JP2021131297A - Pressure sensor - Google Patents

Abstract

To provide a pressure sensor, with which the minute deflection of a diaphragm is efficiently transmitted to a sensing unit through a support member that supports sensing, and a decrease in pressure-resisting performance due to a residual joint stress between the diaphragm and the support member is suppressed.MEANS FOR SOLVING THE PROBLEM: Provided is a pressure sensor 1A comprising: a diaphragm 10 having a pressure-receiving face 11 that receives the pressure of the fluid to be measured and a sensor holding face 12; a sensor chip 20A in which a plurality of resistors constituting a strain gauge are provided; and a plurality of electrically insulating support members 41, 42 extended along the normal of the holding face 12 and joined at one end to the sensor chip 20A. The plurality of support members 41, 42 are joined to an intermediate member 50A, the linear expansion coefficient of which is smaller than that of the diaphragm 10, and fixed to the sensor holding face 12 via this intermediate member 50A.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pressure sensor that detects the pressure of a fluid or the like, particularly a pressure sensor for sanitary use.

Of the pressure sensors that detect the pressure of fluids, sanitary pressure sensors used at manufacturing sites in the fields of foods and pharmaceuticals require hygienic consideration, so corrosion resistance, cleanliness, etc. Strict requirements are imposed on reliability and versatility. Such requirements have become even more stringent in recent years when laws and regulations related to hygiene management have been tightened.

In a sanitary pressure sensor in such a situation, for example, due to the requirement of corrosion resistance, stainless steel (SUS), ceramics, titanium, etc. have high corrosion resistance to the wetted portion where the fluid (for example, liquid) whose pressure is to be measured comes into contact. The material is used. Further, due to the requirement of cleanliness, a flash diaphragm structure that is easy to clean is adopted, and it is designed to have high heat and shock resistance to steam cleaning. Further, due to reliability requirements, a structure that does not use an encapsulant (oil-free structure) and a structure in which the diaphragm is not easily torn (barrier high rigidity) are adopted.

As described above, in the sanitary pressure sensor, the materials and structures used are limited as compared with other pressure sensors. Therefore, it is not easy to further increase the sensitivity while having high withstand voltage performance and suppressing measurement error. For example, in order to have high pressure resistance and reduce hysteresis with respect to pressure to suppress measurement error, it is useful to use a high-rigidity diaphragm with a large film thickness (decreased aspect ratio of diameter to thickness). However, in such a high-rigidity diaphragm, the amount of deformation with respect to a pressure change is very small, and sufficient sensor sensitivity cannot be obtained only by directly sensing this. For this reason, some techniques have been proposed in which a minute amount of deformation of the diaphragm is efficiently transmitted to the sensing unit to increase the sensor sensitivity.

For example, in Patent Document 1, three support members (2a, 2b, 2c) are erected at predetermined positions on the support surface (3B) of the diaphragm (3), and a semiconductor chip is placed on these support members. The pressure sensor (100) is described. In this pressure sensor (100), the minute deflection of the diaphragm (3) is efficiently transmitted to the semiconductor chip (1), which is the sensing unit, through the three support members (2a, 2b, 2c) (specifically). The semiconductor chip 1 is configured to be significantly distorted as compared with the case where the semiconductor chip 1 is directly provided on the support surface 3B), so that the sensor sensitivity is enhanced. The three support members (2a, 2b, 2c) included in the pressure sensor (100) all stand up substantially 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 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 the pedestal, and the pedestal is further erected. A pressure sensor (100) in which a semiconductor chip (1) is placed on a support member and another support member is described. In this pressure sensor (100), the sensor sensitivity is enhanced by efficiently transmitting the minute deflection of the diaphragm (3) to the semiconductor chip (1) which is a sensing unit through the pedestal and the support member. ..

JP-A-2017-120214 JP-A-2017-120212

In the pressure sensor described in Reference 1 above, for example, the diaphragm is made of stainless steel having 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 an insulating property. 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 ). A joint residual stress (tensile residual stress) is generated at a portion where two members having such a large difference in linear expansion coefficient are joined. This joint residual stress becomes more prominent as the coefficient of linear expansion of the two materials to be joined increases, resulting in a situation in which the strength of the diaphragm and the support member is lowered and the pressure resistance performance of the diaphragm is deteriorated. This situation is one of the technical issues that must be resolved urgently in view of the current situation where laws and regulations related to hygiene management are being tightened.

