this configuration, a portion joined to the vertical portion can be formed with respect to the vibration in the in-plane direction (the same plane direction as the main surface of the support substrate 1), and is stronger against the vibration in the in-plane direction. Become. Therefore, the sealing property can be further maintained. The step shape may be a step shape of two or more steps, but may be a single step shape as shown in FIG. In this case, it is effective that the step H is, for example, 25 to 75 μm.

  Further, as shown in FIG. 3A, the bonding material 5 is at least at the corner portion forming the step, and the cutting is performed by a plane perpendicular to the main surface of the support substrate 1 so as to cross the bottom portion 411 of the frame body 41. Even if the entire area of the bottom portion 411 is not bonded to the sealing material 5 in the cross section, it is sufficient that the external vibration is not transmitted to the internal element. However, as shown in FIG. Of the cross sections cut along a plane perpendicular to the main surface of the support substrate 1 so as to cross the bottom portion 411 of the body 41, all the regions of the bottom portion 411 have a cross section bonded to the sealing material 5. preferable. Furthermore, it is preferable that the bonding material 5 is formed so as to climb up to the inner wall surface of the frame body 41 or the wall surface. Thereby, the joining area of the width direction of the bottom part 411 spreads, and adhesiveness (sealing property) improves.

  Furthermore, the cross section in which the entire region of the bottom portion 411 of the frame body 41 is bonded to the sealing material 5 should extend over the entire circumference of the frame body 41, thereby expanding the bonding area in the circumferential direction of the bottom portion 411. , Adhesion (sealability) is improved.

Furthermore, as shown in FIG. 4, a wiring conductor 143, a dielectric layer 144, a wiring conductor 145, and an overcoat layer (for example, a glass layer) 146 are sequentially printed on the upper surface of the support substrate body 11 to form a laminated structure. Thus, when the capacitance is formed on the support substrate main body 11, the print pattern can be expanded from the inside of the frame body 41 to the higher region on the inner wall surface side of the bottom portion 411. In particular, as shown in FIG. 4, the capacitor-forming dielectric layer 144 provided on the main surface of the support substrate 1 is arranged from the inside of the frame body 41 to a region where it is higher on the inner wall surface side of the bottom portion 411. This structure is preferable, and this configuration can increase the area of the dielectric layer 144, increase the capacitance value, and widen the range of capacitance values that can be manufactured. Therefore, a capacitance value that is compatible with the IC to be used can be manufactured.

  The present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the scope of the present invention.

  Next, an example of a method for manufacturing a piezoelectric component according to the present embodiment will be described.

  First, a multi-piece substrate for producing the support substrate 1 is produced. For example, after the raw material powder is mixed with water and a dispersant using a ball mill, a binder, a solvent, a plasticizer, and the like are added to obtain a green sheet. The green sheet is subjected to hole processing as necessary, and then a conductive paste containing metal powder such as gold, silver, copper, aluminum, tungsten or the like is printed and laminated. This is fired at a peak temperature of, for example, 900 ° C. to 1600 ° C.

  Next, for example, after the raw material powder was mixed with water and a dispersant using a ball mill, the piezoelectric body 21 constituting the piezoelectric element 2 was added with a binder, a plasticizer, and the like, and dried and sized. The raw material thus obtained is press-molded and fired to obtain a piezoelectric ceramic. An electrode is formed on the end face of the obtained piezoelectric ceramic, and a polarization treatment is performed by applying a voltage of, for example, 0.4 kV / mm to 6 kV / mm in the thickness direction at a temperature of 25 ° C. to 300 ° C., for example.

  The excitation electrodes 22 and the excitation electrodes 23 formed on the upper and lower surfaces of the piezoelectric body 21 are coated with a metal film on the upper and lower surfaces of the piezoelectric body 21 by using a vacuum deposition method, a PVD method, a sputtering method, or the like. After forming a photoresist film having a thickness of about 1 μm to 10 μm on each metal film using screen printing or the like, it can be formed by patterning by photoetching. The piezoelectric element 2 is produced by cutting the patterned piezoelectric ceramic into a predetermined size by dicing or the like.

