JP2005227228A - Diaphragm type sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure capable of forming stably the effective region of a diaphragm in a diaphragm type sensor having a form wherein the diaphragm is bonded to a support part. <P>SOLUTION: A circular support member 14 having a shape unchanged at the melting temperature of a sealing material is provided close to the diaphragm on the end surface thereof, and a fixing layer 16 is formed along its circumference. Hereby, even when the sealing material is melted when forming the fixing layer 16, flowing into the inner circumferential side from the support member 14 is suppressed. Consequently, the effective region of the diaphragm 12 is formed stably inside the inner circumferential edge of the support member 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diaphragm type sensor that detects a mechanical quantity based on deformation of a diaphragm.

  Diaphragm type sensors that detect deformation (or displacement) exclusively in the thickness direction of the diaphragm, convert it into an electrical signal and output it are known, for example, to detect mechanical quantities such as pressure and acceleration It is used for pressure sensors and acceleration sensors. For example, a resistor is formed in close contact with the diaphragm, and a strain resistance sensor that measures strain resistance that changes when the resistor is deformed as the diaphragm is deformed, or a movable electrode is provided on one surface of the diaphragm. In addition, a fixed side electrode is provided opposite to the movable side electrode, and an electrostatic capacitance is measured for measuring the capacitance between the fixed side electrode and the fixed side electrode that changes when the movable side electrode is deformed along with the deformation of the diaphragm. A capacitive sensor is an example. In general, the former is used for a pressure sensor, and the latter is used for a pressure sensor and an acceleration sensor.

In the diaphragm type sensor as described above, a diaphragm and a support part that supports the diaphragm on a fixed plate are formed as separate members and joined to each other (see, for example, Patent Documents 1 to 3). . Such a configuration is disadvantageous in that the number of parts increases and the members need to be joined to each other, but the processing distortion due to the difference in thickness as in the case where the support is integrally formed. Inconvenience that the dimensional and shape accuracy is lowered due to the occurrence of this is suppressed, so that there is an advantage that a sensor with high thickness accuracy and high detection accuracy can be obtained. In addition, since the individual shapes of the constituent members are simplified and easy to manufacture, the overall manufacturing cost is not particularly high. On the other hand, the simple shape can be easily processed with high accuracy even if the size is increased. There is an advantage that the manufacturing cost decreases as the area of the sensor increases. In addition, a simple thin-plate-shaped diaphragm can be thinned to, for example, about 0.2 (mm) or less, even if it is a brittle material such as ceramics.
JP-A-5-231974 JP-A-6-66659 Japanese Patent No. 2513849

  However, when the diaphragm and the support portion are formed of different members as described above, they are joined to each other by, for example, brazing or a fixing material such as glass or resin. For example, the former is a method of joining a ring-shaped support member to a diaphragm and a fixed plate with a brazing material. However, when the diaphragm or the fixed plate is made of ceramics, the joint surface needs to be made of metal. The joint surface must be metallized. Therefore, the constituent materials of the diaphragm and the fixing plate are limited to materials that can be brazed directly or materials that can be easily metallized, and it is necessary to heat in a reducing atmosphere in order to prevent metal oxidation, and the process is complicated. There is an inconvenience. Moreover, when the diaphragm is made of metal, the brazing material spreads freely in the vicinity of the joint surface when brazed, so that the effective area of the diaphragm (that is, the diaphragm size) determined by the position of the inner periphery of the joint is expected. There is a disadvantage that it is not formed in size and shape. Although there is a brazing method called an active metal method that does not require metallization (see, for example, Patent Document 3), heating in a reducing atmosphere is essential even in this case, and reliability of the joint is usually increased. There is a problem that it is difficult to secure the same level as brazing.

  On the other hand, the bonding method using the latter fixing material has an advantage that the bonding surface is less restricted and can be heated in an oxidizing atmosphere. In this joining method, for example, a fixing material to which a spacer having a spherical shape or other shape or a filler smaller than that is added is applied onto a fixing plate, and the fixing material is softened (or melted) by heating while applying a pressure on a diaphragm. To join each other. When the spacer is included, the height of the support portion is determined by the size thereof, and when the filler is included, the height of the supporting portion is determined by the fluidity of the fixing material controlled thereby and the amount of deformation. Therefore, it is more difficult to stably position the inner periphery of the support portion on a certain curve due to lateral deformation due to pressurization, material flow, etc., so that the effective area of the diaphragm has the intended dimensions and There was a disadvantage that it was not formed in a shape.