The present invention has been created to solve the above problems, and an object of the present invention is to efficiently transmit a minute deflection of the diaphragm 3 to the sensing portion through a support member, and to reduce the pressure resistance performance due to the joint residual stress. Is to provide a suppressed pressure sensor.

The pressure sensor (1A, 1B, 1C) according to the present invention for solving the above problems is located on the opposite side of the first main surface (11) that receives the pressure of the fluid to be measured and the first main surface. A diaphragm (10) having two main surfaces (12), sensor chips (20A, 20B) provided with a plurality of resistors constituting a strain gauge, and extending along the normal line of the second main surface. Further, the plurality of electrically insulating support members (41, 42) having one end bonded to the sensor chip are provided, and the plurality of support members are intermediate members (50A, 50B) having a linear expansion rate smaller than that of the diaphragm. , 50C) and fixed to the second main surface via the intermediate material.

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

Further, in the pressure sensor, the intermediate material connects a plurality of joints (51, 52, 53, 56, 57, 58) to be joined to the plurality of support members and at least two of the plurality of joints. It may be formed so as to be composed of portions (54, 55, 59) so that the thickness of the connecting portion along the normal line is smaller than the thickness of the plurality of joint portions.

Further, in the pressure sensor, the connecting portion may be formed as a thin film thinner than the plate 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 separated from each other.

Further, in the pressure sensor, the intermediate material may be provided so as to form a pair with the support member.

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

Further, in the pressure sensor, the intermediate material is composed of a plurality of materials having different linear expansion coefficients, and the material linearly expands from the side joined with the second main surface toward the side joined with the sensor chip. It may be laminated along the normal line so that the ratio becomes small.

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

According to the present invention, it is possible to provide a pressure sensor in which a decrease in pressure resistance performance due to joint residual stress is suppressed while efficiently transmitting a minute deflection of the diaphragm 3 to a sensing unit through a support member.

FIG. 1 is a cross-sectional view of a pressure sensor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of a pressure sensor according to an embodiment of the present invention and a pipe joined to the pressure sensor. 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 cross-sectional view taken along the line QQ in FIG. FIG. 5 is a conceptual diagram showing a modified mode of the diaphragm included in the pressure sensor according to the embodiment of the present invention. FIG. 6 is a cross-sectional view of a pressure sensor according to another embodiment of the present invention. FIG. 7 is an enlarged plan view of the vicinity of the diaphragm included in the 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 modified mode of the diaphragm included in the pressure sensor according to another embodiment of the present invention. FIG. 10 is a cross-sectional view of a pressure sensor according to another embodiment of the present invention. FIG. 11 is an enlarged plan view of the vicinity of the diaphragm included in the pressure sensor according to another embodiment of the present invention. FIG. 12 is a cross-sectional view taken along the line QQ in FIG. FIG. 13 is a conceptual diagram showing a modified mode of the diaphragm included in the pressure sensor according to another embodiment of the present invention. FIG. 14 is a conceptual diagram showing an intermediate material and a support member included in the pressure sensor according to another embodiment of the present invention. FIG. 15 is a conceptual diagram showing an intermediate material and a support member included in the pressure sensor according to another embodiment of the present invention.

Hereinafter, the first to third embodiments, which are preferred embodiments of the present invention, will be described with reference to FIGS. 1 to 15. The components common to each embodiment are designated by the same reference numerals and the repeated description is omitted. In the description, the horizontal direction, the front-rear direction, and the vertical direction are the directions along the X, Y, and Z axes shown in each figure, or the pressure sensors 1A, 1B, 1C, or the diaphragm 10 shown in each figure. It is defined as the depth direction, the vertical direction, and the horizontal direction with respect to the paper surface, respectively. Here, the + Z direction is defined so as to coincide with the direction in which the pressure P of the fluid F to be measured is applied. Further, each diagram is a conceptual diagram, and the content shown in each diagram is not necessarily the same as the actual pressure sensor.

<< First Embodiment >>
First, the pressure sensor 1A according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 5.

[Composition of pressure sensor]
First, the configuration of the pressure sensor 1A will be described with reference to FIGS. 1 to 4. As shown in FIG. 1, the pressure sensor 1A includes at least a diaphragm 10 and a sensor chip 20A, and further includes a housing 30 that joins and supports the outer peripheral portion of the diaphragm 10. In the pressure sensor 1A having this configuration, the displacement of the diaphragm 10 that receives the pressure P of the fluid F to be measured and bends is detected as an electric signal (for example, a voltage signal) through the sensor chip 20A. The sensor chip 20A is arranged on the surface of the diaphragm 10 (sensor holding surface 12 described later) via the support member 40A and the intermediate member 50A.

