JP7436235B2 - pressure sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pressure sensor that detects the pressure of a fluid or the like, and particularly to a sanitary pressure sensor.

Among pressure sensors that detect fluid pressure, sanitary pressure sensors used at manufacturing sites in the food and pharmaceutical industries require hygienic considerations, so they must have corrosion resistance, cleanliness, Strict requirements are imposed on reliability, versatility, etc. These requirements have become even more stringent in recent years as laws and regulations regarding hygiene management have become stricter.

In sanitary pressure sensors in this situation, for example, due to the requirement of corrosion resistance, the wetted parts that come into contact with the fluid (e.g. liquid) to be measured are made of materials with high corrosion resistance such as stainless steel (SUS), ceramics, and titanium. material is used. In addition, due to cleanliness requirements, a flush diaphragm structure is adopted that is easy to clean, and is designed to have high thermal shock resistance against steam cleaning. Furthermore, due to reliability requirements, a structure that does not use an encapsulant (oil-free structure) and a structure in which the diaphragm is difficult to tear (high barrier rigidity) are adopted.

As described above, sanitary pressure sensors are more limited in the materials and structures that can be used than other pressure sensors. For this reason, it is not easy to achieve even higher sensitivity while having high breakdown voltage performance and suppressing measurement errors. For example, in order to suppress measurement errors by having high pressure resistance and reducing pressure hysteresis, it is useful to use a highly rigid diaphragm with a large membrane thickness (small diameter to thickness aspect ratio). However, in such a highly rigid diaphragm, the amount of deformation due to pressure changes is minute, and sufficient sensor sensitivity cannot be obtained by directly sensing this. For this reason, several techniques have been proposed to improve sensor sensitivity by efficiently transmitting minute amounts of deformation of the diaphragm to the sensing section.

For example, Patent Document 1 discloses that three support members (2a, 2b, 2c) are erected at predetermined positions on the support surface (3B) of a diaphragm (3), and a semiconductor chip is placed on these support members. A pressure sensor (100) is described. In this pressure sensor (100), minute deflection of the diaphragm (3) is efficiently transmitted to the semiconductor chip (1) which is the sensing part through the three supporting members (2a, 2b, 2c) (specifically (The semiconductor chip 1 is configured to be more distorted than when it is directly provided on the support surface 3B), thereby increasing the sensor sensitivity. The three support members (2a, 2b, 2c) of this pressure sensor (100) all stand approximately perpendicular to the support surface (3B), and one of them (support member (2a) ) is arranged at the center (30) of the support surface (3B), and the remaining two (support members (2b, 2c)) are arranged at positions that are point symmetrical with respect to the center (30). It is characterized by

Further, in Patent Document 2, a pedestal (5b) is provided on the support surface (3B) of the diaphragm (3), at least one support member (2b) is erected on this pedestal, and further erected on this pedestal. A pressure sensor (100) is described in which a semiconductor chip (1) is mounted on a support member and another support member. In this pressure sensor (100), the minute deflection of the diaphragm (3) is efficiently transmitted to the semiconductor chip (1), which is the sensing part, through the pedestal and the support member, thereby increasing the sensor sensitivity. .

JP 2017-120214 Publication JP 2017-120212 Publication

In the pressure sensor described in the above cited document 1, for example, the diaphragm is made of stainless steel with a large coefficient of linear expansion (for example, the coefficient of linear expansion of SUS304 is about 17.3×10 ^-6 ), and the support member has insulation properties. It is made of glass having a small coefficient of linear expansion (for example, the coefficient of linear expansion of borosilicate glass is about 3.0×10 ⁻⁶ ). Bonding residual stress (tensile residual stress) is generated at a portion where two members having such a large difference in coefficient of linear expansion are bonded. This bonding residual stress becomes more pronounced as the coefficients of linear expansion of the two materials to be bonded increase, resulting in a situation where the strength of the diaphragm and the support member is reduced and the pressure resistance of the diaphragm is deteriorated. This situation is one of the technical issues that must be resolved as soon as possible in view of the current situation where laws and regulations regarding hygiene management are becoming stricter.

The present invention was created to solve the above problems, and its purpose is to efficiently transmit minute deflections of the diaphragm 3 to the sensing section through the support member, while reducing pressure resistance due to bonding residual stress. The object of the present invention is to provide a pressure sensor in which the pressure is suppressed.

A pressure sensor (1A, 1B, 1C) according to the present invention for solving the above problems has a first main surface (11) that receives the pressure of a fluid to be measured, and a first main surface (11) located on the opposite side of the first main surface. a diaphragm (10) having two principal surfaces (12); a sensor chip (20A, 20B) provided with a plurality of resistors constituting a strain gauge; and a plurality of electrically insulating support members (41, 42) whose one ends are joined to the sensor chip, and the plurality of support members are made of intermediate materials (50A, 50B) having a coefficient of linear expansion smaller than that of the diaphragm. , 50C) and fixed to the second main surface via this intermediate material.

In the pressure sensor, the intermediate material may be made of a material having a higher coefficient of linear expansion than the support member.

Further, in the pressure sensor, the intermediate material may connect a plurality of joint parts (51, 52, 53, 56, 57, 58) joined to the plurality of support members and at least two of these joint parts. (54, 55, 59), and the thickness of the connecting portion along the normal line may be smaller than the thickness of the plurality of joint portions.

Furthermore, in the pressure sensor, the connecting portion may be formed as a thin film that is thinner than the thickness of the diaphragm.

Further, in the pressure sensor, the plurality of support members may be fixed to the second main surface via at least two intermediate members spaced apart from each other.

Furthermore, in the pressure sensor, the intermediate member may be provided to form a pair with the support member.

