Thin-plate thermistor and piezoelectric vibration device with thin-plate thermistor mounted thereon

Abstract

Provided is a thin-plate thermistor in which the resistance characteristics of the thin-plate thermistor are improved in consideration of the surface roughness of one surface and the other surface of a thermistor flat plate. The thin-plate thermistor (5) has: a single-plate thermistor flat plate (51) that includes a second main surface (51b) and a first main surface (51a) that is on the opposite side from the second main surface (51b) and that has a larger surface roughness than the second main surface (51b); a first divided electrode (53a) and a second divided electrode (53b), which are divided on the second main surface (51b) and are formed on the second main surface (51b); and a common electrode (52) formed on the first main surface (51a).

Description

Technical Field

[0001] The present invention relates to a thin plate thermistor used as a temperature sensor and a thin plate thermistor-mounted piezoelectric vibration device having the thin plate thermistor mounted thereon. Background Art

[0002] In recent years, as various electronic devices have become more accurate, there has been a demand for temperature-compensated piezoelectric vibration devices that compensate for frequency fluctuations caused by changes in ambient temperature. Among piezoelectric vibration devices, thermistor-mounted piezoelectric vibration devices that are equipped with a thermistor as a temperature sensor are widely used.

[0003] By measuring the ambient temperature of the piezoelectric vibrator device using a thermistor and transmitting the frequency information and temperature information to an externally mounted temperature compensation circuit, it is possible to obtain temperature-compensated frequency information and ensure the operation of the electronic device with high accuracy.

[0004] Such a thermistor-mounted piezoelectric vibration device has a structure in which a crystal resonator piece having an excitation electrode formed thereon is housed in a ceramic package, and a thermistor is mounted on the outside thereof to detect the ambient temperature surrounding the crystal resonator (see, for example, Patent Document 1).

[0005] The following thermistors are sold and used on the market. They have a stacked structure in which a plurality of thermistor material layers and an operating electrode are stacked in multiple layers, and the thickness thereof is about 0.3 mm to 0.1 mm.

[0006] Prior Art Literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2016-100737 Summary of the invention

[0009] Problems to be solved by the invention

[0010] In addition, thermistors are required to detect the temperature environment surrounding the crystal oscillator with a small time difference. However, thermistors used so far also have a stacked structure, which requires a certain thickness (height). In addition, the electrodes of the thermistors with a stacked structure are composed of thick film electrodes obtained by screen printing, etc., which is not suitable for thinning thermistors.

[0011] Therefore, it is considered that the thermistor is provided with a structure in which electrodes are formed on the surface of a single thermistor plate, instead of a laminated structure in which a plurality of thermistor material layers and an operating electrode are laminated multiple times, but the thermistor in which electrodes are formed on the surface of a single thermistor plate has not been put into practical use so far. In such a thermistor in which electrodes are formed on the surface of a single thermistor plate, a first split electrode and a second split electrode are formed on one surface of the thermistor plate, which are divided into two and serve as operating electrodes, respectively, and a common electrode is formed on the other surface (the surface opposite to the one surface) of the thermistor plate to serve as a relay electrode. In such a case, the first split electrode, the second split electrode and the common electrode are arranged in consideration of the surface roughness of the one surface and the other surface of the thermistor plate, thereby expecting an improvement in the resistance characteristics of the thermistor.

[0012] In view of the above problems, the present invention aims to provide a thin plate thermistor that achieves improved resistance characteristics of the thin plate thermistor by taking into account the surface roughness of one surface and other surfaces of the thermistor plate, and a thin plate thermistor-mounted piezoelectric vibration device mounted with the thin plate thermistor.

[0013] Means for solving problems

[0014] In order to achieve the above object, the present invention relates to a thin plate thermistor, characterized in that the thin plate thermistor comprises: a single-plate thermistor plate, which includes a surface and another surface on the opposite side of the one surface and having a surface roughness greater than that of the one surface; a first split electrode and a second split electrode formed on the one surface and split on the one surface; and a common electrode formed on the other surface.

[0015] According to this structure, the first split electrode and the second split electrode, which are the operating electrodes, are formed on one surface of the thermistor plate with a small surface roughness. Therefore, compared with the case where the first split electrode and the second split electrode, which are the operating electrodes, are formed on other surfaces with a large surface roughness, the area of ​​the first split electrode and the second split electrode is less likely to be uneven, and the unevenness of the resistance characteristics of the thin plate thermistor can be suppressed. In particular, in the thin plate thermistor, the resistance characteristics are determined by the area of ​​the first split electrode and the second split electrode facing the thermistor plate. Therefore, forming the first split electrode and the second split electrode, which have strict requirements on the area, on one surface with a small surface roughness is a structure that is beneficial to stabilizing the resistance characteristics of the thin plate thermistor.

[0016] In addition, by forming the first split electrode and the second split electrode on a surface with a small surface roughness, the first split electrode and the second split electrode are closely attached to the surface of the thermistor plate with high adhesion and stable conductivity. Therefore, when a measuring probe or the like is brought into contact with the first split electrode and the second split electrode, a stable connection can be made, and the resistance characteristics of the thin plate thermistor can be accurately measured.

[0017] Furthermore, by forming a common electrode that serves as a relay electrode on the other surface of the thermistor plate with a large surface roughness, the total amount of the conductor related to the common electrode increases by an amount corresponding to the increase in the surface area of ​​the portion forming the common electrode relative to the apparent area, thereby improving the conduction performance. The common electrode plays a role in not causing the thin plate thermistor to generate an unnecessary resistance value, and the conduction performance does not decrease by an amount corresponding to the increase in the surface area of ​​the common electrode, so the resistance value of the thin plate thermistor does not deteriorate. In particular, in a miniaturized thin plate thermistor, when the resistance value of the common electrode increases, it is difficult to satisfy the characteristics below the prescribed resistance value, but by forming the common electrode on the other surface of the thermistor plate with a large surface roughness, the characteristics below the prescribed resistance value can be satisfied.

[0018] Furthermore, the first divided electrodes, the second divided electrodes, and the common electrode may be PVD (Physical Vapor Deposition) films.

[0019] According to this structure, the electrodes (first divided electrodes, second divided electrodes, and common electrode) have a dense film structure, and can be provided with electrodes excellent in conductivity and adhesion to the thermistor plate. In addition, the electrodes can be formed so that the area of ​​the electrodes becomes a desired area, and as a result, the resistance characteristics of the thin plate thermistor can be stabilized. This is particularly effective for stabilizing the resistance characteristics of a miniaturized thin plate thermistor.

[0020] In addition, the present invention relates to a piezoelectric vibration device with a thin plate thermistor mounted thereon, characterized in that the piezoelectric vibration device with a thin plate thermistor mounted thereon has a piezoelectric vibration device and the thin plate thermistor, the piezoelectric vibration device comprising: a piezoelectric vibration plate having an excitation electrode composed of a plurality of metal film layers formed on its surface; a first sealing member bonded to a main surface of one side of the piezoelectric vibration plate; and a second sealing member bonded to a main surface of the other side of the piezoelectric vibration plate, the thin plate thermistor being bonded to the surface of the piezoelectric vibration device.

[0021] According to this configuration, by using a thin plate thermistor having excellent resistance characteristics, it is possible to improve the detection accuracy of the temperature of the piezoelectric vibration plate.

[0022] In addition, the present invention relates to another thin plate thermistor-mounted piezoelectric vibration device, characterized in that the thin plate thermistor-mounted piezoelectric vibration device comprises: a piezoelectric vibration plate having an excitation electrode composed of multiple metal film layers formed on the surface; the thin plate thermistor; and a package that accommodates the piezoelectric vibration plate and the thin plate thermistor.

[0023] According to this configuration, by using a thin plate thermistor having excellent resistance characteristics, it is possible to improve the detection accuracy of the temperature of the piezoelectric vibration plate.

[0024] Effects of the Invention

[0025] According to the present invention, the first split electrode and the second split electrode, which are to be the operating electrodes, are formed on one surface of the thermistor plate with a small surface roughness. Therefore, compared with the case where the first split electrode and the second split electrode, which are to be the operating electrodes, are formed on other surfaces with a large surface roughness, it is less likely to cause unevenness in the area of ​​the first split electrode and the second split electrode, and unevenness in the resistance characteristics of the thin plate thermistor can be suppressed. In particular, in the thin plate thermistor, the resistance characteristics are determined by the area of ​​the first split electrode and the second split electrode facing the thermistor plate. Therefore, forming the first split electrode and the second split electrode, which have strict requirements on the area, on one surface with a small surface roughness is a structure that is advantageous for stabilizing the resistance characteristics of the thin plate thermistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 (a) is a perspective view of a thin plate thermistor according to a first embodiment of the present invention. Figure 1 (b) is a BB cross-sectional view of the thin-plate thermistor in (a).