  In the technique described in Patent Document 1, a concave groove is formed on the upper surface of the fixing plate along the inner peripheral edge of the support portion (that is, along the electrode peripheral edge) as a countermeasure against the above inconvenience. This suppresses the spread of the fixing material around the circumference. However, on a diaphragm without a concave groove, the position of the inner peripheral edge of the fixing material varies due to the ease of wetting with the diaphragm and the distribution of the coating amount. It is difficult.

  The present invention has been made in the background of the above circumstances, and its purpose is to provide a structure that can stably form an effective area of a diaphragm in a diaphragm type sensor in which a diaphragm and a support portion are joined. It is to provide.

  In order to achieve such an object, the gist of the present invention is that a thin plate-like diaphragm member and a support portion that supports the diaphragm member on a fixed portion by being fixed to a peripheral portion of one surface of the diaphragm member. And a mechanical quantity transmission unit for transmitting the mechanical quantity to be measured to the diaphragm member, and detecting the displacement in the thickness direction of the diaphragm part according to the transmitted mechanical quantity to measure the mechanical quantity. A diaphragm type sensor of the above type, wherein the support part is (a) a fixing part that is located on the outer peripheral part and is made of a fixing material for fixing the diaphragm member to the fixing part, and (b) an annular shape. Then, it is located on the inner peripheral side of the fixing portion and is brought into intimate contact with the diaphragm member at one end surface, and the outer peripheral surface is in intimate contact with the fixing portion, and the melting temperature of the fixing material And a damming portion for maintaining the shape.

  In this way, an annular damming portion whose shape does not change at the melting temperature of the fixing material is provided in close contact with the diaphragm member at its end face, and the fixing portion is formed along the outer periphery thereof. Even when the fixing material is melted when forming the, the inflow from the damming portion to the inner peripheral side is suppressed. Therefore, since the effective area of the diaphragm member is stably formed inside the inner peripheral edge of the damming portion, a highly accurate effective area corresponding to the dimension and shape accuracy of the damming portion can be obtained. As a result, the damming portion also serves as a spacer that determines the mutual distance between the diaphragm and the fixed portion.

  As the constituent material of the damming portion, any material can be used as long as it does not melt at the fixing temperature. For example, a material in which ceramic powder is dispersed in a glass material having a high softening point, a refractory metal, or the like is used. Preferably used.

  Here, preferably, the diaphragm type sensor includes a pressure chamber in which the working fluid is stored and a fluid inlet / outlet through which the working fluid enters and exits, and the fluid pressure in the pressure chamber is opposite to the pressure chamber in the diaphragm member. This is a pressure sensor in which the diaphragm member is deformed in accordance with the pressure difference with the one side surface. In this aspect, the pressure chamber and the fluid inlet / outlet correspond to a mechanical quantity transmission unit, and the transmitted mechanical quantity is a fluid pressure guided from the fluid inlet / outlet to the pressure chamber. As the working fluid, an appropriate liquid and gas can be used depending on the measurement target. For example, when the measurement object is the pressure of these liquids and gases, they may be configured to enter and exit the pressure chamber.

  Preferably, the diaphragm sensor is an acceleration sensor that includes a weight body on one surface of the diaphragm member, and the diaphragm member is deformed in accordance with acceleration acting on the weight body. In this aspect, the weight body corresponds to a mechanical quantity transmission unit, and the transmitted mechanical quantity is acceleration acting on the weight body. The present invention is suitably applied to such pressure sensors and acceleration sensors. The deformation mainly occurs in the thickness direction.

  Preferably, the diaphragm type sensor includes a movable side electrode provided on one surface of the diaphragm member, and a fixed side electrode provided on a predetermined fixed member facing the movable side electrode, A capacitive sensor that measures acceleration or pressure based on the change in capacitance between the movable electrode and the fixed electrode caused by the displacement of the movable electrode along with the deformation of the diaphragm member. is there. The damming portion also functions as a spacer for determining the fixing height of the diaphragm member, so that the desired fixing height can be obtained with certainty. It becomes easier.

