JP2010178198A - Surface acoustic wave element and piezoelectric device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface acoustic wave element excellent in aging characteristics and reflow characteristics, and to provide a piezoelectric device equipped with the same. <P>SOLUTION: The surface acoustic wave element 2 includes a piezoelectric substrate 21 formed of a piezoelectric material having piezoelectricity, and an IDT 22 which is provided on one surface of the piezoelectric substrate 21 and causes the piezoelectric substrate 21 to excite a surface acoustic wave. The thickness of the piezoelectric substrate 21 is 60 to 200 μm. In addition, the piezoelectric substrate 21 is curved so as to be dented toward both sides at which the IDTs 22 are provided by stress that is generated by shrinkage forces of component materials of the IDTs 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface acoustic wave element and a piezoelectric device.

A surface acoustic wave element is a circuit element that performs signal processing by converting an electrical signal into a surface wave, and is widely used as a filter, a resonator, and the like. As such a surface acoustic wave element, one having a configuration in which an IDT electrode (comb electrode) is provided on a piezoelectric substrate having a piezoelectric property such as quartz is known (for example, Patent Document 1).
The surface acoustic wave element described in Patent Document 1 has a configuration in which an IDT electrode and a pair of reflectors are provided on a quartz substrate. In such a surface acoustic wave device, conventionally, in order to sufficiently secure the mechanical strength of the surface acoustic wave device, the quartz substrate is made thick. The IDT electrode and the reflector are formed by, for example, forming a conductive film (a thin film made of a metal material such as aluminum) on a quartz substrate by vapor deposition, and forming the conductive film into a predetermined pattern by etching. Is used.

  In such a surface acoustic wave element, since the piezoelectric substrate is thick, it is difficult for the piezoelectric substrate to warp (bend) in the surface direction, and as a result, the stress generated by the contraction of the metal film (IDT electrode and reflector) is relieved. Instead, it remains in the surface acoustic wave element (near the boundary between the piezoelectric substrate and the IDT). As described above, in a surface acoustic wave element in which stress remains in the surface acoustic wave element, the stress remaining in the surface acoustic wave element greatly changes due to temperature change (heat generation by driving) of the surface acoustic wave element. Due to the change, the resonance frequency is greatly changed, the aging characteristic is deteriorated (the change with time of the frequency characteristic is increased), and the reflow characteristic is deteriorated.

Japanese Patent Laid-Open No. 2005-136938

  An object of the present invention is to provide a surface acoustic wave element having excellent aging characteristics and reflow characteristics and a piezoelectric device including the same.

Such an object is achieved by the present invention described below.
The surface acoustic wave device of the present invention includes a piezoelectric substrate made of a piezoelectric material having piezoelectricity,
A comb-like electrode provided on one surface of the piezoelectric substrate, for exciting a surface acoustic wave in the piezoelectric substrate;
The piezoelectric substrate has a thickness of 60 μm to 200 μm,
The piezoelectric substrate is warped so as to be dented on the surface side on which the comb electrode is provided due to a stress generated by a contraction force of the constituent material of the comb electrode.
As a result, a surface acoustic wave device having excellent aging characteristics and reflow characteristics can be provided.

In the surface acoustic wave element of the present invention, it is preferable that the piezoelectric material is composed mainly of quartz.
Thereby, the frequency characteristic can be improved.
In the surface acoustic wave device according to the present invention, it is preferable that the average thickness of the comb electrode is 0.3 μm to 0.8 μm.
Thereby, the stress generated by the contraction force of the constituent material constituting the comb electrode can be made moderate with respect to the mechanical strength of the piezoelectric substrate.

In the surface acoustic wave device according to the present invention, a pair of reflectors disposed so as to face each other via the comb-tooth electrode is formed on one surface of the piezoelectric substrate, and the piezoelectric substrate is viewed in plan view. The area occupancy of the comb electrode and the pair of reflectors with respect to the piezoelectric substrate is preferably 20 to 40%.
Thereby, the stress generated by the contraction force of the constituent material constituting the comb electrode can be made moderate with respect to the mechanical strength of the piezoelectric substrate.