Further, in the pressure sensor, the bonding area between the intermediate material and the second main surface may be smaller than the bonding area between the intermediate material and the support member.

Furthermore, in the pressure sensor, the intermediate material is made of a plurality of materials having different coefficients of linear expansion, and the materials linearly expand from the side where it joins with the second main surface toward the side where it joins with the sensor chip. The layers may be stacked along the normal line so that the ratio is small.

In the above description, as an example, reference numerals on the drawings corresponding to the constituent elements of the invention are written in parentheses.

According to the present invention, it is possible to provide a pressure sensor in which a minute deflection of the diaphragm 3 is efficiently transmitted to the sensing portion through the support member, and a decrease in pressure resistance due to bonding residual stress is suppressed.

FIG. 1 is a sectional view of a pressure sensor according to an embodiment of the invention. FIG. 2 is a sectional view of a pressure sensor and piping connected thereto according to an embodiment of the present invention. FIG. 3 is an enlarged plan view of the vicinity of the diaphragm included in the pressure sensor according to the embodiment of the present invention. FIG. 4 is a sectional view taken along the line QQ in FIG. 3. FIG. 5 is a conceptual diagram showing a modification of the diaphragm included in the pressure sensor according to the embodiment of the present invention. FIG. 6 is a sectional view of a pressure sensor according to another embodiment of the invention. FIG. 7 is an enlarged plan view of the vicinity of a diaphragm included in a pressure sensor according to another embodiment of the present invention. FIG. 8 is a cross-sectional view taken along the line QQ in FIG. FIG. 9 is a conceptual diagram showing a modification of a diaphragm included in a pressure sensor according to another embodiment of the present invention. FIG. 10 is a sectional view of a pressure sensor according to another embodiment of the invention. FIG. 11 is an enlarged plan view of the vicinity of a diaphragm included in a pressure sensor according to another embodiment of the present invention. FIG. 12 is a sectional view taken along the line QQ in FIG. 11. FIG. 13 is a conceptual diagram showing a modification of a diaphragm included in a pressure sensor according to another embodiment of the present invention. FIG. 14 is a conceptual diagram showing an intermediate member and a support member included in a pressure sensor according to another embodiment of the present invention. FIG. 15 is a conceptual diagram showing an intermediate member and a support member included in a pressure sensor according to another embodiment of the present invention.

First to third embodiments, which are preferred embodiments of the present invention, will be described below based on FIGS. 1 to 15. Components common to each embodiment are given the same reference numerals and repeated explanations will be omitted. Note that the left-right direction, front-back direction, and up-down direction in the explanatory text refer to directions along the X, Y, and Z axes shown in each figure, or directions of the pressure sensors 1A, 1B, 1C or diaphragm 10 shown in each figure. Defined as the depth direction, vertical direction, and horizontal direction with respect to the paper surface. Here, the +Z direction is defined to match the direction in which the pressure P of the fluid F to be measured is applied. Furthermore, each figure is a conceptual diagram, and the contents shown in each are not necessarily the same as those of an actual pressure sensor.

<<First embodiment>>
First, a pressure sensor 1A according to a first embodiment of the present invention will be described based on FIGS. 1 to 5.

[Pressure sensor configuration]
First, the configuration of the pressure sensor 1A will be explained based on FIGS. 1 to 4. As shown in FIG. 1, this pressure sensor 1A includes at least a diaphragm 10 and a sensor chip 20A, and further includes a housing 30 that joins to and supports the outer circumference of the diaphragm 10. In the pressure sensor 1A having this configuration, the displacement of the diaphragm 10 which bends upon receiving the pressure P of the fluid F to be measured is detected as an electrical signal (for example, a voltage signal) through the sensor chip 20A. This sensor chip 20A is disposed on the surface of the diaphragm 10 (sensor holding surface 12, which will be described later) via a support member 40A and an intermediate member 50A.

[Diaphragm 10]
As shown in FIG. 1, the diaphragm 10 is a disc-shaped thin plate member, and as described above, the outer peripheral edge 10a of the diaphragm 10 is connected to the housing 30, more specifically, the opening 31 of the housing 30, which will be described later. It is joined to the defining inner peripheral side wall surface 31a by, for example, welding. As a result, the diaphragm 10 forms a thin film partition wall that separates a space formed inside the housing 30 (a space 30V to be described later) from a space V through which the fluid to be measured F flows in and out, as shown in FIG. are doing.

The lower surface of the diaphragm 10 forms a pressure receiving surface 11 that comes into contact with the fluid F to be measured and receives its pressure P. This pressure receiving surface 11 is a portion corresponding to the first main surface described in the claims. Further, on the upper surface thereof, that is, the surface located on the opposite side to the pressure receiving surface 11, as shown in FIGS. 1 to 4, a sensor chip 20A is disposed and held via a support member 40 and an intermediate member 50. A sensor holding surface 12 is formed. This sensor holding surface 12 is a portion corresponding to the second main surface described in the claims.

The diaphragm 10 is made of a material with high corrosion resistance, such as stainless steel (SUS) or titanium. These materials have relatively large coefficients of linear expansion; for example, the coefficient of linear expansion of SUS304 is approximately 17.3/K×10 ⁻⁶ , and the coefficient of linear expansion of titanium is approximately 11.3/K×10 ⁻⁶ . be.

[Sensor chip 20A]
The sensor chip 20A is an element equipped with a circuit that detects mechanical displacement of the diaphragm 10 as an electrical signal, and as described above, is arranged approximately at the center of the sensor holding surface 12 formed on the diaphragm 10. There is. The sensor chip 20A is composed of a substrate made of a semiconductor material such as Si, and a strain gauge made of a Wheatstone bridge circuit formed on the upper surface 20Aa of this substrate. The lengths of the four resistance elements (for example, diffused resistance) included in the Wheatstone bridge circuit change according to the deformation of the diaphragm 10 (more specifically, the deformation of the sensor holding surface 12 of the diaphragm 10 on which it is placed). It is configured so that the resistance value increases or decreases by expanding and contracting. Thereby, deformation of the diaphragm 10 is detected as a change in the voltage value at the midpoint of the Wheatstone bridge circuit.