  Preferably, the diaphragm type sensor includes a resistor formed in close contact with one surface of the diaphragm member, and measures the pressure based on the strain resistance of the resistor deformed in accordance with the deformation of the diaphragm member. This is a strain resistance type sensor. The present invention is preferably applied to such a type of sensor.

  Preferably, the damming portion is configured separately from the fixing portion, and is fixed to the fixing portion with a fixing material that is melted at a temperature at which the shape of the damming portion is maintained. is there. In other words, the damming portion and the fixing portion may be formed integrally or separately, but the joining can be easily performed simultaneously with the joining of the diaphragm member. Thus, the damming portion that determines the effective area of the diaphragm member can be formed with high accuracy.

  Preferably, the diaphragm member is made of a material having a thermal expansion coefficient approximate to the constituent material of the fixed portion when the diaphragm member becomes high temperature when fixed to the fixed portion. For example, when the fixing portion is made of alumina, which is generally used as a constituent material, a material that approximates the thermal expansion coefficient of alumina is selected. For example, a metal such as ceramics having the same material as that of the fixed portion or having a thermal expansion coefficient comparable to that of the fixed portion, Kovar or 42 alloy (that is, Fe-42% Ni alloy) is preferable. On the other hand, when the fixing between the diaphragm member and the fixed portion is performed at a low temperature of, for example, 200 (° C.) or less, it is not necessary to consider the thermal expansion coefficient, and any material can be used for the diaphragm member. An advantage of configuring the diaphragm member with ceramics is that, for example, a strain resistance circuit can be easily formed because of having high insulating properties. Further, the advantage of being made of metal is that the diaphragm member can be easily formed and the movable electrode of the capacitive sensor can also be used.

  The diaphragm member can be made of metal, ceramics, semiconductor, or the like. When made of metal, a diaphragm having good workability and excellent impact resistance can be obtained. In the case of using ceramics, it is possible to obtain a diaphragm that can easily form an electric circuit and is excellent in environmental resistance such as high temperature, wear, reaction with a fluid, and the like. In addition, in the case of being composed of semiconductors, it is possible to employ semiconductor technology established in the formation of diaphragms, containers, and various circuits, so that it is possible to form a fine pattern and to process a large number of elements simultaneously, and to easily manufacture a small sensor. . When the diaphragm member is made of metal and the fixing material is a brazing material, the damming portion is preferably made of a material that does not get wet with the brazing material (that is, has a small contact angle). . For example, ceramics and glass materials are suitable.

Preferably, when the diaphragm member is made of metal, the metal material has a thermal expansion coefficient larger than that of the support portion. In this way, tension is applied to the diaphragm member in the cooling process after joining involving heating, so that there is an advantage that deformation is more uniform when pressure, acceleration, or the like is applied. The difference in thermal expansion coefficient is preferably about 5 × 10 ⁻⁷ to 30 × 10 ⁻⁷ (/ ° C.), for example. If the difference is smaller than this, a sufficiently large tension cannot be applied, and if the difference is larger, deformation or breakage is caused.

  Preferably, the damming portion is made of glass or a mixture of glass and ceramic powder that does not soften at a temperature when the diaphragm member is fixed to the fixing portion. Such a damming portion can be formed by simple screen printing if an ink is prepared by kneading a glass powder or a mixed powder of glass and ceramics with a vehicle in which a resin is dissolved in a solvent. Therefore, there is an advantage that a highly accurate damming portion can be easily formed. In particular, a mixed powder of glass and ceramics is preferable because the thermal expansion can be easily adjusted and the strength of the glass can be increased. If the glass is melted by baking after printing, the damming portion is airtightly fixedly formed on the fixed portion or the diaphragm member. In this way, when the damming portion is formed by printing or the like, as described above, the diaphragm member and the fixed portion can be formed as separate parts, and can be fixedly formed on the fixed portion or the diaphragm member. It is. If it does in this way, formation of a blocking part will become easy. In the case of forming on the diaphragm member, the flow of the fixing material at the time of joining the diaphragm and the fixed portion can be generated only on the fixed portion, which is particularly preferable.

  In addition to forming the pattern on the fixed part or the diaphragm as described above, the dam part is formed by machining or a chemical method on one surface of the fixed part or the diaphragm, for example. It can also be formed by a processing method of removing with an appropriate thickness dimension.

