JP2011163884A - Pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure sensor simply manufactured and reliable. <P>SOLUTION: The pressure sensor 1 has: a package 4 with a diaphragm 2 having a thinned section 21; a pair of wires 51, 52 provided in the diaphragm 2, and extracted from the interior to the exterior of the package 4; a piezoelectric vibration piece 6 accommodated within the package 4, and having a piezoelectric vibration piece body 61 and a pair of electrodes 62, 63; and a pair of conductive bumps 71, 72 intervening between the piezoelectric vibration piece 6 and the diaphragm 2, and bonding them. The bump 71 electrically connects the electrode 62 and the wire 51. The bump 72 electrically connects the electrode 63 and the wire 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pressure sensor.

  2. Description of the Related Art Conventionally, a configuration in which, for example, a double tuning fork type piezoelectric vibrating piece is mounted on a diaphragm is known as a pressure sensor. In the pressure sensor having such a configuration, the double tuning fork type piezoelectric vibrating piece is deformed together with the diaphragm by the applied pressure, and by measuring the resonance frequency of the double tuning fork type piezoelectric vibrating piece that changes in accordance with the degree of the deformation, The magnitude of the pressure applied to the pressure sensor is detected (see, for example, Patent Document 1).

  As shown in Patent Document 1, the pressure sensor includes a diaphragm having a thin-walled portion, a package formed by joining a base opposite to the diaphragm, and a piezoelectric vibrating piece accommodated in the package. . The diaphragm is formed with a pair of protrusions that protrude from the thin portion toward the inside of the package, and a piezoelectric vibrating piece is fixed to the protrusions. In this manner, by fixing the piezoelectric vibrating piece through the protrusion, the diaphragm and the piezoelectric vibrating piece are prevented from coming into contact when the diaphragm is bent by pressure.

  In such a pressure sensor of Patent Document 1, in order to apply a voltage to the excitation electrode included in the piezoelectric vibrating piece (that is, to connect the excitation electrode to a power source), it is necessary to draw the excitation electrode to the outside of the package. . As this method, although not described in Patent Document 1, a method of drawing the wiring to the outside of the package by forming the wiring connected to the electrode over the inner surface of the diaphragm is usually used. In addition, as a method of forming such wiring, a method of forming a metal film on the surface of the diaphragm by vapor deposition or the like and forming the metal film into a desired pattern using a photolithography technique and an etching method. Can be used.

  Here, in the pressure sensor of Patent Document 1, in order to pull out the excitation electrode to the outside of the package, the wiring must be formed at least on the inner surface of the thin portion and the side surface of the protruding portion. Will occur. That is, since the side surface of the protrusion is perpendicular to the inner surface of the thin portion, in order to deposit the metal film uniformly on the inner surface of the thin portion and the side surface of the protrusion, for example, by changing the posture of the diaphragm, the deposition is performed multiple times. This must be done and the manufacturing process becomes complicated.

Further, as a method for drawing out the wiring, a piezoelectric vibrating reed layer in which a double tuning fork type piezoelectric vibrating piece, a frame portion, and a beam connecting them are formed as one layer is provided between the diaphragm and the base, and the beam and the frame There is also known a method of drawing out the wiring through the section (for example, see Patent Document 2). However, in such a configuration, there is a problem that the beam acts like a “replacement rod” and the sensitivity (reliability) of the double tuning fork type piezoelectric vibrating piece is lowered.
As described above, in the conventional pressure sensor, it is difficult to achieve both simplification of the manufacturing method and reliability.

JP 2009-68882 A JP 2008-241287 A

  An object of the present invention is to provide a pressure sensor in which simplification of the manufacturing method and reliability are compatible.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.
[Application Example 1]
The pressure sensor of the present invention includes a package including a diaphragm having a thin wall portion,
A pair of wires provided on the diaphragm and drawn from the inside of the package to the outside;
A piezoelectric vibrating piece housed in the package and having a piezoelectric vibrating piece body and a pair of electrodes formed on the piezoelectric vibrating piece body;
A pair of conductive bumps interposed between the piezoelectric vibrating piece and the diaphragm, and joined to the piezoelectric vibrating piece and the diaphragm;
One of the pair of bumps electrically connects one electrode of the pair of electrodes and one wiring of the pair of wires, and the other bump The other electrode is provided so as to be electrically connected to the other wiring.
Thereby, it is possible to provide a pressure sensor in which simplification of the manufacturing method and reliability are compatible.

