JP4635917B2 - Surface mount type piezoelectric vibration device - Google Patents

Description

  The present invention relates to a piezoelectric vibration device such as a crystal resonator used for an electronic device, a mobile wireless device, and the like, and more particularly to a piezoelectric vibration device corresponding to an ultra-small size.

  Currently used piezoelectric vibrators have a configuration in which excitation electrodes are formed on the front and back surfaces of a piezoelectric diaphragm. For example, a thickness-shear vibrator using an AT-cut quartz diaphragm is often used. Such a crystal diaphragm is housed in a box-shaped ceramic package, and is electrically and mechanically joined to the package, and the quartz diaphragm is closed by closing the opening of the ceramic package with a flat lid. It was hermetically sealed.

Various configurations have been studied and adopted for this hermetic sealing method. For example, a glass sealing configuration in which a ceramic package using a glass material as a bonding material and a lid are bonded with a glass material, or between a ceramic package and a lid. A brazing material sealing structure in which a metal brazing material is interposed between the metal brazing material and melt-bonded by the metal brazing material, or a metal film formed on the package and the lid is formed by seam welding which is a kind of resistance welding. A seam sealing configuration that is melt-bonded can be used.

  By the way, ceramic packages are widely used as packages for electronic components. However, since the structure has a plurality of ceramic layers and metal wiring layers, there is a limit to downsizing and low profile as packages for electronic components. . In particular, along with the miniaturization of electronic devices, mobile wireless devices, etc., hybridization of electronic components at a high density has been rapidly progressing, and ceramic packages having a conventional configuration may not be applicable.

In order to cope with such ultra-miniaturization, a configuration has been devised in which a ceramic substrate is not used but a plate-like substrate is used and bonded. For example, in Japanese Patent Laid-Open No. 2001-267875 (Patent Document 1), a vibrator substrate on which a pair of vibration electrodes is formed, a base substrate that supports the vibrator substrate, and a lid substrate that covers the vibrator substrate. The vibrator substrate, the base substrate, and the lid substrate are hermetically sealed by eutectic bonding, the vibrator substrate includes a vibrator piece on which first and second vibration electrodes are formed, and the vibrator A first wiring electrode supporting the piece and connected to the first vibration electrode is formed on substantially the entire surface, and a second wiring electrode connected to the second vibration electrode is formed on the other surface. A frame portion formed on the entire surface, and first and second external electrodes connected to the first wiring electrode and the second wiring electrode on the corner side wall of the frame portion, respectively; A featured crystal unit. Is disclosed.

  The above-described vibrator substrate, the base substrate that supports the vibrator substrate, and the lid substrate that covers the vibrator substrate are joined by, for example, a gold-tin eutectic alloy. By the way, the piezoelectric vibration device normally performs frequency adjustment (trimming) on the piezoelectric vibration plate after the package is accommodated. In the configuration of Patent Document 1, a light-transmitting material is used for the lid substrate or the base substrate, and the vibrator substrate, the base substrate, and the lid substrate are bonded together, and then the metal film constituting the excitation electrode is removed by laser light. A method for trimming is disclosed. Such frequency adjustment causes trimmed metal grains to remain in the package, which may deteriorate the characteristics.

When performing frequency adjustment before hermetic sealing, for example, a method of performing frequency adjustment on the vibrator substrate after joining the base substrate and the vibrator substrate in the configuration of Patent Document 1, and then joining the lid substrate can be considered. In the above-described bonding material configuration, since the eutectic alloy of gold tin is used for bonding both the base substrate and the vibrator substrate and the lid substrate and the vibrator substrate, the first bonding material is melted and airtight when the lid substrate is bonded. There was a possibility that the performance would decrease.
JP 2001-267875 A

  The present invention has been made in view of the above points, and the object of the present invention is to respond to ultra-miniaturization and ultra-low profile, easily adjust the characteristics, and improve the hermetic sealing performance. Is intended to provide.

According to a first aspect of the present invention, there is provided a surface mounted piezoelectric vibration device having a piezoelectric vibration plate on which an excitation electrode is formed and a frame partly connected to the piezoelectric vibration plate and disposed on the outer periphery of the piezoelectric vibration plate. A surface-mounted piezoelectric vibration device comprising a piezoelectric diaphragm with a frame comprising: a first case and a second case for holding a part of the piezoelectric diaphragm with a frame from above and below by a bonding material;
The melting point of the second bonding material used for bonding the second case and the piezoelectric diaphragm with frame is lower than the melting point of the first bonding material used for bonding the first case and the frame-equipped piezoelectric diaphragm. It is characterized by.