  Preferably, the fixing part is made of glass or glass in which ceramic powder is dispersed. In this way, the glass is excellent in air tightness and can be bonded to a metal or ceramic with a high bonding force, so that the diaphragm member can be securely bonded and the pressure chamber of the pressure sensor is formed on the inside thereof. However, it is easy to ensure the airtightness.

  Preferably, the damming portion has an annular shape, more preferably a perfect circular shape. In this way, since the effective area of the diaphragm member is circular, it can be uniformly deformed, so that a diaphragm type sensor with more stable characteristics can be obtained. That is, the damming portion can be used in an appropriate shape according to the desired effective area shape of the diaphragm member, and can be configured with an appropriate closed curved contour shape such as a rectangular tube shape, An annular shape, particularly a perfect annular shape is preferred.

  Preferably, the diaphragm sensor is a pressure sensor, and the fixing portion seals between the diaphragm member and the fixing portion on the outer peripheral side of the damming portion. In this case, the pressure chamber of the pressure sensor is suitably formed on the inner peripheral side of the fixing portion.

  Preferably, the interval between the fixed portion and the diaphragm member is larger on the outer peripheral side of the damming portion than on the inner peripheral side thereof. In this way, even when the mutual distance between the fixed portion and the diaphragm member is set to be small within the effective area of the diaphragm, the height dimension of the fixing portion on the outer peripheral side of the damming portion (from the fixed portion to the diaphragm member). The dimension in the direction of heading) can be made large enough to secure sufficient fixing strength, liquid tightness or air tightness. For example, in an aspect in which electrodes are formed on the opposing surfaces of the fixed portion and the diaphragm member in the capacitive sensor, the distance between them may be relatively small, for example, 50 (μm) or less. It is difficult to ensure the height dimension of the fixing portion if the distance between them is made flat and the distance between them is made uniform over the entire surface. If it does as mentioned above, it is possible to ensure a suitable height dimension also in such a case. The mutual interval in the outer peripheral portion is ensured by, for example, forming the opposing surface of at least one of the fixing portion and the diaphragm member (preferably the fixing portion) to be lower than the inner periphery at the outer periphery than the damming portion. it can.

  Further, it is preferable that the fixing portion is formed in close contact with the damming portion. In this way, the effective area of the diaphragm member is on the inner side of the inner peripheral edge of the fixed portion in the deformation direction away from the fixed portion. And the shape accuracy is increased.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a cross-sectional view schematically showing the structure of a capacitive pressure sensor 10 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II. In FIGS. 1 and 2, the diaphragm 12 is supported by an annular support member 14 and fixed to a disk-shaped fixing plate 18 by a fixing layer 16 formed on the outer peripheral side thereof. Further, for example, a circular fixed side electrode 24 and a movable side electrode 26 are fixedly formed on the inner surfaces 20 and 22 of the fixed plate 18 and the diaphragm 12 facing each other.

  The diaphragm 12 is made of ceramics such as alumina, and is a flat and uniform thin disk having a diameter of about 16 (mm) and a thickness of about 0.3 (mm). It is. The diaphragm 12 is manufactured by, for example, densely sintering a plate prepared by an appropriate forming method such as powder press molding and grinding both surfaces flatly and smoothly. The movable side electrode 26 is made of, for example, Au, and has a diameter of about 8 (mm) and a thickness of about 1 (μm), and is smaller on the inner surface 22 of the diaphragm. The diameter is formed on the inner peripheral side by thick film or thin film technology.

  The support member 14 is made of, for example, glass that does not soften at the fixing process temperature or a mixture of glass and ceramics. For example, the support member 14 has an inner diameter of about 9 (mm) and a diameter of the diaphragm 12. It has a sufficiently small outer diameter of about 10 (mm) and a thickness dimension (height dimension) of about 0.1 (mm). This thickness dimension determines the mutual interval between the fixed side electrode 24 and the movable side electrode 26, and is determined according to the pressure to be detected. For example, the thickness dimension is as small as about 10 (μm). Can also be set. Further, as the constituent material of the support member 14, a material capable of maintaining the size and shape at the melting temperature of the constituent material of the fixing layer 16 (for example, a glass material described later) is selected. Further, the diameter of the movable electrode 26 is determined so as to be sufficiently smaller than the inner diameter of the support member 14. In this embodiment, the support member 14 corresponds to a damming portion.