[Housing 30]
As shown in FIG. 1, the housing 30 is a substantially cylindrical casing element having an opening 31 on the inside, and is made of a metal material with high corrosion resistance, such as stainless steel (SUS). The housing 30 is provided at its lower portion with a ferrule flange portion 30f that connects with the ferrule flange portion Hf of the pipe H so as to protrude radially outward. The pressure sensor 1A and the pipe H are connected to each other by vertically clamping the ferrule flange portion 30f and the ferrule flange portion Hf, which overlap each other, by the clamp C. As described above, the inner circumferential side wall surface 31a of the opening 31 is joined to the outer circumferential edge 10a of the diaphragm 10 at the lower part thereof, and together with the diaphragm 10, more specifically, the sensor holding surface 12 of the diaphragm 10, the fluid to be measured is A cylindrical space 30V is formed which is isolated from the inside of the pipe H through which F flows in and out. This space 30V communicates with the atmosphere, for example, and the above-mentioned sensor chip 20A is placed inside.

[Support member 40A]
The support member 40A is a member that functions as a pillar that supports the sensor chip 20A, and is disposed so as to stand up perpendicularly to the sensor holding surface 12 of the diaphragm 10, as shown in FIGS. Two columnar members (extending along the normal direction (Z-axis direction) of the holding surface 12), specifically, a first support member 41 and a second support member 42 of the same shape formed in a quadrangular prism shape. It consists of The first support member 41 and the second support member 42 are made of an electrically insulating material, preferably a material with low thermal conductivity, such as glass, specifically borosilicate glass (Pyrex, a registered trademark). )). The first support member 41 and the second support member 42 have one end (top) joined to the lower surface 20Ab of the sensor chip 20A, more specifically, near both left and right ends of the lower surface 20Ab, and the other end to the intermediate member 50A. It is joined to the upper surface 50Aa.

The intermediate member 50A is joined to the sensor holding surface 12 of the diaphragm 10, as described later, and the first support member 41 and the second support member 42 are connected to the sensor holding surface 12 of the diaphragm 10 via the intermediate member 50A. It is fixed in the above-mentioned manner (standing vertically). The first support member 41 and the second support member 42 are fixed to two points, a first support point P41A and a second support point P42A, which are symmetrical with respect to the center point P0 of the diaphragm 10, for example, in a plan view. There is. Here, the center point P10 of the diaphragm 10 is the point at which the diaphragm 10 is at its most vertically (Z-axis direction) when a pressure greater than the pressure (for example, atmospheric pressure) applied to the sensor holding surface 12 is applied to the pressure receiving surface 11. Defined as a point with a large displacement. The center point P10 coincides with the geometric center point, as shown in FIG. 3, when the thickness of the disc-shaped diaphragm 10 is uniform and the rigidity is not biased.

[Intermediate material 50A]
The intermediate member 50A is a member interposed between the diaphragm 10 and the support member 40A, and is formed of a thin plate member that is substantially rectangular in plan view, as shown in FIG. 3, for example. The intermediate material 50A is a material whose coefficient of linear expansion is smaller than that of the material forming the diaphragm 10, for example, stainless steel (SUS) (the coefficient of linear expansion of SUS304 is approximately 17.3/K×10 ⁻⁶ ). Preferably, the coefficient of linear expansion is higher than that of the material forming the support member 40A (support members 41, 42), for example, glass (the coefficient of linear expansion of borosilicate glass is approximately 3.0×10 ⁻⁶ ). Made from large pieces of material. An example of this preferred intermediate material 50A is Kovar (the coefficient of linear expansion of Kovar is approximately 5.2/K×10 ⁻⁶ ).

As shown in FIGS. 3 and 4, the intermediate material 50A is located in a region where the diaphragm 10 deforms (deflects) in response to the pressure P of the fluid F to be measured, and its center point coincides with the center point P0 of the diaphragm 10. It is joined to the sensor holding surface 12 by spot welding or the like through the lower surface 50Ab. In addition, the lower ends of the first support member 41 and the second support member 42 of the intermediate member 50A are joined, for example, near both ends of the upper surface 50Aa by spot welding or the like. As a result, the first support member 41 and the second support member 42 are fixed to the first support point P41A and the second support point P42A, which are symmetrical with respect to the center point P0 of the diaphragm 10.

[Operation mode of pressure sensor 1A]
Next, the operation mode of the pressure sensor 1A will be explained based on FIG. 5. FIG. 5 is a diagram schematically showing the displacement of the first support member 41, the second support member 42, the intermediate member 50A, and the sensor chip 20A in the XZ cross section when the diaphragm 10 is deformed.

When a fluid to be measured F having a pressure P greater than the pressure applied to the sensor holding surface 12 (for example, atmospheric pressure) comes into contact with the pressure receiving surface 11, the center point P10 of the diaphragm 10 made of a thin plate member protrudes upward (in the +Z direction). It deforms (deflects) into a roughly conical shape. At this time, the thin film-like intermediate material 50A also deforms (deflects) following the deformation of the diaphragm 10.

