Pressure sensor

Abstract

The invention provides a pressure sensor which can prevent sensitivity reduction and fluid leakage even if the pressure sensor receives pressure from fluid. A pressure sensor according to the present invention is provided with: a housing (32) having a space, which is a flow path (33) for a fluid, in the interior thereof; a sensor chip (31) provided with a strain detection unit (31b) and comprising a thin film semiconductor; and a strain transmission material (36) provided inside the housing (32). The strain-transmitting material (36) is provided with: a pressure-receiving surface (36a) that is in contact with a space that is a flow path (33); and a joining surface (36b) that is fixed to the inner surface of the housing (32) and that is positioned on the opposite side from the pressure-receiving surface (36a) with respect to the strain-transmitting material (36). The entirety of the sensor chip (31) is embedded inside the strain transmission material (36).

Description

Technical Field

[0001] The present invention relates to a pressure sensor, and in particular to a pressure sensor that can be arranged in a dispensing device. Background Art

[0002] The pressure sensor for measuring the pressure of the fluid is composed of, for example, a thin film semiconductor strain sensor and is used in a dispensing device. The dispensing device is provided in, for example, an automatic analyzer and uses a nozzle to suck or discharge a sample (specimen) or a reagent as a liquid. The pressure sensor provided in the dispensing device is sometimes used to detect abnormalities such as nozzle blockage and empty suction.

[0003] Patent document 1 describes an example of an existing pressure sensor for measuring the pressure of a fluid. The pressure sensor described in Patent document 1 includes a sensor chip supported on a base plate. The sensor chip includes a sensor diaphragm that generates strain according to the pressure of the fluid and detects the pressure. The base plate is bonded to the supporting diaphragm. The central portion of the supporting diaphragm includes a pressure introduction hole for guiding the pressure of the fluid to the sensor chip. The pressure-receiving portion of the sensor chip is located at a position in the same direction as the bonding portion of the sensor chip and the base plate relative to the sensor chip.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2006-3234 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In the existing pressure sensor composed of a thin film semiconductor strain sensor, as described in Patent Document 1, the sensor chip is usually fixed to the housing (or base) of the pressure sensor, and the joint between the sensor chip and the housing and the pressure-bearing part of the sensor chip are located in the same direction relative to the sensor chip. In this structure, the flow path of the fluid is formed by the housing, and not only the pressure-bearing part of the sensor chip but also the joint between the sensor chip and the housing are in direct contact with the fluid. Therefore, if the joint between the sensor chip and the housing is subjected to the pressure of the fluid, tensile stress in the direction of peeling the joint from the housing is generated, and there is a concern that the joint will be peeled from the housing. If the joint between the sensor chip and the housing is peeled off, it will become a cause of reduced sensitivity of the pressure sensor and leakage of the fluid from the joint. In this way, in the existing pressure sensor, if it is subjected to pressure from the fluid, tensile stress is generated at the joint between the sensor chip and the housing, which may lead to reduced sensitivity and leakage of the fluid.

[0009] An object of the present invention is to provide a pressure sensor which can prevent a decrease in sensitivity and leakage of the fluid even when the pressure is applied to the fluid.

[0010] Means for solving problems

[0011] The pressure sensor of the present invention comprises: a housing having a space as a flow path of a fluid inside; a sensor chip having a strain detection portion and composed of a thin film semiconductor; and a strain transfer material disposed inside the housing. The strain transfer material comprises: a pressure receiving surface in contact with the space; and a bonding surface located on the opposite side of the pressure receiving surface relative to the strain transfer material and fixed to the inner surface of the housing. The entire sensor chip is buried inside the strain transfer material.

[0012] Effects of the Invention

[0013] According to the present invention, it is possible to provide a pressure sensor which can prevent a decrease in sensitivity and leakage of the fluid even when the pressure is applied to the fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a diagram showing a basic structure of a dispensing device including a pressure sensor according to a first embodiment of the present invention.