  The fixing plate 18 is made of alumina or the like, for example, and has a diameter approximately the same as that of the diaphragm 12 and a thickness dimension of approximately 4 (mm). The fixed side electrode 24 is made of an Au film or the like, and is coaxially formed on the inner surface 20 of the fixed plate with the same area and thickness as the movable side electrode 26.

  A disk-shaped (or columnar) space 28 surrounded by the diaphragm 12, the fixed plate 18, and the support member 14 is a pressure chamber in which a working fluid such as gas or liquid is stored. , Upward or downward in FIG. 1 (that is, a direction approaching or separating from the fixed electrode 24) in accordance with a differential pressure between the working fluid pressure in the pressure chamber 28 and the pressure outside the diaphragm 12 (for example, atmospheric pressure). It can be bent and deformed. The fixing layer 16 fixes the diaphragm 12 and the fixing plate 18 in an air-tight or liquid-tight manner so that the working fluid does not leak to each other at the outer peripheral edge. That is, strictly speaking, the pressure chamber 28 is formed inside the inner peripheral edge of the fixed layer 16. Further, a working fluid inlet / outlet 30 having a diameter of about 2 (mm), for example, penetrating in the thickness direction is provided in the central portion of the fixing plate 18, and the pressure in the pressure chamber 28 is an operation to be measured. It is raised by flowing in a working fluid whose pressure changes in response to a change in the fluid or pressure of the measurement object, while it is lowered by letting out the working fluid. In the present embodiment, the fixed plate 18 corresponds to a fixed portion, and the pressure chamber 28 and the working fluid inlet / outlet 30 constitute a dynamic quantity transmitting portion.

  In addition, since the support member 14 is positioned on the inner peripheral side of the diaphragm 12, only the inner peripheral side portion of the support member 14 is bent and deformed according to the pressure change. It is done. Therefore, in this embodiment, the effective area of the diaphragm 12 is a range inside the support member inner peripheral edge 32, and the movable electrode 26 is formed in the effective area. Further, the fixed side electrode 24 and the movable side electrode 26 are respectively connected to wirings provided outside the pressure chamber 28 via extraction terminals (not shown).

The fixed layer 16 is made of, for example, SiO ₂ —B ₂ O ₃ —PbO-based glass or a mixed material of such glass and ceramic powder such as alumina. For example, FIG. ) And (b), as schematically shown in the implementation state of the joining process, these are fixed by being melted while being interposed between the diaphragm 12 and the fixed plate 18. In FIG. 3A, the support member 14 is fixed at a predetermined position on the fixing plate 18 or is arranged by using an appropriate positioning method, and a glass sealing material 34 for forming the fixing layer 16 on the outer peripheral side thereof. Is applied, for example. The glass sealing material 34 is provided so as to rise slightly above the support member 14, and the diaphragm 12 is placed thereon as shown in FIG. 3 (b). When this is melted by heating to a predetermined temperature determined according to the type of the sealing material 34 in this state, the glass having increased fluidity and adhesiveness is fixed on the fixing member 18 and the diaphragm 12 while spreading. Then, the diaphragm 12 is joined to the fixing member 18.

  In this joining process, according to the present embodiment, the melted glass (sealing material 34) tries to flow so as to spread in all directions, but the flow to the inner peripheral side is hindered by the support member 14. , It will spread only to the outer peripheral side. The end surface of the support member 14 is brought into close contact with the lower surface 22 of the diaphragm 12 (that is, one surface on the pressure chamber 28 side) so as to prevent the flow of the sealing material 34 toward the inner peripheral side. Therefore, the inner peripheral edge of the fixing layer 16 is formed along the outer peripheral edge of the support member 14 and does not spread to the inner peripheral side. As a result, the effective area of the diaphragm 12 is determined only by the support member 14, and no dimensional change or shape change due to the fixed layer 16 spreading to the inner peripheral side occurs. In this embodiment, the fixing layer 16 corresponds to a fixing portion, and the supporting member 14 and the fixing layer 16 constitute a supporting portion, and the supporting portion is constituted by a member different from the fixing plate 18.