  Then, using the conductive bonding material 3, a large number of piezoelectric elements 2 are mounted on the substrate and fixed. When the conductive bonding material 3 is a conductive adhesive in which metal powder is dispersed in a resin, the conductive adhesive 3 is applied onto the wiring conductors 141 and 142 using a dispenser or the like, and the piezoelectric material is piezoelectric. The element 2 may be mounted and the conductive adhesive resin may be cured by heating or ultraviolet irradiation.

  Next, frequency adjustment is performed in a state where the piezoelectric element 2 is mounted on a multi-piece substrate. In the frequency adjustment, the excitation electrodes 22 and 23 formed on the surface of the piezoelectric element 2 are etched with an ion gun or the like, and matched with the IC by changing the length or thickness or changing the design value. The oscillation frequency is adjusted by connecting an oscillation frequency measurement terminal to the signal terminals 121 and 122 and the ground terminal 13 at the time of ion gun irradiation and measuring the oscillation frequency. When the oscillation frequency is reached, the ion gun is irradiated. Implement by stopping.

  And the bottom part 411 (opening peripheral surface) of the frame 41 of the cap 4 is joined to the peripheral part of the upper surface of the support substrate 1 so that the piezoelectric element 2 may be covered. As the cap 4, a multi-cap assembly cap sheet having a plurality of recesses is used, and the multi-cap assembly sheet is placed on the substrate so that the recesses cover the piezoelectric element 2. The convex portion of the collective cap sheet that becomes the surface) is joined to the peripheral edge of the upper surface of the support substrate 1. For example, the sealing material 5 (thermosetting insulating adhesive) is applied to the convex portion of the assembly cap sheet that becomes the bottom 411 (opening peripheral surface) of the prepared cap 4, and the cap 4 is supported on the support substrate 1. Put it on the top surface. Thereafter, the cap 4 or the support substrate 1 is heated to raise the temperature of the sealing material 5 to 100 to 150 ° C. to be cured, and the cap 4 is bonded to the upper surface of the support substrate 1.

  The configuration in which the bottom portion 411 of the frame body 41 of the cap 4 has a height difference in the region between the inner wall surface and the outer wall surface may be processed in advance with a mold or the like.

  Finally, it is cut by dicing or the like along the boundary of each piezoelectric component (piece).

  The piezoelectric component of the present invention is manufactured by the above method. According to the method as described above, it is possible to manufacture a piezoelectric component having a small frequency variation even with a temperature change with high productivity.

1: Support substrate 11: Support substrate body 121, 122: Signal terminal 13: Ground terminal 141, 142: Wiring conductor 2: Piezoelectric element 21: Piezoelectric body 22, 23: Excitation electrode 3: Conductive bonding material 4: Cap 41: Frame 411: Bottom 42: Top plate 5: Sealing material

Claims (5)

A support substrate; a piezoelectric element mounted on the support substrate; and a cap made of a frame body and a top plate provided on the support substrate so as to cover the piezoelectric element, wherein the bottom of the frame body is a sealing material Piezoelectric parts joined by:
The bottom of the frame has a shape with a height difference in which the region on the inner wall surface near the inner wall surface of the frame is higher than the region on the outer wall surface near the outer wall surface of the frame ,
A piezoelectric component, wherein a capacitor forming dielectric layer provided on the main surface of the support substrate is disposed from the inner side of the frame to a higher region on the inner wall surface side of the bottom. .   2. The piezoelectric component according to claim 1, wherein a bottom portion of the frame body has a plurality of bonding surfaces bonded to the sealing material.   The piezoelectric component according to claim 2, wherein a bottom portion of the frame body is stepped.   Of the cross-section cut along a plane perpendicular to the main surface of the support substrate so as to cross the bottom of the frame, the entire area of the bottom has a cross-section bonded to a sealing material. The piezoelectric component according to any one of claims 1 to 3.   5. The piezoelectric component according to claim 4, wherein a cross section in which all regions of a bottom portion of the frame body are bonded to a sealing material extends over the entire circumference of the frame body.

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