[0015] Figure 2 This is a diagram showing the state of the interior of the pipe in the arm immediately after the nozzle sucks the liquid.

[0016] Figure 3 FIG. 1 is a schematic diagram showing an example of a cross section of a conventional pressure sensor.

[0017] Figure 4A This is an exploded perspective view of the pressure sensor of Example 1.

[0018] Figure 4B This is a cross-sectional view of the pressure sensor of Example 1 taken on a plane perpendicular to the direction of the flow path.

[0019] Figure 5 This is an exploded perspective view showing only the sensor chip, bonding wires, and lead frame in the pressure sensor of Example 1.

[0020] Figure 6 This is an exploded perspective view showing only the sensor chip, bonding wires, lead frame, and cover member in the pressure sensor according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0021] The pressure sensor of the present invention comprises a housing constituting a flow path of a fluid and a sensor chip disposed inside the housing. Even if the pressure from the fluid is applied, no tensile stress is generated at the joint between the sensor chip and the housing, thereby preventing a decrease in sensitivity and leakage of the fluid. Therefore, the present invention can provide a pressure sensor with high reliability.

[0022] Hereinafter, a pressure sensor according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the drawings used in this specification, the same or corresponding components are denoted by the same reference numerals, and duplicate descriptions of these components may be omitted.

[0023] Example 1

[0024] Reference Figures 1 to 5 A pressure sensor according to a first embodiment of the present invention will be described. Hereinafter, as an example, a configuration in which the pressure sensor of this embodiment is provided in a sample dispensing mechanism of a dispensing device will be described.

[0025] Figure 1 1 is a diagram showing a basic structure of a dispensing device 1 including a pressure sensor 15 according to the present embodiment. The dispensing device 1 includes a flow path system, a sample dispensing mechanism 13 , and a control unit 14 .

[0026] The flow path system of the dispensing device 1 includes a nozzle 2, a syringe pump 4, a solenoid valve 5, a gear pump 6, and a tank 7 for storing system water, and these components are connected by a pipe 8. The sample dispensing mechanism 13 includes an arm 16 having a nozzle 2, and sucks or discharges liquid (for example, a sample, system water) through the nozzle 2. The control unit 14 controls the dispensing device 1. For example, a motor that drives the sample dispensing mechanism 13 and the like is controlled by the control unit 14.

[0027] The syringe pump 4 includes a container 9 , a plunger 10 , a ball screw 11 , and a drive motor 12 . The drive motor 12 is controlled by a control unit 14 .

[0028] The arm 16 has the pressure sensor 15 of this embodiment inside. The arm 16 moves the nozzle 2 to a position for sucking and discharging liquid, and thus can perform rotational movement and vertical movement.

[0029] Figure 2 This is a diagram showing the state of the interior of the pipe 8 in the arm 16 immediately after the nozzle 2 sucks the liquid.

[0030] The interior of the pipe 8 is filled with system water 21 as water for syringe pressure transmission. By transmitting the pressure generated by the syringe pump 4 into the pipe 8, the nozzle 2 can suck or discharge the liquid 22 (for example, a sample, system water).

[0031] When the nozzle 2 sucks the liquid 22, the plunger 10 in the syringe pump 4 is pulled out from the container 9 while the electromagnetic valve 5 is closed. When the nozzle 2 discharges the liquid 22, the plunger 10 in the syringe pump 4 is pressed into the container 9 while the electromagnetic valve 5 is closed. In addition, when the nozzle 2 sucks the liquid 22 such as the sample, the nozzle 2 sucks the liquid 22 after sucking the segmentation air 23 for segmentation so that the liquid 22 is not mixed with the system water 21 in the pipe 8.