[Diaphragm 10]
As shown in FIG. 1, the diaphragm 10 is a disk-shaped thin plate member, and as described above, the outer peripheral edge 10a thereof forms a housing 30, and more specifically, an opening 31 of a housing 30, which will be described later. It is joined to the inner peripheral side wall surface 31a to be defined by welding, for example. As a result, as shown in FIG. 2, the diaphragm 10 forms a thin-film partition wall that isolates the space formed inside the housing 30 (the space 30V described later) and the space V into which the fluid F to be measured flows in and out. 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 the pressure P. The pressure receiving surface 11 is a portion corresponding to the first main surface described in the claims. Further, as shown in FIGS. 1 to 4, the sensor chip 20A is arranged and held on the upper surface thereof, that is, the surface located on the side opposite to the pressure receiving surface 11, via the support member 40 and the intermediate member 50. The sensor holding surface 12 is formed. The sensor holding surface 12 is a portion corresponding to the second main surface described in the claims.

The diaphragm 10 is made of a highly corrosion resistant material, such as stainless steel (SUS) or titanium. These materials have a relatively large coefficient of linear expansion, for example, the coefficient of linear expansion of SUS304 is about 17.3 / K × ^10-6 , and the coefficient of linear expansion of titanium is about 11.3 / K × ^10-6 . be.

[Sensor chip 20A]
The sensor chip 20A is an element provided with a circuit for detecting the mechanical displacement of the diaphragm 10 as an electric signal, and is arranged substantially in the center of the sensor holding surface 12 formed on the diaphragm 10 as described above. There is. The sensor chip 20A is composed of, for example, 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 the substrate. The four resistance elements (for example, diffusion resistance) included in the Wheatstone bridge circuit are displaced in length according to the deformation of the diaphragm 10 (more specifically, the deformation of the sensor holding surface 12 of the mounted diaphragm 10). It is configured so that the resistance value increases or decreases by (expanding and contracting). As a result, the 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 inside, and is made of a metal material having high corrosion resistance, for example, stainless steel (SUS). The housing 30 is provided with a ferrule flange portion 30f to be joined to the ferrule flange portion Hf of the pipe H so as to project outward in the radial direction at the lower portion thereof. The pressure sensor 1A and the pipe H are connected to each other by vertically overlapping the ferrule flange portion 30f and the ferrule flange portion Hf being sandwiched in the vertical direction by the clamp C. As described above, the inner peripheral side wall surface 31a of the opening 31 is joined to the outer peripheral edge 10a of the diaphragm 10 at the lower portion thereof, and together with the diaphragm 10, more specifically, the sensor holding surface 12 of the diaphragm 10, the fluid to be measured. It forms a columnar space 30V 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 arranged inside.

[Support member 40A]
The support member 40A is a member that functions as a pillar that supports the sensor chip 20A, and is arranged so as to stand upright with respect to the sensor holding surface 12 of the diaphragm 10 as shown in FIGS. 1 to 4. Two columnar members (extended along the normal direction (Z-axis direction) of the holding surface 12), specifically, a first support member 41 and a second support member 42 having the same shape formed in a square columnar shape. It is composed of. The first support member 41 and the second support member 42 are made of an electrically insulating material, preferably a material having a low thermal conductivity, for example, glass, specifically borosilicate glass (Pyrex, registered trademark). )) Is formed from. One end (top) of the first support member 41 and the second support member 42 is joined to the lower surface 20Ab of the sensor chip 20A, more specifically, to the vicinity of the left and right ends of the lower surface 20Ab, and the other end is the intermediate member 50A. It is joined to the upper surface 50Aa.

As will be described later, the intermediate member 50A is joined to the sensor holding surface 12 of the diaphragm 10, 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. Is fixed in the above mode (vertically standing mode). The first support member 41 and the second support member 42 are fixed to two first support points P41A and a second support point P42A that are point-symmetric with respect to the center point P0 of the diaphragm 10 in a plan view, for example. There is. Here, the center point P10 of the diaphragm 10 means that the diaphragm 10 is most vertically (Z-axis direction) in a state where a pressure larger than the pressure applied to the sensor holding surface 12 (for example, atmospheric pressure) is applied to the pressure receiving surface 11. It is defined as a point that is greatly displaced. The center point P10 coincides with the geometric center point as shown in FIG. 3 when the thickness of the disk-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, for example, a thin plate member having a substantially rectangular shape in a plan view, as shown in FIG. The intermediate material 50A is a material whose linear expansion coefficient is smaller than that of a material forming the diaphragm 10, for example, a linear expansion coefficient of stainless steel (SUS) (the linear expansion coefficient of SUS304 is about 17.3 / K × ^10-6). It is formed from, preferably, rather than the material forming the support member 40A (support members 41, 42), for example, the coefficient of linear expansion of glass (the coefficient of linear expansion of borosilicate glass is about 3.0 × ^10-6). It is made of a large material. Examples of the intermediate material 50A having this preferred form include Kovar (the coefficient of linear expansion of Kovar is about 5.2 / K × ^10-6 ).