[Application Example 2]
In the pressure sensor of the present invention, it is preferable that the bump is made of a conductive adhesive.
This simplifies the configuration of each bump.
[Application Example 3]
In the pressure sensor of the present invention, the adhesive preferably contains a gap material.
Thereby, a thin part and a piezoelectric vibrating piece can be spaced apart reliably.
[Application Example 4]
In the pressure sensor according to the aspect of the invention, it is preferable that the bump has a nucleus and a conductive portion having conductivity provided so as to cover the periphery of the nucleus.
This simplifies the configuration of each bump.

[Application Example 5]
In the pressure sensor of the present invention, the diaphragm has a frame portion formed so as to surround the thin portion,
The frame portion has an extending portion that extends in a predetermined direction and has a tapered cross section.
Each of the wirings is preferably formed so as to straddle the extending portion.
Thereby, each wiring can be formed easily and reliably.

[Application Example 6]
In the pressure sensor of the present invention, the diaphragm has a pair of extending portions opposed to each other through the thin portion,
One of the pair of wirings is formed so as to straddle one of the extended portions of the pair of extending portions, and the other wiring is formed of the other extending portion. It is preferable to be formed so as to straddle.
Thereby, the excessive approach of a pair of wiring is prevented, the insulation state between a pair of wiring can be ensured reliably, and a short circuit etc. can be prevented.

[Application Example 7]
In the pressure sensor of the present invention, it is preferable that the separation direction of the pair of extending portions is equal to the separation direction of the pair of bumps.
Thereby, the total length of each wiring can be shortened.
[Application Example 8]
In the pressure sensor according to the aspect of the invention, it is preferable that each of the wirings is formed so as to straddle the extending portion closer to the bump to which the wiring is connected.
Thereby, the total length of each wiring can be shortened.

[Application Example 9]
In the pressure sensor of the present invention, the piezoelectric vibrating piece is preferably a double tuning fork type vibrating piece.
Thereby, the outstanding pressure detection capability can be exhibited.
[Application Example 10]
In the pressure sensor of the present invention, it is preferable that each of the diaphragm and the vibrating piece main body is made of quartz.
As a result, it is possible to suppress the warpage and bending of the package resulting from the difference in the linear expansion coefficient, the occurrence of cracks due to these, and the like. In addition, warping and bending of the piezoelectric vibrating piece caused by the difference in linear expansion coefficient can be suppressed, and the detection accuracy of the pressure sensor can be improved.

It is sectional drawing which shows 1st Embodiment of the pressure sensor of this invention. It is a figure (a top view and a sectional view) showing a diaphragm which the pressure sensor shown in FIG. 1 has. It is a figure (perspective view and sectional drawing) which shows the double tuning fork type piezoelectric vibrating piece which the pressure sensor shown in FIG. 1 has. It is sectional drawing explaining the action | operation of the pressure sensor shown in FIG. It is sectional drawing explaining the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing explaining the manufacturing method of the pressure sensor shown in FIG. It is sectional drawing which shows 2nd Embodiment of the pressure sensor of this invention.

Hereinafter, a pressure sensor of the present invention will be described in detail based on an embodiment shown in the accompanying drawings.
1 is a cross-sectional view showing a first embodiment of the pressure sensor of the present invention, FIG. 2 is a view showing a diaphragm of the pressure sensor shown in FIG. 1 (plan view and cross-sectional view), and FIG. FIG. 4 is a diagram (a perspective view and a sectional view) showing a double tuning fork type piezoelectric vibrating piece 6 included in the pressure sensor shown in FIG. 4, FIG. 4 is a sectional view for explaining the operation of the pressure sensor shown in FIG. It is sectional drawing explaining the manufacturing method of the pressure sensor shown in FIG. In the following description, the upper side in FIGS. 1, 4, 5, and 6 is referred to as “upper”, and the lower side is referred to as “lower”.