[0032] After the nozzle 2 discharges the liquid 22, the nozzle 2 is cleaned. In cleaning the nozzle 2, while the cleaning water is brought into contact with the outer wall of the nozzle 2, the system water 21 inside the nozzle 2 is pushed out from the nozzle 2. When the system water 21 is pushed out from the nozzle 2 during cleaning of the nozzle 2, the solenoid valve 5 is opened to utilize the pressure of the gear pump 6. Therefore, when cleaning the nozzle 2, the system water 21 is pushed out at a higher pressure than when pushed out by the syringe pump 4.

[0033] The dispensing device 1 includes a pressure sensor 15 in the pipe 8 to detect abnormalities such as clogging of the nozzle 2 and empty suction that may occur during the dispensing operation. The pressure sensor 15 monitors the pressure of the system water 21 and detects pressure changes that occur when the nozzle 2 has abnormalities.

[0034] The installation position of the pressure sensor 15 can be determined arbitrarily. In the present embodiment, as an example, in order to sensitively capture the pressure change of the nozzle 2, the pressure sensor 15 is installed in a position relatively close to the nozzle 2, that is, inside the arm 16. The pressure sensor 15 is not limited to being installed inside the arm 16, for example, it can also be installed on the side of the sample dispensing mechanism 13.

[0035] use Figure 3 The structure of a conventional general pressure sensor and its problems will be described.

[0036] Figure 3 1 is a schematic diagram showing an example of a cross section of a conventional pressure sensor 15a. The pressure sensor 15a includes a sensor chip 31 made of a thin film semiconductor and a housing 32 to which the sensor chip 31 is bonded, and measures a fluid flowing in a flow path 35. A strain gauge portion 31b is provided on the surface of the central portion of the sensor chip 31. Figure 3 The cross section shown is a cross section of a plane passing through the strain gauge portion 31 b and along the normal direction of the sensor chip 31 . Figure 3 The sensor chip 31 is shown deformed by receiving pressure p from the fluid.

[0037] The sensor chip 31 is configured to withstand the pressure p of the fluid flowing in the flow path 35, and is bonded to the housing 32 by a bonding agent 40. The fluid flowing in the flow path 35 as the measurement object is, for example, the system water 21. The sensor chip 31 is deformed by the pressure p of the fluid to be measured, and the pressure p of the fluid to be measured is measured by measuring the strain caused by the deformation. The strain is measured by the strain gauge part 31b.

[0038] In the pressure sensor 15a, when the sensor chip 31 is deformed by the pressure p from the fluid to be measured, a force in a direction of peeling the bond between the sensor chip 31 and the bonding agent 40 and between the housing 32 and the bonding agent 40 is generated. Therefore, in the conventional pressure sensor 15a, the sensor chip 31 may be peeled off from the housing 32 when subjected to excessive pressure or repeated pressure. In addition, in the conventional pressure sensor 15a, a part of the surface of the sensor chip 31 and the above-mentioned bonding surface are in contact with the fluid to be measured and the outside air, so there is a concern that the bonding surface may be deteriorated and the bonding force may be reduced due to the influence of the humidity of the fluid to be measured and the outside air.

[0039] The pressure sensor 15 of this embodiment can solve these problems. Figure 4A , Figure 4B as well as Figure 5 , the structure and features of the pressure sensor 15 of this embodiment are described.

[0040] Figure 4A and Figure 4B It is a diagram showing an example of the structure of the pressure sensor 15 according to the present embodiment. Figure 4A An exploded perspective view of the pressure sensor 15 is shown. Figure 4B A cross-sectional view of the pressure sensor 15 taken along a plane perpendicular to the extending direction of the flow path is shown.

[0041] The pressure sensor 15 includes a sensor chip 31 made of a thin film semiconductor, a housing 32 that accommodates the sensor chip 31, and a strain transmission material 36 provided inside the housing 32, and uses a fluid flowing in a flow path 33 as a measurement object. The flow path 33 of the fluid is a space formed inside the housing 32. A strain gauge portion 31b as a strain detection portion is provided on the surface of the central portion of the sensor chip 31. The fluid flowing in the flow path 33 as the measurement object is, for example, system water 21.