[0027] Figure 2 (a) means Figure 1 A plan view of the first main surface of a thin plate thermistor, Figure 2 (b) means Figure 1 A plan view of the second major surface of a thin plate thermistor.

[0028] Figure 3 It is used to illustrate Figure 1 A diagram showing a portion of the thin-plate thermistor manufacturing process (laser irradiation of the thermistor flat plate wafer).

[0029] Figure 4 It is a plan view of a thin plate thermistor mounting type piezoelectric vibration device according to a second embodiment of the present invention.

[0030] Figure 5 yes Figure 4 AA cross-sectional view of a thin-plate thermistor-mounted piezoelectric vibration device.

[0031] Figure 6 (a) means Figure 4 A plan view of a first principal surface of a piezoelectric vibration plate in a sandwich structure device, Figure 6 (b) means Figure 4 A plan view of the second principal surface of a piezoelectric vibration plate in a sandwich structure device.

[0032] Figure 7 (a) means Figure 4 A plan view of a first main surface of a first sealing member in a sandwich structure device, Figure 7 (b) means Figure 4 A plan view of the second main surface of the first sealing member in the sandwich structure device.

[0033] Figure 8 (a) means Figure 4 A plan view of a first main surface of a second sealing member in a sandwich structure device, Figure 8 (b) means Figure 4 A plan view of a second main surface of a second sealing member in a sandwich structure device.

[0034] Fig. 9 It is an exploded perspective view of a thin plate thermistor mounting type piezoelectric vibration device according to a third embodiment of the present invention.

[0035] Fig.10 Yes Assembly Fig. 9 Bottom view of a thin plate thermistor-mounted piezoelectric vibration device.

[0036] Fig.11 yes Fig.10 CC cross-sectional view of a thin-plate thermistor-mounted piezoelectric vibration device.

[0037] Fig.12 It is a cross-sectional view of a thin plate thermistor mounting type piezoelectric vibration device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0038] 《First Implementation Mode》

[0039] Below, refer to Figures 1 to 3 The thin plate thermistor according to the first embodiment of the present invention will be described in detail. Figures 1 to 3 , and the following instructions Figures 4 to 8 Each figure of FIG. 1 is illustrated using the same X-axis, Y-axis, and Z-axis.

[0040] First, refer to Figure 1 to Figure 2 The structure of the thin plate thermistor 5 will be described. Figure 1 (a) is a three-dimensional diagram of the thin plate thermistor 5, Figure 1(b) is Figure 1 (a) is a perspective view of the thin-plate thermistor 5 taken along the line BB. Figure 2 (a) is shown in Figure 1 A plan view of a first main surface 51a as one main surface of the thin plate thermistor 5 shown in FIG. Figure 2 (b) is shown in Figure 1 The second main surface 51b of the thin plate thermistor 5 shown in FIG. 1 is a plan view of the main surface (the other main surface) on the opposite side (back side) to the first main surface 51a. Figure 1 and Figure 2 In the figure, the electrodes (common electrode 52 and divided electrodes 53 ) are shaded, and the thermistor plate 51 is depicted without being shaded.

[0041] The thin plate thermistor 5 is a thinned NTC (Negative Temperature Coefficient) thermistor. The NTC thermistor is a type of thermistor whose resistance value decreases as the temperature rises.

[0042] Thin plate thermistor 5 Figure 1 As shown in (a) and (b), the thermistor plate 51 is composed of a single plate, a common electrode 52 formed on the first main surface 51a of the thermistor plate 51 and serving as a relay electrode, and a polarization electrode 53 formed by dividing the second main surface 51b of the thermistor plate 51 and serving as an operating electrode.

[0043] The thermistor plate 51 is thin and has a rectangular shape in a plan view. For example, a semiconductor ceramic plate containing manganese as a main component or a semiconductor ceramic plate containing manganese and nickel as main components is used as the thermistor plate 51 .

[0044] In the thermistor plate 51, the surface roughness of the first main surface 51a (the central part of the first main surface 51a) is greater than the surface roughness of the second main surface 51b. It should be noted that when comparing the surface roughness of the first main surface 51a with the surface roughness of the second main surface 51b, unless otherwise specified, the surface roughness of the central part of the main surface (the first main surface 51a, the second main surface 51b) forming most of the electrodes (the common electrode 52, the divided electrode 53) is compared. In addition, in the first main surface 51a of the thermistor plate 51, the surface roughness of the end is smaller than the surface roughness of the central part. In the order of the central part of the first main surface 51a, the second main surface 51b, and the end of the first main surface 51a, the surface roughness is from large to small (the surface roughness of the central part of the first main surface 51a>the surface roughness of the second main surface 51b>the surface roughness of the end of the first main surface 51a). In other words, the smoother surfaces (slippery surfaces) are arranged in order of the end of the first main surface 51 a , the second main surface 51 b , and the center of the first main surface 51 a .

[0045] In addition, a projection exists at least in a part of the end of the first main surface 51a of the thermistor plate 51. The projection is formed by a solidified portion 51D obtained by solidifying the thermistor plate 51 (thermistor plate wafer 51A serving as the basis of the thermistor plate 51) after melting, and the solidified portion 51D is a laser mark (see Figure 3 ).

[0046] The common electrode 52 is Figure 2 As shown in (a), the common electrode 52 is formed on the entire surface (or substantially the entire surface) of the first main surface 51a of the thermistor plate 51. The common electrode 52 is a metal thin film, which is a PVD (Physical Vapor Deposition) film-forming method such as sputtering or vacuum evaporation.

[0047] The segmented electrode 53 is as follows Figure 2 As shown in (b) of FIG. 5 , the thermistor flat plate 51 is divided and arranged at two locations at both ends with a certain interval in one direction along the second main surface 51b. It should be noted that, hereinafter, one of the divided electrodes 53 is sometimes referred to as the "first divided electrode 53a", and the other of the divided electrodes 53 is sometimes referred to as the "second divided electrode 53b". The divided electrodes 53 (the first divided electrode 53a, the second divided electrode 53b) are metal thin films, which are PVD films formed by PVD film forming methods such as sputtering or vacuum evaporation. By setting the common electrode 52 and the divided electrodes 53 (the first divided electrode 53a, the second divided electrode 53b) as PVD films, it is possible to manufacture an extremely thin-walled thin-plate thermistor 5.

[0048] The thin plate thermistor 5 is constituted of terminals as a resistor by the first split electrode 53a and the second polarized electrode 53b formed on the second main surface 51b of the thermistor flat plate 51. The conductive path of the thin plate thermistor 5 is a path from the split electrode of one of the first split electrode 53a and the second polarized electrode 53b to the split electrode of the other of the first split electrode 53a and the second polarized electrode 53b via the common electrode 52. With such a structure, the cross-sectional area of ​​the conductive path can be increased, and the conductive path can be set as a path in which the surfaces between the first polarized electrode 53a and the second split electrode 53b and the common electrode 52 are opposite to each other. Therefore, the resistance value can be reduced by electrodes (common electrode 52, first split electrode 53a, second split electrode 53b) with a small area, the resistance characteristics of the thin plate thermistor 5 are easily stabilized, and the withstand voltage performance of the thin plate thermistor 5 is improved.

[0049] However, when the thin plate thermistor 5 is configured such that the distance between the first split electrode 53a and the second split electrode 53b is small, although it also depends on the applied voltage, the path from the split electrode of one of the first polarizable electrode 53a and the second polarizable electrode 53b to the split electrode of the other of the first split electrode 53a and the second polarizable electrode 53b (this path is a path that does not pass through the common electrode 52) is dominant as a conductive path, and the desired resistance value may not be obtained. Therefore, if Figure 1 As shown in (b), when the distance between the first polarizable electrode 53a and the common electrode 52 is set to G2a, the distance between the second polarizable electrode 53b and the common electrode 52 is set to G2b, and the distance between the first polarizable electrode 53a and the second polarizable electrode 53b is set to G1, it is preferably set to satisfy G2a+G2b<G1. When set in this way, the desired resistance value can be obtained, and the accuracy of the temperature detected by the thin plate thermistor 5 can be stabilized.

[0050] In addition, the larger the contact area between the first split electrode 53a and the second split electrode 53b and the temperature detection object device, the more accurately the thin plate thermistor 5 can detect the temperature of the temperature detection object device. Therefore, it is better that the area of ​​the first split electrode 53a and the second split electrode 53b is large, but when the area is too large, a short circuit is likely to occur between the first split electrode 53a and the second split electrode 53b. On the other hand, when the contact area between the first split electrode 53a and the second split electrode 53b and the temperature detection object device is small, the accuracy of the temperature of the temperature detection object device detected by the thin plate thermistor 5 is reduced. Therefore, although it also depends on the desired resistance value, it is preferred that the total area of ​​the first split electrode 53a and the second split electrode 53b is set to be within the range of 40% to 85% of the area of ​​the second main surface 51b of the thermistor flat plate 51. When set in this way, the thin plate thermistor 5 can perform stable temperature detection. When the total area of ​​the first split electrode 53a and the second split electrode 53b is less than 40% of the area of ​​the second main surface 51b of the thermistor plate 51, the first split electrode 53a and the second split electrode 53b of the thin plate thermistor 5 are too small, and the resistance value of the thin plate thermistor 5 is too high, and the temperature of the temperature detection target device may not be accurately detected. In addition, when the total area of ​​the first split electrode 53a and the second split electrode 53b exceeds 85% of the area of ​​the second main surface 51b of the thermistor plate 51, a short circuit may occur between the first split electrode 53a and the second split electrode 53b, and the thermistor may not function as a thermistor.

