Pressure Sensors

Abstract

To provide a pressure sensor with which it is possible to improve the strength required for practical use.SOLUTION: A pressure sensor comprises a package 14 having a sensor chip accommodation space, and a support diaphragm 13 secured to the package 14 so as to divide the sensor chip accommodation space into two spaces. A sensor chip 11 for pressure detection, stacked and secured to the middle part of the support diaphragm 13, is provided. The sensor chip 11 is provided with a stress dispersion part 36 in a portion of which a displaced support diaphragm 13 is pressed against. The stress dispersion part 36 is formed in such a shape as to disperse the stress occurring to the support diaphragm 13 as a displaced support diaphragm 13 is pressed against it.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a pressure sensor having a sensor chip secured over a support diaphragm. [Background technology]

[0002] Diaphragm vacuum gauges are used to measure gas pressure (especially vacuum level). An example of a pressure sensor used in a diaphragm vacuum gauge is described in Patent Document 1. The configuration of the pressure sensor disclosed in Patent Document 1 is shown in Fig. 7. The pressure sensor 1 shown in Fig. 7 includes a sensor chip 3 that is fixed to and overlapped on a support diaphragm 2. The support diaphragm 2 is formed in an annular shape when viewed in the thickness direction as shown in Fig. 8(A), and is supported by being sandwiched between a lower package 4a and an upper package 4b ​​of a package 4 (see Fig. 7) that houses the sensor chip 3.

[0003] The inside of the package 4 is divided into a reference pressure chamber 5 below the support diaphragm 2 and a detection pressure chamber 6 above the support diaphragm 2 in Fig. 7. The sensor chip 3 is formed in a rectangular shape when viewed in the thickness direction of the support diaphragm 2, as shown in Fig. 8(A), and is disposed in the center of the support diaphragm 2. The sensor chip 3 is composed of a chip body 3a located in the reference pressure chamber 5 and a support member 3b located in the detection pressure chamber 6, and is joined to the support diaphragm 2 with the support diaphragm 2 sandwiched between the chip body 3a and the support member 3b.

[0004] The chip body 3a has a diaphragm (not shown) on which the pressure in the reference pressure chamber 5 and the pressure in the detection pressure chamber 6 act, and is configured to detect the pressure in the detection pressure chamber 6 based on electrostatic capacitance. In the pressure sensor 1 used in the diaphragm vacuum gauge, the reference pressure chamber 5 is normally kept at a vacuum, and a pressure close to a vacuum is introduced into the detection pressure chamber 6 as the pressure to be detected. The normal environment in which a vacuum gauge is used is a low pressure close to a vacuum, and it can be used as long as its strength is ensured for that environment. However, when the vacuum gauge is mounted in a device, it is exposed to atmospheric pressure and there is a risk that atmospheric pressure may be introduced into the detection pressure chamber 6, so in terms of practicality, care must be taken in designing the strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-30203 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the pressure sensor 1 as shown in FIG. 7, when atmospheric pressure is introduced into the detection pressure chamber 6 and the support diaphragm 2 is significantly deformed, problems may occur. That is, as shown in FIG. 8(B), when the support diaphragm 2 is pushed by atmospheric pressure and is significantly displaced so as to be convex toward the reference pressure chamber 5 as shown by the two-dot chain line, the corners 7 of the sensor chip 3 are pressed against the support diaphragm 2. FIG. 8(B) is a cross-sectional view taken along the line VIII-VIII in FIG. 8(A). Since the sensor chip 3 is formed in a rectangular shape as shown in FIG. 8(A), at this time, each of the four corners 7 presses the support diaphragm 2. When the support diaphragm 2 is pushed by the corners 7 of the sensor chip 3 in this way, stress is generated at each of the four points of the support diaphragm 2, concentrating at one point.

[0007] The results of an analysis of the magnitude of stress generated in the support diaphragm 2 at this time are shown in Figure 9. In Figure 9, the magnitude of stress is shown by light and dark colors, with the greater the stress, the darker the color. As can be seen from Figure 9, the stress is greatest at the portion corresponding to the corner 7. When a large pressure is applied to each of the four locations of the support diaphragm 2 in this manner, there is a risk that the support diaphragm 2 may break at the stress concentration points.