As shown in FIGS. 3 and 4, the intermediate material 50A is in a region where the diaphragm 10 receives the pressure P of the fluid to be measured and deforms (deflects), 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 at the position where the sensor is to be formed. Further, in the intermediate member 50A, for example, the lower ends of the first support member 41 and the second support member 42 are joined to the vicinity of 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 located at positions symmetrical with respect to the center point P0 of the diaphragm 10.

[Operation mode of pressure sensor 1A]
Subsequently, the operation mode of the pressure sensor 1A will be described with reference to FIG. FIG. 5 is a diagram schematically showing the displacements 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 the fluid F to be measured, which has a pressure P larger 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 projects upward (+ Z direction). It deforms (deflects) into a substantially conical shape. At this time, the thin film intermediate material 50A is also deformed (deflected) following the deformation of the diaphragm 10.

A first support that stands substantially 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 at a point-symmetrical position and away from the center point P10. The member 41 and the second support member 42 are tilted so as to be substantially 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 joined to the lower surface 20b of the sensor chip 20A, are both displaced by approximately the same amount in the + Z direction, and one (first support member 41) is −. The other (second support member 42) is displaced in the + X direction while being displaced in the X direction (see the arrow in FIG. 5). The amount of displacement in the ± X direction at the tops of the first support member 41 and the second support member 42 is the height of each support member (specifically, the height from the sensor holding surface 12 to the top of each support member). It grows proportionally. That is, the displacement amount of the diaphragm 10 is transmitted to the sensor chip 20A in a form amplified by the first support member 41 and the second support member 42. The sensor chip 20A outputs an electric signal (for example, a voltage signal) corresponding to the displacement amount of the amplified diaphragm 10.

[Effect 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 in the form of being amplified in the ± X direction through the support member 40A. Therefore, the sensor chip 20A is greatly pulled in the left-right direction (+ X direction and −X direction) even for a small pressure fluctuation that slightly displaces the diaphragm 10. As a result, the resistance element constituting 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 accuracy. Will be possible.

Further, an intermediate member 50A having a linear expansion coefficient smaller than that of the diaphragm 10 and larger than that of the support member 40A is interposed between the diaphragm 10 and the support member 40A, so that the joint residual stress between the two members is interposed. Can be reduced. As a result, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10.

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

Compared with the pressure sensor 1A, the pressure sensor 1B has the number of columnar members constituting the support member 40B, the positions where they are provided, and the form of the sensor chip 20B supported by the support member 40B (joining with the support member 40B). The form of the portion) and the form of the intermediate member 50B for fixing the support member 40B to the sensor holding surface 12 of the diaphragm 10 are different, and the configurations other than these are the same.

[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 constituting the support member 40A, and these members. It is composed of a third support member 43 having the same shape and the same material as the above. Similar to 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 (the upper surface 51a of the first joint 51 and the upper surface 52a of the second joint 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 the left and right ends of the upper surface of the intermediate member 50B. Further, one end (top) and the other end of the added third support member 43 are substantially the center of the lower surface 20Bb of the sensor chip 20B and the substantially center of the upper surface of the intermediate member 50B (the upper surface 53a of the third joint portion 53 described later). It is joined to each.

[Intermediate material 50B]
The intermediate member 50B is a member interposed between the diaphragm 10 and the support member 40B, and is formed of the same material as the intermediate member 50A, that is, a material whose linear expansion coefficient is smaller than that of the material forming the diaphragm 10. , Preferably made of a material larger than the material forming the support member 40B. As shown in FIGS. 6 and 8, for example, the intermediate member 50B is composed of a first joint portion 51, a second joint portion 52 and 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 as, for example, substantially rectangular parallelepiped portions. The shapes of the first joint portion 51, the second joint portion 52, and the third joint portion 53 may be different.