A first support that stands approximately perpendicular to the sensor holding surface 12 via an intermediate member 50A and is fixed to a first support point P41A and a second support point P42A that are point-symmetrical and distant from the center point P10. The member 41 and the second support member 42 are each tilted so as to be approximately line symmetrical with respect to the Z axis. As a result, the tops of the first support member 41 and the second support member 42, which are connected to the lower surface 20b of the sensor chip 20A, are both displaced by approximately the same amount in the +Z direction, and one (the first support member 41) is - It is displaced in the X direction, and the other (second support member 42) is displaced in the +X direction (see the arrow in FIG. 5). The amount of displacement in the ±X direction at the top of the first support member 41 and the second support member 42 depends on the height of each support member (specifically, the height from the sensor holding surface 12 to the top of each support member). becomes proportionally larger. That is, the amount of displacement of the diaphragm 10 is amplified by the first support member 41 and the second support member 42 and transmitted to the sensor chip 20A. The sensor chip 20A outputs an electric signal (for example, a voltage signal) according to the amplified displacement amount of the diaphragm 10.

[Effects of pressure sensor 1A]
According to the pressure sensor 1A having the above configuration, as described above, the amount of deformation of the diaphragm 10 is transmitted to the sensor chip 20A through the support member 40A in the form of being amplified in the ±X direction. Therefore, the sensor chip 20A is pulled significantly in the left-right direction (+X direction and −X direction) even with a small pressure change that slightly displaces the diaphragm 10. As a result, the resistance element that constitutes the strain gauge (Wheatstone bridge circuit) provided on the sensor chip 20A is sufficiently displaced (expanded and contracted) to the extent that the output fluctuates, and the pressure of the fluid to be measured is detected with high precision. It becomes possible to do so.

Further, by interposing the intermediate material 50A between the diaphragm 10 and the support member 40A, the coefficient of linear expansion of which is smaller than that of the diaphragm 10 and larger than that of the support member 40A, the bonding residual stress between the two members is reduced. can be reduced. Thereby, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10.

<<Second embodiment>>
Next, a pressure sensor 1B according to a second embodiment of the present invention will be described based on FIGS. 6 to 9.

The pressure sensor 1B is different from the pressure sensor 1A in terms of the number of columnar members constituting the support member 40B, the positions where these members are provided, and the form of the sensor chip 20B supported by the support member 40B (joint with the support member 40B). The structure is the same except for the shape of the intermediate member 50B that fixes the support member 40B to the sensor holding surface 12 of the diaphragm 10.

[Support member 40B]
As shown in FIGS. 6 and 8, the support member 40B includes three columnar members, specifically, the same members as the first support member 41 and the second support member 42 that constitute the support member 40A, and these members. and a third support member 43 having the same shape and made of the same material. Like the support member 40A, the first support member 41 and the second support member 42 constituting the support member 40B have one end (top) of the lower surface 20Bb of the sensor chip 20B described later, more specifically, the lower surface 20Bb. It is joined to the vicinity of both left and right ends (upper surface 51a of the first joint portion 51 and upper surface 52a of the second joint portion 52, which will be described later). Further, the other ends of the first support member 41 and the second support member 42 are joined to the vicinity of both left and right ends of the upper surface of the intermediate member 50B. Furthermore, one end (top) and the other end of the added third support member 43 are located approximately in the center of the lower surface 20Bb of the sensor chip 20B and approximately in the center of the upper surface of the intermediate member 50B (the upper surface 53a of the third joint portion 53, which will be described later). are connected to each other.

[Intermediate material 50B]
The intermediate material 50B is a member interposed between the diaphragm 10 and the support member 40B, and is made of the same material as the intermediate material 50A, that is, a material whose coefficient of linear expansion is smaller than that of the material forming the diaphragm 10. , preferably made of a larger material than the material forming support member 40B. For example, as shown in FIGS. 6 and 8, the intermediate material 50B is composed of a first joint portion 51, a second joint portion 52, a third joint portion 53, and a first joint portion 54 and a second joint portion 55. There is.

The first joint portion 51, the second joint portion 52, and the third joint portion 53 all have the same shape, and are formed, for example, as a substantially rectangular parallelepiped portion. Note that the first joint portion 51, the second joint portion 52, and the third joint portion 53 may have different shapes.

The height (thickness) of the first joint 51 , second joint 52 , and third joint 53 is set to be larger than, for example, the thickness of the diaphragm 10 , and is approximately perpendicular to the sensor holding surface 12 . It is joined to the holding surface in an upright state.

The first joint part 51, the second joint part 52, and the third joint part 53 are connected to the first support member 41, the second support member 42, and the third support member 43 through upper surfaces 51a, 52a, and 53a, for example, by spot welding. It is joined by Further, the first joint portion 51, the second joint portion 52, and the third joint portion 53 are joined to the sensor holding surface 12 through the lower surfaces 51b, 52b, and 53b, respectively, by spot welding, for example. Here, the surface area Su of the upper surfaces 51a, 52a, 53a is set to be equal to or slightly larger than the surface area of the lower end surfaces of the supporting members 41, 42, 43 to be joined. Further, in the present embodiment, the surface area Sd of the lower surfaces 51b, 52b, and 53b is equal to the surface area Su of the upper surfaces 51a, 52a, and 53a, but is made smaller than the surface area Su of the first joint portion 51 and the The shapes of the second joint portion 52 and the third joint portion 53 may be changed. Thereby, the bonding area between the lower surfaces 51b, 52b, 53b and the sensor holding surface 12 becomes smaller, and the influence on the deformation of the diaphragm 10 can be suppressed.

As shown in FIG. 7, the first joint part 51 and the second joint part 52 of the three joint parts are connected to a first support point P41B and a first support point P41B, which are located symmetrically with respect to the center point P10 of the diaphragm 10. The third joint portion 53 is provided at a third support point P43B that coincides with the center point P10. Thereby, the third support member 43 is fixed at the center point P10 (third support point P43B), and the first support member 41 and the second support member 42 are fixed at the center point P0 (third support point P43B) of the diaphragm 10. It will be fixed to the first support point P41B and the second support point P42B, which are located point-symmetrically with respect to the first support point P41B and the second support point P42B.