  In short, according to this embodiment, the annular support member 14 whose shape does not change at the melting temperature of the sealing material 34 is provided in close contact with the diaphragm 12 at its end face, and the fixing layer 16 is formed along the outer periphery thereof. Therefore, even when the sealing material 34 is melted when the fixing layer 16 is formed, it is suppressed from flowing into the inner peripheral side from the support member 14. Therefore, since the effective area of the diaphragm 12 is stably formed inside the inner peripheral edge of the support member 14, a highly accurate effective area corresponding to the size and shape accuracy of the support member 14 can be obtained. As a result, the support member 14 also serves as a spacer that determines the mutual distance between the diaphragm 12 and the fixed plate 18.

  Next, another embodiment of the present invention will be described. In the following embodiments, portions common to the above-described embodiments are denoted by the same reference numerals and description thereof is omitted. In the pressure sensor 36 shown in FIG. 4, an electrode fixing member 38 having a bottomed cylindrical shape is fixed on the diaphragm 12 at its opening end surface, and a movable side electrode 40 is provided on the upper surface of the diaphragm 12. Fixed side electrodes 42 are respectively fixedly formed on the inner surface of the plate 38. The electrode fixing member 38 is made of, for example, alumina, and the inner bottom surface thereof is separated from the upper surface of the diaphragm 12 by a distance of about 20 (μm) corresponding to the pressure to be detected. In this embodiment, no electrode is formed on the fixed plate 18 and the lower surface of the diaphragm 12, and the space 28 surrounded by them and the support member 14 functions to transmit the pressure to be measured to the diaphragm 12. Have only.

  Further, the inner peripheral edge 44 of the electrode fixing member 38 is formed more sufficiently on the outer peripheral side than the inner peripheral edge 32 of the support member 14. Therefore, since nothing is provided on the upper surface side of the diaphragm 12 as a damming portion, the sealing material that protrudes from the joining end surface of the electrode fixing member 38 can spread to the inner peripheral side. However, since the effective area of the diaphragm 12 is determined by the innermost fixed portion, that is, the inner peripheral edge 32, the effective area can be formed with high accuracy even with this configuration.

  FIG. 5 shows a configuration example when the present invention is applied to the strain resistance type pressure sensor 46, and corresponds to FIG. In FIG. 5, a piezoresistive element 50 is fixed to an appropriate portion of the upper surface 48 of the diaphragm 12. The resistance element 50 is composed of, for example, a thick film or a thin film. Further, the resistance element 50 is connected to an external wiring through a take-out electrode (not shown) so that its resistance value and change in resistance value can be measured. When the diaphragm 12 is bent and deformed, a corresponding stress is applied to the resistance elements 50. Therefore, the resistance values of the resistance elements 50 change, and the pressure at which the diaphragm 12 is bent and deformed based on the measured resistance value change. Is detected.

  In the pressure sensors 10, 36, and 46 described above, the working fluid inlet / outlet 30 is provided in the fixed plate 18, and the pressure chamber 28 functions as a measurement pressure detection unit. If the pressure chamber 28 is configured as a closed space without being provided, it can function as a reference pressure section by keeping the pressure constant. In this case, a pressure change on one surface of the diaphragm 12 opposite to the pressure chamber 28 is detected.

  FIG. 6 is a diagram corresponding to FIG. 1 showing a configuration example in which the present invention is applied to a capacitance type acceleration sensor 52. In FIG. 6, an annular fixing member 54 is disposed below the diaphragm 12, the supporting member 14 is disposed on the annular end surface, and the diaphragm 12 is fixed by the fixing layer 16 provided on the outer peripheral side thereof. Has been. Therefore, the lower surface of the diaphragm 12 is in an open state, and for example, a cylindrical weight body 56 is fixed to the lower surface of the diaphragm 12 at a position inside the inner peripheral surface of the fixing member 54. The weight body 56 has its size, mass, etc. determined according to the magnitude of acceleration to be measured.

  In such an acceleration sensor 52, when acceleration occurs in the left-right direction in FIG. 6, for example, in the horizontal direction, the diaphragm 12 is exclusively deformed in the thickness direction by the inertial force of the weight body 56. The capacitance between the side electrodes 42 changes, and the generated acceleration is detected. The present invention is also used for such an acceleration sensor 52.