A pressure sensor 1 shown in FIG. 1 is housed in a package 4 composed of a diaphragm 2 and a base 3, a pair of lead wires (wirings) 51 and 52 that electrically connect the inside and outside of the package 4, and the package 4. The double tuning fork type piezoelectric vibrating piece (piezoelectric vibrating piece) 6 and a pair of conductive bumps 71 and 72 that join the diaphragm 2 and the double tuning fork type piezoelectric vibrating piece 6 are provided. In such a pressure sensor 1, the pair of excitation electrodes 62 and 63 included in the double tuning fork type piezoelectric vibrating piece 6 are electrically connected to the wirings 51 and 52 via the bumps 71 and 72. 621 and 622 are drawn out of the pressure sensor 1.
The pressure sensor 1 according to the present embodiment has a rectangular (rectangular) shape in plan view. However, the planar view shape of the pressure sensor 1 is not limited to this, and may be, for example, a circle, a pentagon or more polygon.

Hereinafter, each component of the pressure sensor 1 will be sequentially described in detail.
The diaphragm 2 has a thin-walled portion 21 that is deformed by receiving external pressure (pressure from above in FIG. 1), and a frame-shaped frame portion 22 formed around the thin-walled portion 21. . That is, it can be said that the diaphragm 2 has a concave portion opened at a central portion excluding an edge portion of the lower surface (surface on the base 3 side), and has a thin-walled bottom surface.

  2A is a plan view of the diaphragm 2 viewed from the base 3 side, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. 2A. As shown in the figure, the frame portion 22 is formed so as to protrude toward the base 3 side. The frame portion 22 intersects the first direction with a pair of first extending portions 221 and 223 extending in the first direction (perpendicular in the present embodiment) in a plan view of the diaphragm 2. A total of four extending portions of the second extending portions 222 and 224 extending in the second direction are connected in a frame shape. Among the extending portions 221 to 224, the first extending portions 221 and 223 have a rectangular (rectangular or square) cross-sectional shape. That is, the extending portions 221 and 223 have a constant width W in the height direction (that is, the thickness direction of the diaphragm). One of the extending portions 222 and 224 has a trapezoidal cross-sectional shape. That is, the extending portions 222 and 224 are both tapered such that the width gradually decreases from the base 3 side (that is, from the lower side to the upper side in FIG. 2B).

In the present embodiment, the extending portions 222 and 224 are tapered. However, the shape of the frame portion 22 is not limited to this, and for example, all the extending portions 221 to 224 are tapered. It may be formed, and only one extending portion may be tapered. Moreover, the taper-shaped part may be formed only in a part of one extension part.
In addition, the diaphragm 2 having such a shape (that is, a shape having the tapered extending portions 222 and 224) has an X cut (cut perpendicular to the X axis) crystal flat plate (crystal element) as will be described later. Plate), a Y-cut quartz plate, and a Z-cut quartz plate can be easily obtained.

  As shown in FIG. 1, a base 3 is provided so as to face such a diaphragm 2. The base 3 has a plate-like base portion 31 and a frame portion 32 erected from the edge portion of the base portion 31. That is, it can be said that the base 3 has a box shape having a concave portion opened in the central portion excluding the edge portion of the upper surface (the surface on the diaphragm 2 side). And the space S is formed by the said recessed part formed in the base 3 facing the said recessed part formed in the diaphragm 2, In this space S, the double tuning fork type piezoelectric vibrating piece 6 is accommodated.

  The space S is preferably in a vacuum state. Thereby, the CI (Crystal Impedance) value of the double tuning fork type piezoelectric vibrating piece 6 can be lowered, and the frequency stability can be improved. In order to make the space S into a vacuum state, for example, a method of joining the diaphragm 2 and the base 3 in a vacuum state (in a vacuum environment), a through hole is made in the base 3 (base 31), and the pressure is reduced to normal pressure. After the diaphragm 2 and the base 3 are joined together, the space S is evacuated through the through hole, and the through hole is filled with a filler (eg, gold tin AuS or gold germanium AuGe) and sealed. Can be mentioned.

  The constituent materials of the diaphragm 2 and the base 3 are not particularly limited, and for example, various types of glass such as quartz glass and non-alkali glass, crystalline materials such as quartz can be used. It is preferable to be configured. Furthermore, as the constituent material of the diaphragm 2 and the base 3, it is preferable to use the same material as the constituent material of the piezoelectric vibrating piece main body 61 of the double tuning fork type piezoelectric vibrating piece 6. That is, in this embodiment, it is preferable that the diaphragm 2 and the base 3 are each made of quartz.