In the surface acoustic wave device of the present invention, the surface acoustic wave element includes a fixed substrate that is provided on the other surface side of the piezoelectric substrate and fixes the piezoelectric substrate.
It is preferable that the piezoelectric substrate is fixed to the fixed substrate with an adhesive at a position where the piezoelectric substrate does not overlap with the comb electrode in a plan view.
As a result, even if the adhesive contracts, the comb-tooth electrode is not displaced, so that a desired frequency characteristic can be exhibited.

In the surface acoustic wave device of the present invention, the piezoelectric substrate has a longitudinal shape, and is fixed to the fixed substrate at one end in the longitudinal direction, and the other end of the piezoelectric substrate is a free end. It is preferable.
Thereby, since it can suppress that stress remains in a piezoelectric substrate, an aging characteristic and a reflow characteristic become more excellent.

In the surface acoustic wave device according to the aspect of the invention, it is preferable that the comb-tooth electrode is provided so as to be shifted to the free end side with respect to the central portion of the piezoelectric substrate.
Thereby, the area | region fixed to the fixed board | substrate of a piezoelectric substrate can be ensured easily.
In the surface acoustic wave device according to the aspect of the invention, the separation distance between the piezoelectric substrate and the fixed substrate at the fixed end of the piezoelectric substrate may be the separation between the piezoelectric substrate and the fixed substrate at the free end of the piezoelectric substrate. It is preferable that the distance is shorter than the distance.
Thereby, contact with a fixed board | substrate and a piezoelectric material board | substrate (especially free end side) can be prevented.

In the surface acoustic wave device according to the aspect of the invention, the separation distance between the piezoelectric substrate and the fixed substrate at the fixed end of the piezoelectric substrate may be a separation between the piezoelectric substrate and the fixed substrate at a central portion of the piezoelectric substrate. It is preferable that the distance is shorter than the distance.
Thereby, wetting and spreading of the adhesive can be prevented.
The piezoelectric device of the present invention includes the surface acoustic wave element of the present invention.
Thereby, a piezoelectric device having excellent aging characteristics and reflow characteristics can be provided.

It is sectional drawing which shows suitable embodiment of the piezoelectric device (piezoelectric device of this invention) provided with the surface acoustic wave element of this invention. It is a perspective view which shows the surface acoustic wave element of this invention. It is the sectional view on the AA line in FIG. 2, and the sectional view on the BB line. FIG. 2 is a top view and a bottom view of a package included in the piezoelectric device shown in FIG. 1. It is sectional drawing which shows the state which molded the piezoelectric device shown in FIG. It is a figure which shows a reflow process. It is a graph which shows the reflow variation | change_quantity of a resonant frequency. It is a graph which shows the heat cycle variation | change_quantity of a resonant frequency. It is a graph which shows the aging variation | change_quantity of a resonant frequency.

Hereinafter, a surface acoustic wave element of the present invention and a piezoelectric device including the surface acoustic wave element (piezoelectric device of the present invention) will be described in detail based on embodiments shown in the accompanying drawings.
FIG. 1 is a cross-sectional view illustrating a preferred embodiment of a piezoelectric device (a piezoelectric device of the present invention) including the surface acoustic wave element of the present invention, and FIG. 2 is a perspective view illustrating the surface acoustic wave element of the present invention. 3 is a cross-sectional view taken along line AA and BB in FIG. 2, FIG. 4 is a top view and bottom view of the package included in the piezoelectric device shown in FIG. 1, and FIG. 5 is a piezoelectric view shown in FIG. It is sectional drawing which shows the state which molded the device. 1 to 5 are referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.
A piezoelectric device 1 shown in FIG. 1 includes a surface acoustic wave element 2, a mounting substrate 4 for mounting (fixing / supporting) the surface acoustic wave element 2 via a plurality of spacers 51, a surface acoustic wave element 2, and a mounting substrate 4. And an electronic component 6 provided on the mounting substrate 4 so as to be positioned between the two. Hereinafter, these will be described in detail in order.