[0051] Next, the manufacturing process of the thin plate thermistor 5 is described. In the manufacturing process of the thin plate thermistor 5, a material mainly composed of manganese or manganese and nickel (Mn-Fe-Ni-Ti material, Mn-Fe material, etc.) is made into a paste together with a binder, etc., and a wafer-state thermistor plate 51 is made on a green sheet using a film forming technique such as a screen printing technique or a doctor blade technique, and then the wafer 51A, which is the basis of the thermistor plate 51, is sintered by a sintering technique (sintering forming step). It should be noted that, hereinafter, the wafer 51A, which is the basis of the thermistor plate 51, may also be referred to as a "thermistor plate wafer 51A".

[0052] In the sintering step, the green sheet is placed on a sintering mount made of alumina (Al 2 O 3 ) and sintered. However, when the sintering temperature is higher than the melting point of manganese, manganese contained in the green sheet dissolves into the sintering mount. Therefore, when comparing the surface roughness of the first surface 51aA of the thermistor plate wafer 51A and the surface roughness of the second surface 51bA of the thermistor plate wafer 51A, manganese is dissolved on the first surface 51aA of the thermistor plate wafer 51A, so the surface roughness of the first surface 51aA is greater than the surface roughness of the second surface 51bA, the first surface 51aA being the surface of the thermistor plate wafer 51A that is in contact with the firing mount (the surface that becomes the first main surface 51a of the thermistor plate 51), and the second surface 51bA being the surface of the thermistor plate wafer 51A that is on the side opposite to the surface in contact with the firing mount (the back side) (the surface that becomes the second main surface 51b of the thermistor plate 51).

[0053] Following the sintering step, a break line forming step is performed. In this break line forming step, a break line (small groove) 51B is formed in the thermistor flat plate wafer 51A.

[0054] In the fracture line forming step, first, the thermistor flat wafer 51A is fractured from the first surface 51aA to the side. Figure 3 The dotted line in (a) is shown as Figure 3 As shown in (b), the irradiation area is small and the energy density (W / cm 2 ) The large laser LA1 forms a thin film on the first surface 51aA without penetrating the thermistor plate wafer 51A. Figure 3 After the fracture line 51B is formed by the first stage of laser irradiation, as shown in (c) of FIG. Figure 3 As shown in (c) of FIG. 5 , steep and tall burrs 51C are generated at both ends of the fracture line 51 b of the thermistor flat wafer 51A, and chips and the like are easily generated in the burrs 51C.

[0055] After the first stage of laser irradiation, in order to remove the burrs 51C generated by the first stage of laser irradiation, the thermistor flat wafer 51A is subjected to laser irradiation from the first surface 51aA side where the fracture line 51B is formed. Figure 3 The dotted line portion in (a) is shown in FIG. Figure 3 As shown in (d), the irradiation area is large and the energy density (W / cm 2) is a small laser LA2 (second-stage laser irradiation). When comparing the first-stage laser irradiation with the second-stage laser irradiation, the irradiation area in the second-stage laser irradiation is larger than that in the first-stage laser irradiation, and the energy density (W / cm2) in the second-stage laser irradiation is 2 ) is greater than the energy density (W / cm 2 ) is small. The flash 51C melts under the laser irradiation in the second stage, and the melted portion solidifies thereafter, thereby forming a solidified portion 51D as a laser mark. After the solidified portion 51D is formed, in each area (area that becomes one thermistor plate 51) surrounded by the fracture line 51B of the first surface 51aA of the thermistor plate wafer 51A, the surface roughness of the end portion is smaller than that of the central portion, and a plurality of protrusions (protrusions lower than the height of the flash 51C) are formed on at least a portion of the end portion, thereby ensuring a curved surface at the end portion.

[0056] Here, in the thermistor flat plate wafer 51A after the fracture line forming step, the surface roughness of the end of the area surrounded by the fracture line 51B in the first surface 51aA is the smallest, the surface roughness of the second surface 51bA is the second smallest, and the surface roughness of the central part of the area surrounded by the fracture line 51B in the first surface 51aA is the largest.

[0057] It should be noted that, in the fracture line forming step, between the first stage laser irradiation and the second stage laser irradiation, the thermistor flat plate wafer 51A may be irradiated from the first surface 51aA side where the fracture line 51B is formed. Figure 3 The portion of (a) depicted by the dotted line within the single-dot chain line is laser irradiated to make the depth of the fracture line 51B of the laser irradiated portion deeper or penetrate it (laser irradiation in the intermediate stage). In this way, it is possible to suppress the thin plate thermistor 5 from being damaged when the thermistor flat plate wafer 51 is broken along the fracture line 51B. When comparing the laser irradiation in the intermediate stage with the laser irradiation in the first stage and the laser irradiation in the second stage, for example, the irradiation area in the laser irradiation in the intermediate stage = the irradiation area in the laser irradiation in the first stage < the irradiation area in the laser irradiation in the second stage, and the value of the light intensity per unit area in the laser irradiation in the intermediate stage ≥ the energy density (W / cm 2 )>Energy density in the second stage of laser irradiation(W / cm 2 ).

[0058] The electrode forming step is performed after the fracture line forming step. In this electrode forming step, electrodes (common electrode 52, first split electrode 53a, second split electrode 53b) are formed on the thermistor plate wafer 51A. In the electrode forming step, an electrode film (metal film) is formed by sputtering on a predetermined area (area of ​​the first surface 51aA surrounded by the fracture line 51B) of the thermistor plate wafer 51A after the fracture line forming step, and the common electrode 52 is formed by patterning using a photolithography technique. An electrode film (metal film) is formed by sputtering on a predetermined area (area on the back side of the area of ​​the first surface 51aA surrounded by the fracture line 51B) of the thermistor plate wafer 51A after the fracture line forming step, and the first split electrode 53a and the second split electrode 53b are formed by patterning using a photolithography technique.

[0059] As a specific metal material for the common electrode 52, the first polarized electrode 53a, and the second polarized electrode 53b, for example, a laminated film structure is used, in which a Ti film is formed as a base layer, a NiTi film composed of an alloy of Ni and Ti is formed on the upper layer (intermediate layer), and an Au film is formed on the surface as a main layer (uppermost layer). In the case of a laminated film structure using a Ti film, a NiTi film, and an Au film, when the thin plate thermistor 5 is finally soldered to the mounting substrate, solder corrosion is not likely to occur and stable conductive bonding can be performed. It should be noted that a structure in which a TiO2 film is formed between the base layer (Ti film) and the intermediate layer (NiTi film) in the above-mentioned laminated film structure may also be used. In addition, the metal film structure between the first polarization electrode 53a and the second split electrode 53b and the common electrode 52 may be different. For example, the metal film structure of the first polarization electrode 53a and the second split electrode 53b may be set to a stacked film structure of a Ti film, a NiTi film and an Au film, or the film structure of the common electrode 52 may be set to a stacked film structure of a Ti film and an Au film.

[0060] Furthermore, in the above-mentioned electrode film structure, a Cr film or a Ti film may be formed as a base layer and a stacked film structure such as an Au film, an Ag film, or a Pt film may be formed as an upper layer, or a film structure using only a Cu film may be formed. It should be noted that in the case of using a base layer of a Cr film or a Ti film and a stacked film structure of an Au film, an Ag film, or a Pt film, or a single-layer film structure of a Cu film, bonding can be performed using a conductive resin adhesive.

[0061] After the electrode forming step, the thermistor flat plate wafer 51A on which the common electrode 52, the first divided electrode 53a, and the second divided electrode 53b are formed is broken along the breaking line 51B (breaking step). Thus, the thin plate thermistor 5 on which the common electrode 52, the first divided electrode 53a, and the second divided electrode 53b are formed is divided into individual pieces, and the thin plate thermistor 5 is completed.

[0062] According to the above-mentioned thin plate thermistor 5, the surface roughness of the end portion of the first main surface 51a of the thermistor plate 51 is smaller than that of the central portion, so that it is difficult to generate a fracture or a notch on the first main surface 51a side of the end portion of the thermistor plate 51, and as a result, the mechanical strength of the thin plate thermistor 5 can be improved. In addition, on the first main surface 51a of the thermistor plate 51, there is a protrusion at least in a part of the end portion, so it is difficult to generate a fracture or a notch on the first main surface 51a side of the end portion of the thermistor plate 51, and as a result, the mechanical strength of the thin plate thermistor 5 can be improved.