  In this way, by configuring the diaphragm 2 and the base 3 with the same material, it is possible to suppress unintentional warping and bending of the pressure sensor 1 resulting from the difference in linear expansion coefficient, and generation of cracks caused by these. can do. Further, by configuring the diaphragm 2 and the base 3 with the same material as that of the piezoelectric vibrating piece main body 61, it is possible to suppress warping and bending of the piezoelectric vibrating piece main body 61 caused by the difference in linear expansion coefficient as described above. And the detection accuracy of the pressure sensor 1 can be improved.

  The package 4 is configured by joining the diaphragm 2 and the base 3 as described above so that the concave portions thereof face each other. The bonding method of the diaphragm 2 and the base 3 is not particularly limited, but a method using an adhesive such as low melting glass or epoxy, a bonding member containing an alkoxide, an organosiloxy group, etc. Various bonding methods such as a method of bonding by irradiation, a eutectic bonding method of bonding via a metal film such as a gold-tin alloy film, direct bonding, and anodic bonding can be used.

Such a package 4 is formed with a pair of lead-out wirings 51 and 52 that electrically connect the inside and outside of the package. As shown in FIG. 2, the lead-out wiring 51 has a terminal 511 formed in the thin portion 21, and is formed so as to straddle (over) the extension portion 222 of the extension frame portion 22 from the terminal 511. Has been. On the other hand, the lead-out wiring 52 has a terminal 521 formed in the thin-walled portion 21, and is formed so as to straddle (over) the extended portion 224 of the extending frame portion 22 from the terminal 521.
In this way, by forming the lead-out wirings 51 and 52 so as to straddle the tapered extending portions 222 and 224, the lead-out wirings 51 and 52 can be easily and reliably formed. A method for forming the lead wires 51 and 52 will be described later in the description of the manufacturing method.

Further, by forming the lead wires 51 and 52 so as to straddle the different extending portions 222 and 224, the lead wires 51 and 52 are prevented from being excessively approached, and the insulation state between the lead wires 51 and 52 is reliably ensured. It can be ensured and a short circuit or the like can be prevented.
The lead wires 51 and 52 are formed so that the separation direction of the terminals 511 and 521 is the same as the separation direction of the second extending portions 222 and 224. The lead-out wiring 51 is formed so as to straddle the extension portion 222 of the second extension portions 222 and 224 that is closer to the terminal 511. Similarly, the lead-out wiring 52 is the second extension portion 222 and 224. The extension portions 222 and 224 are formed so as to straddle the extension portion 224 closer to the terminal 521. By forming the lead wires 51 and 52 in this way, the total length of the lead wires 51 and 52 can be shortened.

The constituent material of the lead-out wirings 51 and 52 is not particularly limited as long as it is substantially conductive. For example, a metal material such as gold, silver, copper, aluminum or an alloy containing these, carbon black, or the like. An ionic substance such as NaCl, Cu (CF ₃ SO ₃ ) ₂ is dispersed in a carbon-based material, an electroconductive polymer material such as polyacetylene, polyfluorene or a derivative thereof, or a matrix resin such as polyvinyl alcohol or polycarbonate. And various conductive materials such as conductive oxide materials such as ion conductive polymer materials, indium oxide (IO), indium tin oxide (ITO), fluorine-doped tin oxide (FTO), etc. One or two or more of them can be used in combination.

A double tuning fork type piezoelectric vibrating piece 6 is accommodated inside the package 4 (space S). As shown in FIG. 3A, the double tuning fork type piezoelectric vibrating piece 6 includes a piezoelectric vibrating piece main body 61 and a pair of excitation electrodes (electrodes) 62 and 63 formed on the piezoelectric vibrating piece main body 61. Yes.
The piezoelectric vibrating reed body 61 includes a pair of base portions 611 and 612 that are provided apart from each other, and a double tuning fork type vibrating portion 613 that connects the base portions 611 and 612. The vibrating portion 613 includes two vibrating beams 613a and 613b having a longitudinal shape extending in parallel with each other with a gap therebetween. By having the two vibration beams 613a and 613b as described above, it is possible to suppress the vibration leakage of the vibration unit 613 and to obtain the pressure sensor 1 that exhibits excellent resolution. The number of vibration beams is not limited to two as in the present embodiment, and may be one (ie, a single beam type piezoelectric vibration piece) or three or more.
The piezoelectric vibrating reed body 61 having such a shape can be integrally formed from a single flat plate using a photolithography technique and various etching methods such as wet etching.