  According to each of the above configurations, the first case and the framed piezoelectric diaphragm are first joined, and in this state, for example, the frequency adjustment described above is performed on the framed piezoelectric diaphragm, and then the second case Even when the case and the frame-equipped piezoelectric diaphragm are joined, the second case and the frame-equipped piezoelectric element are obtained from the melting point of the first bonding material used for joining the first case and the frame-equipped piezoelectric diaphragm. Since the melting point of the second bonding material used for bonding to the diaphragm is low, the bonding between the first case and the framed piezoelectric diaphragm is not adversely affected. For example, there is no problem that the bonding material is softened or melted to deteriorate the airtightness.

  As a more specific configuration, as shown in claim 2, a piezoelectric diaphragm having an excitation electrode formed thereon, a frame disposed on the outer periphery of the piezoelectric diaphragm, and the piezoelectric diaphragm and the frame are coupled to each other. A piezo-electric diaphragm with a frame comprising a linking part, an extraction electrode formed on at least a part of the linking part, and a circumferential metal film formed on the front and back of the frame, and a frame of the piezo-electric diaphragm with the frame A first case and a second case having a circumferential connection metal film corresponding to the metal film formed on the body, and having a connection electrode to the extraction electrode, and holding the framed piezoelectric diaphragm from above and below by a bonding material A surface mount type piezoelectric vibration device comprising: a second case and a frame-equipped piezoelectric vibration based on a melting point of a first bonding material used for joining the first case and the frame-equipped piezoelectric vibration plate. The melting point of the second bonding material used for bonding to the plate is low. Can be mentioned a surface mount type piezoelectric vibrating device.

  According to each of the above-described configurations, the second case used for joining the second case and the frame-attached piezoelectric diaphragm from the melting point of the first bonding material used for joining the first case and the frame-attached piezoelectric diaphragm. Since the melting point of the bonding material is low, the first case and the frame-attached piezoelectric diaphragm are first joined, and then various manufacturing and adjustment operations are performed on the piezoelectric diaphragm and the like. When the case is hermetically sealed, there is no adverse effect on the previous bonding material at the time of hermetic sealing joining by the second case.

  In addition, the structure having the metal film formed on the frame and the circumferential connection metal film formed on the first case and the second case makes it easy to join the two together for hermetic sealing. Since the case and the second case have connection electrodes connected to the extraction electrode of the piezoelectric diaphragm, the piezoelectric diaphragm is hermetically sealed and the excitation electrode and extraction electrode formed on the piezoelectric diaphragm are connected to the case. Can be easily connected.

According to a third aspect of the present invention, in each of the above-described configurations, the surface-mounting type in which the second case and the framed piezoelectric diaphragm are bonded after the first case and the framed piezoelectric diaphragm are bonded. A piezoelectric vibration device may be used.

  According to each said structure, melting | fusing point of the joining material used for joining of a 2nd case and the said piezoelectric diaphragm with a frame is lower than melting | fusing point of the joining material used for joining with a 1st case and the said piezoelectric diaphragm with a frame. By first joining the first case and the piezoelectric diaphragm with the frame, and after performing various manufacturing and adjustment operations on the piezoelectric diaphragm and the like before hermetic sealing by the second case, Even if the second case and the frame-attached piezoelectric diaphragm are joined by the bonding material, the first case and the frame-attached piezoelectric diaphragm are not adversely affected.

According to a fourth aspect of the present invention, in each of the above configurations, the piezoelectric diaphragm is formed of an AT-cut quartz diaphragm, and the connecting portion is formed in a direction inclined by 30 degrees with respect to the Z-axis direction of the AT cut. It is good also as a structure. The tilt angle may be +30 degrees or −30 degrees with respect to the Z axis, and the drawer may be set near 30 degrees.

According to the fourth aspect, since the drawing direction of the connecting portion is drawn in a direction inclined by 30 degrees with respect to the Z-axis of the AT-cut quartz plate, the influence of the support on the piezoelectric diaphragm can be eliminated. That is, the direction of the angle of about 30 degrees is a region where the stress sensitivity is zero in the AT-cut quartz diaphragm, and the piezoelectric vibration device having stable characteristics can suppress the influence of stress in joining to the frame as much as possible. Can be obtained.

According to a fifth aspect of the present invention, in each of the above-described structures, the first and second bonding materials are a metal brazing material, a glass material, or a metal fine particle-containing paste material. There may be.

The metal fine particle-containing paste material is, for example, a metal having an average particle diameter of 1 to 100 nm, a surface coated with an organic film, and metal fine particles from which the organic film is removed by heating dispersed in an organic solvent. A fine particle paste bonding material can be mentioned. Examples of the metal fine particles include metal materials such as gold, silver, copper, nickel, titanium, tin, and palladium.

Metal brazing material, glass material or metal fine particle-containing paste material can be used to heat and melt the bonding material by heating the piezoelectric vibration device. This is effective for manufacturing.