First, the surface acoustic wave element 2 will be described.
As shown in FIG. 2, the surface acoustic wave element 2 is arranged on a piezoelectric substrate 21 having a longitudinal shape, an IDT (comb electrode) 22 provided on the upper surface of the piezoelectric substrate 21, and both sides of the IDT 22. It has a pair of reflectors 23 a and 23 b and a package 3 that accommodates the piezoelectric substrate 21.
The piezoelectric substrate 21 has a longitudinal shape. The piezoelectric substrate 21 is a substrate that can excite, for example, an SH wave type surface acoustic wave or a Rayleigh wave type surface acoustic wave. Such a piezoelectric substrate 21 is made of quartz. By configuring the piezoelectric substrate 21 with quartz, the surface acoustic wave element 2 can exhibit excellent frequency characteristics. The piezoelectric substrate 21 may be made of a crystalline piezoelectric material other than quartz, such as lithium tantalate, lithium niobate, lithium tetraborate, and the like.

  The cut angle of the piezoelectric substrate 21 is not particularly limited, and can be appropriately selected based on the use of the piezoelectric device 1 (surface acoustic wave element 2), desired characteristics, and the like. As the cut angle of the piezoelectric substrate 21, for example, when an SH wave type surface acoustic wave is used (excited), (0 °, 38 °, 90 °) or (0 °, 121 °, 90 °) in Euler angle display. In the case of using a Rayleigh wave type surface acoustic wave, (0 °, 121 °, 0 °), (0 °, 121 °, 43 °), etc. may be mentioned.

  The thickness of the piezoelectric substrate 21 is about 60 μm to 200 μm, and preferably 60 μm to 100 μm. By setting the thickness of the piezoelectric substrate 21 within the above numerical range, the thickness of the piezoelectric substrate 21 becomes sufficiently thin, and is generated by the contraction force of the constituent materials of the IDT 22 and the reflectors 23a and 23b, as will be described later. The piezoelectric substrate 21 warps (bends) so as to be recessed on the upper surface side due to the stress (hereinafter also referred to simply as “stress”). As a result, almost no stress remains on the piezoelectric substrate 21 (particularly, the region where the IDT 22 is formed; the same applies hereinafter), and the piezoelectric device 1 has excellent aging characteristics and reflow characteristics.

  The IDT 22 is provided near the center of the piezoelectric substrate 21. Such an IDT 22 includes a pair of electrodes 22a and 22b. The electrodes 22a and 22b are arranged so that the electrode fingers 221a and 221b are engaged with each other. When a voltage is applied between the electrodes 22a and 22b, a periodic distortion occurs between the electrode fingers 221a and 221b due to the piezoelectric effect of the piezoelectric substrate 21, and a surface acoustic wave is excited. The excited surface acoustic wave propagates along the continuous direction of the electrode fingers 221a and 221b (that is, the longitudinal direction of the piezoelectric substrate 21).

The pair of reflectors 23 a and 23 b are arranged on both sides of the IDT 22 in the above-described propagation direction of the surface acoustic wave (longitudinal direction of the piezoelectric substrate 21). Such reflectors 23a and 23b have a function of reflecting the surface acoustic wave propagating to the piezoelectric substrate 21 and confining it between the reflectors 23a and 23b.
The IDT 22 and the reflectors 23a and 23b are formed so as to be shifted to one end side (right end side in FIG. 2) of the piezoelectric substrate 21 as a whole. A pair of extraction electrodes 24 a and 24 b are formed on the other end side (left end side in FIG. 2) of the piezoelectric substrate 21. The extraction electrodes 24a and 24b are electrically connected to the electrodes 22a and 22b, respectively.

  The average thickness of the IDT 22 (electrodes 22a and 22b) and the average thickness of the reflectors 23a and 23b are not particularly limited, but are preferably about 0.3 μm to 0.8 μm, and preferably 0.5 μm to 0. More preferably, it is about 7 μm. By setting the numerical value in such a range, it is possible to prevent the stress applied to the piezoelectric substrate 21 from becoming excessively large (that is, the stress applied to the piezoelectric substrate 21 with respect to the mechanical strength of the piezoelectric substrate 21). Can be reasonable). Therefore, the piezoelectric device 21 has excellent aging characteristics and reflow characteristics without excessively bending the piezoelectric substrate 21.