[0042] Figure 4B The cross section shown is a cross section on a plane that passes through the strain gauge portion 31 b and is orthogonal to the direction in which the fluid flows in the flow path 33 (a plane along the normal direction of the sensor chip 31 ).

[0043] Here, the normal direction of the sensor chip 31 is defined as the "up and down direction", the extension direction of the flow path 33 (the direction in which the fluid flows in the flow path 33) is defined as the "flow path direction", and the direction orthogonal to the up and down direction and the flow path direction is defined as the "lateral direction".

[0044] The housing 32 includes an upper housing 32a and a lower housing 32b located below the upper housing 32a, and includes a flow path 33 in which the system water 21 flows. The upper housing 32a and the lower housing 32b are in contact with each other, and their contact surfaces 32c are sealed by a sealing member so that the system water 21 does not leak out of the housing 32. The sealing member can be, for example, an O-ring, a sealant, etc. In addition, the housing 32 does not necessarily need to be composed of two parts (the upper housing 32a and the lower housing 32b), and for example, it can be composed of one part by insert molding, etc., or it can be composed of three or more parts.

[0045] Screw parts (not shown) are provided at both ends in the flow direction of the flow path 33. The flow path 33 can be connected to the pipe 8 of the dispensing device 1 via a joint using the screw parts.

[0046] The strain transmission material 36 is fixed to the inner surface of the shell 32 (i.e., the wall surface of the flow path 33). The surface of the strain transmission material 36 fixed to the inner surface of the shell 32 is called a bonding surface 36b. When the strain transmission material 36 comes into contact with the system water 21 flowing in the flow path 33, it is compressed by the pressure of the system water 21. The surface of the strain transmission material 36 that comes into contact with the system water 21 is called a pressure-receiving surface 36a. The pressure-receiving surface 36a is a surface that comes into contact with the space of the flow path 33 as a fluid and receives the pressure of the system water 21. The bonding surface 36b is located at a position opposite to the pressure-receiving surface 36a with respect to the strain transmission material 36. The strain transmission material 36 can be composed of a soft elastic body, for example, a gel-like substance such as silicone gel.

[0047] The pressure sensor 15 can include a lead frame 45 electrically connected to the sensor chip 31. The lead frame 45 is provided in contact with the sensor chip 31 in the vertical direction. In addition, the vertical relationship between the lead frame 45 and the sensor chip 31 can be arbitrarily determined, and which one is arranged on the upper side (in the upper side). Figure 4B In the present embodiment, the sensor chip 31 is located above the lead frame 45 as an example.

[0048] The entire sensor chip 31 and a portion of the lead frame 45 are buried inside the strain transmission material 36 .

[0049] The lead frame 45 includes an aperture 45a as an opening (hole) penetrating the lead frame 45. The aperture 45a is open in the range of the portion facing the sensor chip 31 including the strain gauge portion 31b. That is, the portion of the lead frame 45 facing the strain gauge portion 31b of the sensor chip 31 and a portion of its periphery is open as the aperture 45a.

[0050] The portion of the sensor chip 31 opened by the aperture 45a (i.e., the portion facing the aperture 45a) is the diaphragm portion 31a as the deformation portion. Since the lead frame 45 is provided with the aperture 45a, the strain generated by the compression of the strain transmission material 36 is transmitted from the strain transmission material 36 to the diaphragm portion 31a of the sensor chip 31, and the diaphragm portion 31a is bent and deformed. The sensor chip 31 measures the strain using the strain gauge portion 31b, thereby measuring the pressure of the system water 21 flowing in the flow path 33 inside the housing 32.

[0051] The lead frame 45 is provided for extracting the output from the sensor chip 31. The lead portion of the lead frame 45 is electrically connected to the electrode portion of the sensor chip 31 through the bonding wire 46. A portion of the lead frame 45 protrudes to the outside of the housing 32, and the lead portion extends to the protruding portion. The lead frame 45 and the housing 32 are sealed by the sealing member 37. The sealing member 37 can use any member, for example, the strain transfer material 36 can be used for the sealing member 37, an O-ring can be used, or a gasket formed on the lead frame 45 can be used.