The present invention also proposes a manufacturing method using the above configuration. For example, according to a sixth aspect of the present invention, in the method for manufacturing a surface-mount type piezoelectric vibration device according to any one of the first to fifth aspects, the first case and the piezoelectric vibration plate with a frame are connected to the first case. After bonding with a bonding material, characteristic adjustment is performed on the exposed surface of the piezoelectric diaphragm, and then the frame-attached piezoelectric diaphragm and the second case are bonded with a second bonding material to achieve hermetic sealing. It is characterized by doing.

For the characteristic adjustment, for example, frequency adjustment is performed on the excitation electrode or other electrical characteristics are adjusted. The frequency adjustment is performed, for example, by reducing or increasing the thickness of the metal film constituting the excitation electrode.

According to the sixth aspect of the present invention, after the first case and the piezoelectric diaphragm with a frame are bonded with a bonding material, characteristic adjustment is performed on the exposed surface of the piezoelectric diaphragm, and then the piezoelectric diaphragm with the frame And the second case are hermetically sealed. As a result, it is possible to obtain a surface-mounted piezoelectric vibration device with good airtightness that can be sufficiently adjusted in characteristics and that does not adversely affect the bonding of the first case and the piezoelectric diaphragm with frame during hermetic sealing.

Furthermore, the present invention also discloses a manufacturing method in units of wafers for obtaining a large number of surface-mount type piezoelectric vibration devices. That is, as shown in claim 7, a piezoelectric diaphragm in which an excitation electrode is formed, a frame body arranged on the outer periphery of the piezoelectric diaphragm, a connecting portion for connecting the piezoelectric diaphragm and the frame body, Forming a framed piezoelectric diaphragm wafer having a plurality of framed piezoelectric diaphragms, each including a lead electrode formed on at least a part of the portion, and a circumferential metal film formed on the front and back of the frame; And having a peripheral connection metal film corresponding to the metal film formed on the frame of the framed piezoelectric diaphragm, and having a connection electrode with the extraction electrode, and having one main surface of the framed piezoelectric diaphragm A step of forming a first case wafer having a plurality of first cases held by the second bonding material, and a circumferential connection metal film corresponding to the metal film formed on the frame of the frame-attached piezoelectric diaphragm And having a connection electrode with the extraction electrode and having a frame Forming a second case wafer having a plurality of second cases for holding the other main surface of the piezoelectric diaphragm with a second bonding material, the first case wafer, and the framed piezoelectric diaphragm wafer; The first bonding material, a step of adjusting the frequency by adjusting the mass of the excitation electrode exposed on each piezoelectric diaphragm after the bonding step, and the step of adjusting the frequency after the frequency adjusting step. A step of hermetically sealing the attached piezoelectric diaphragm wafer and the second case wafer with a second bonding material having a melting point lower than that of the first bonding material; and A method for manufacturing a surface-mount type piezoelectric vibration device, comprising: a step of cutting a bonded body into pieces for each surface-mount type piezoelectric vibration device. The frequency adjustment may be performed, for example, by mass reduction (removal) or mass increase (addition) with respect to the excitation electrode.

  According to the above manufacturing method, a first case wafer, the framed piezoelectric diaphragm wafer, and a second case wafer are prepared, and the first case wafer and the framed piezoelectric diaphragm wafer are first bonded. After the joining step, the step of adjusting the frequency by adjusting the mass of the exposed excitation electrode of each piezoelectric diaphragm is sequentially performed sequentially with respect to the excitation electrode of each piezoelectric diaphragm. Frequency adjustment can be performed and efficient manufacturing can be performed.

  Then, after the frequency adjusting step, the step of performing hermetic sealing by bonding the frame-equipped piezoelectric diaphragm wafer and the second case wafer with a second bonding material having a melting point lower than the bonding material of the body 1 In addition, airtight sealing can be performed on a large number of piezoelectric vibration devices at once. With the manufacturing method described above, a highly accurate piezoelectric vibration device that has been subjected to frequency adjustment can be obtained in a favorable airtight state.

  According to the present invention, it is possible to obtain a piezoelectric vibrating device that can cope with ultra-miniaturization and ultra-low profile, can be easily adjusted in characteristics, and has improved hermetic sealing performance.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
A first embodiment of the present invention will be described with reference to FIGS. 1 to 9 by taking a surface-mounted crystal resonator as an example. 1 is a plan view of a framed piezoelectric diaphragm mounted on a first case showing the present embodiment, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3 is a cross-sectional view taken along line BB in FIG. 4 is a plan view showing a framed piezoelectric diaphragm wafer, FIG. 5 is a plan view of a first case wafer, FIG. 6 is a plan view of a second case wafer, FIG. 7 is a diagram showing frequency adjustment, and FIG. FIG. 9 is a detailed diagram showing the adjustment, and FIG. 9 is a diagram showing the dividing step.