  In plan view of the piezoelectric substrate 21, the area of the upper surface of the piezoelectric substrate 21 is S1, the area of the IDT 22 (the total area of the electrodes 22a and 22b) is S2, and the total area of the reflectors 23a and 23b. When S3 is S3, (S2 + S3) is preferably about 0.2S1 to 0.4S2. That is, the area occupation ratio of the IDT 22 and the reflectors 23a and 23b with respect to the upper surface of the piezoelectric substrate 21 is preferably about 20% to 40%. Thereby, it can prevent that the stress added to the piezoelectric substrate 21 becomes large too much. Therefore, the piezoelectric device 21 has excellent aging characteristics and reflow characteristics without excessively bending the piezoelectric substrate 21.

Each of the IDT 22, the reflectors 23a and 23b, and the extraction electrodes 24a and 24b is composed mainly of aluminum having excellent conductivity. When an aluminum alloy containing aluminum as a main material is used, the content ratio of the metal added to aluminum may be 10% or less by weight.
Note that the constituent materials of the IDT 22, the reflectors 23a and 23b, and the extraction electrodes 24a and 24b are not particularly limited as long as they have electrical conductivity. In addition to aluminum, for example, iron, nickel, cobalt, gold, Various metals such as platinum, silver, copper, manganese, and magnesium, or alloys containing at least one of these metals can be used.

  Such IDT 22, reflectors 23a and 23b, and extraction electrodes 24a and 24b can be formed as follows, for example. That is, first, an aluminum film is formed on one surface of the piezoelectric substrate 21 by sputtering. Next, a mask having a pattern corresponding to the IDT 22 (electrodes 22a and 22b), the reflectors 23a and 23b, and the extraction electrodes 24a and 24b is formed on the aluminum film. Then, the unnecessary aluminum film is removed by dry etching, whereby the IDT 22, the reflectors 23a and 23b, and the extraction electrodes 24a and 24b can be formed.

  When the IDT 22, the reflectors 23a and 23b, and the extraction electrodes 24a and 24b are formed by the manufacturing method as described above, the piezoelectric substrate 21 is subjected to stress generated by the contraction of aluminum (aluminum film). As described above, since the piezoelectric substrate 21 is thin, when such stress is applied, the piezoelectric substrate 21 is placed on the upper surface side (IDT 22, reflectors 23a and 23b and the drawer as shown in FIGS. 2 and 3). It warps (bends) so as to be recessed in the surface on which the electrodes 24a and 24b are formed. When the piezoelectric substrate 21 warps (bends) in this manner, the stress is relieved and the piezoelectric substrate 21 is in a state in which almost no stress remains. Thus, the aging characteristic and the reflow characteristic can be made excellent by warping the piezoelectric substrate 21 so as to be recessed toward the upper surface side so as to relieve stress. This is considered to be as follows.

  In the conventional surface acoustic wave device, the piezoelectric substrate is thick (generally about 300 μm). Therefore, when forming IDTs and reflectors, depending on the stress generated by the contraction force of these constituent materials, the piezoelectric substrate does not bend (cannot bend), and stress remains on the piezoelectric substrate. It was in a state. The stress remaining on the piezoelectric substrate changes as the contraction force of the constituent material changes due to heat generated when the surface acoustic wave element is driven. That is, in such a surface acoustic wave element, the stress remaining on the piezoelectric substrate during driving is greatly changed, and this change in stress is considered to have an adverse effect on the aging characteristics. In addition, it is considered that the stress remaining in the piezoelectric substrate changes greatly due to heat applied during reflow as described later, and this change in stress has an adverse effect on the reflow characteristics.

  On the other hand, in the surface acoustic wave element of the present invention, the piezoelectric substrate is warped so as to be recessed toward the surface on which the IDT is provided due to the stress generated by the contraction force of the constituent material of the IDT or reflector (in other words, For example, the piezoelectric substrate is configured to be thin enough to be deflected by the stress generated by the contraction force of the constituent material of the IDT or reflector). Therefore, almost no stress remains on the piezoelectric substrate. Therefore, even if the temperature changes during driving of the surface acoustic wave element, the stress remaining on the piezoelectric substrate hardly changes, and the surface acoustic wave element of the present invention has excellent aging characteristics. In addition, the residual stress on the piezoelectric substrate hardly changes due to heat applied during reflow, and the surface acoustic wave device of the present invention has excellent reflow characteristics.