The first connecting portion 54 and the second connecting portion 55 are both formed as thin film-like members that extend along (parallel to) the sensor holding surface 12 . The first connecting part 54 is connected to the lower end of the first joint part 51 (the end close to the sensor holding surface 12) and the lower end of the second joint part 52, thereby connecting these two parts. Further, the second connecting portion 55 is connected to the lower end portion of the second joint portion 52 and the lower end portion of the third joint portion 53 to connect these two parts. In this way, by forming the first connecting part 54 and the second connecting part 55 as thin film-like members and connecting the lower ends of each joint, relative movement (relative displacement) of each joint can be achieved. is possible. That is, each joint can be individually displaced (moved) following the deformation without interfering with each other (while maintaining a posture perpendicular to the fixed sensor holding surface 12) (Fig. 9 reference). Further, by making the first connecting portion 54 and the second connecting portion 55 into the above-described configuration, even if each connecting portion of the intermediate member 50B is formed as a thick portion, the diaphragm 10 is prevented from deforming due to this. This makes it possible to minimize the influence of deformation (hinder to deformation).

Note that the relative movement (relative displacement) of the joint part is partially regulated depending on the position where the joint part and the connecting part are connected. That is, the relative movement (relative displacement) of the joint can be controlled by the connection position. Therefore, it is desirable to change the connection position as appropriate depending on the position where the sensor chip 20B is disposed. As one of the connection modes having the above-mentioned regulating function, there is a third embodiment (a connection mode of a connecting portion 59 that connects the first joint portion 56 and the third joint portion 58 in the intermediate material 50C), which will be described later.

[Operation mode of pressure sensor 1B]
Next, the operation mode of the pressure sensor 1B will be explained based on FIG. 9. Similar to FIG. 5, FIG. 9 shows the first support member 41, second support member 42, third support member 43, and intermediate member 50B (first joint 51, second joint 52, a third joint portion 53, a first connecting portion 54, a second connecting portion 55), and a diagram schematically showing the displacement of the sensor chip 20B in the XZ cross section.

When a fluid to be measured F having a pressure P greater than the pressure applied to the sensor holding surface 12 (for example, atmospheric pressure) comes into contact with the pressure receiving surface 11, the center point P10 of the diaphragm 10 made of a thin plate member protrudes upward (in the +Z direction). It deforms (deflects) into a roughly conical shape. At this time, the intermediate material 50B having the thin film-like first connecting part 54 and the second connecting part 55 of the above-mentioned form may have the first connecting part 51, the second connecting part 52, and the third connecting part 53 having a large thickness. Even if the diaphragm 10 is deformed by these joints, the joints follow the deformation without interfering with each other (each joint is attached to the sensor holding surface 12 to which it is fixed). deform (move) (while maintaining a vertical posture).

Due to the above deformation (movement) of the intermediate material 50B, the third support member 43, which is erected at the center point P10 (third support point P43B) via the third joint 53 of the intermediate material 50B, moves along the Z-axis. It is displaced (specifically, it is displaced in the +Z direction). As a result, the top of the third support member 43 that is joined to the lower surface 20b of the sensor chip 20B is displaced in the +Z direction by an amount that is approximately the same as the amount of displacement of the diaphragm 10. Also, a first support point P41B stands up substantially perpendicularly to the sensor holding surface 12 via the first joint 51 and the second joint 52 of the intermediate material 50B, and is located at a point-symmetrical position and away from the center point P10. The first support member 41 and the second support member 42 fixed to the second support point P42B are each tilted so as to be approximately symmetrical with respect to the Z-axis. As a result, the tops of the first support member 41 and the second support member 42, which are connected to the lower surface 20b of the sensor chip 20B, are both displaced by approximately the same amount in the +Z direction, and one (the first support member 41) is - It is displaced in the X direction, and the other (second support member 42) is displaced in the +X direction. As described above, the amount of displacement of the tops of the first support member 41 and the second support member 42 in the ±X direction is determined by the height of each support member (specifically, from the sensor holding surface 12 to the top of each support member). height). That is, the amount of displacement of the diaphragm 10 is transmitted to the sensor chip 20B in a form that is amplified by the first support member 41 and the second support member 42.

[Effect of pressure sensor 1B]
According to the pressure sensor 1B having the above configuration, as described above, the amount of deformation of the diaphragm 10 is amplified in the ±X direction through the first support member 41 and the second support member 42 of the support member 40B, and the third support member 43 The displacement in the +Z direction is transmitted to the sensor chip 20B through the sensor chip 20B. The amount of deformation transmitted to this sensor chip 20B is larger than that of the sensor chip 20A by the displacement in the +Z direction. Therefore, even with a small pressure change that slightly displaces the diaphragm 10, the sensor chip 20B is pulled significantly in the left-right direction (+X direction and −X direction) and in the +Z direction. As a result, the resistance element that constitutes the strain gauge (Wheatstone bridge circuit) provided on the sensor chip 20B is sufficiently displaced (expanded and contracted) to the extent that the output fluctuates, and the pressure of the fluid to be measured is detected with high precision. It becomes possible to do so.

Furthermore, by interposing the intermediate material 50B between the diaphragm 10 and the support member 40B, the coefficient of linear expansion of which is smaller than that of the diaphragm 10 and larger than that of the support member 40B, it is possible to prevent bonding between the two members. Stress can be reduced. Thereby, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10. This effect is due to the joints that are thicker than the diaphragm 10 and have a large heat capacity, that is, the first joint 51, the second joint 52, and the third joint that have a large effect of thermally isolating the diaphragm 10 and the support member 40B. The provision of the joint portion 53 makes this more noticeable.