[0052] The sensor chip 31 can be electrically connected to the outside of the housing 32 through the lead portion of the lead frame 45. In the conventional pressure sensor, if the sensor chip 31 is disposed inside the housing 32, it is difficult to connect wiring to the sensor chip 31 to electrically connect the sensor chip 31 to the outside of the housing 32. The pressure sensor 15 of the present embodiment can electrically connect the sensor chip 31 to the outside of the housing 32 through the lead frame 45 electrically connected to the sensor chip 31.

[0053] The pressure sensor 15 of this embodiment is characterized in that the strain transfer material 36 has: a pressure-bearing surface 36a, which is in contact with the flow path 33 of the fluid and receives pressure from the fluid; and a bonding surface 36b, which is located on the opposite side of the pressure-bearing surface 36a relative to the strain transfer material 36 and is in contact with the inner surface of the shell 32 (i.e., the wall surface of the flow path 33), and the sensor chip 31 is entirely buried inside the strain transfer material 36.

[0054] Due to the feature that the bonding surface 36b is located on the opposite side of the pressure-receiving surface 36a with respect to the strain transmission material 36, when the pressure-receiving surface 36a receives pressure from the fluid in the strain transmission material 36, compressive stress is generated on the bonding surface 36b. That is, in the strain transmission material 36, the pressure-receiving surface 36a receives pressure from the fluid, thereby generating a force in a direction of pressing the bonding surface 36b toward the housing 32, so in principle the bonding surface 36b will not be peeled off from the housing 32.

[0055] Since the entire sensor chip 31 is buried inside the strain transmission material 36, the interface between the sensor chip 31 and the strain transmission material 36 is not exposed to the system water 21 or external air. Therefore, the bonding strength between the sensor chip 31 and the strain transmission material 36 is not reduced by the humidity of the system water 21 or external air.

[0056] Therefore, even if the pressure sensor 15 of the present embodiment is subjected to pressure from the fluid, it is possible to prevent a decrease in sensitivity of the sensor chip 31 due to peeling and leakage of the fluid from a portion to which the sensor chip 31 is bonded.

[0057] Figure 5 This is an exploded perspective view showing only the sensor chip 31 , the bonding wires 46 , and the lead frame 45 in the pressure sensor 15 of the present embodiment. The electrode portion 31 c of the sensor chip 31 is electrically connected to the lead portion 45 b of the lead frame 45 via the bonding wires 46 .

[0058] The aperture 45a provided on the lead frame 45 is preferably in a shape having a long side direction and a short side direction, such as a rectangular shape, an elliptical shape, a rounded rectangular shape, etc. Figure 5 In FIG. 1 , as an example, a rectangular aperture 45 a is shown whose long side direction is the flow path direction and whose short side direction is the lateral direction.

[0059] The diaphragm portion 31a of the sensor chip 31 is a portion of the sensor chip 31 opened by the aperture 45a. Therefore, the shape of the diaphragm portion 31a is determined by the shape of the aperture 45a, and is preferably a shape having a long side direction and a short side direction, such as a rectangle, an ellipse, or a rounded rectangle.

[0060] When the diaphragm portion 31 a having a long side direction and a short side direction is deformed by the pressure from the system water 21 , a difference occurs in magnitude between the strain in the long side direction and the strain in the short side direction in the strain gauge portion 31 b .

[0061] When the diaphragm portion 31a has a shape having a long side direction and a short side direction, it is preferable to use a sensor chip that detects the strain in the long side direction and the short side direction of the strain gauge portion 31b and outputs the difference between the strains as the sensor chip 31. By using such anisotropic sensor chips 31 capable of detecting strain, the pressure sensor 15 can improve the detection sensitivity of pressure. In addition, such sensor chips 31 can use existing sensor chips.