Next, the package 3 that houses and fixes the piezoelectric substrate 21 will be described.
As shown in FIG. 1, the package 3 includes a plate-shaped base substrate (fixed substrate) 31, a frame-shaped frame member 32, and a plate-shaped lid member 33. The base substrate 31, the frame member 32, and the lid member 33 are stacked in this order from the mounting substrate 4 side. The base substrate 31, the frame member 32, and the frame member 32 and the lid member 33 are each, for example, a seam. They are joined by welding. The package 3 accommodates the piezoelectric substrate 21 in the internal space S defined by the base substrate 31, the frame member 32, and the lid member 33.

As a constituent material of such a base substrate 31, those having insulating properties (non-conductive) are preferable. For example, various ceramics such as various glasses, oxide ceramics, nitride ceramics, carbide ceramics, polyimide Various resin materials such as can be used.
Moreover, as a constituent material of the frame member 32 and the lid member 33, the same constituent material as the base substrate 31, various metal materials such as Al and Cu, various glass materials, and the like can be used, for example. In particular, when a material having optical transparency such as a glass material is used as the constituent material of the lid member 33, the following effects can be exhibited. That is, first, a metal coating portion (not shown) is formed on the piezoelectric substrate 21 in advance. As a result, even after the surface acoustic wave element 2 is accommodated in the package 3, the metal covering portion is irradiated with a laser through the lid member 33, and the metal covering portion is removed to remove the piezoelectric substrate 21. By reducing the mass (by the mass reduction method), the frequency of the surface acoustic wave element 2 can be adjusted.

As shown in FIGS. 1 and 2, an epoxy-based, polyimide-based, etc. adhesive 39 is applied (stacked) on the upper surface of the base substrate 31. The end of the substrate 21 on the side where the extraction electrodes 24a and 24b are formed is placed. Then, the piezoelectric substrate 21 is fixed to the base substrate 31 by curing the adhesive 39.
That is, one end (the end on the side where the extraction electrodes 24a and 24b are formed) of the piezoelectric substrate 21 is a fixed end, and the other end is a free end. Thus, by setting one end as a free end, the warp of the piezoelectric substrate 21 as described above is not hindered, and it is possible to prevent stress from remaining in the piezoelectric substrate 21. Further, for example, when the frame member 32 and the lid member 33 are joined by seam welding, the package 3 may be bent as a whole when the members are exposed to a high temperature, as in the present embodiment. If the piezoelectric substrate 21 is cantilevered, the bending of the package 3 will not be transmitted to the piezoelectric substrate 21, so that unintentional warping of the piezoelectric substrate 21 can be prevented.

Further, when fixed in this manner, the piezoelectric substrate 21 can be fixed to the package 3 via the adhesive 39 at a position that does not overlap with the region where the IDT 22 is formed in a plan view of the piezoelectric substrate 21. Thereby, even if the adhesive 39 contracts (for example, contraction at the time of drying), the IDT 22a is not displaced, and the piezoelectric device 1 can exhibit a desired frequency characteristic.
In particular, in the present embodiment, the IDT 22 and the reflectors 23a and 23b are formed so as to be shifted to the free end side of the piezoelectric substrate 21, and therefore, a region for fixing the piezoelectric substrate 21 to the base substrate 31 (that is, A large area) where the adhesive 39 is brought into contact can be secured. Therefore, the piezoelectric substrate 21 can be more securely fixed to the base substrate 31 via the adhesive 39 at a position that does not overlap with the region where the IDT 22 is formed.

  In the state where the piezoelectric substrate 21 is fixed to the base substrate 31, the separation distance L 1 between the fixed end of the piezoelectric substrate 21 and the base substrate 31 is the separation distance between the free end of the piezoelectric substrate 21 and the base substrate 31. It is preferably shorter than L2. Thereby, the piezoelectric substrate 21 can be prevented from coming into contact with the base substrate 31. As a result, the surface acoustic wave element 2 can exhibit desired frequency characteristics.