[0008] An object of the present invention is to provide a pressure sensor capable of improving the strength required for practical use. [Means for solving the problem]

[0009] In order to achieve this object, the pressure sensor of the present invention comprises a package having a sensor chip accommodating space, a support diaphragm fixed to the package so as to divide the sensor chip accommodating space into two spaces, and a sensor chip for detecting pressure which is fixed and overlapped on the center of the support diaphragm, wherein the sensor chip has a stress distribution portion provided in a portion against which the displaced support diaphragm is pressed, and the stress distribution portion is formed in a shape that distributes the stress generated in the support diaphragm when the displaced support diaphragm is pressed against it.

[0010] The present invention may be directed to the pressure sensor, wherein the sensor chip is formed in a rectangular shape having a pair of vertical side ends extending vertically when viewed in the thickness direction of the support diaphragm, a pair of horizontal side ends extending horizontally between the pair of vertical side ends, and a rounded portion that is curved so as to be convex toward the outside of the sensor chip and connects the vertical side ends and the horizontal side ends, and the stress distribution portion may be constituted by the rounded portion.

[0011] In the pressure sensor of the present invention, the sensor chip is formed in a rectangular shape having a pair of vertical side ends extending vertically when viewed in the thickness direction of the support diaphragm, a pair of horizontal side ends extending horizontally between the pair of vertical side ends, and a chamfered portion extending in a direction inclined relative to the vertical side ends and the horizontal side ends and connecting the vertical side ends and the horizontal side ends, and the stress distribution portion may be constituted by the chamfered portion.

[0012] In the pressure sensor of the present invention, the sensor chip is formed in a rectangular shape when viewed from the thickness direction of the support diaphragm, and has a base fixed to the support diaphragm and a protrusion protruding laterally from the base so as to create a gap between the support diaphragm and the base, and the surface of the protrusion facing the support diaphragm comprises an inclined surface that slopes so that the thickness of the protrusion gradually becomes thinner as it approaches the base toward the protruding end of the protrusion, and the stress distribution portion may be formed by the inclined surface.

[0013] In the pressure sensor of the present invention, the package, the support diaphragm and the sensor chip may constitute a detection unit of a diaphragm vacuum gauge, and the support diaphragm may be formed so as to divide the sensor chip accommodating space into a reference pressure chamber maintained in a vacuum state and a detection pressure chamber into which a pressure to be detected is introduced. Effect of the Invention

[0014] According to the present invention, when the support diaphragm is displaced, it comes into contact with the stress dispersion portion of the sensor chip, and this contact disperses the stress generated in the support diaphragm. Therefore, it is possible to provide a pressure sensor capable of improving the strength required for practical use. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a cutaway perspective view showing a main part of a pressure sensor according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing a support diaphragm and a sensor chip according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing the entire pressure sensor. [Figure 4] FIG. 4 is a schematic diagram showing the state of stress generation. [Diagram 5] FIG. 5 is a diagram showing a sensor chip and a support diaphragm according to the second embodiment. [Figure 6]FIG. 6 is a diagram showing a sensor chip and a support diaphragm according to the third embodiment. [Figure 7] FIG. 7 is a perspective view showing a part of a conventional sensor chip and a support diaphragm. [Figure 8] FIG. 8 is a diagram showing a conventional sensor chip and a supporting diaphragm. [Figure 9] FIG. 9 is a schematic diagram showing a state in which stress is generated. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] (First embodiment) An embodiment of a pressure sensor according to the present invention will be described in detail below with reference to Figures 1 to 4. A sensor chip 11 shown in Figure 1 can be used in a pressure sensor 12 as shown in Figure 3, and is fixed to the center of a support diaphragm 13 and supported by a chip-accommodating package 14 for the pressure sensor 12 via the support diaphragm 13.

[0017] 3 is used in a diaphragm vacuum gauge, and includes a chip housing package 14 that houses a sensor chip 11, and a heating case 15 that covers the chip housing package 14. The heating case 15 includes a case body 15a located on the innermost side, a heater 15b that surrounds the case body 15a, and a heat insulating material 15c that covers the case body 15a including the heater 15b.