  FIG. 7 is an enlarged view showing a main part for explaining another example of the structure of the support part in the pressure sensor 10 or the like shown in FIG. In FIG. 7, the fixing plate 60 of the pressure sensor 58 has a stepped portion 62 at the outer peripheral edge portion on the inner surface 20 side. The stepped portion 62 is formed into a curved surface whose thickness dimension is sharply reduced from the inner surface 20 toward the outer peripheral side, and whose thickness dimension is substantially constant in the vicinity of the outer peripheral surface. For this reason, in the illustrated state in which the diaphragm 12 is joined, the distance between the diaphragm 12 and the fixed plate 60 is increased, for example, by about twice as much as the inner peripheral side at the outer peripheral edge. Therefore, the fixing layer 64 formed in this portion has a thickness dimension (height dimension) that is approximately twice that of the case where the fixing plate 60 is formed with a uniform thickness dimension throughout. It has become a preparation.

  Therefore, according to such a pressure sensor 58, for example, even when the distance between the inner surfaces 20, 22 is as small as about 20 (μm), the thickness of the sealing layer necessary to ensure the fixing strength and the air tightness. There is an advantage that is secured. That is, it is known that there is an optimum thickness for exhibiting sufficient adhesive force in the bonding with the glass sealing material, but according to the present embodiment, the electrode interval and the sealing thickness are independently set. Each can be set to an optimum value.

  The capacitive sensor 66 shown in FIG. 8 is configured in the same manner as the sensors 36 and 52 shown in FIGS. 4 and 6 except that the configuration of the left end is different. In this embodiment, a substantially flat electrode fixing plate 68 is used in place of the electrode fixing member 38, and the electrode fixing plate 68 is supported on the diaphragm 12 by the support member 70 and is airtight by the fixing layer 72. It is fixed to. The support member 70 and the fixing layer 72 are configured in the same manner as the support member 14 and the fixing layer 16. That is, it is made of the same material, and the inner diameter and the outer diameter of the support member 70 are the same as those of the support member 14. Moreover, the supporting members 14 and 70 are provided coaxially, and those inner peripheral surfaces are located on one cylindrical surface.

  Therefore, according to this aspect, since the effective area of the diaphragm 12 is determined with high precision by the support members 14 and 70 on both surfaces thereof, the diaphragm 12 is deformed to be deformed in both the upper and lower surfaces as the pressure and acceleration increase or decrease. If possible, there is an advantage that the same measurement accuracy can be ensured in any case of the increase or decrease. 4 and 6, when concentrated to the upper side in the figure, stress concentrates on the inner peripheral edge of the fixed portion of the diaphragm 12, and peeling from the support member 14 is likely to occur. According to the embodiment, since both surfaces are pressed by the support members 14 and 70 having the same inner diameter and provided coaxially, even if such stress concentration occurs, there is an advantage that peeling does not easily occur. . That is, a long life can be obtained even when used in an environment where a large pressure or acceleration is repeatedly applied.

  In the above-described embodiment, the diaphragm 12 is made of alumina / ceramics, but may be made of a metal material. In this way, the metal is cheaper than ceramics, and, for example, the thinner and more accurate diaphragm 12 of about 0.05 (mm) can be easily manufactured, so that more accurate measurement is possible. There are advantages. Further, since joining by brazing is possible, there is an advantage that it is easy to ensure strength. However, there is a point to be devised when using either the strain resistance type or the capacitance type, which will be described.

  First, since the metal material has conductivity, in a strain resistance type sensor in which a plurality of piezoresistive elements 50 are formed, a gap between the resistive element 50 and the diaphragm 12 is used to electrically insulate them from each other. Must be electrically isolated. For this insulation treatment, for example, a metal surface treatment technique such as glass coating (saddle) can be used. Insulating treatment is required only for the surface on which the resistance element 50 is formed. However, if a glass film is formed on only one surface, a high-temperature heat treatment is applied in the formation process, Since the diaphragm 12 is warped due to a difference in thermal conductivity or the like, it is preferable to form a glass film having the same thickness on both sides with the same material to cancel the stresses on both sides. In addition, such a glass film has an advantage of providing insulation to the diaphragm 12 made of metal and at the same time enhancing its environmental resistance.