[0063] In addition, by providing the solidified portion 51D at the end of the first main surface 51a of the thermistor plate 51, the surface state of the end of the first main surface 51a of the thermistor plate 51 can be smoothed to ensure a curved surface, thereby making it difficult to generate a crack or a notch on the first main surface 51a side of the end of the thermistor plate 51, and as a result, the mechanical strength of the thin plate thermistor 5 can be improved. In addition, by making the solidified portion 51D a laser mark, a curved surface at the solidified portion 51D can be easily formed.

[0064] In addition, since the first split electrode 53a and the second split electrode 53b, which are the operating electrodes, are formed on the second main surface 51b, which has a small surface roughness, of the thermistor plate 51, the area formed by the first split electrode 53a and the second split electrode 53b is less likely to vary compared to the case where the first split electrode 53a and the second split electrode 53b, which are the operating electrodes, are formed on the first main surface 51a, which has a large surface roughness, and the variation in the resistance characteristics of the thin plate thermistor 5 can be suppressed. In particular, in the thin plate thermistor 5, the resistance characteristics are determined by the area of ​​the first split electrode 53a and the second split electrode 53b facing the thermistor plate 51, and therefore, forming the first split electrode 53a and the second split electrode 53b, which have strict requirements on the area, on the second main surface 51b, which has a small surface roughness, is a structure that is advantageous for stabilizing the resistance characteristics of the thin plate thermistor 5.

[0065] In addition, by forming the first split electrode 53a and the second split electrode 53b on the second main surface 51b having a small surface roughness of the thermistor flat plate 51, the first split electrode 53a and the second split electrode 53b have high adhesion to the second main surface 51b of the thermistor flat plate 5 and stable conductivity, so that when a measuring probe or the like is brought into contact with the first split electrode 53a and the second split electrode 53b, a stable connection can be made, and the resistance characteristics of the thin plate thermistor 5 can be accurately measured.

[0066] In addition, by forming the common electrode 52 as a relay electrode on the first main surface 51a of the thermistor flat plate 51 having a large surface roughness, the total amount of the conductor related to the common electrode 52 increases by an amount corresponding to the increase in the surface area of ​​the portion where the common electrode 52 is formed relative to the apparent area, thereby improving the conduction performance. The common electrode 52 plays a role in preventing the thin plate thermistor 5 from generating an unnecessary resistance value, and the conduction performance does not decrease by an amount corresponding to the increase in the surface area of ​​the common electrode 52, so the resistance value of the thin plate thermistor 5 does not deteriorate. In particular, in the miniaturized thin plate thermistor 5, when the resistance value of the common electrode 52 increases, it is difficult to satisfy the characteristics below the prescribed resistance value, but by forming the common electrode 52 on the first main surface 51a of the thermistor flat plate 5 having a large surface roughness, the characteristics below the prescribed resistance value can be satisfied.

[0067] In addition, the PVD film of the first divided electrode 53a, the second divided electrode 53b, and the common electrode 52 is formed by a PVD film forming method such as sputtering or vacuum evaporation, so that the first divided electrode 53a, the second divided electrode 53b, and the common electrode 52 have a dense film structure, and can be excellent in conductivity and adhesion to the thermistor plate 5. In addition, the electrode can be formed so that the area of ​​the electrode becomes a desired area, and as a result, the resistance characteristics of the thin plate thermistor 5 can be stabilized. In particular, it is effective for stabilizing the resistance characteristics of the miniaturized thin plate thermistor 5.

[0068] Second Implementation Method

[0069] Below, refer to Figures 4 to 8 A thin plate thermistor-mounted piezoelectric vibration device according to a second embodiment of the present invention will be described in detail.

[0070] Figure 4 It is a plan view of the thin plate thermistor mounting type piezoelectric vibration device 1 . Figure 5 yes Figure 4 FIG. 2 shows a cross-sectional view of the device 1 taken along the line AA in the plan view. Figure 4 and Figure 5As shown, a piezoelectric vibration device (hereinafter sometimes referred to as a "sandwich structure device") 2 having a sandwich structure and the above-mentioned thin plate thermistor 5 mounted on the sandwich structure device 2 is shown. It should be noted that the "thin plate thermistor mounted piezoelectric vibration device 1" may be simply referred to as "device 1" hereinafter. In the device 1, for example, the thickness of the sandwich structure device 2 is about 120μm, while the thickness of the thin plate thermistor 5 can be set to less than half of the sandwich structure device 2 (about 50μm).

[0071] Sandwich structure device 2 such as Figure 5 As shown, the piezoelectric diaphragm 10, the first sealing member 20 and the second sealing member 30 are provided. In the sandwich device 2, the piezoelectric diaphragm 10 is bonded to the first sealing member 20, and the piezoelectric diaphragm 10 is bonded to the second sealing member 30, thereby forming a substantially rectangular parallelepiped sandwich structure package.

[0072] Figure 6 (a) is a plan view showing the first principal surface 11 which is one principal surface (a bonding surface to be bonded to the first sealing member 20 ) of the single-body piezoelectric vibration plate 10 before bonding. Figure 6 (b) is a plan view showing the second principal surface 12 as the other principal surface (joining surface joined to the second sealing member 30) in the single piezoelectric vibration plate 10 before bonding. The piezoelectric vibration plate 10 is a piezoelectric substrate made of a piezoelectric material such as quartz crystal, and its two principal surfaces (first principal surface 11 and second principal surface 12) are formed into flat and smooth surfaces (mirror finish). In this embodiment, an AT-cut quartz crystal plate that performs thickness shear vibration is used as the piezoelectric vibration plate 10.

[0073] It should be noted that Figures 4 to 8 In the figures, in the piezoelectric vibration plate 10, the two main surfaces of the piezoelectric vibration plate 10 become XZ planes, the direction parallel to the short side direction becomes the X-axis direction, the direction parallel to the long side direction becomes the Z-axis direction, and the direction perpendicular to the XZ plane becomes the Y-axis direction.

[0074] The piezoelectric vibration plate 10 includes a vibration portion 13 formed in a substantially rectangular shape, an outer frame portion 14 surrounding the outer periphery of the vibration portion 13, and a holding portion 15 holding the vibration portion 13 by connecting the vibration portion 13 and the outer frame portion 14. It should be noted that the space between the vibration portion 13 and the outer frame portion 14 is a cutout portion (an opening portion penetrating the piezoelectric vibration plate 10 in the thickness direction) except for the portion where the holding portion 15 is formed. Thus, the piezoelectric vibration plate 10 has a structure in which the vibration portion 13, the outer frame portion 14, and the holding portion 15 are integrally provided. A pair of excitation electrodes (a first excitation electrode 111 on the first principal surface 11 side and a second excitation electrode 121 on the second principal surface 12 side) are formed on the first principal surface 11 and the second principal surface 12 of the piezoelectric vibration plate 10.

[0075] In the present embodiment, the holding portion 15 is provided at only one place between the vibration portion 13 and the outer frame portion 14. In addition, the vibration portion 13 and the holding portion 15 are formed to be thinner than the outer frame portion 14. Due to the difference in thickness between the outer frame portion 14 and the holding portion 15, the natural frequencies of the piezoelectric vibrations of the outer frame portion 14 and the holding portion 15 are different, and the piezoelectric vibrations are not propagated to the outer frame portion 14. It should be noted that the formation position of the holding portion 15 is not limited to one place, and the holding portion 15 may also be provided at two places between the vibration portion 13 and the outer frame portion 14.

[0076] The first excitation electrode 111 is provided on the first principal surface 11 side of the vibration portion 13, and the second excitation electrode 121 is provided on the second principal surface 12 side of the vibration portion 13. The first excitation electrode 111 and the second excitation electrode 121 are each connected to an extraction electrode (extraction wiring electrode film) for connecting these excitation electrodes to an external electrode terminal (a first extraction electrode 112 on the first principal surface 11 side, and a second extraction electrode 122 on the second principal surface 12 side). The first extraction electrode 112 is extracted from the first excitation electrode 111 and connected to a connection bonding pattern 114 formed on the outer frame portion 14 via the holding portion 15. The second extraction electrode 122 is extracted from the second excitation electrode 121 and connected to a connection bonding pattern 124 formed on the outer frame portion 14 via the holding portion 15.

[0077] The first main surface 11 and the second main surface 12 of the piezoelectric vibration plate 10 are respectively formed with bonding patterns for bonding the piezoelectric vibration plate 10 to the first sealing member 20 and the second sealing member 30. The bonding patterns include a sealing pattern for airtightly sealing the internal space of the package and a conductive pattern for conducting wiring and electrodes. Figure 6 (a), (b), Figure 7 (b) and Figure 8 In (a), the bonding region forming the bonding pattern is shown by hatching with oblique lines.