Further, in the state where the piezoelectric substrate 21 is fixed to the base substrate 31, the separation distance L <b> 1 between the fixed end of the piezoelectric substrate 21 and the base substrate 31 is the center of the piezoelectric substrate 21 (the most recessed portion). The distance is preferably shorter than the distance L3 from the base substrate 31. As a result, the distance between the piezoelectric substrate 21 and the base substrate 31 gradually increases from the fixed end toward the free end. Therefore, when the piezoelectric substrate 21 is fixed to the base substrate 31 by the adhesive 39, the adhesive 39 is piezoelectric. It is possible to prevent the body substrate 21 from spreading on the free end side. Thereby, the piezoelectric substrate 21 and the base substrate 31 can be bonded at a predetermined position and at a predetermined height.
A pair of internal terminals 34 a and 34 b are formed on the upper surface of the base substrate 31 so as to be exposed to the internal space S. As shown in FIG. 4A, the internal terminals 34a and 34b are electrically connected to the extraction electrodes 24a and 24b by wire bonding or the like, respectively.

As shown in FIG. 4B, four external terminals 35a, 35b, 35c, and 35d are provided on the lower surface of the base substrate 31 so as to be positioned at the four corners. The external terminals 35 a to 35 d are positioned so as to face four connection terminals 41 (described later) provided on the mounting substrate 4.
Out of these four external terminals 35a to 35d, the external terminals 35a and 35b are hot terminals electrically connected to the internal terminals 34a and 34b through via holes formed in the base substrate 31, respectively. The other two external terminals 35c and 35d are dummy terminals for increasing the bonding strength (the bonding strength between the spacer 51 and the package 3) when the package 3 is mounted on the mounting substrate 4, for example.

Such internal terminals 34a and 34b and external terminals 35a to 35d can be formed, for example, by applying gold plating to an underlying layer of tungsten and nickel plating.
The surface acoustic wave element 2 has been described above. By providing such a surface acoustic wave element 2, the piezoelectric device 1 can constitute a SAW device such as a SAW resonator or a SAW oscillator.

Next, the mounting substrate 4 on which the surface acoustic wave element 2 as described above is mounted (fixed) will be described. The mounting substrate 4 has a substantially rectangular shape in plan view, and is slightly larger than the base substrate 31 of the package 3 described above.
Such a mounting substrate 4 may be a rigid substrate, a flexible substrate, or a rigid flexible substrate. In addition, the constituent material of the mounting substrate 4 is preferably an insulating (non-conductive) material, for example, various ceramics such as various glasses, oxide ceramics, nitride ceramics, carbide ceramics, polyimide, etc. Various resin materials can be used.

  Further, as shown in FIG. 1, four connection terminals 41 and a wiring pattern 42 are formed on the upper surface (the surface on the package 3 side) of the mounting substrate 4. The four connection terminals 41 are formed near the corners of the mounting substrate 4 so as to face the external terminals 35a to 35d of the package 3, respectively. Of these four connection terminals 41, the connection terminals 41 corresponding to the external terminals (hot terminals) 35a and 35b are electrically connected to the wiring pattern 42, respectively.

On the other hand, a plurality of mounting terminals 43 that are electrically and mechanically connected to, for example, a circuit board (not shown) on which the piezoelectric device 1 is mounted are formed on the lower surface of the mounting substrate 4. Each mounting terminal 43 is electrically connected to the wiring pattern 42 through a via hole formed in the mounting substrate 4.
Note that, on the lower surface of the mounting substrate 4, a writing terminal for rewriting (adjusting) a characteristic inspection of the IC 6 described later and various information inside the IC (for example, temperature compensation information of the piezoelectric device) as necessary. May be formed.

  An electronic component 6 is mounted on the central portion of the upper surface of the mounting substrate 4. The electronic component 6 is, for example, an integrated circuit element (hereinafter also simply referred to as “IC”) as a circuit element for driving the surface acoustic wave element 2. As shown in FIG. 1, such an IC 6 is mounted on the mounting substrate 4 by an insulating (non-conductive) adhesive or an adhesive member 44 such as an adhesive sheet, and further, wire bonding (metal wire 45). ) To be electrically connected to the wiring pattern 42. Thereby, each terminal (the connection terminal 41 and the mounting terminal 43) and the IC 6 are electrically connected via the wiring pattern.

  Such a mounting substrate 4 fixes the package 3 via four spacers 51 on the upper surface side. These spacers 51 have a function of forming a gap for mounting the IC 6 and the like between the mounting substrate 4 and the package 3. Thereby, since the package 3 and the IC 6 can be stacked (stacked) in the height direction of the piezoelectric device 1, the size of the piezoelectric device 1 can be reduced.