  The constituent material of the piezoelectric vibrating reed body 61 is not particularly limited as long as it is a material having piezoelectric characteristics, but is preferably quartz. By using quartz, a piezoelectric vibrating reed body 61 (double tuning fork type piezoelectric vibrating reed 6) having excellent temperature characteristics and vibration characteristics can be obtained. When the piezoelectric vibrating reed body 61 is formed of a quartz substrate, for example, a quartz substrate cut out at a cut angle called a so-called X cut can be used as the quartz substrate.

The pair of excitation electrodes 62 and 63 has a vibration mode of the double tuning fork type piezoelectric vibrating piece 6 with respect to a central axis J of the double tuning fork type piezoelectric vibrating piece 6 (an axis substantially parallel to the extending direction of the vibration beams 613a and 613b). It is arranged to vibrate in a symmetric mode.
Specifically, as shown in FIGS. 3A to 3D, the excitation electrode 62 includes a plurality of electrode pieces 621 formed on the vibration beams 613 a and 613 b and an extraction electrode 622 formed on the base 611. These are electrically connected. Similarly, the excitation electrode 63 has a plurality of electrode pieces 631 formed on the vibration beams 613a and 613b and an extraction electrode 632 formed on the base 612, which are electrically connected. . The lead electrodes 622 and 632 are respectively formed on the surface of the piezoelectric vibrating reed body 61 on the diaphragm 2 side.

  The electrode pieces 621 and 6311 are formed so as to be alternately positioned in the longitudinal direction and the circumferential direction of the vibration beams 613a and 613b, and the arrangement of the vibration beams 613a and 613b is reversed (symmetric). It is formed as follows. By adopting such an electrode arrangement, it is possible to efficiently vibrate the double tuning fork type piezoelectric vibrating piece 6 in the above-described vibration mode.

The constituent material of the excitation electrodes 62 and 63 is not particularly limited as long as it is substantially conductive. For example, a metal material such as gold, silver, copper, aluminum or an alloy containing these, carbon black, or the like. An ionic substance such as NaCl, Cu (CF ₃ SO ₃ ) ₂ is dispersed in a carbon-based material, an electroconductive polymer material such as polyacetylene, polyfluorene or a derivative thereof, or a matrix resin such as polyvinyl alcohol or polycarbonate. And various conductive materials such as conductive oxide materials such as ion conductive polymer materials, indium oxide (IO), indium tin oxide (ITO), fluorine-doped tin oxide (FTO), etc. One or two or more of them can be used in combination.
The double tuning fork-type piezoelectric vibrating piece 6 having such a configuration (shape) has good sensitivity to extension / compression stress and has excellent resolution as a pressure-sensitive element. Therefore, the pressure sensor 1 using the double tuning fork type piezoelectric vibrating piece 6 can exhibit an excellent pressure detection capability.

The twin tuning fork type piezoelectric vibrating piece 6 has been described in detail above. However, such a double tuning fork type piezoelectric vibrating piece 6 is fixed to the thin portion 21 of the diaphragm 2 via a pair of conductive bumps 71 and 72 ( Fixed).
As shown in FIG. 1, the bump 71 is formed between the base 611 of the double tuning fork type piezoelectric vibrating piece 6 and the thin portion 21 of the diaphragm 2, and fixes the base 611 to the diaphragm 2. . Further, the bump 71 is provided so as to come into contact with the extraction electrode 622 formed on the base 611 and the terminal 511 formed on the diaphragm 2. As a result, the excitation electrode 62 and the lead wiring 51 are electrically connected via the conductive bump 71. That is, the excitation electrode 62 is drawn out of the pressure sensor 1 (package 4) by the bump 71 and the lead wiring 51.