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

The first joint portion 51, the second joint portion 52, and the third joint portion 53 are, for example, spot welded through the first support member 41, the second support member 42, and the third support member 43, respectively, through the upper surfaces 51a, 52a, and 53a. 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 support members 41, 42, 43 to be joined. Further, in the present embodiment, the surface area Sd of the lower surfaces 51b, 52b, 53b is equal to the surface area Su of the upper surfaces 51a, 52a, 53a, but the surface areas Su of the first joint portions 51, 52b, 53a are smaller than the surface area Su. The shapes of the two joints 52 and the third joint 53 may be changed. As a result, the joint 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 portion 51 and the second joint portion 52 of the above three joint portions are the first support point P41B and the second support point P41B located at a position symmetrical with respect to the center point P10 of the diaphragm 10. It is arranged at the two support points P42B, and the third joint portion 53 is arranged at the third support point P43B that coincides with the center point P10. As a result, the third support member 43 is fixed to the center point P10 (third support point P43B), and the first support member 41 and the second support member 42 are fixed to 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 in a position symmetrical with respect to the point.

Both the first connecting portion 54 and the second connecting portion 55 are formed as thin film-like members extending (parallel) along the sensor holding surface 12. The first connecting portion 54 is connected to the lower end portion of the first joint portion 51 (the end portion close to the sensor holding surface 12) and the lower end portion of the second joint portion 52 to connect these two portions. 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 portions. In this way, the first connecting portion 54 and the second connecting portion 55 are formed as thin film-like members, and the lower end portions of the respective joint portions are connected to each other, whereby the relative movement (relative displacement) of the respective joint portions is achieved. Is possible. That is, each joint can be individually displaced (moved) according to the deformation (while maintaining a posture perpendicular to the fixed sensor holding surface 12) without interfering with each other (FIG. 9). reference). Further, by adopting the first connecting portion 54 and the second connecting portion 55 in the above-described form, even if each joint portion of the intermediate member 50B is formed as a thick portion, the diaphragm 10 is deformed due to this. It becomes possible to minimize the influence of (deformation hindrance).

The relative movement (relative displacement) of the joint portion is partially restricted depending on the position where the joint portion and the connecting portion are connected. That is, the relative movement (relative displacement) of the joint can be controlled by the connection position. Therefore, it is desirable that the connection position is appropriately changed according to the position where the sensor chip 20B is arranged. As one of the connection modes having the above-mentioned regulation function, there is a third embodiment described later (a connection form of the connecting portion 59 connecting the first joint portion 56 and the third joint portion 58 in the intermediate member 50C).

[Operation mode of pressure sensor 1B]
Subsequently, the operation mode of the pressure sensor 1B will be described with reference to FIG. FIG. 9 shows the first support member 41, the second support member 42, the third support member 43, and the intermediate member 50B (first joint portion 51, second joint portion) when the diaphragm 10 is deformed, as in FIG. 52, the third joint portion 53, the first connecting portion 54, the second connecting portion 55), and the displacement of the sensor chip 20B in the XZ cross section are schematically shown.

When the fluid F to be measured, which has a pressure P larger 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 projects upward (+ Z direction). It deforms (deflects) into a substantially conical shape. At this time, the intermediate member 50B provided with the thin film-shaped first connecting portion 54 and the second connecting portion 55 of the above-described form has, for example, a thick first joint portion 51, a second joint portion 52, and a third joint portion 53. Even so, these joints do not hinder the deformation of the diaphragm 10, and the joints do not interfere with each other and follow the deformation (with respect to the sensor holding surface 12 to which each joint is fixed). Deforms (moves) while maintaining a vertical posture.

Due to the above deformation (movement) of the intermediate member 50B, the third support member 43 erected at the center point P10 (third support point P43B) via the third joint portion 53 of the intermediate member 50B is formed along the Z axis. Displace (specifically, displace in the + Z direction). As a result, the top of the third support member 43 to be joined to the lower surface 20b of the sensor chip 20B is displaced in the + Z direction by substantially the same amount as the displacement amount of the diaphragm 10. Further, the first support point P41B stands up substantially perpendicular to the sensor holding surface 12 via the first joint portion 51 and the second joint portion 52 of the intermediate member 50B, and is 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 tilted so as to be substantially 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 joined to the lower surface 20b of the sensor chip 20B, are both displaced by approximately the same amount in the + Z direction, and one (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 the height of each support member (specifically, from the sensor holding surface 12 to the top of each support member). It increases in proportion to the height of. That is, the displacement amount of the diaphragm 10 is transmitted to the sensor chip 20B in a form 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 the sensor chip 20B is larger than that of the sensor chip 20A by the amount of displacement in the + Z direction. Therefore, the sensor chip 20B is largely pulled in the left-right direction (+ X direction and −X direction) and in the + Z direction even for a small pressure fluctuation that slightly displaces the diaphragm 10. As a result, the resistance element constituting 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 accuracy. Will be possible.