[0018] The chip housing package 14 is formed by a cylindrical lower package 17 having a detection pressure introducing pipe 16 provided at one end (the lower end in FIG. 3), a cylindrical upper package 18 joined to the opening of the lower package 17 via a support diaphragm 13, and a cover 19 that closes the opening of the upper package 18. The cover 19 is provided with an electrode shield portion 21 for passing an electrode lead pin 20 electrically connected to the sensor chip 11.

[0019] The support diaphragm 13 is formed in an annular shape {see FIG. 2(A)}, and its outer periphery is sandwiched between a lower package 17 and an upper package 18 and joined to these members for support. In FIG. 1, the lower package 17 is depicted as being positioned above the upper package 18. FIG. 2(A) is a plan view showing the support diaphragm 13 and the sensor chip 11 as viewed from the thickness direction of the support diaphragm 13.

[0020] The sensor chip 11 is composed of a chip body 11a and a support member 11b that sandwich the support diaphragm 13 from one side and the other side in the thickness direction. The chip body 11a and the support member 11b are bonded in a state where they are overlapped on the support diaphragm 13. A through hole 22 in the center of the support diaphragm 13 is blocked by the chip body 11a. A hole 23 is formed in the support member 11b so as not to block the through hole 22 of the support diaphragm 13.

[0021] The sensor chip 11 and the support diaphragm 13 divide the sensor chip housing space 24 in the chip housing package 14 into two spaces. These two spaces are a reference pressure chamber 25 located above the support diaphragm 13 in FIG. 3, and a detection pressure chamber 26 located below the support diaphragm 13. The chip body 11a of the sensor chip 11 is located in the reference pressure chamber 25. The reference pressure chamber 25 communicates with a space 27 inside the case body 15a through a communication hole (not shown) formed in the cover 19, and is maintained in a vacuum state. The pressure to be detected is introduced into the detection pressure chamber 26 via the detection pressure introduction pipe 16.

[0022] When the sensor chip 11 is used in a diaphragm vacuum gauge, it is configured to detect the pressure in the detection pressure chamber 26 based on the electrostatic capacitance that changes according to the pressure in the reference pressure chamber 25 and the pressure in the detection pressure chamber 26. In this case, the sensor chip 11, the support diaphragm 13, and the chip housing package 14 that houses these members constitute the detection section 28 (see FIG. 3) of the diaphragm vacuum gauge. The pressure sensor 12 shown in FIG. 3 is configured by fixing the sensor chip 11, which detects pressure based on electrostatic capacitance, to the support diaphragm 13. However, the pressure sensor of the present invention is not limited to such a configuration. The present invention can be applied to any pressure sensor as long as the sensor chip is fixed to the support diaphragm. For this reason, the internal structure of the sensor chip 11 is omitted in FIGS. 1 and 2.

[0023] 2(A), the sensor chip 11 is formed in a rectangular shape having a pair of vertical side ends 31, 31 extending in the vertical direction, a pair of horizontal side ends 32, 32 extending in the horizontal direction between the pair of vertical side ends 31, 31, and a rounded portion 33 that is curved so as to be convex toward the outside of the sensor chip 11 and connects the vertical side ends 31 and the horizontal side ends 32, when viewed in the thickness direction of the support diaphragm 13. The rounded portion 33 in this embodiment is formed in an arc shape with the center of the sensor chip 11 being the center of the arc.

[0024] In addition, the sensor chip 11 according to this embodiment has a base 34 fixed to the support diaphragm 13, and a protrusion 35 protruding laterally from the base 34 so as to create a gap S between the base 34 and the support diaphragm 13, as shown in FIG. 2(B). When atmospheric pressure is introduced into the detection pressure chamber 26 while the reference pressure chamber 25 is in a vacuum state, the support diaphragm 13 to which the sensor chip 11 is bonded elastically deforms to become convex toward the reference pressure chamber 25, as shown by the two-dot chain line in Fig. 2(B). Fig. 2(B) is a cross-sectional view taken along line II-II in Fig. 2(A).