  On the other hand, the bump 72 is formed between the base 612 of the double tuning fork type piezoelectric vibrating piece 6 and the thin portion 21 of the diaphragm 2, and fixes the base 612 to the diaphragm 2. Further, the bump 72 is provided so as to contact the extraction electrode 632 formed on the base 612 and the terminal 521 formed on the diaphragm 2. Thereby, the excitation electrode 63 and the lead-out wiring 52 are electrically connected via the conductive bump 72. That is, the excitation electrode 63 is drawn out of the pressure sensor 1 (package 4) by the bump 72 and the lead wiring 52.

  As described above, in this embodiment, the bump 71 of the pair of bumps 71 and 72 sufficiently separated (insulated) from each other is used to connect the excitation electrode 62 and the lead-out wiring 51, and the bump 72 is excited. Since it is used to connect the electrode 63 and the lead-out wiring 52, the lead-out wirings 51 and 52 can be reliably insulated. Therefore, malfunction of the pressure sensor 1 can be prevented.

  The bumps 71 and 72 are made of, for example, a conductive adhesive. Although it does not specifically limit as an adhesive agent which has electroconductivity, For example, adhesive agents, such as an epoxy type and a polyimide type, which mixed conductive particles, such as a metal filler (metal fine particles, such as silver powder and copper powder), and carbon fiber, are used. be able to. By configuring the bumps 71 and 72 with such an adhesive, the configuration and formation of the bumps 71 and 72 are simplified. Therefore, manufacture of the pressure sensor 1 becomes easy. Furthermore, the double tuning fork type piezoelectric vibrating piece 6 and the diaphragm can be firmly fixed.

  In particular, in the present embodiment, a gap agent (not shown) made of, for example, metal or resin fine particles is mixed with the conductive adhesive forming the bumps 71 and 72. Thus, the bumps 71 and 72 function as spacers that separate the thin portion 21 of the diaphragm 2 and the double tuning fork type piezoelectric vibrating piece 6. The diameter (size) of the gap agent to be mixed is not particularly limited, and may be selected according to a predetermined distance between the thin portion 21 and the double tuning fork type piezoelectric vibrating piece 6.

Thus, by arranging the thin portion 21 and the double tuning fork type piezoelectric vibrating piece 6 apart from each other, as will be described later (as shown in FIG. 4B), the thin portion 21 is bent under pressure. In this case, the thin wall portion 21 can be effectively prevented from coming into contact with the double tuning fork type piezoelectric vibrating piece 6. As a result, the accuracy of the pressure sensor 1 can be improved.
The configuration of the pressure sensor 1 has been described above.

  Such a pressure sensor 1 detects a pressure as follows. That is, when the pressure sensor 1 is applied with a pressure as shown in FIG. 4A, the thin portion 21 of the diaphragm 2 is expanded so that the two bumps 71 and 72 are expanded as shown in FIG. 4B. Bend. Due to the bending of the thin portion 21, a force in the bending direction is also applied to the double tuning fork type piezoelectric vibrating piece 6 fixed to the bumps 71 and 72, and pulling (extending in the longitudinal direction) accompanying the expansion of the bumps 71 and 72 is performed. ) Power is applied. The double tuning fork type piezoelectric vibrating piece 6 has a characteristic that the oscillation frequency increases when a tensile stress is applied to the vibrating portion 613 (vibrating beams 613a and 613b), and therefore the pressure applied to the pressure sensor 1 is reduced. The magnitude can be derived based on the detected amount of change in the oscillation frequency by detecting the amount of change in the oscillation frequency of the double tuning fork type piezoelectric vibrating piece 6 by a detection unit (not shown).

Next, a manufacturing method of the pressure sensor 1 will be described with reference to FIGS.
First, as shown in FIG. 5A, a quartz flat plate is processed to have a desired outer shape by using a photolithography technique and a wet etching method, and the diaphragm 2 and the base 3 are obtained.
In particular, the diaphragm 2 uses the X-cut quartz plate (crystal base plate), the Y-cut quartz plate, or the Z-cut quartz plate to easily form the extending portions 222 and 224 having the tapered shape as described above. be able to. Specifically, due to the anisotropy of the crystal structure of these quartz plates, when the outer shape is formed by wet etching, one direction parallel to the plane direction of the quartz plate (indicated by an arrow Y in FIG. 5). In other words, a taper surface having an inclination in a certain direction appears in a cross section perpendicular to the cross-sectional direction. By taking advantage of the properties of such a quartz crystal plate and using the tapered surface as a side surface of the extending portions 222 and 224, the diaphragm 2 can be easily formed into a desired outer shape (without further processing after etching). can do.
In addition, a crystal flat plate cut out at a cut angle other than the crystal flat plate described above is formed by various etching methods, and then, for example, sand blasting is performed to form tapered extending portions 222 and 224. Can do.