Further, by interposing an intermediate member 50B having a linear expansion coefficient smaller than that of the diaphragm 10 and larger than that of the support member 40B between the diaphragm 10 and the support member 40B, the joint residue between the two members is interposed. The stress can be reduced. As a result, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10. This effect is obtained by forming a joint portion having a larger heat capacity than the diaphragm 10, that is, a first joint portion 51, a second joint portion 52, and a third joint portion having a large effect of thermally separating the diaphragm 10 and the support member 40B. It becomes more remarkable by providing the joint portion 53.

Further, since the intermediate member 50B is provided with the connecting portions (first connecting portion 54 and second connecting portion 55), even if the intermediate member 50B has a joint portion having a large height (thickness), the diaphragm 10 can be formed by this. It is possible to suppress the deformation from being hindered as much as possible. As a result, the effect of reducing the joint residual stress and the measurement accuracy (sensitivity) can be compatible at a high level.

Further, by forming the intermediate material 50B as one component, the number of components is reduced and the assembling property is improved. For example, when an intermediate material in which each joint is configured as an individual component is arranged at three support points (first support point P41B, second support point P42B, third support point P43B), each support point (3). It is necessary to position each support point), but if the intermediate material is formed from one component, positioning at two support points is sufficient. As a result, deterioration (variation) in assembly accuracy can be suppressed.

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

Compared with the pressure sensor 1B, the pressure sensor 1C differs 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), and the configurations other than these are the same.

[Intermediate material 50C]
The intermediate material 50C is formed of a material having a linear expansion coefficient smaller than that of the material forming the diaphragm 10, and is preferably formed of a material having a linear expansion coefficient smaller than that of the material forming the support member 40B, similarly to the intermediate materials 50A and 50B in the above embodiment. It is made of a large material. As shown in FIGS. 10 and 12, for example, the intermediate member 50C is composed of a first joint portion 56, a second joint portion 57 and a third joint portion 58, and a connecting portion 59.

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

The height (thickness) of the first joint portion 56, the second joint portion 57, and the third joint portion 58 is set to be larger than, for example, the thickness of the diaphragm 10, and is substantially perpendicular to the sensor holding surface 12. It is joined to the holding surface in an upright state. Although the first joint portion 56 and the third joint portion 58 are integrally connected through the connecting portion 59, the first joint portion 56, the third joint portion 58, and the second joint portion 57 are separate bodies. Is formed as.

The first joint portion 56, the second joint portion 57, and the third joint portion 58 include the first support member 41, the second support member 42, and the third support member 43 constituting the support member 40B, and the upper surfaces 56a, 57a, 58a. Through, 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 support members 41, 42, 43 to be joined. Further, as described above, the surface area Sd of the lower surfaces 56b, 57b, 58b is formed to be smaller than the surface area Su of the upper surfaces 51a, 52a, 53a. By adopting this form, the support members 41, 42, and 43 are joined in a stable state, and the joining area with the sensor holding surface 12 is reduced, which affects the deformation of the diaphragm 10 (prevents deformation). ) Can be suppressed.

As shown in FIG. 11, the first joint 56 is arranged at the first support point P41C that coincides with the center point P10 of the diaphragm 10, and the second joint 57 is on the X-axis and from the center point P10. Is also arranged at the second support point P42C closer to + X, and the third joint 58 is located at the third support point P43C located between the first support point P41C and the second support point P42C on the X axis. It is arranged. As a result, the first support member 41 is fixed to the center point P10 (first support point P41C), and the second support member 42 and the third support member 43 are both on the X-axis and are the center points 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 (parallel) along the sensor holding surface 12, and the upper end portion of the first joint portion 56 and the upper end portion of the third joint portion 58 are formed. It is integrally connected to the unit. The connecting portion 59 of this form is the direction in which the pressure P of the fluid F to be measured is applied (direction along the Z axis) with respect to the relative movement (relative displacement) between the first joint portion 56 and the third joint portion 58 to be connected. ) Is not regulated, but is controlled so as to regulate the in-plane (in the XY plane) perpendicular to the direction. As a result, the third joint portion 58 moves (displaces) in the XY plane so as to follow the first joint portion 56.