  The surface-mounted crystal resonator includes a piezoelectric diaphragm 1 with a frame, a first case 2 joined below the piezoelectric diaphragm with the frame, and a second case 3 joined above the piezoelectric diaphragm with the frame. And consist of The piezoelectric diaphragm 1 with a frame is formed of a flat AT-cut quartz diaphragm, and a frame 11 is formed on the quartz diaphragm 10 and the outer periphery thereof with a predetermined interval 10e. The crystal diaphragm 10 has a shape having a cutout portion in which four corners of a rectangular shape are cut out. The notch portion of the quartz crystal plate 10 and the frame body 11 are connected by connecting portions 10a, 10b, 10c, and 10d, whereby the quartz plate 10, the frame body 11, and each connecting portion form an integral configuration. Yes. The frame body 11 has a rectangular circumferential configuration, and projecting portions 11a, 11b, 11c, and 11d corresponding to the cutout portions of the crystal diaphragm are formed on the inner side of the four corners.

Excitation electrodes 12 and 13 are formed opposite to each other on the front and back of the center portion of the quartz crystal diaphragm, and the excitation electrode 12 is drawn out to the frame by extraction electrodes 12a and 12b. The extraction electrodes 12a and 12b extend to the protrusions 11b and 11d through the connecting parts 10b and 10d, and are extracted to the back surface of the quartz crystal plate through the through holes 11bb and 11db formed in the protrusions. Yes. The excitation electrode 13 formed on the back surface of the crystal diaphragm is drawn out to the frame by lead electrodes 13a and 13b (not shown). The extraction electrodes 13a and 13b extend to the protrusions 11a and 11c through connecting parts 10a and 10c (not shown), and the surface of the quartz crystal plate through through holes 11ab and 11cb formed in the protrusions. Has been pulled up to. In each through hole, an electrode film is formed by thin film forming means such as a vacuum evaporation method. With such a configuration, the excitation electrodes 12 and 13 are drawn out to the front and back of the diagonal protrusions of the frame.

In the frame body 11, circumferential metal films 14 and 15 are formed on the front and back sides of the frame-like portion outside each protrusion. In this embodiment, the metal films 14 and 15 are not electrically connected to the excitation electrodes 12 and 13, respectively, but may be connected in a state where the excitation electrodes are not short-circuited. Further, the circumferential metal films 14 and 15 may be formed up to the outer peripheral edge of the frame, but may be formed inside the outer peripheral edge. With such a configuration, a short circuit between the metal films 14 and 15 can be suppressed.

A first case 2 is joined to the lower part of the framed piezoelectric diaphragm 1. The first case 2 is made of a quartz plate or a ceramic plate and has a recess 20 in the central portion. A bank portion 21 is formed around the concave portion 20, and the planar shape of the bank portion corresponds to the frame body 11, and the bank body and the bank portions corresponding to the projecting portions 11 a, 11 b, 11 c, and 11 d Is formed. The concave portion is not necessarily required. If the excitation space (cavity) of the crystal diaphragm 10 can be formed by adjusting the bonding material and the metal film thickness described later, the concave portion may not be formed.

For example, in the case of a quartz plate, the recess 20 may be formed by etching using a photolithography technique, or by a dry etching method such as ion milling or a sand blast method. The processing is performed in combination with a technique for masking areas other than the non-processed area in order to form a recess only in a predetermined area.

The first case 2 is formed with through holes 22, 23, 24, and 25 (partially not shown) penetrating front and back at positions corresponding to the through hole forming regions of the protrusions. Connection electrodes 22a, 23a, 24a, 25a (not shown in part) are formed on the upper surfaces of the through holes 22, 23, 24, 25, respectively, and lead electrodes 22b, 23b, 24b are formed on the lower surfaces of the through holes. , 25b (partially not shown). In addition, a metal material is formed in the through hole, and the excitation electrodes 12 and 13 of the crystal diaphragm 10 are connected to the extraction electrode of the first case by such a configuration. Further, a circumferential metal film 26 is formed on the outer peripheral region of the surface of the first case 2. The metal film 26 is formed corresponding to the metal film 15 formed on the frame body 11.

A metal brazing material is used to join the piezoelectric diaphragm with frame and the first case. The electrode material provided on the lower surface of the through holes 11ab, 11bb, 11cb, 11db and the extraction electrodes 22a, 23a, 24a, 25a Are joined by a first joining material (metal brazing material) S1. In addition, the metal film 26 of the first case and the metal film 15 of the frame body are bonded together by the first bonding material (metal brazing material) S1, so that the frame-equipped piezoelectric diaphragm and the first case are electromechanical. To join. In the above example, the through holes 22, 23, 24, 25 of the case are formed below the through holes formed in the projecting portion of the frame body. It may be shifted. In this case, since the area for forming the first bonding material is widened for electrical connection, the bonding strength is improved.

The through hole and each electrode (metal material) are formed by an etching technique using the above-mentioned photolithography technique, or by a dry etching method such as ion milling, a sand blasting method, a vacuum deposition method, or the like. To do.