  Next, after a metal layer made of chromium is formed on the lower surface of the diaphragm 2, a metal layer made of gold is formed on the metal layer. These metal layers can be formed by vapor deposition or the like. Next, these metal layers are formed into a predetermined pattern using a photolithography technique and a wet etching method, thereby forming lead-out wirings 51 and 52 as shown in FIG.

  Here, the side surfaces of the extended portions 222 and 224 where the lead wirings 51 and 52 are formed are tapered and inclined with respect to the thickness direction of the thin portion 21, so that the surface of the diaphragm 2 is deposited by vapor deposition. When forming the metal layer, the metal layer having a sufficient thickness can be formed on the surfaces of the thin portions 21 and the surfaces of the extensions 222 and 224. That is, since the metal layer having a sufficient thickness can be formed at a necessary position on the surface of the diaphragm 2 while keeping the posture of the diaphragm 2 constant, the formation of the lead wires 51 and 52 is facilitated. .

Next, as shown in FIG. 5C, a conductive adhesive is applied on the lower surface of the diaphragm 2 and on the terminals 511 and 521 of the lead wires 51 and 52 to form bumps 71 and 72, respectively. .
Next, as shown in FIG. 6A, the double tuning fork type piezoelectric vibrating piece 6 manufactured in advance is brought into contact with the bumps 71 of the excitation electrodes 62 and the extraction electrodes 632 of the excitation electrodes 63 are bumps. The bumps 71 and 72 are placed so as to come into contact with the bumps 72. Next, by curing the bumps 71 and 72 (conductive adhesive), the double tuning fork type piezoelectric vibrating piece 6 is fixed to the diaphragm 2 via the bumps 71 and 72. At the same time, the excitation electrodes 62 and 63 are electrically connected to the lead wires 51 and 52 through the bumps 71 and 72.
Next, as shown in FIG. 6 (b), the diaphragm 2 and the base 3 are joined via an adhesive (not shown). And the inside of the space S is made into a vacuum state as needed.
The pressure sensor 1 is obtained by the above process.

  In the pressure sensor 1 having such a configuration, the lead wires 51 and 52 and the bumps 71 and 72 can be easily formed, and the excitation electrodes 62 and 63 can be easily pulled out of the pressure sensor 1 (package 4). Can do. In addition, since the beam for supporting the double tuning fork type piezoelectric vibrating piece 6 is not provided for conventional use, the reliability of the double tuning fork type piezoelectric vibrating piece 6 is improved. That is, according to the pressure sensor 1, both the simplification of the manufacturing method and the reliability can be achieved.

Second Embodiment
Next, a second embodiment of the pressure sensor of the present invention will be described.
FIG. 7 is a cross-sectional view showing a second embodiment of the pressure sensor.
Hereinafter, the pressure sensor according to the second embodiment will be described with a focus on differences from the above-described embodiment, and description of similar matters will be omitted.
The pressure sensor according to the second embodiment of the present invention is the same as that of the first embodiment described above except that the configuration of the conductive bumps is different. In FIG. 7, the same components as those in the first embodiment described above are denoted by the same reference numerals.

As shown in FIG. 7, in the pressure sensor 1A of the present embodiment, solder balls are used as the conductive bumps 71A and 72A. This simplifies the configuration of the bumps 71A and 72A.
The bump 71A has a spherical shape. The bump 71A includes a spherical core 711A and solder (conductive portion) 712A coated on the surface of the core 711A. The core 711A has a melting point higher than that of the solder 712A. The material of the core 711A is not particularly limited as long as it is higher than the melting point of the solder 712A. For example, various metal materials such as gold, silver, and copper can be used. Similar to the bump 71A, the bump 72A includes a spherical core 721A and solder (conductive material layer) 722A coated on the surface of the core 721A.