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

[Operation mode of pressure sensor 1C]
Subsequently, the operation mode of the pressure sensor 1C will be described with reference to FIG. FIG. 13 shows the first support member 41, the second support member 42, the third support member 43, and the intermediate member 50C (first joint portion 56, second joint portion 57, third joint portion) when the diaphragm 10 is deformed. 58, the connecting portion 59), and the displacement of the sensor chip 20B in the XZ cross section are schematically shown.

When the fluid F to be measured, which has a pressure P larger 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 projects upward (+ Z direction). It transforms into a substantially conical shape. At this time, the vicinity of the center point P10 is formed as a hemispherical curved surface having a large curvature, and the outer side thereof is a curved surface close to the conical base surface. Therefore, the portion outside the vicinity of the center point P10 is formed as a slope having substantially the same inclination in the XZ cross section.

Of the intermediate members 50C arranged on the surface (sensor holding surface 12) of the diaphragm 10 accompanied by the above deformation, the first joint portion 56 is arranged at the center point P10 (first support point P41C), so that it is located on the Z axis. It moves (displaces) in the along direction (+ Z direction).
Further, the second joint portion 57 is alone at the second support point P42C located on the X-axis and on the + X side of the center point P0 of the diaphragm 10, that is, the second support point P42C located on the slope. Because it is arranged in, it moves (displaces) in a direction perpendicular to the slope, for example, in a direction along an axis Z'inclined by an angle α with respect to the Z axis.
On the other hand, although the third joint portion 58 is arranged at the third support point P43C located on the slope like the second support point P42C, the third joint portion 58 is arranged in the + Z direction via the connecting portion 59 having the control function. Since it is connected to the first joint portion 56 that is displaced, the movement (displacement) in the XY plane is restricted. Therefore, the third joint 58 is closer to the first joint 56 side than the direction perpendicular to the slope (axis Z'), that is, the angle β (β <α) with respect to the Z axis. It will move (displace) in the direction along the axis Z ″ that is tilted only by.

In this way, the first joint portion 56, the second joint portion 57, and the third joint portion 58 move (displace) in different directions (directions along the axis Z, the axis Z ′, and the axis Z ″). The first support member 41, the second support member 42, and the third support member 43 to be joined to the upper surface of each joint also have different directions (directions along the axis Z, the axis Z ′, and the axis Z ″). It will move (displace). In other words, relative displacement occurs in the X and Z directions before and after the deformation of the diaphragm 10 between the tops of these three support members. The relative displacements in the two directions are 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 displacement amount of the diaphragm 10 is transmitted to the sensor chip 20 in a form 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 arranged, 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 constituting the support member 40B are formed. The 42 and the third support member 43 are displaced in the 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, both of the two support members are in the same direction ( It will be displaced in the 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 deformation of the diaphragm 10. That is, in the above embodiment, the region of the sensor chip 20B supported by these two support members does not displace (expand / contract) before and after the deformation of the diaphragm 10. 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, which is transmitted to the sensor chip 20. Therefore, according to the pressure sensor 1C having the above configuration, even a small pressure fluctuation that slightly displaces the diaphragm 10 is greatly pulled in the X direction and the Z direction in the entire region of the sensor chip 20. As a result, the resistance element constituting the strain gauge (Wheatstone bridge circuit) provided on the sensor chip 20 is displaced (expanded / contracted) to the extent that the output fluctuates, and the pressure of the fluid to be measured can be detected with high accuracy. Becomes possible.

Further, by interposing an intermediate member 50C having a linear expansion coefficient smaller than that of the diaphragm 10 and larger than that of the support member 40B between the diaphragm 10 and the support member 40B, the joint residue between the two members is interposed. The stress can be reduced. As a result, it is possible to suppress a decrease in the pressure resistance performance of the diaphragm 10. This effect is obtained by forming a joint portion having a larger heat capacity than the diaphragm 10, that is, a first joint portion 56, a second joint portion 57, and a third joint portion having a large effect of thermally separating the diaphragm 10 and the support member 40B. It becomes more remarkable by providing the joint portion 58.

Further, as described above, the shape of each joint portion is such that the joint area with the sensor holding surface 12 is small, and the first joint portion 56, the third joint portion 58, and the second joint portion 57 are separated. By forming it as a body, the influence of the arrangement of the intermediate member 50C on the deformation of the diaphragm 10 (which hinders the deformation) can be suppressed as much as possible. As a result, the effect of reducing the joint residual stress and the measurement accuracy (sensitivity) can be compatible at a high level.