  The four spacers 51 are provided between the external terminals 35a of the package 3 and the corresponding connection terminals 41, between the external terminals 35b and the corresponding connection terminals 41, and between the external terminals 35c and the corresponding connection terminals 41. And between the external terminal 35d and the corresponding connection terminal 41. Such a spacer 51 is joined to the external terminals 35 a to 35 d and the connection terminal 41 by solder (brazing material).

  Here, it is preferable that at least the spacers 51 corresponding to the external electrodes (hot electrodes) 35a and 35b have conductivity. As a result, the external terminal 35a and the corresponding connection terminal 41 are electrically connected via the spacer 51 provided therebetween, and the external terminal 35b and the corresponding connection terminal 41 are connected to each other. These can be electrically connected via a spacer 51 provided between them. Thereby, the number of parts of the piezoelectric device 1 can be reduced, and the manufacturing can be simplified, the cost can be reduced, and the size can be reduced.

  The configuration of such a spacer 51 is not particularly limited, and for example, various metal materials having conductivity such as Au, Ag, Cu, and Al may be configured as a main material, and various resin materials, You may comprise by forming electroconductive films, such as plating, on the surface of the nonelectroconductive base | substrate comprised with ceramics. Alternatively, a solder ball in which solder is coated on the surface of a ball made of copper may be used. Moreover, the spacer 51 does not need to have electroconductivity. In this case, the external terminal 35a and the corresponding connection terminal 41 (the external terminal 35b and the corresponding connection terminal 41) can be electrically connected by wire bonding or the like.

The piezoelectric device 1 has been described above. As shown in FIG. 5, the mold material 8 made of a resin having fluidity is poured into the piezoelectric device 1, and the upper surface of the lid member 33 of the package 3 and the mounting substrate. The entire piezoelectric device 1 may be covered with the molding material 8 so that the lower surfaces of the four are exposed to the outside.
The piezoelectric device of the present invention has been described based on the illustrated embodiments. However, the present invention is not limited to these embodiments, and the configuration of each part is replaced with an arbitrary configuration having the same function. be able to. Moreover, other arbitrary structures and processes may be added.

1. Creation of piezoelectric device (Example 1)
First, a quartz substrate (piezoelectric substrate) having Euler angles (0 °, 127 °, 0 °) was prepared. As for the size of the quartz substrate, (length × width × thickness) was (0.8 mm × 2.7 mm × 60 μm). An aluminum film having an average thickness of 0.6 μm (6000 mm) was formed on one surface of the quartz substrate by sputtering. Next, this aluminum film was etched into a predetermined pattern to integrally form a pair of IDTs, a pair of reflectors, and extraction electrodes. The area occupation ratio of the IDT and the reflector with respect to the surface of the quartz substrate was 33%. The number of IDT pairs was 100, the number of reflectors was 100 for each reflector, and the crossing width was 40λ (λ is the wavelength of the surface acoustic wave).
The member thus obtained was housed in a package to obtain a surface acoustic wave device. The surface acoustic wave element was incorporated into a piezoelectric device as shown in FIG. 1 to obtain a piezoelectric device.

(Example 2)
A piezoelectric device was obtained in the same manner as in Example 1 except that the thickness of the quartz substrate was 100 μm.
(Example 3)
A piezoelectric device was obtained in the same manner as in Example 1 except that the thickness of the quartz substrate was 200 μm.
(Comparative Example 1)
A piezoelectric device was obtained in the same manner as in Example 1 except that the thickness of the quartz substrate was changed to 300 μm.

2. Various Measurements For the piezoelectric devices of Examples 1 to 3 and Comparative Example 1 obtained as described above, the resonance frequency reflow change amount, the resonance frequency heat cycle change amount, and the resonance frequency aging change amount were respectively determined by the following methods. It was measured by.
(2-1) Reflow change amount of resonance frequency For each of Examples 1 to 3 and Comparative Example 1, the change in resonance frequency before and after the predetermined reflow was measured. The reflow was performed twice according to the graph shown in FIG. The result is shown in FIG.