A second case 3 is formed on the upper part of the framed piezoelectric diaphragm 1. The second case 3 is made of a quartz plate or a ceramic plate, and has a recess 30 in the central portion. A bank portion 31 is formed around the concave portion 30, and the planar shape of the bank portion is the same as that of the first case, corresponding to the frame body 11, and the frame body 11 and the protruding portions 11 a and 11 b. , 11c, and 11d. In addition, about the 2nd case, it is not necessary to form the bank part corresponding to a protrusion part. The concave portion 30 is not necessarily required, and the concave portion may not be formed when an excitation space (cavity) of the crystal diaphragm 10 can be formed by adjusting a bonding material or a metal film thickness described later. A frame-shaped metal film 36 is formed in the outer peripheral region of the back surface of the second case (on the frame-side piezoelectric diaphragm side). The metal film 36 is formed corresponding to the metal film 14 formed on the frame.

  A second diaphragm (metal brazing material) S2 is used to join the piezoelectric diaphragm with frame and the second case, and the metal film 14 of the frame body and the metal film of the second case are joined to the second joint. It joins by material (metal brazing material) S2. As a result, the frame-attached piezoelectric diaphragm and the second case are joined, and hermetic sealing is performed. The second bonding material S2 is made of a material having a melting point lower than that of the first bonding material S1.

  Note that an electromagnetic shield configuration may be adopted by forming a conductive material on the upper surface of the second case and grounding the conductive material. For this earth connection, either an extraction electrode may be used, or an earth extraction electrode may be provided separately.

As an example of the above-described metal brazing material, the first bonding material S1 used for joining the piezoelectric diaphragm 1 with a frame and the first case 2 is made of a gold germanium (Au—Ge) brazing material, and a piezoelectric with a frame. The second bonding material S2 used for bonding the diaphragm 1 and the second case 3 is made of a gold tin (Au—Sn) brazing material. The melting point of the first bonding material S1 is set higher than that of 356 ° C. and the melting point 280 ° C. of the second bonding material S2. Therefore, the framed piezoelectric diaphragm and the first case are first brazed with the first bonding material S1, and after adjustment and thermal stabilization operations are performed as necessary, the second bonding material S2 is used. Even in the case of brazing, the first bonding material is not melted or softened during the latter brazing, and a surface-mount type piezoelectric vibration device with stabilized characteristics can be obtained. The metal brazing material is formed in advance on the framed piezoelectric diaphragm or the first and second cases, or a sheet-shaped metal brazing material is interposed between the framed piezoelectric diaphragm and the first and second cases. Bonding is performed.

Further, although the metal brazing material is used as the bonding material, the bonding material can be applied as long as the first bonding material has a higher melting point than the second bonding material. For example, a metal brazing material such as a low melting point metal, solder, lead-free solder, etc. other than the above may be used, tin-lead glass material, tin phosphate glass material, silver phosphate glass material, bismuth glass material, vanadium oxide system A glass bonding material such as a glass material may be used, or a metal fine particle-containing paste material may be used. Alternatively, these bonding materials may be combined and applied as the first and second bonding materials.

Next, a method for manufacturing a surface-mounted piezoelectric vibration device according to the present invention will be described with reference to FIGS. This manufacturing method shows a manufacturing example in units of wafers. FIG. 4 shows a framed piezoelectric diaphragm wafer W1 in which a large number of framed piezoelectric diaphragms 1 each consisting of a combination of a crystal diaphragm 10 and a frame 11 as shown in FIG. ing. In FIG. 4, the description of the excitation electrode and the like is omitted. This example illustrates a framed piezoelectric diaphragm wafer in which 20 framed piezoelectric diaphragms 1 are formed in a matrix, and each of a first case wafer and a second case wafer described later includes 20 cases. An example in which is formed is shown. These many piezoelectric diaphragms with frames are subjected to outer shape processing and excitation electrode formation by photolithography.

FIG. 5 shows a first case wafer W2 in which a large number of first cases 2 are formed in a matrix (only a part is shown). The wafer uses quartz, and a concave portion, a bank portion, and a metal film are formed as a first case. This shape processing is also performed by a photolithography technique.

FIG. 6 shows a second case wafer W3 in which a plurality of second cases 3 are formed in a matrix (only a part is shown). Quartz is also used for the wafer, and a concave portion, a bank portion, and a metal film are formed as necessary as second cases. This shape processing is also performed by a photolithography technique.