[0078] As sealing patterns in the piezoelectric vibration plate 10, a first vibration side bonding pattern 113 is formed on the first main surface 11, and a second vibration side bonding pattern 123 is formed on the second main surface 12. The first vibration side bonding pattern 113 and the second vibration side bonding pattern 123 are provided on the outer frame portion 14, and are formed in a ring shape when viewed from a plane. The area inside the first vibration side bonding pattern 113 and the second vibration side bonding pattern 123 becomes a sealing area of ​​the vibration portion 13 (an area that becomes the internal space of the package after bonding). The first excitation electrode 111 and the second excitation electrode 121 are not electrically connected to the first vibration side bonding pattern 113 and the second vibration side bonding pattern 123.

[0079] As the conductive pattern in the piezoelectric diaphragm 10, four connection bonding patterns 115 are formed outside the sealing region (outside the vibration side first bonding pattern 113) in the first main surface 11, and connection bonding patterns 114 and 116 are formed in the sealing region (inside the vibration side first bonding pattern 113). In addition, four connection bonding patterns 125 are formed outside the sealing region (outside the vibration side second bonding pattern 123) in the second main surface 12, and a connection bonding pattern 124 is formed in the sealing region (inside the vibration side second bonding pattern 123). The connection bonding patterns 115 on the first main surface 11 side and the connection bonding patterns 125 on the second main surface 12 side are respectively provided in the regions near the four corners (corners) of the outer frame portion 14.

[0080] In addition, in the piezoelectric vibration plate 10, a plurality of through holes 16 are formed between the first main surface 11 and the second main surface 12, and a through electrode for achieving conduction between the first main surface 11 and the second main surface 12 is formed on the inner wall surface of each through hole 16. Specifically, four through holes 16 and through electrodes are formed to achieve conduction between the connection bonding pattern 115 and the connection bonding pattern 125, and one through hole 16 and through electrode are formed to achieve conduction between the connection bonding pattern 116 and the connection bonding pattern 124.

[0081] In the piezoelectric vibration plate 10, the first excitation electrode 111, the second excitation electrode 121, the first extraction electrode 112, the second extraction electrode 122, the vibration side first bonding pattern 113, the vibration side second bonding pattern 123, and the connection bonding patterns 114 to 116, 124, 125 can be formed by the same process. Specifically, it can be formed by a base layer (Ti film) formed by physical vapor growth on both main surfaces (the first main surface 11 and the second main surface 12) of the piezoelectric vibration plate 10, and a bonding film (Au film) formed by physical vapor growth on the base layer. In addition, the structure of the stacked film forming the bonding pattern is not limited to a two-layer structure of a Ti film and an Au film, and can also be a structure of three or more layers including other films (for example, a barrier film formed between the Ti film and the Au film).

[0082] Figure 7 (a) is a plan view showing the first main surface 21 which is one main surface (outer surface) of the single-body first sealing member 20 before bonding. Figure 7 (b) is a plan view showing the second principal surface 22 as the other principal surface (joining surface to the piezoelectric vibration plate 10) of the first sealing member 20 of the single body before joining. The first sealing member 20 is a rectangular substrate formed of a single glass wafer or a quartz crystal wafer, and the second principal surface 22 of the first sealing member 20 is formed into a flat and smooth surface (mirror finish).

[0083] On the first main surface 21 of the first sealing member 20, Figure 7 As shown in (a) of FIG. 1 , two electrode patterns 211 and wiring patterns 212 and 213 are formed. The electrode pattern 211 is a mounting pad for mounting the thin plate thermistor 5 (see FIG. 1 ). Figure 4 ). The wiring pattern 212 is used to connect the second excitation electrode 121 to the external electrode terminal 321 (see Figure 8 The wiring pattern 213 is a wiring pattern that is a part of the wiring path that connects the first excitation electrode 111 to the external electrode terminal 321 .

[0084] On the second main surface 22 of the first sealing member 20, Figure 7 As shown in (b), a bonding pattern for bonding the first sealing member 20 to the piezoelectric vibration plate 10 is formed. The bonding pattern includes a sealing pattern for airtightly sealing the internal space of the package and a conducting pattern for conducting wiring and electrodes.

[0085] As a sealing pattern in the first sealing member 20, a sealing side first bonding pattern 221 is formed. The sealing side first bonding pattern 221 is formed in a ring shape when viewed from a plane, and the area inside it becomes a sealing area. As a conductive pattern in the first sealing member 20, four connecting bonding patterns 222 are formed near the four corners (corners) outside the sealing area (outside the sealing side first bonding pattern 221), and connecting bonding patterns 223 to 225 are formed in the sealing area (inside the sealing side first bonding pattern 221). It should be noted that the connecting bonding pattern 224 is connected to the connecting bonding pattern 225 through a wiring pattern 226.

[0086] In addition, in the first sealing member 20, a plurality of through holes 23 are formed between the first main surface 21 and the second main surface 22, and a through electrode for achieving conduction between the first main surface 21 and the second main surface 22 is formed on the inner wall surface of each through hole 23. Specifically, four through holes 23 and through electrodes are formed to achieve conduction between the electrode pattern 211 or the wiring patterns 212, 213 and the connection bonding pattern 222, one through hole 23 and through electrode are formed to achieve conduction between the wiring pattern 212 and the connection bonding pattern 223, and one through hole 23 and through electrode are formed to achieve conduction between the wiring pattern 213 and the connection bonding pattern 225.

[0087] In the first sealing member 20, the sealing side first bonding pattern 221, the connection bonding patterns 222 to 225, and the wiring pattern 226 can be formed by the same process. Specifically, they can be formed by a base layer (Ti film) formed by physical vapor phase growth on the second main surface 22 of the first sealing member 20, and a bonding film (Au film) formed by physical vapor phase growth and stacking on the base layer.

[0088] Figure 8 (a) is a plan view showing the first principal surface 31 which is one principal surface (a bonding surface to be bonded to the piezoelectric vibration plate 10 ) of the second sealing member 30 which is a single body before bonding. Figure 8 (b) is a plan view showing the second principal surface 32 as the other principal surface (outer surface) of the second sealing member 30 of the single body before bonding. The second sealing member 30 is a rectangular parallelepiped substrate formed of a glass wafer or a quartz crystal wafer, and the first principal surface 31 of the second sealing member 30 is formed into a flat and smooth surface (mirror finish).

[0089] On the first main surface 31 of the second sealing member 30, Figure 8 As shown in (a) of FIG. 1 , a bonding pattern for bonding the second sealing member 30 to the piezoelectric vibration plate 10 is formed. The bonding pattern includes a sealing pattern for airtightly sealing the internal space of the package and a conducting pattern for conducting wiring and electrodes.

[0090] As a sealing pattern in the second sealing member 30, a sealing side second bonding pattern 311 is formed. The sealing side second bonding pattern 311 is formed in a ring shape when viewed in a plan view, and the area inside it becomes a sealing area. As a conductive pattern in the second sealing member 30, four connecting bonding patterns 312 are formed near the four corners (corners) outside the sealing area (outside the sealing side second bonding pattern 311).

[0091] On the second main surface 32 of the second sealing member 30, Figure 8 As shown in (b) of FIG. 1 , four external electrode terminals 321 are provided to electrically connect the device 1 to the outside. The external electrode terminals 321 are located at four corners (corners) of the second sealing member 30 .

[0092] In addition, in the second sealing member 30, a plurality of through holes 33 are formed between the first main surface 31 and the second main surface 32, and a through electrode for achieving conduction between the first main surface 31 and the second main surface 32 is formed on the inner wall surface of each through hole 33. Specifically, four through holes 33 and through electrodes are formed to achieve conduction between the connection bonding pattern 312 and the external electrode terminal 321.

[0093] In the second sealing member 30, the sealing side second bonding pattern 311 and the bonding bonding pattern 312 can be formed by the same process. Specifically, they can be formed by a base layer (Ti film) formed by physical vapor phase growth on the first main surface 31 of the second sealing member 30, and a bonding film (Au film) formed by physical vapor phase growth and stacking on the base layer.

[0094] In the sandwich structure device 2, the piezoelectric vibration plate 10 and the first sealing member 20 are diffusion-bonded in a state where the first vibration side bonding pattern 113 and the first sealing side bonding pattern 221 as sealing patterns are overlapped, and the piezoelectric vibration plate 10 and the second sealing member 30 are diffusion-bonded in a state where the second vibration side bonding pattern 123 and the second sealing side bonding pattern 311 as sealing patterns are overlapped, thereby manufacturing a sandwich structure package. That is, the first vibration side bonding pattern 113 and the first sealing side bonding pattern 221 are bonded to form a sealing pattern layer between the piezoelectric vibration plate 10 and the first sealing member 20, and the second vibration side bonding pattern 123 and the second sealing side bonding pattern 311 are bonded to form a sealing pattern layer between the piezoelectric vibration plate 10 and the second sealing member 30. As a result, the internal space of the package, that is, the storage space of the vibration plate 13, is hermetically sealed.