[0062] Furthermore, by using such a sensor chip 31, the influence of thermal strain that generates isotropic strain, that is, the influence of temperature change can be reduced. Therefore, the pressure sensor 15 can reduce the change in output characteristics caused by temperature change.

[0063] The strain transmission material 36 is preferably made of a material having a rigidity sufficiently smaller than that of the housing 32. Generally, the housing 32 is made of a material having a rigidity sufficiently large so that deformation caused by the pressure of the system water 21 is sufficiently small. By making the strain transmission material 36 have a rigidity sufficiently smaller than that of the housing 32, only the strain transmission material 36 is efficiently deformed with respect to the water pressure of the system water 21. Thus, the pressure sensor 15 can improve the pressure detection sensitivity.

[0064] Example 2

[0065] Reference Figure 6 A pressure sensor according to a second embodiment of the present invention will be described. The pressure sensor 15 of this embodiment has the same structure as the pressure sensor 15 of the first embodiment, but is different from the pressure sensor 15 of the first embodiment in that the sensor chip 31 has a cover member. Hereinafter, the pressure sensor 15 of this embodiment will be described mainly in terms of the differences from the pressure sensor 15 of the first embodiment.

[0066] Figure 6 This is an exploded perspective view showing only the sensor chip 31 , the bonding wires 46 , the lead frame 45 , and the cover member 34 in the pressure sensor 15 of the present embodiment.

[0067] The cover member 34 is provided on the surface of the sensor chip 31 and is a member that covers and protects the strain gauge portion 31b. The cover member 34 is provided on the surface of the sensor chip 31 opposite to the surface in contact with the lead frame 45 in the vertical direction, and is buried in the strain transmission material 36. The cover member 34 can be made of, for example, silicon, and is bonded to the sensor chip 31 using an adhesive member such as a thermosetting adhesive.

[0068] The cover member 34 has a cavity 34a. The cavity 34a is a concave portion provided on the surface of the cover member 34 that contacts the sensor chip 31 and surrounds the strain gauge portion 31b. The sensor chip 31 is deformable in the portion facing the cavity 34a, and the deformable portion functions as the diaphragm portion 31a. The cavity 34a is preferably in a shape having a long side direction and a short side direction, such as a rectangle, an ellipse, a rounded rectangle, or the like. Figure 6 In FIG. 1 , as an example, an elliptical (long circular) cavity 34 a is shown whose long side direction is the flow path direction and whose short side direction is the lateral direction.

[0069] The outer shape line of the cavity 34a when the cavity 34a is projected onto the sensor chip 31 is referred to as the outer shape projection line 51 of the cavity 34a. The outer shape line of the aperture 45a when the aperture 45a is projected onto the sensor chip 31 is referred to as the outer shape projection line 50 of the aperture 45a. The outer shape line of the cover member 34 when the cover member 34 is projected onto the sensor chip 31 is referred to as the outer shape projection line 52 of the cover member 34. In the pressure sensor 15 of the present embodiment, the outer shape projection line 51 of the cavity 34a is located on the strain gauge portion 31b side (inner side) than the outer shape projection line 50 of the aperture 45a, and the outer shape projection line 52 of the cover member 34 is located on the inner side than the outer shape line 53 of the sensor chip 31.

[0070] The sensor chip 31 included in the pressure sensor 15 of the present embodiment is small, and is generally manufactured by cutting the sensor chip formed in a grid shape on a silicon wafer into a rectangular shape using a semiconductor process. The outer projection line 52 of the cover member 34 is located inside the outer line 53 of the sensor chip 31, so that a manufacturing method of cutting the cover member 34 after forming the cover member 34 by a semiconductor process can be realized for the wafer on which the sensor chip is formed. Therefore, the outer dimensions and installation position of the cover member 34 can be determined with high precision using a semiconductor process.