First, the frame-attached piezoelectric diaphragm wafer W1 is overlapped and bonded onto the first case wafer W2 (first bonding step). Prior to the first bonding step, the first bonding material S1 (gold germanium brazing) is formed on the frame-like metal film 26 and the extraction electrodes 22a, 23a, 24a, and 25a previously formed in each first case 2. Each material is formed. Therefore, the piezoelectric film wafer W1 with a frame is overlapped and bonded to the first case wafer W2, so that the metal film 15 and the frame-shaped metal film 26 of each frame and the bottom surface of the through hole of the frame-shaped piezoelectric vibration plate are formed. The formed electrode material and the extraction electrodes 22a, 23a, 24a, and 25a are bonded through the first bonding material S1. Note that the first bonding material may be formed on the frame-side piezoelectric diaphragm wafer side.

The atmosphere is heated at a predetermined temperature with the wafers stacked. Specifically, a set of one or a plurality of the above stacked wafers is accommodated in a heating furnace in a vacuum or an inert gas atmosphere, and heated to the melting temperature of the first bonding material 1 according to a predetermined temperature profile. Thus, the frame-attached piezoelectric diaphragm and the first case of each wafer are joined. By such a first bonding step, it is possible to obtain a wafer bonded body in which the quartz crystal plates with the excitation electrodes 12 exposed at the top are arranged in a matrix.

Next, as shown in FIG. 7, frequency adjustment is performed on the exposed excitation electrode 12 (frequency adjustment step). In this embodiment, the metal film thickness of the excitation electrode is reduced by ion milling, which is a kind of dry etching method, and the frequency is adjusted. Specifically, the adjustment operation is performed for each frame-attached piezoelectric diaphragm. A milling mask M in which an adjustment window M1 is formed on a metal plate is applied to each frame-attached piezoelectric diaphragm, and ion milling is performed from above. When ion milling is performed, the frequency of the piezoelectric diaphragm is monitored by measuring the frequency of the piezoelectric diaphragm in real time or by repeating adjustment and measurement. After adjusting to a predetermined frequency, the next framed piezoelectric diaphragm is adjusted in the same procedure, and the frequencies of the piezoelectric diaphragms of all the wafers are adjusted. The operation of the mask for milling, the operation of the adjustment window, the execution of ion milling, and the frequency measurement may be performed under centralized control by the control unit.

FIG. 8 is a detailed view showing frequency adjustment by ion milling focusing on one piezoelectric vibration device. The ions output from the ion milling device T reduce the electrode film thickness of the excitation electrode 12 of the crystal diaphragm 10 through the adjustment window M1 of the mask M. The frequency being adjusted is measured, for example, via the connection electrodes 24b and 25b formed in the first case, and the adjustment is finished when a predetermined frequency is reached. In addition to the ion milling, the frequency adjustment method can be a partial vapor deposition method as a mass addition method, for example.

After the frequency adjustment is completed for all the quartz diaphragms, the second case wafer 3 covers the framed piezoelectric diaphragm wafer and hermetically seals (second bonding step, FIG. 9A). reference). In the second bonding step, the internal atmosphere of the piezoelectric vibration device is determined. For example, when performing vacuum sealing, airtight sealing is performed using a vacuum heating furnace, and when performing airtight sealing in an inert gas atmosphere, for example, airtight sealing is performed in a heating furnace having an inert gas atmosphere such as nitrogen gas. I do. As a specific example of the vacuum sealing, the upper surface, that is, the excitation electrode 2 side is covered with the second case wafer with respect to the set of the framed piezoelectric diaphragm wafer W1 and the first case wafer W2. A gold-tin (Au—Sn) brazing material, which is the second bonding material S2, is formed in advance on the outer metal film 36 on the second case wafer side, and the second bonding is performed by covering with the second case wafer. The material S2 and the metal film 14 of the frame are in contact with each other, and in this state, heating is performed in a vacuum heating furnace. A predetermined vacuum state is maintained in a vacuum heating furnace, the bonding material 2 is melted by a predetermined temperature profile, and brazing is performed. Since the melting temperature at this time can be performed at a lower temperature than the first bonding step as described above, the first bonding material S1 (metal brazing material) in the first bonding step is not melted or softened. Through the above steps, it is possible to obtain a wafer bonded body in a state where the quartz diaphragm 10 is hermetically sealed. The wafers can be joined with high accuracy without any positional deviation by aligning with the marker N.

Next, as shown in FIG. 9B, the wafer bonded body is separated into each piezoelectric vibration device (division step). The dividing step may be performed by dicing, or a scribe groove may be provided on the wafer in advance, and the scribe groove may be divided into individual points. As described above, the surface-mounted piezoelectric vibrating device R divided from the wafer can be obtained by the first bonding step, the frequency adjusting step, the second bonding step, and the dividing step.