[0095] At this time, the connecting bonding patterns as the conductive patterns are also bonded to each other, and the bonded conductive patterns form a conductive pattern layer between the piezoelectric diaphragm 10 and the first sealing member 20 or between the piezoelectric diaphragm 10 and the second sealing member 30. In the sandwich structure device 2, the first excitation electrode 111 and the second excitation electrode 121 are connected to Figure 8 The external electrode terminals 321 at the lower right and upper left of (b) are electrically connected to each other.

[0096] The thin plate thermistor 5 is mounted on the sandwich structure device 2 by setting the second main surface 51b on which the split electrodes 53 are formed as the lower surface (the bonding surface to the sandwich structure device 2), and the split electrodes 53 are electrically bonded to the electrode pattern 211 of the first sealing member 20. In addition, the thin plate thermistor 5 mounted on the sandwich structure device 2 can be connected to the Figure 8 The upper right and lower left external electrode terminals 321 of (b) are electrically connected.

[0097] As described above, the thin plate thermistor 5 has a wide area of ​​metal electrodes (common electrode 52, divided electrodes 53), and can play a role as a shield member for the sandwich structure device 2 in an advantageous position. Since the thin plate thermistor 5 is also used as a shield member, the thin plate thermistor 5 is arranged in the sandwich structure device 2 in a manner that at least a part of the thin plate thermistor 5 overlaps with the vibration part 13 of the sandwich structure device 2 when the device 1 is viewed from above (see FIG. 1 ). Figure 4). In addition, it is more preferable that the thin plate thermistor 5 is arranged so as to overlap the entire first excitation electrode 111 and the second excitation electrode 121 in a planar view, because the shielding effect of the thin plate thermistor 5 can be maximized.

[0098] In addition, the thin plate thermistor 5 is arranged in the sandwich structure device 2 at least at two mutually opposing sides of the sandwich structure device 2 in such a manner that both ends of the thin plate thermistor 5 overlap the outer frame portion 14. The first sealing member 20 and the second sealing member 30 in the sandwich structure device 2 are extremely thin substrates and use brittle materials such as glass and quartz crystal. Therefore, the strength of the central part of the sandwich structure device 2 (the region where the outer frame portion 14 does not exist in the piezoelectric vibration plate 10) is particularly low. In such a sandwich structure device 2, when the thin plate thermistor 5 is arranged in the region of the central part of the sandwich structure device 2, there is a possibility that the first sealing member 20 will be broken due to the pressing force when the thin plate thermistor 5 is mounted. In contrast, by bonding the thin plate thermistor 5 to the outer peripheral part of the sandwich structure device 2 (the region where the outer frame portion 14 exists in the piezoelectric vibration plate 10), that is, by arranging the thin plate thermistor 5 in such a manner that the end of the thin plate thermistor 5 overlaps the outer frame portion 14, it is possible to suppress the breakage of the first sealing member 20 and ensure the strength of the device 1. In particular, the thin plate thermistor 5 is overlapped with the sealing portion (sealing pattern such as the vibration side first bonding pattern 113) of the sandwich structure device 2, so that the strength of the device 1 is stabilized. Figure 4 and Figure 5 , an example is shown in which both ends of the thin plate thermistor 5 are arranged to overlap with the outer frame 14 at two sides opposite to each other in the short side direction of the sandwich structure device 2, but the thin plate thermistor 5 may also overlap with the outer frame 14 at two sides opposite to each other in the long side direction of the sandwich structure device 2. In addition, the thin plate thermistor 5 may be arranged to overlap not only the two sides opposite to each other of the sandwich structure device 2, but also three or four sides.

[0099] The segmented electrodes 53 and the electrode pattern 211 are bonded to each other by a conductive resin adhesive 61 (see Figure 5 ) and can be electrically connected. However, this is not limited to this, and the split electrode 53 and the electrode pattern 211 can also be connected by Au (gold) bumps. In addition, the gap between the thin plate thermistor 5 and the sandwich structure device 2 (the gap without the conductive resin adhesive 61) is filled with a non-conductive resin adhesive 62 (see Figure 5 ). The non-conductive resin adhesive 62 may be a sealing resin that not only fills the lower surface of the thin plate thermistor 5 but also seals the entire thin plate thermistor 5. It should be noted that a silicone-based resin can be used as the conductive resin adhesive 61, and an epoxy-based resin can be used as the non-conductive resin adhesive 62.

[0100] In this way, when the thin plate thermistor 5 is surface-bonded to the sandwich structure device 2 by the conductive resin adhesive 61 and the non-conductive resin adhesive 62, the thermal conductivity between the thin plate thermistor 5 and the sandwich structure device 2 can be improved. As a result, the thin plate thermistor 5 can be kept at a temperature close to that of the vibration part 13 of the sandwich structure device 2. In addition, regarding the surface bonding between the sandwich structure device 2 and the thin plate thermistor 5, there is also an advantage that the strength of the device 1 can be improved.

[0101] When the conductive resin adhesive 61 and the non-conductive resin adhesive 62 are used for bonding the thin plate thermistor 5, it is preferred that the thermal conductivity of the conductive resin adhesive 61 is higher than that of the non-conductive resin adhesive 62. Thus, the thermal conductivity between the thin plate thermistor 5 and the sandwich structure device 2 can be further improved. In addition, it is preferred that the thin plate thermistor 5 is surface-bonded to the first main surface 21 of the first sealing member 20 through the conductive resin adhesive 61 and the non-conductive resin adhesive 62 with more than half (50% to 100%) of the area of ​​the thin plate thermistor 5 when viewed in a plane. Thus, the heat conduction between the thin plate thermistor 5 and the sandwich structure device 2 can be sufficiently ensured, and the accuracy of the temperature of the sandwich structure device 2 detected by the thin plate thermistor 5 can be sufficient. In addition, it is preferred that the hardness of the non-conductive resin adhesive 62 is higher than that of the conductive resin adhesive 61. This can alleviate stress between the thin plate thermistor 5 and the sandwich structure device 2 and improve the package strength of the device 1 .

[0102] According to the thin plate thermistor mounted piezoelectric vibration device 1 described above, the end of the thermistor flat plate 51 is not prone to fracture or chipping, and the thin plate thermistor 5 of the first embodiment having excellent resistance characteristics can achieve improved temperature detection accuracy. In particular, the thin plate thermistor 5 is mechanically and electrically bonded to the sandwich structure device 2 at the second main surface 51b having a small surface roughness, so that the first main surface 51a of the thin plate thermistor 5 is arranged in a manner that it becomes the surface on the opposite side of the surface facing the sandwich structure device 2 (piezoelectric vibration plate 10), and at least a solidified portion 51D (curved surface) is arranged on the outer surface of the thin plate thermistor 5, thereby becoming the surface side that is not prone to fracture or chipping at the end of the thin plate thermistor 5, and thus it can be expected that the mechanical strength can be improved.

[0103] 《Third Implementation Mode》

[0104] Below, refer to Figures 9 to 11 A thin plate thermistor-mounted piezoelectric vibration device according to a third embodiment of the present invention will be described in detail. Fig. 9 This is an exploded perspective view of a thin-plate thermistor-mounted piezoelectric vibration device XcX. Fig.10 is Fig. 9 1 is a bottom view of a thin plate thermistor mounting type piezoelectric vibration device XcX in an exploded perspective view. Fig.11 yes Fig.10 CC cross-sectional view of a thin-plate thermistor-mounted piezoelectric vibration device XcX.

[0105] Thin plate thermistor mounted piezoelectric vibration device XcX Figures 9 to 11 As shown, the device includes a package 1X having an upper housing portion 11AX and a lower housing portion 11BX, a piezoelectric vibration plate 2X housed in the upper housing portion 11AX, the above-mentioned thin plate thermistor 5 housed in the lower housing portion 11BX, and a cover 3X for airtightly sealing the upper housing portion 11A.

[0106] The package 1X is made of ceramic and has a rectangular parallelepiped shape as a whole, and has an upper housing portion 11AX opened at the top and a lower housing portion 11BX opened at the bottom. The upper housing portion 11AX and the lower housing portion 11BX are structured such that the closed portions (bottom portions) are back-to-back with respect to the substrate 11CX.

[0107] The upper storage part 11AX is a concave rectangular storage structure with an opening at the top, and mounting electrodes 16X and 17X made of a metal film are formed at the bottom of the upper storage part 11AX. The mounting electrodes 16X and 17X are arranged in a direction along the short side of the package 1X. A rectangular sealing part 10X is provided at a position higher than the bottom on the outer periphery of the upper storage part 11AX, and a metal film layer is formed on the sealing part 10X.