Furthermore, since the connecting portions (first connecting portion 54 and second connecting portion 55) are provided in the intermediate member 50B, even if the connecting portion has a large height (thickness) as described above, the diaphragm 10 can be Obstruction of deformation can be suppressed as much as possible. Thereby, it is possible to achieve both the effect of reducing the bonding residual stress and the measurement accuracy (sensitivity) at a high level.

Furthermore, since the intermediate material 50B is formed as one component, the number of components is reduced and ease of assembly is improved. For example, when placing an intermediate material in which each joint is configured as an individual component at three support points (first support point P41B, second support point P42B, third support point P43B, etc.), each support point (3 However, if the intermediate material is formed from one part, positioning at two support points is sufficient. Thereby, deterioration (variation) in assembly accuracy can be suppressed.

<<Third embodiment>>
Next, a pressure sensor 1C according to a third embodiment of the present invention will be described based on FIGS. 10 to 13.

The pressure sensor 1C is different from the pressure sensor 1B in the form and fixing position of the intermediate member 50C interposed between the sensor holding surface 12 of the diaphragm 10 and the support member 40B (in this relationship, the support member 40B and the sensor The position where the chip 20B is arranged is also different), but the other configurations are the same.

[Intermediate material 50C]
The intermediate material 50C, like the intermediate materials 50A and 50B in the above embodiment, is formed from a material whose coefficient of linear expansion is smaller than that of the material forming the diaphragm 10, and preferably, the coefficient of linear expansion is smaller than that of the material forming the support member 40B. Made from large pieces of material. The intermediate material 50C is composed of a first joint part 56, a second joint part 57, a third joint part 58, and a connecting part 59, as shown in FIGS. 10 and 12, for example.

The first joint portion 56, the second joint portion 57, and the third joint portion 58 all have the same shape, and for example, are vertically sectioned so that the joint surface with the sensor holding surface 12 is smaller than the joint surface with the support member 40B. The surface shape (cross-sectional shape on the XZ plane) is formed as an inverted trapezoidal hexahedron. However, the shape is not limited to this, and the first joint portion 56, second joint portion 57, and third joint portion 58 may have different shapes.

The height (thickness) of the first joint portion 56 , second joint portion 57 , and third joint portion 58 is set to be larger than, for example, the thickness of the diaphragm 10 , and the heights (thicknesses) of the first joint portion 56 , the second joint portion 57 , and the third joint portion 58 are set to be larger than, for example, the thickness of the diaphragm 10 . It is joined to the holding surface in an upright state. Note that although the first joint 56 and the third joint 58 are integrally connected through the connecting part 59, the first joint 56, the third joint 58, and the second joint 57 are separate bodies. It is formed as.

The first joint portion 56, the second joint portion 57, and the third joint portion 58 are connected to the first support member 41, the second support member 42, and the third support member 43 that constitute the support member 40B, and the upper surfaces 56a, 57a, and 58a. For example, they are joined by spot welding. Further, the first joint portion 56, the second joint portion 57, and the third joint portion 58 are joined to the sensor holding surface 12 through the lower surfaces 56b, 57b, and 58b, respectively, by spot welding, for example. Here, the surface area Su of the upper surfaces 56a, 57a, 58a is set to be equal to or slightly larger than the surface area of the lower end surfaces of the supporting members 41, 42, 43 to be joined. Moreover, the surface area Sd of the lower surfaces 56b, 57b, and 58b is formed to be smaller than the surface area Su of the upper surfaces 51a, 52a, and 53a, as described above. With this configuration, it is stably joined to the support members 41, 42, and 43, and the joint area with the sensor holding surface 12 is reduced, which affects the deformation of the diaphragm 10 (i.e., prevents deformation). ) can be suppressed.

As shown in FIG. 11, the first joint portion 56 is disposed at a first support point P41C that coincides with the center point P10 of the diaphragm 10, and the second joint portion 57 is located on the X-axis from the center point P10. The third joint 58 is also disposed at a second support point P42C closer to +X, and the third joint 58 is located at a third support point P43C located on the X axis between the first support point P41C and the second support point P42C. It is arranged. As a result, the first support member 41 is fixed at the center point P10 (first support point P41C), and the second support member 42 and the third support member 43 are both located on the X axis and at the center point of the diaphragm 10. It will be fixed to the second support point P42C and the third support point P43C located on the same side (+X side) with respect to P0.

As shown in FIG. 12, the connecting portion 59 is formed as a thin film-like portion extending along (parallel to) the sensor holding surface 12, and connects the upper end of the first connecting portion 56 and the upper end of the third connecting portion 58. The parts are integrally connected. The connecting part 59 of this form has a relation to the relative movement (relative displacement) between the first joint part 56 and the third joint part 58 to be connected, in the direction in which the pressure P of the fluid to be measured F is applied (the direction along the Z axis). ) is not restricted, but is controlled to be restricted in a plane perpendicular to the direction (in the XY plane). As a result, the third joint portion 58 moves (displaces) within the XY plane so as to follow the first joint portion 56 .

In this embodiment, the shape of the joint is such that the joint area with the sensor holding surface 12 as described above is small, and the first joint 56 and the third joint 58 are connected to the second joint. By forming the portion 57 as a separate body, the influence on the deformation of the diaphragm 10 (obstruction of deformation) is suppressed to a small level.

[Operation mode of pressure sensor 1C]
Next, the operation mode of the pressure sensor 1C will be explained based on FIG. 13. FIG. 13 shows the first support member 41, second support member 42, third support member 43, and intermediate member 50C (first joint 56, second joint 57, third joint) when the diaphragm 10 is deformed. 58, a connecting portion 59), and a diagram schematically showing the displacement of the sensor chip 20B in the XZ cross section.