  By using such bumps 71A and 72A, the diaphragm 2 and the double tuning fork type piezoelectric vibrating piece 6 can be joined by the solders 712A and 722A while the cores 711A and 721A function as spacers. Furthermore, the excitation electrode 62 and the lead-out wiring 51 can be electrically connected via the solder 712A, and the excitation electrode 63 and the lead-out wiring 52 can be electrically connected via the solder 722A.

A method (process) for joining the diaphragm 2 and the double tuning fork type piezoelectric vibrating piece 6 using the bumps 71A and 72A is not particularly limited. For example, bumps 71A and 72A are first placed on terminals 511 and 521 formed on diaphragm 2, and then heated above the melting point of solders 712A and 722A and below the melting point of cores 711A and 721A, and solders 712A and 722A are By melting, the bumps 71A and 72A and the terminals 511 and 521 are joined. Next, the double tuning fork piezoelectric vibrating piece 6 is placed on the bumps 71A and 72A, heated again in the same manner as described above, and the solders 712A and 722A are melted, whereby the bumps 71A and 72A and the double tuning fork piezoelectric vibrating piece 6 are Join. Thereby, the diaphragm 2 and the double tuning fork type piezoelectric vibrating piece 6 can be joined via the bumps 71A and 72A.
According to the second embodiment as described above, the same effect as that of the first embodiment can be exhibited.

  As mentioned above, although the pressure sensor of the present invention has been described based on the illustrated embodiments, the present invention is not limited to these, 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. Moreover, you may combine each embodiment mentioned above suitably.

  DESCRIPTION OF SYMBOLS 1, 1A ... Pressure sensor 2 ... Diaphragm 21 ... Thin part 22 ... Frame part 221, 223 ... 1st extension part 222, 224 ... 2nd extension part 3 ... Base 31 ... ... Base 32 ... Frame 4 ... Package 51, 52 ... Lead-out wiring 511, 521 ... Terminal 6 ... Double tuning fork type piezoelectric vibrating piece 61 ... Piezoelectric vibrating piece body 611, 612 ... Base 613 ... Vibration Numeral 62, 63... Excitation electrode 621, 631... Electrode piece 622, 632... Extraction electrode 613 a, 613 b. Solder S …… Space J …… Axis

Claims (10)

A package comprising a diaphragm having a thin-walled portion;
A pair of wires provided on the diaphragm and drawn from the inside of the package to the outside;
A piezoelectric vibrating piece housed in the package and having a piezoelectric vibrating piece body and a pair of electrodes formed on the piezoelectric vibrating piece body;
A pair of conductive bumps interposed between the piezoelectric vibrating piece and the diaphragm, and joined to the piezoelectric vibrating piece and the diaphragm;
One of the pair of bumps electrically connects one electrode of the pair of electrodes and one wiring of the pair of wires, and the other bump A pressure sensor provided to electrically connect the other electrode and the other wiring.   The pressure sensor according to claim 1, wherein the bump is made of a conductive adhesive.   The pressure sensor according to claim 2, wherein the adhesive includes a gap material.   The pressure sensor according to claim 1, wherein the bump has a nucleus and a conductive portion having conductivity provided so as to cover the periphery of the nucleus. The diaphragm has a frame portion formed so as to surround the thin portion,
The frame portion has an extending portion that extends in a predetermined direction and has a tapered cross section.
The pressure sensor according to claim 1, wherein each of the wirings is formed so as to straddle the extending portion. The diaphragm has a pair of extending portions facing each other through the thin-walled portion,
One of the pair of wirings is formed so as to straddle one of the extended portions of the pair of extending portions, and the other wiring is formed of the other extending portion. The pressure sensor according to claim 4, wherein the pressure sensor is formed so as to straddle.   The pressure sensor according to claim 6, wherein a separation direction of the pair of extending portions is equal to a separation direction of the pair of bumps.   8. The pressure sensor according to claim 6, wherein each of the wirings is formed so as to straddle the extending portion closer to the bump to which the wiring is connected.   The pressure sensor according to claim 1, wherein the piezoelectric vibrating piece is a double tuning fork type vibrating piece.   The pressure sensor according to claim 1, wherein each of the diaphragm and the vibration piece main body is made of quartz.

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