[0108] The carrying electrodes 16X and 17X are composed of multiple metal films and are stacked in the order of W (tungsten) layer, Ni (nickel) layer, and Au (gold) layer. The W layer is formed integrally with the ceramic material constituting the package body by firing, and the Ni layer and the Au layer are formed on the W layer by electroplating. The sealing part 10X also has the same metal layer structure as the carrying electrodes 16X and 17X and has a stacked structure in which the W layer, the Ni layer, and the Au layer are stacked in the order. It should be noted that the carrying electrodes 18X, 19X and the installed electrodes 12X, 13X, 14X, and 15X described later are also manufactured by the same manufacturing method, and they respectively have a stacked structure in which the W layer, the Ni layer, and the Au layer are stacked in the order.

[0109] The lower storage part 11BX is a concave rectangular storage structure with an opening at the bottom, and the mounting electrodes 18X and 19X made of a metal film are formed at the bottom of the lower storage part 11BX. The mounting electrodes 18X and 19X are rectangular in shape with long sides and short sides, and are formed in a manner such that the long side of the mounting electrode 18X and the long side of the mounting electrode 19X are opposite to each other in the direction along the long side of the package 1X. It should be noted that the mounting electrodes 18X and 19X may also be formed in a manner such that they are arranged in the direction along the short side of the package 1X.

[0110] The four corners of the lower storage portion 11BX are provided with mounting electrodes 12X, 13X, 14X, and 15X at a position higher than the bottom. The mounting electrodes 12X, 13X, 14X, and 15X are each rectangular in shape, and the mounting electrodes 12X and 14X are electrically connected to the mounting electrodes 16X and 17X through internal wiring in the package 1X, and the mounting electrodes 13X and 15X are electrically connected to the mounting electrodes 18X and 19X through internal wiring in the package 1X.

[0111] An AT-cut quartz crystal plate is used in the piezoelectric vibration plate 2X, and the piezoelectric vibration plate 2X is a rectangular plate as a whole. The piezoelectric vibration plate 2X has excitation electrodes 21X and 22X formed on the surface and the central part of the inner side thereof, and the excitation electrodes 21X and 22X are led out to the outer peripheral part of the piezoelectric vibration plate 2X through the wide band-shaped lead-out electrodes 21aX and 22aX. The excitation electrodes 21X and 22X are rectangular in shape, and the excitation electrode 21X is led out from one short side corner of the main surface of one of the piezoelectric vibration plate 2X through the lead-out electrode 21aX to the end of the main surface of one of the piezoelectric vibration plate 2X, and the excitation electrode 22X is led out from one short side corner of the main surface of the other of the piezoelectric vibration plate 2X through the lead-out electrode 22aX to the end of the main surface of the other of the piezoelectric vibration plate 2X. Thus, the excitation electrodes 21X and 22X are led out to the short side of one of the piezoelectric vibration plate 2X.

[0112] The excitation electrodes 21X, 22X and the extraction electrodes 21aX, 22aX are structures of metal films formed by stacking thin films, and have a stacked structure in which a Ti (titanium) layer is formed in contact with the piezoelectric vibration plate 2X and an Au (gold) layer is formed on the upper part. It should be noted that the metal film structure may also be a structure other than the above structure, for example, a well-known metal film structure in which the base metal is set as a Cr (chromium) layer and the upper layer is set as an Ag (silver) layer can be used. The excitation electrodes 21X, 22X and the extraction electrodes 21aX, 22aX can be formed as a PVD film by a PVD film forming method such as sputtering or vacuum evaporation.

[0113] The thin plate thermistor 5 has the second main surface 51 b on which the split electrodes 53 are formed as the upper surface (joining surface with the package 1X), and the split electrodes 53 (first and second split electrodes 53 a , 53 b ) are electrically joined to the mounting electrodes 18X, 19X at the bottom of the lower housing portion 11BX and mounted in the package 1X.

[0114] The cover 3X is made of a thin metal plate or a ceramic plate and has a rectangular shape corresponding to the outer dimensions of the sealing portion 10X of the package 1X. It should be noted that the structures of the cover 3X and the sealing portion 10X are different depending on the airtight sealing method of the package 1X. For example, in the case where the cover 3X and the sealing portion 10X are joined by seam welding, the cover 3X adopts a structure in which a core material is made of kovar alloy and a Ni-plated film is formed on its surface. In addition, a structure in which a ring-shaped metal frame is welded is used for the sealing portion 10X, for example, the cover 3X is joined to the metal frame (sealing portion 10X) by seam welding in a vacuum atmosphere or an inert gas atmosphere. As a result, the interior of the package 1X (the interior of the upper storage portion 11AX) can be set to a stable state of a vacuum atmosphere or an inert gas atmosphere.

[0115] When airtight sealing is performed by welding using metal solder such as AuSu solder, for example, AuSu solder is pre-formed in a circumferential shape on the cover 3X, and Au electroplating is pre-performed on the upper layer of the sealing part 10X, and both are heated under a specified atmosphere and temperature environment, thereby enabling airtight sealing based on metal welding.

[0116] A paste-like conductive resin adhesive S1 is applied to the mounting electrodes 16X and 17X of the upper storage part 11AX of the package 1X by a dispenser or the like. The conductive resin adhesive S1 is composed of, for example, a silicone resin adhesive containing a metal filler, but other resin materials such as a polyimide-based resin material may also be used. The piezoelectric vibration plate 2X on which electrodes are formed is mounted on the applied conductive resin adhesive S1. Specifically, the piezoelectric vibration plate 2X is mounted on the upper storage part 11AX in such a manner that the lead-out electrodes 21aX and 22aX are partially bonded to the conductive resin adhesive S1. Then, the conductive resin adhesive S1 is cured by heating to conductively bond the piezoelectric vibration plate 2X to the mounting electrodes 16X and 17X (mechanically electrically bonded). It should be noted that the conductive resin adhesive S1 may be applied again from above the piezoelectric vibration plate 2X as needed. An example of a structure in which the electrodes are applied again is shown in this embodiment.

[0117] The upper housing portion 11AX is hermetically sealed by the cover 3X, and the cover 3X is hermetically sealed by joining the sealing portion 10X. In the present embodiment, metal solder sealing is performed by metal solder S2, and the metal solder S2 is, for example, AuSu solder.

[0118] The thin plate thermistor 5 is conductively bonded to the lower storage portion 11BX of the package 1X. A conductive resin adhesive S1 is applied to the mounting electrodes 18X and 19X by a dispenser or the like. The thin plate thermistor 5 is stored in the lower storage portion 11BX in such a manner that the split electrodes 53 (the first split electrode 53a and the second split electrode 53b) correspond to the applied conductive resin adhesive S1. Then, the conductive resin adhesive S1 is cured by heating to conductively bond the first split electrode 53a and the second split electrode 53b of the thin plate thermistor 5 to the mounting electrodes 18X and the mounting electrodes 19X (mechanically electrically bonded). It should be noted that the conductive bonding of the thin plate thermistor 5 may also be solder bonding.

[0119] The resin material M is injected into the lower storage part 11BX storing the thin plate thermistor 5 by a dispenser or the like, and the thin plate thermistor 5 is covered with the resin material M. Thereafter, the resin material M is cured by heating. In the present embodiment, a polyimide resin is used as the resin material M, but other resin materials may be used. Thus, the thin plate thermistor 5 is protected from the outside air, so that stable temperature detection can be performed.

[0120] According to the above-mentioned thin plate thermistor mounting type piezoelectric vibration device XcX, the end of the thermistor plate 51 is less likely to be broken or chipped, and the thin plate thermistor 5 of the first embodiment having excellent resistance characteristics is provided, thereby improving the temperature detection accuracy.

[0121] 《Fourth Implementation Mode》

[0122] Below, refer to Fig.12 A thin plate thermistor-mounted piezoelectric vibration device according to a fourth embodiment of the present invention will be described in detail. Fig.12 It is a cross-sectional view of a thin-plate thermistor-mounted piezoelectric vibration device XcY.

[0123] The thin plate thermistor mounted piezoelectric vibration device XcY has a structure in which a piezoelectric vibration plate 2X and a thin plate thermistor 5 are housed inside a housing portion 51Y of a package 1Y of the thin plate thermistor mounted piezoelectric vibration device XcY. The package 1Y is made of ceramic with internal wiring formed therein, and has a housing portion 51Y having an opening at the top. Mounting electrodes 54Y and 55Y (mounting electrode 55Y is not shown) for the piezoelectric vibration plate 2X and mounting electrodes 56Y and 57Y for the thin plate thermistor 5 are formed at the bottom of the housing portion 51Y. In addition, mounting electrodes 52Y and 53Y are formed on the bottom surface.