  Further, since the heat treatment is performed as described above also when the diaphragm 12 is joined to the fixing plate 18 or the fixing member 54, the support member 14 is preferably made of a material whose thermal expansion coefficient approximates that of the diaphragm 12. . However, if those constituent materials are selected so that the thermal expansion coefficient of the diaphragm 12 is slightly larger than the thermal expansion coefficient of the support member 14, the tension acts on the diaphragm 12 in the cooling process of the joining process. It is more preferable that the diaphragm 12 does not loosen after joining. Examples of materials that satisfy such conditions include Fe—Ni alloys, Fe—Ni—Cr alloys, Fe—Ni—Co alloys, and various alloys of these systems. These alloys are discolored by being oxidized at a high temperature, solderability is deteriorated, and corrosion resistance is relatively low. Therefore, it is preferable to perform a plating treatment with Ni, Au, or the like. However, it is preferable to oxidize the portion fixed to the sealing material 34 made of glass or the like in order to improve wettability.

  Further, since the diaphragm 12 made of metal can be used also as the movable side electrode in the capacitance type sensor, the trouble of separately forming the movable side electrodes 26 and 40 can be omitted and the terminal can be easily taken out. There are advantages. However, since the electrode exists on the support member 14 outside the bending deformation range of the diaphragm 12, that is, the portion where the electrode fixing member 38 is joined, the electrode fixing generally having a dielectric constant larger than that of the measurement object. The capacity of the member 38 is also measured, and there is a problem that measurement sensitivity is lowered. Such a problem can be avoided by the following method, for example.

  In the first method, for example, the interval between the movable side electrode 26 and the fixed side electrode 24 is made as small as possible, or the fixed side electrode 24 is made as small as possible, thereby joining the fixed side electrode 24 and the diaphragm 12. The angle formed by the line connecting the two and the fixed plate 18 is reduced.

  The second method is to reduce the area of the metal present at the junction between the diaphragm 12 and the electrode fixing member 38 or increase the distance between the electrodes. For example, it is possible to reduce the area by providing a notch or a through-hole or the like in the peripheral portion of the diaphragm 12, and if a concave portion is formed in the outer peripheral portion of one surface of the diaphragm 12 on the fixed side electrode 24 side, The distance between the electrodes can be increased.

  In addition to these, there is a method of separating an electric field formed by providing an auxiliary electrode around the fixed side electrode 24.

  As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

It is a schematic diagram for demonstrating the cross-section of the pressure sensor of one Example of this invention. It is II-II sectional view taken on the line of the pressure sensor of FIG. (a), (b) is a figure explaining the joining process which is the principal part of the manufacturing process of the pressure sensor of FIG. It is a schematic diagram for demonstrating the cross-sectional structure of the capacitive pressure sensor of the other Example of this invention. It is a schematic diagram for demonstrating the cross-section of the strain resistance type pressure sensor of other Example of this invention. It is a schematic diagram for demonstrating the cross-sectional structure of the electrostatic capacitance type acceleration sensor of other Example of this invention. It is a figure explaining the principal part of the cross-sectional structure of the electrostatic capacitance type sensor of other Example of this invention. It is a figure explaining the principal part of the cross-sectional structure of the electrostatic capacitance type sensor of other Example of this invention.

Explanation of symbols

10: Capacitance type pressure sensor, 12: Diaphragm, 14: Support member, 16: Adhering layer, 18: Fixed plate, 28: Pressure chamber

Claims (1)

A thin plate-shaped diaphragm member, a support portion that supports the diaphragm member on a fixed portion by being fixed to a peripheral portion of one surface of the diaphragm member, and a mechanical amount to be measured is transmitted to the diaphragm member A diaphragm type sensor that detects a displacement in the thickness direction of the diaphragm portion in accordance with the transmitted mechanical quantity and measures the mechanical quantity, and the support part includes:
A fixing portion that is located on the outer periphery and is made of a fixing material for fixing the diaphragm member to the fixing portion;
It forms an annular shape and is positioned on the inner peripheral side of the fixing portion and is brought into close contact with the diaphragm member at one end surface, and the outer peripheral surface is brought into close contact with the fixing portion and maintains its shape at the melting temperature of the fixing material A diaphragm type sensor including a damming portion.

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