When a fluid to be measured F having a pressure P greater than the pressure applied to the sensor holding surface 12 (for example, atmospheric pressure) comes into contact with the pressure receiving surface 11, the center point P10 of the diaphragm 10 made of a thin plate member protrudes upward (in the +Z direction). It deforms into a roughly conical shape. At this time, the area near the center point P10 is formed as a hemispherical curved surface with a large curvature, and the area outside that area is a curved surface close to a truncated conical surface. Therefore, the portion outside the vicinity of the center point P10 is formed as a slope with substantially equal inclination in the XZ cross section.

Of the intermediate material 50C disposed on the surface (sensor holding surface 12) of the diaphragm 10 undergoing the above-mentioned deformation, the first joint portion 56 is disposed at the center point P10 (first support point P41C); move (displace) in the direction along (+Z direction).
Further, the second joint portion 57 is attached to a second support point P42C located on the +X side with respect to the center point P0 of the diaphragm 10 on the Therefore, it moves (displaces) in a direction perpendicular to the slope, for example, along an axis Z' inclined at an angle α with respect to the Z axis.
On the other hand, although the third joint part 58 is disposed at the third support point P43C, which is located on the slope like the second support point P42C, it can be moved in the +Z direction via the connection part 59 having the control function. Since it is connected to the first joint portion 56 that is displaced, movement (displacement) in the XY plane is restricted. Therefore, the third joint 58 is formed in a direction closer to the first joint 56 than in a direction perpendicular to the slope (axis Z'), that is, at an angle β (β<α) with respect to the Z axis. This results in movement (displacement) in the direction along the axis Z'' that is tilted by the amount.

In this way, the first joint part 56, the second joint part 57, and the third joint part 58 can move (displace) in different directions (directions along the axis Z, axis Z', and axis Z''). Therefore, the first support member 41, second support member 42, and third support member 43 that are connected to the upper surface of each joint are also moved in different directions (directions along the axis Z, axis Z', and axis Z''). It will move (displace). In other words, relative displacement occurs between the tops of these three support members in the X direction and the Z direction before and after the diaphragm 10 is deformed. The relative displacement in the two directions is transmitted to the sensor chip 20. Here, as described above, the relative displacement in the X direction increases in proportion to the height of each support member (specifically, the height from the sensor holding surface 12 to the top of each support member). That is, the amount of displacement of the diaphragm 10 is transmitted to the sensor chip 20 in a form that is amplified by the first support member 41, the second support member 42, and the third support member 43.

[Effect of pressure sensor 1C]
When the intermediate member 50C is not provided, that is, when the support member 40B is directly erected on the sensor holding surface 12 of the diaphragm 10, the first support member 41 and the second support member that constitute the support member 40B 42 and the third support member 43 are displaced in a direction perpendicular to the sensor holding surface 12. In this case, in the form in which the second support member 42 and the third support member 43 are erected on the slope located outside the vicinity of the center point P10, these two support members both move in the same direction ( (direction along the Z' axis). In this displacement mode, there is no relative displacement between the top of the second support member 42 and the top of the third support member 43 before and after the diaphragm 10 is deformed. That is, in the above embodiment, the area of the sensor chip 20B supported by these two support members does not displace (expand or contract) before or after the diaphragm 10 is deformed. Therefore, in the above embodiment, the pressure of the fluid to be measured cannot be detected with high accuracy.

On the other hand, according to the pressure sensor 1C having the above configuration, as described above, the second support member 42 and the third support member 43 are erected on the slope located outside the vicinity of the center point P10. is also amplified between the tops of these two support members according to the relative displacement in the Z direction and the height of each support member (specifically, the height from the sensor holding surface 12 to the top of each support member). A relative displacement in the X direction occurs, and this is transmitted to the sensor chip 20. Therefore, according to the pressure sensor 1C having the above configuration, even in response to a small pressure change that slightly displaces the diaphragm 10, the entire area of the sensor chip 20 is significantly pulled in the X direction and the Z direction. As a result, the resistance element that constitutes the strain gauge (Wheatstone bridge circuit) provided in the sensor chip 20 is displaced (expanded and contracted) to such an extent that the output fluctuates, making it possible to detect the pressure of the fluid to be measured with high precision. becomes possible.

In addition, by interposing the intermediate material 50C between the diaphragm 10 and the support member 40B, the coefficient of linear expansion of which is smaller than that of the diaphragm 10 and larger than that of the support member 40B, it is possible to prevent bonding between the two members. Stress can be reduced. Thereby, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10. This effect is due to the joints formed thicker than the diaphragm 10 and having a large heat capacity, that is, the first joint 56, the second joint 57, and the third joint that have a large effect of thermally isolating the diaphragm 10 and the support member 40B. The provision of the joint portion 58 makes this more noticeable.

Further, as described above, the shape of each joint is such that the joint area with the sensor holding surface 12 is small, and the first joint 56 and the third joint 58 are separated from the second joint 57. By forming the intermediate member 50C as a body, it is possible to suppress as much as possible the influence on the deformation of the diaphragm 10 (obstructing the deformation) due to the provision of the intermediate member 50C. Thereby, it is possible to achieve both the effect of reducing the bonding residual stress and the measurement accuracy (sensitivity) at a high level.

≪Modification example≫
As an example of a partially modified version of the above embodiment, there is an intermediate material 50B' shown in FIG. 14, for example. This intermediate material 50B' corresponds to the intermediate material 50B in the second embodiment from which the first connecting part 54 and the second connecting part 55 are removed, and includes a first joint part 51', a second joint part 52 ' and a third joint part 53'. Note that the other configurations are the same as the intermediate material 50B.