The present invention is not limited to the above embodiment. For example, another embodiment of the configuration of the framed piezoelectric diaphragm will be described with reference to FIGS. In either case, a quartz plate is used, but another single crystal piezoelectric material or a piezoelectric ceramic plate may be used. FIG. 10 shows a configuration in which the crystal diaphragm 40 is cantilevered with respect to the frame body 41. The piezoelectric diaphragm 4 with a frame includes a crystal diaphragm 40 on which excitation electrodes 42 and 43 (43 on the back surface is not shown) are formed, and a frame body that is arranged on the outer periphery of the crystal diaphragm 40 with a predetermined interval 40e. 41 and connecting portions 40a and 40b that connect the crystal diaphragm and the frame. The connecting portions 40a and 40b have a cantilevered support structure that is drawn out to only one side in the Z-axis direction, and the drawing-out direction of the connecting portion is drawn at an angle of ± 30 degrees with respect to the Z-axis. This angle of 30 degrees is a region where the stress sensitivity is zero in the AT-cut quartz diaphragm, and is configured to be able to suppress the influence of stress in joining with the frame as much as possible. In particular, in the present invention, since the frame body is firmly held by the upper and lower cases, it is difficult to transmit the influence of holding stress to the quartz diaphragm, and a piezoelectric vibrating device having stable characteristics can be obtained.

Projections 41a and 41b are formed in the frame 41, and through holes 41ab and 41bb are formed in the protrusions, respectively. A connection electrode is formed on the upper and lower surfaces of the through hole, and an electrode material is also formed inside the through hole so that electrical connection with the first case or the like is possible. According to the configuration shown in FIG. 10, by performing cantilever support, in addition to the above-described effects, the deterioration of characteristics due to vibration suppression due to support and the like are suppressed, and the formation angle of the connecting portion is specified. It is possible to obtain a piezoelectric vibration device having good characteristics that is not easily affected.

The configuration shown in FIG. 11 shows a configuration in which the quartz diaphragm 50 is elliptical and is supported on both sides of the frame 51. The piezoelectric diaphragm 5 with a frame is disposed on the quartz diaphragm 50 on which elliptical excitation electrodes 52 and 53 (53 on the back surface are not shown) are formed, and on the outer periphery of the quartz diaphragm 50 with a predetermined interval 50e. Frame body 51, and connecting portions 50a, 50b, 50c, and 50d that connect the crystal diaphragm and the frame body. The connecting portions 50a, 50b, 50c, and 50d are both-end supported structures drawn in both directions in the Z-axis direction, and the connecting portion is drawn out at an angle of ± 30 degrees with respect to the Z-axis. This angle of 30 degrees is a region where the stress sensitivity is zero in the quartz diaphragm, and is configured to be able to suppress the influence of stress in joining with the frame as much as possible.

Projections 51a, 51b, 51c, 51d are formed in the frame 51, and through holes 51ab, 51bb, 51cb, 51db are formed in the protrusions, respectively. A connection electrode is formed on the upper and lower surfaces of the through hole, and an electrode material is also formed inside the through hole so that electrical connection with the first case or the like is possible. According to the configuration shown in FIG. 11, the outer shape of the quartz diaphragm is elliptical, and the excitation electrode is elliptical, so that it is not easily affected by unnecessary vibration such as a contour system, and the formation angle of the connecting portion is specified. Therefore, it is possible to obtain a piezoelectric vibration device having good characteristics that is hardly affected by the support.

The configuration shown in FIG. 12 shows a configuration in which the crystal diaphragm 60 has a rectangular shape and is supported at both ends with respect to the frame body 61. The piezoelectric diaphragm 6 with a frame is disposed on the quartz diaphragm 60 on which elliptical excitation electrodes 62 and 63 (the rear surface 63 is not shown) are formed, and on the outer periphery of the quartz diaphragm 60 with a predetermined interval 60e. Frame 61 and connecting portions 60a and 60b for connecting the crystal diaphragm and the frame. The connecting portions 50a and 50b have a both-end support structure drawn in both directions in the Z-axis direction, and the connecting portion is drawn out at an angle of ± 30 degrees with respect to the Z-axis. This angle of 30 degrees is a region where the stress sensitivity is zero in the quartz diaphragm, and is configured to be able to suppress the influence of stress in joining with the frame as much as possible.

Projections 61a and 61b are formed in the frame 61, and through holes 61ab and 61bb are formed in the protrusions, respectively. A connection electrode is formed on the upper and lower surfaces of the through hole, and an electrode material is also formed inside the through hole so that electrical connection with the first case or the like is possible. According to the configuration shown in FIG. 12, a piezoelectric vibration device having good characteristics that has good impact resistance due to the dual-supporting configuration and is less susceptible to the support because the forming angle of the connecting portion is specified is obtained. Can do.

  In the examples of the above embodiments, a surface-mount type crystal resonator using an AT-cut crystal diaphragm is illustrated, but the present invention can also be applied to a tuning-fork crystal resonator, a crystal filter, and an SC-cut crystal resonator. Alternatively, a single crystal piezoelectric material such as lithium tantalate or a piezoelectric ceramic may be used. As for the case material, ceramic or the like may be used in addition to the crystal plate.