[0071] In addition, the outer shape projection line 51 of the cavity 34a is located at a position closer to the inside than the outer shape projection line 50 of the aperture 45a, so that the shape of the diaphragm portion 31a is determined by the outer shape projection line 51 of the cavity 34a. The cover member 34 can be manufactured with high precision by a semiconductor process. Therefore, in the pressure sensor 15 of the present embodiment, the manufacturing deviation of the shape of the diaphragm portion 31a determined by the shape of the cavity 34a of the cover member 34 can be made very small. Therefore, the deviation of the sensitivity of the sensor chip 31 caused by the deviation of the shape of the diaphragm portion 31a can also be reduced.

[0072] The pressure sensor 15 of the present embodiment has an effect of reducing the variation in sensitivity of the sensor chip 31 in addition to the effects of the pressure sensor 15 of the first embodiment.

[0073] In addition, the present invention is not limited to the above-mentioned embodiments, and various modifications are possible. For example, the above-mentioned embodiments are examples described in detail in order to easily explain the present invention, and the present invention is not limited to a method that must have all the structures described. In addition, a part of the structure of a certain embodiment can be replaced with the structure of another embodiment. In addition, the structure of another embodiment can be added to the structure of a certain embodiment. In addition, a part of the structure of each embodiment can be deleted, or other structures can be added or replaced.

[0074] Explanation of symbols

[0075] 1: dispensing device; 2: nozzle; 4: injection pump; 5: solenoid valve; 6: gear pump; 7: tank; 8: piping; 9: container; 10: plunger; 11: ball screw; 12: drive motor; 13: sample dispensing mechanism; 14: control unit; 15: pressure sensor; 15a: existing pressure sensor; 16: arm; 21: system water; 22: liquid; 23: segmented air; 31: sensor chip; 31a: diaphragm; 31b: strain gauge; 31c: electrode; 32: housing; 32a: upper 1: upper shell; 32b: lower shell; 32c: contact surface between upper shell and lower shell; 33: flow path; 34: cover part; 34a: cavity; 35: flow path; 36: strain transfer material; 36a: pressure-bearing surface; 36b: bonding surface; 37: sealing part; 40: bonding agent; 45: lead frame; 45a: aperture; 45b: lead part; 46: bonding wire; 50: outer projection line of aperture; 51: outer projection line of cavity; 52: outer projection line of cover part; 53: outer shape line of sensor chip.

Claims

1. A pressure sensor, It is characterized in that have: a housing having a space therein as a flow path for a fluid; A sensor chip including a strain detection unit and composed of a thin film semiconductor; and a strain transfer material disposed within the interior of the housing, The strain transmission material comprises: a pressure receiving surface which contacts the space; and a bonding surface which is located on the opposite side of the pressure receiving surface with respect to the strain transmission material and is fixed to the inner surface of the housing. The entire sensor chip is buried inside the strain transfer material.

2. The pressure sensor according to claim 1, It is characterized in that The strain transfer material is less rigid than the shell.

3. The pressure sensor according to claim 1, It is characterized in that A lead frame is provided so as to be in contact with the sensor chip and is electrically connected to the electrode of the sensor chip. The lead frame includes an opening portion that opens in a range facing a portion of the sensor chip including the strain detection unit.

4. The pressure sensor according to claim 3, It is characterized in that A cover member is provided on a surface of the sensor chip opposite to a surface in contact with the lead frame, The cover member includes a recessed portion on a surface in contact with the sensor chip, the recessed portion surrounding the strain detection portion in a shape having a long side direction and a short side direction. When the recess, the opening, and the cover member are projected onto the sensor chip, the projected outer shape line of the recess is located inside the projected outer shape line of the opening, and the projected outer shape line of the cover member is located inside the outer shape line of the sensor chip.

5. The pressure sensor according to claim 3, It is characterized in that A portion of the lead frame is buried in the interior of the strain transfer material, and another portion protrudes to the outside of the housing.

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