[0124] The lead electrodes 21aX and 22aX (see Fig. 9) are conductively bonded (mechanically and electrically bonded) to the mounting electrodes 54Y and 55Y by the conductive resin adhesive S1, and the piezoelectric diaphragm 2X is accommodated in the accommodation portion 51Y of the package 1Y. In addition, the first and second divided electrodes 53a and 53b formed on the second main surface 51b of the thin plate thermistor 5 are conductively bonded (mechanically and electrically bonded) to the mounting electrodes 56Y and 57Y by the conductive resin adhesive S1, and the thin plate thermistor 5 is accommodated in the accommodation portion 51Y of the package 1Y.

[0125] The piezoelectric vibration plate 2X and the thin plate thermistor 5 are housed in a parallel state inside the housing portion 51Y of the package 1Y and are hermetically sealed by a cover 3X.

[0126] According to the above-mentioned thin plate thermistor mounting type piezoelectric vibration device XcY, the end of the thermistor plate 51 is less likely to be broken or chipped, and the thin plate thermistor 5 of the first embodiment having excellent resistance characteristics is provided, thereby improving the temperature detection accuracy.

[0127] It should be noted that the thin plate thermistor is not limited to the thin plate thermistor 5 of the above-mentioned embodiment, and various modifications can be made.

[0128] For example, in the above-mentioned embodiment, for example, for the thermistor plate wafer 51, the first stage laser irradiation and the second stage laser irradiation are performed from the first surface 51aA side having a large surface roughness, but instead of this, the first stage laser irradiation and the second stage laser irradiation may be performed from the second surface 51bA side having a small surface roughness, thereby, in the second main surface 51b of the thermistor plate 51, the surface roughness of the end portion is smaller than the surface roughness of the central portion, and it is raised at least in a portion of the end portion, and the thermistor plate 51 has a solidified portion (other solidified portion) at the end portion of the second main surface 52b. Alternatively, the thermistor plate wafer 51 may be subjected to laser irradiation in the first stage and laser irradiation in the second stage from the first surface 51aA side and the second surface 51bA side, respectively, so that the surface roughness of the end portion of each of the first main surface 51a and the second main surface 51b of the thermistor plate 51 is smaller than that of the central portion, and at least a portion of the end portion is raised, and the thermistor plate 51 has a solidified portion and other solidified portions at the end portions of each of the first main surface 51a and the second main surface 51b. In the latter case, the thermistor plate 51 has a solidified portion at the end portions of each of the first main surface 51a and the second main surface 51b, so that it is difficult to generate a break or a notch on both the first main surface 51a side and the second main surface 51b side of the end portion of the thermistor plate 51, and as a result, the mechanical strength of the thin plate thermistor 5 can be further improved.

[0129] In the above-mentioned embodiment, for example, the thin plate thermistor 5 may not include the common electrode 52. In addition, for example, the thin plate thermistor 5 may not include the common electrode 52, and the first divided electrode 53a and the second divided electrode 53b may be replaced by the first divided electrode and the second divided electrode including a second main surface portion disposed on a part of the second main surface 51b of the thermistor plate 51, a side surface portion connected to the second main surface portion and disposed on the side surface of the thermistor plate 51, and a first main surface portion connected to the side surface portion and disposed on the first main surface 51a of the thermistor plate 51.

[0130] The advantage of using the above-mentioned thin plate thermistor 5 is miniaturization and thinning. By combining it with the sandwich structure device 2, it is beneficial to the miniaturization and thinning of the device. From this point of view, it is preferred to combine the thin plate thermistor 5 with the sandwich structure device 2. It should be noted that the thin plate thermistor 5 of the above-mentioned embodiment can be applied to existing packages other than the above-mentioned packages such as sandwich structure devices. For example, it can also be applied to molded resin sealed packages. In the molded resin sealed package, the piezoelectric vibration device and the thin plate thermistor are placed flat on the upper part of the glass epoxy substrate that becomes the base substrate in a state of being arranged side by side through a bonding member, and are electrically connected to the terminal part of the substrate by wire bonding, etc. Moreover, it becomes a structure covered by a molding resin on the upper part including these components. In such a structure, improvement in thermal conductivity can be expected.

[0131] In addition, in the above-mentioned embodiment, a laser is used to form the solidified portion 51D at the end of the thermistor plate 51, but the present invention is not limited thereto, and for example, an electron beam or the like may be used to form the solidified portion 51D at the end of the thermistor plate 51 using a method other than laser. Furthermore, by polishing the planes with different surface roughnesses, the surface roughnesses of one surface and the other surfaces of the thermistor plate can also be made different.

[0132] In addition, a thin reinforcing member such as a quartz crystal wafer or aluminum foil that can obtain a certain degree of structural strength can also be attached to the common electrode 52 of the thin plate thermistor 5 of the above-mentioned embodiment. If a hard material such as a quartz crystal wafer is used as a reinforcing member, the strength of the thin plate thermistor 5 is greatly increased, and the installation of the thin plate thermistor 5 to the sandwich structure device 2 is easy. In the case of using a quartz crystal wafer as a reinforcing member, it is desirable to form a film for improving the adhesion on the common electrode 52 in advance. In addition, if an insulating material is used as a reinforcing member, after the thin plate thermistor 5 is mounted on the sandwich structure device 2, the top surface of the device 1 (the surface on the opposite side (back side) of the surface of the reinforcing member facing the common electrode 52) may not be subjected to insulation treatment.

[0133] In the above embodiment, a sintered product obtained by sintering pure metal such as molybdenum or tungsten as a sintered material may be arranged on the first main surface 51a of the thermistor plate 51 to serve as a common electrode. This can improve the strength of the thin plate thermistor 5 and reduce the thickness of the thermistor plate 51 by an amount corresponding to the thickness of the sintered product serving as the common electrode 52. In addition, since tungsten has the same degree of thermal conductivity as aluminum, the heat transfer of the thin plate thermistor 5 as a whole becomes faster, and the thermal responsiveness of the thin plate thermistor 5 can be improved.

[0134] In addition, in the above-mentioned embodiment, for example, the common electrode 52 may be formed on the first main surface 51a of the thermistor plate 51 by applying Ag paste to the entire surface or substantially the entire surface of the first main surface 51a of the thermistor plate 51 and sintering it. In this case, the common electrode 52 functions as a relay electrode and also functions as a reinforcing member for improving the strength of the thin plate thermistor 5. The common electrode 52 may be formed on the first main surface 51a of the thermistor plate 51 using Cr-Au instead of Ag paste, and then epoxy resin as a reinforcing member may be provided on the surface of the common electrode 52 on the opposite side (back side) to the surface facing the thermistor plate 51. In these cases, the strength of the thin plate thermistor 5 can be improved while preventing the deterioration of the resistance characteristics of the thin plate thermistor 5.

[0135] Furthermore, the contents of the above-described embodiment and the contents of the modified examples may be combined as appropriate.

[0136] Industrial Applicability

[0137] The present invention is widely applicable to a thin plate thermistor used as a temperature sensor and a thin plate thermistor-mounted piezoelectric vibration device in which the thin plate thermistor is mounted.

[0138] Description of Reference Numerals

[0139] 1: Piezoelectric vibration device with thin-plate thermistor

[0140] 2: Sandwich structure device

[0141] 5: Thin plate thermistor

[0142] 51: Thermistor plate

[0143] 51a: First main surface

[0144] 51b: Second main surface

[0145] 52: Shared electrode

[0146] 53, 53a, 53b: split electrodes.

Claims

1. A thin plate thermistor, characterized in that: The thin plate thermistor has: A single-plate thermistor flat plate, comprising a surface and another surface on the opposite side of the surface and having a surface roughness greater than that of the surface; a first split electrode and a second split electrode formed on the one surface and split on the one surface; as well as A common electrode is formed on the other surface.

2. The thin plate thermistor according to claim 1, characterized in that: The first divided electrodes, the second divided electrodes, and the common electrode are PVD (physical vapor deposition) films.

3. A piezoelectric vibration device with a thin-plate thermistor, characterized in that: The thin plate thermistor mounted piezoelectric vibration device comprises a piezoelectric vibration device and the thin plate thermistor according to claim 1 or 2, The piezoelectric vibration device comprises: a piezoelectric vibration plate having an excitation electrode composed of a plurality of metal film layers formed on the surface; a first sealing member bonded to one main surface of the piezoelectric vibration plate; and a second sealing member bonded to the other main surface of the piezoelectric vibration plate. The thin plate thermistor is bonded to a surface of the piezoelectric vibration device.

4. A piezoelectric vibration device with a thin-plate thermistor, characterized in that: The thin plate thermistor mounted piezoelectric vibration device comprises: A piezoelectric vibration plate having an excitation electrode composed of a plurality of metal film layers formed on its surface; The thin plate thermistor according to claim 1 or 2; as well as A package accommodates the piezoelectric vibration plate and the thin plate thermistor.

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