(2-2) Resonance Frequency Change in Heat Cycle For each of Examples 1 to 3 and Comparative Example 1, changes in resonance frequency before and after a predetermined heat cycle were measured. In addition, the heat cycle made -55 degreeC (30 minutes) and 125 degreeC (30 minutes) 1 cycle, and performed this 1000 cycles. The result is shown in FIG.
(2-3) Aging change amount of resonance frequency For each of Embodiments 1 to 3 and Comparative Example 1, the change in resonance frequency before and after being driven continuously at 125 ° C. for 2000 hours was measured. The result is shown in FIG.

3. Evaluation As shown in FIG. 7, each of Examples 1 to 3 had a smaller amount of reflow change in the resonance frequency than Comparative Example 1. Further, as shown in FIG. 8, each of Examples 1 to 3 had a smaller heat cycle change amount of the resonance frequency than Comparative Example 1. Further, as shown in FIG. 9, each of Examples 1 to 3 had a smaller amount of aging change in the resonance frequency than Comparative Example 1.

  DESCRIPTION OF SYMBOLS 1 ... Piezoelectric device 2 ... Surface acoustic wave element 21 ... Piezoelectric substrate 22 ... IDT 22a, 22b ... Electrode 221a, 221b ... Electrode finger 23a, 23b ... Reflector 24a, 24b ... Extraction electrode 3 …… Package 31 …… Base substrate 32 …… Frame member 33 …… Cover member 34a, 34b …… Internal terminals 35a to 35d …… External terminals 39 …… Adhesive 4 …… Mounting substrate 41 …… Connection terminal 42 …… Wiring pattern 43 ... Mounting terminal 44 ... Adhesive member 45 ... Metal wire 51 ... Spacer 6 ... Electronic component (IC) 8 ... Mold material L1, L2, L3 ... Separation distance S ... Internal space

Claims (10)

A piezoelectric substrate composed of a piezoelectric material having piezoelectricity;
A comb-like electrode provided on one surface of the piezoelectric substrate, for exciting a surface acoustic wave in the piezoelectric substrate;
The piezoelectric substrate has a thickness of 60 μm to 200 μm,
2. The surface acoustic wave device according to claim 1, wherein the piezoelectric substrate is warped so as to be dented to a surface side on which the comb electrode is provided due to a stress generated by a contraction force of a constituent material of the comb electrode.   The surface acoustic wave device according to claim 1, wherein the piezoelectric material is composed of quartz as a main material.   The surface acoustic wave device according to claim 2, wherein the comb electrode has an average thickness of 0.3 μm to 0.8 μm.   On one surface of the piezoelectric substrate, a pair of reflectors are formed so as to face each other with interdigital electrodes interposed therebetween, and the piezoelectric substrate with respect to the piezoelectric substrate is seen in plan view. The surface acoustic wave device according to any one of claims 1 to 3, wherein an area occupation ratio of the comb electrode and the pair of reflectors is 20 to 40%. Provided on the other surface side of the piezoelectric substrate, and having a fixed substrate for fixing the piezoelectric substrate;
The elasticity according to any one of claims 1 to 4, wherein the piezoelectric substrate is fixed to the fixed substrate via an adhesive at a position that does not overlap the comb-tooth electrode in a plan view of the piezoelectric substrate. Surface wave device.   6. The elastic body according to claim 5, wherein the piezoelectric substrate has a longitudinal shape, and is fixed to the fixed substrate at one end in the longitudinal direction, and the other end of the piezoelectric substrate is a free end. Surface wave device.   The surface acoustic wave device according to claim 6, wherein the comb electrode is provided so as to be shifted toward the free end side from a central portion of the piezoelectric substrate.   The distance between the piezoelectric substrate and the fixed substrate at the fixed end of the piezoelectric substrate is shorter than the distance between the piezoelectric substrate and the fixed substrate at the free end of the piezoelectric substrate. A surface acoustic wave device according to claim 1.   The distance between the piezoelectric substrate and the fixed substrate at the fixed end of the piezoelectric substrate is shorter than the distance between the piezoelectric substrate and the fixed substrate at the center of the piezoelectric substrate. The surface acoustic wave device according to any one of the above.   A piezoelectric device comprising the surface acoustic wave element according to claim 1.

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