≪Modification example≫
As an example in which a part of the above embodiment is modified, for example, there is an intermediate material 50B'shown in FIG. The intermediate member 50B'corresponds to the intermediate member 50B in the second embodiment in which the first connecting portion 54 and the second connecting portion 55 are removed, and the first joint portion 51'and the second joint portion 52'. It is composed of ′ and a third joint portion 53 ′. The other configurations are the same as those of the intermediate material 50B.

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

Further, as an example in which a part of the above embodiment is modified, for example, there is an intermediate material 50C'shown in FIG. The intermediate material 50C'is a two-layer structure of the intermediate material 50C in the third embodiment. Specifically, the first joint portion 56', the second joint portion 57', and the third joint portion in which the total heights of the first joint portion 56, the second joint portion 57, and the third joint portion 58 constituting the intermediate member 50C are lowered are lowered. The fourth joint portion 56 ″, the fifth joint portion 57 ″, and the sixth joint portion of a substantially rectangular body having a lower surface having a shape complementary to the upper surface on the upper surface (the surface to be joined to the support member 40B) of the portion 58 ″. 58 ″ is placed, and a second connecting portion 59 ″ is provided to integrally connect the upper end portions of the fourth joint portion 56 ″ and the sixth joint portion 58 ″.

The linear expansion coefficient of the material forming the fourth joint 56 ″, the fifth joint 57 ″, the sixth joint 58 ″, and the second joint 59 ″ is the first joint 56 ″, the second joint. It is smaller than that of the material forming the joint portion 57'and the third joint portion 58'and the first connecting portion 59', and larger than that of the material forming the support member 40B. As a result, the joint residual stress generated when the support member 40B is fixed to the surface of the diaphragm 10 (sensor holding surface 12) can be further reduced.

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

Although the embodiments according to the present invention have been described above, the present invention is not limited to the embodiments, and various modifications can be made without departing from the gist thereof. Further, even if the configuration is not directly described in the specification and the drawings, it is within the scope of the technical idea of the present invention as long as the action and effect of the present invention are exhibited. Further, the above description and the embodiments shown in each figure can be combined with each other as long as there is no contradiction in the purpose, configuration, and the like.

For example, in the above embodiment, a semiconductor chip including a strain gauge is used as a pressure detection method (sensing principle) by deforming the diaphragm, but the present invention is not limited to this, and for example, a capacitance type sensor. A pressure detection method (sensing principle) using a metal strain gauge or a resistance gauge formed by deposition 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 ... 2nd support member, 43 ... 3rd support member, 50A, 50B, 50C ... Intermediate material, 51, 56 ... 1st joint, 52, 57 ... 2nd joint, 53, 58 ... 3rd joint, 54 ... 1st connecting portion, 55 ... 2nd connecting portion, 59 ... connecting portion.

Claims (8)

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 with multiple resistors that make up a strain gauge,
A plurality of electrically insulating support members extending along the normal of the second main surface and having one end joined to the sensor chip.
With
A pressure sensor in which the plurality of support members are joined to an intermediate material having a linear expansion coefficient smaller than that of the diaphragm and fixed to the second main surface via the intermediate material. In the pressure sensor according to claim 1,
The intermediate material is a pressure sensor made of a material having a coefficient of linear expansion larger than that of the support member. In the pressure sensor according to claim 1 or 2.
The intermediate material is composed of a plurality of joints to be joined to the plurality of support members and a connecting portion connecting at least two of the plurality of joints, and the thickness of the connecting portion along the normal is the said. A pressure sensor formed so as to be smaller than the thickness of a plurality of joints. In the pressure sensor according to claim 3,
The connecting portion is a pressure sensor formed as a thin film thinner than the plate thickness of the diaphragm. In the pressure sensor according to any one of claims 1 to 4.
A pressure sensor in which the plurality of support members are fixed to the second main surface via at least two intermediate members that are separated from each other. In the pressure sensor according to claim 5,
The intermediate material is a pressure sensor provided so as to form a pair with the support member. In the pressure sensor according to any one of claims 1 to 6.
A pressure sensor in which the joint area between the intermediate material and the second main surface is smaller than the joint area between the intermediate material and the support member. In the pressure sensor according to any one of claims 1 to 7.
The intermediate material is composed of a plurality of materials having different linear expansion coefficients, and the material is said to have a smaller linear expansion coefficient from the side joined to the second main surface toward the side joined to the sensor chip. Pressure sensors stacked along the line.

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