The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

  It can be applied to mass production of piezoelectric vibration devices such as crystal oscillators and crystal oscillators.

The top view which shows embodiment by this invention. AA sectional drawing of FIG. BB sectional drawing of FIG. The top view of a piezoelectric diaphragm wafer with a frame. The top view of a 1st case wafer. The top view of a 2nd case wafer. The figure which shows a frequency adjustment process. Detail drawing which shows a frequency adjustment process. The figure which shows a division | segmentation process. The figure which shows other embodiment. The figure which shows other embodiment. The figure which shows other embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric diaphragm 2 with a frame 1st case 3 2nd case S1 1st joining material S2 2nd joining material

Claims (7)

A piezoelectric diaphragm with a frame comprising a piezoelectric diaphragm on which an excitation electrode is formed and a frame partly connected to the piezoelectric diaphragm and disposed on the outer periphery of the piezoelectric diaphragm, and a part of the piezoelectric diaphragm with the frame A surface-mount type piezoelectric vibration device comprising a first case and a second case for holding the substrate from above and below by a bonding material,
The melting point of the second bonding material used for bonding the second case and the piezoelectric diaphragm with frame is lower than the melting point of the first bonding material used for bonding the first case and the frame-equipped piezoelectric diaphragm. A surface-mounted piezoelectric vibration device characterized by A piezoelectric diaphragm having excitation electrodes formed thereon, a frame disposed on the outer periphery of the piezoelectric diaphragm, a connecting portion connecting the piezoelectric vibrating plate and the frame, and formed on at least a part of the connecting portion A framed piezoelectric diaphragm comprising an extraction electrode and a circumferential metal film formed on the front and back of the frame;
It has a circumferential metal film corresponding to the metal film formed on the frame of the framed piezoelectric diaphragm, and has a connection electrode to the extraction electrode, and the framed piezoelectric diaphragm is held from above and below by a bonding material A first case and a second case,
A surface mount type piezoelectric vibration device comprising:
The melting point of the second bonding material used for bonding the second case and the piezoelectric diaphragm with frame is lower than the melting point of the first bonding material used for bonding the first case and the frame-equipped piezoelectric diaphragm. A surface-mounted piezoelectric vibration device characterized by The surface-mount type piezoelectric vibration device according to claim 1, wherein the second case and the piezoelectric diaphragm with frame are joined after the first case and the piezoelectric diaphragm with frame are joined. The surface mounting according to claim 2 or 3 , wherein the piezoelectric diaphragm is formed of an AT-cut crystal diaphragm, and the connecting portion is formed in a direction inclined by 30 degrees with respect to the Z-axis direction of the AT cut. Type piezoelectric vibration device. The surface-mount type piezoelectric vibration device according to claim 1, wherein the bonding material is a metal brazing material, a glass material, or a metal fine particle-containing paste material. A method for manufacturing a surface-mounted piezoelectric vibrating device according to any one of claims 1 to 5,
After the first case and the framed piezoelectric diaphragm are bonded with the first bonding material, the characteristics of the exposed surface of the piezoelectric diaphragm are adjusted, and then the framed piezoelectric diaphragm and the second A method for manufacturing a surface-mount type piezoelectric vibration device, wherein the case is hermetically sealed by bonding with a second bonding material. A piezoelectric diaphragm having excitation electrodes formed thereon, a frame disposed on the outer periphery of the piezoelectric diaphragm, a connecting portion connecting the piezoelectric vibrating plate and the frame, and formed on at least a part of the connecting portion Creating a framed piezoelectric diaphragm wafer having a plurality of framed piezoelectric diaphragms composed of extraction electrodes, circumferential metal films formed on the front and back of the frame, and
A peripheral connection metal film corresponding to the metal film formed on the frame body of the frame-attached piezoelectric diaphragm, and a connection electrode to the extraction electrode, wherein one main surface of the frame-attached piezoelectric diaphragm has a first surface Producing a first case wafer having a number of first cases held by one bonding material;
A peripheral connecting metal film corresponding to the metal film formed on the frame body of the framed piezoelectric diaphragm, a connection electrode to the extraction electrode, and the other main surface of the framed piezoelectric diaphragm being the first main surface. Producing a second case wafer having a plurality of second cases held by the bonding material of 2;
Bonding the first case wafer and the frame-attached piezoelectric diaphragm wafer with a first bonding material;
After the joining step, a step of adjusting the frequency of the exposed excitation electrode of each piezoelectric diaphragm,
After the frequency adjusting step, hermetically sealing by bonding the framed piezoelectric diaphragm wafer and the second case wafer with a second bonding material having a melting point lower than that of the first bonding material; Cutting the airtightly sealed bonded assembly into individual surface-mounted piezoelectric vibrating devices; and
A method for manufacturing a surface-mount type piezoelectric vibration device comprising:

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