According to the pressure sensor equipped with the intermediate material 50B' having the above configuration, compared to the pressure sensor 1B equipped with the intermediate material 50B, the influence on the deformation of the diaphragm 10 due to the provision of the intermediate material (which hinders the deformation) ) can be made smaller.

Furthermore, as an example of a partially modified version of the above embodiment, there is an intermediate material 50C' shown in FIG. 15, for example. This intermediate material 50C' is a two-layer structure of the intermediate material 50C in the third embodiment. Specifically, the first joint part 56', the second joint part 57', and the third joint part have a lower overall height of the first joint part 56, the second joint part 57, and the third joint part 58 that constitute the intermediate material 50C. A fourth joint part 56'', a fifth joint part 57'', and a sixth joint part each having a substantially rectangular parallelepiped bottom surface having a shape complementary to the top surface of the portion 58' (the surface joined to the support member 40B). 58'', and further provided with a second connecting portion 59'' that integrally connects the upper ends of the fourth joint portion 56'' and the sixth joint portion 58''.

The linear expansion coefficients of the materials forming the fourth joint 56'', the fifth joint 57'', the sixth joint 58'', and the second joint 59'' are as follows: It is smaller than that of the material forming the joint part 57', the third joint part 58', and the first connecting part 59', and larger than that of the material forming the support member 40B. Thereby, bonding residual stress that occurs when fixing the support member 40B to the surface of the diaphragm 10 (sensor holding surface 12) can be further reduced.

Further, by providing a multiplexed connection section consisting of the first connection section 59' and the second connection section 59'', the connection strength and connection rigidity are increased. As a result, the relative movement (relative displacement) between the two connected joints, for example, in the plane perpendicular to the direction in which the pressure P of the fluid to be measured F is applied (direction along the Z axis) (in the XY plane The relative movement (relative displacement) of the inside) can be more reliably regulated.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various changes can be made without departing from the gist thereof. Further, even if the configuration is not directly described in the specification or drawings, it is within the scope of the technical idea of the present invention as long as it achieves the functions and effects of the present invention. Further, the embodiments described above and shown in the figures can be combined with each other as long as there is no contradiction in purpose, structure, etc.

For example, in the above embodiment, a semiconductor chip including a strain gauge is used as a pressure detection method (sensing principle) using diaphragm deformation, but the invention is not limited to this. For example, a capacitive sensor, A pressure detection method (sensing principle) using a metal strain gauge or resistance gauge formed into a film by sputtering or the like may be used.

1A, 1B, 1C...pressure sensor, 10...diaphragm, 11...pressure receiving surface, 12...sensor holding surface, 20A, 20B...sensor chip, 30...housing, 40A, 40B...support member, 41...first support member, 42 ...Second support member, 43...Third support member, 50A, 50B, 50C...Intermediate material, 51, 56...First joint part, 52, 57...Second joint part, 53, 58...Third joint part, 54 ...first connection part, 55...second connection part, 59...connection part.

Claims (9)

a diaphragm having a first main surface that receives the pressure of the fluid to be measured and a second main surface located on the opposite side of the first main surface;
A sensor chip equipped with multiple resistors forming a strain gauge;
a plurality of electrically insulating support members extending along the normal line of the second main surface and having one end joined to the sensor chip;
Equipped with
The plurality of supporting members are joined to an intermediate material having a coefficient of linear expansion smaller than that of the diaphragm and fixed to the second main surface via this intermediate material ,
The intermediate material includes a plurality of joint parts joined to the plurality of support members and a connecting part connecting at least two of the plurality of joint parts, and the thickness of the connecting part along the normal line is equal to the thickness of the connecting part along the normal line. A pressure sensor formed to have a thickness smaller than the thickness of the plurality of joints . a diaphragm having a first main surface that receives the pressure of the fluid to be measured and a second main surface located on the opposite side of the first main surface;
A sensor chip equipped with multiple resistors forming a strain gauge;
a plurality of electrically insulating support members extending along the normal line of the second main surface and having one end joined to the sensor chip;
Equipped with
The plurality of supporting members are joined to an intermediate material having a coefficient of linear expansion smaller than that of the diaphragm and fixed to the second main surface via this intermediate material,
A pressure sensor in which a bonding area between the intermediate material and the second main surface is smaller than a bonding area between the intermediate material and the support member. The pressure sensor according to claim 1 or 2,
In the pressure sensor, the intermediate material is made of a material having a higher coefficient of linear expansion than the support member. The pressure sensor according to claim 2 or claim 3 citing claim 2,
The intermediate material includes a plurality of joint parts joined to the plurality of support members and a connecting part connecting at least two of the plurality of joint parts, and the thickness of the connecting part along the normal line is equal to the thickness of the connecting part along the normal line. A pressure sensor formed to have a thickness smaller than the thickness of the plurality of joints. A pressure sensor according to any one of claims 1 and 3 and 4 referring to claim 1,
In the pressure sensor, the connecting portion is formed as a thin film thinner than the plate thickness of the diaphragm. The pressure sensor according to any one of claims 1 to 5,
A pressure sensor in which the plurality of support members are fixed to the second main surface via at least two intermediate members spaced apart from each other. The pressure sensor according to claim 6,
The intermediate member is a pressure sensor provided so as to be paired with the support member. A pressure sensor according to claim 1 and any one of claims 3 to 7 referring to claim 1,
A pressure sensor in which a bonding area between the intermediate material and the second main surface is smaller than a bonding area between the intermediate material and the support member. The pressure sensor according to any one of claims 1 to 8,
The intermediate material is made of a plurality of materials having different coefficients of linear expansion, and the materials are subjected to the method so that the coefficient of linear expansion decreases from the side where the material is bonded to the second main surface to the side where it is bonded to the sensor chip. Pressure sensors stacked along a line.

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