[0025] In this case, the support diaphragm 13 comes into contact with the rounded portion 33 of the sensor chip 11. The stress generated in the support diaphragm 13 when the support diaphragm 13 is pressed against this rounded portion 33 is dispersed along the rounded portion 33. The results of an analysis of the magnitude of the stress generated in the support diaphragm 13 at this time are shown in Figure 4. In Figure 4, the magnitude of the stress is indicated by the shade of color, with the color becoming darker as the stress increases.

[0026] 4, the portion where the stress is high occurs along the rounded portion 33. Therefore, the rounded portion 33 becomes a stress dispersing portion 36 formed in a shape that disperses the stress generated in the support diaphragm 13 when the displaced support diaphragm 13 is pressed against it. Therefore, according to this embodiment, when the support diaphragm 13 is displaced, it comes into contact with the stress distribution portion 36 (rounded portion 33) of the sensor chip 11, and this contact distributes the stress generated in the support diaphragm 13, thereby providing a pressure sensor that can improve the strength required for practical use.

[0027] The sensor chip 11 and supporting diaphragm 13, and chip housing package 14 according to this embodiment constitute the detection section 28 of the diaphragm vacuum gauge. The supporting diaphragm 13 is formed so as to divide the sensor chip housing space 24 into a reference pressure chamber 25 which is maintained in a vacuum state, and a detection pressure chamber 26 into which the pressure to be detected is introduced. Therefore, by using the pressure sensor 12 according to this embodiment, it is possible to manufacture a diaphragm vacuum gauge in which the support diaphragm will not be damaged even if atmospheric pressure is introduced into the detection pressure chamber.

[0028] (Second embodiment) The sensor chip of the pressure sensor according to the present invention can be configured as shown in Figures 5(A) and (B). Figure 5(A) is a plan view of the support diaphragm and the sensor chip viewed from the thickness direction of the support diaphragm. Figure 5(B) is a cross-sectional view taken along line VV in Figure 5(A). In these figures, members that are the same as or equivalent to those described in Figures 1 to 3 are designated by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0029] The sensor chip 41 shown in FIG. 5(A) is composed of a chip body 41a and a support member 41b that sandwich the support diaphragm 13 from one side and the other side in the thickness direction. The chip body 41a corresponds to the chip body 11a when the first embodiment is adopted, and the support member 41b corresponds to the support member 11b when the first embodiment is adopted. When viewed from the thickness direction of the support diaphragm 13, the sensor chip 41 is formed in a rectangular shape having a pair of vertical side ends 31, 31 extending in the vertical direction, a pair of horizontal side ends 32, 32 extending in the horizontal direction between the pair of vertical side ends 31, 31, and a chamfered portion 42 that extends in a direction inclined with respect to the vertical side ends 31 and the horizontal side ends 32 and connects the vertical side ends 31 and the horizontal side ends 32. The angle between the vertical side ends 31 and the chamfered portion 42 and the angle between the horizontal side ends 32 and the chamfered portion 42 are both obtuse angles.

[0030] When atmospheric pressure is introduced into the detection pressure chamber 26 while the reference pressure chamber 25 is in a vacuum state, the support diaphragm 13 to which the sensor chip 41 is bonded elastically deforms to become convex toward the reference pressure chamber 25, as shown by the two-dot chain line in Fig. 5(B). In this embodiment, the support diaphragm 13 deformed in this manner is pressed against the chamfered portion 42. Therefore, the stress generated in the support diaphragm 13 due to contact with the sensor chip 41 at this time is dispersed along the chamfered portion 42. In this embodiment, the chamfered portion 42 corresponds to the stress dispersion portion 36 described above.

[0031] Therefore, when the supporting diaphragm 13 is displaced, it comes into contact with the stress dispersing portion 36 (chamfered portion 42) of the sensor chip 41, and this contact disperses the stress generated in the supporting diaphragm 13. Therefore, even in this embodiment, it is possible to provide a pressure sensor that can improve the strength required for practical use.

[0032] (Third embodiment) The sensor chip of the pressure sensor according to the present invention can be configured as shown in Fig. 6(A) to (C). Fig. 6(A) is a plan view of the support diaphragm and the sensor chip viewed from the thickness direction of the support diaphragm. Fig. 6(B) is a cross-sectional view taken along the line VI-VI in Fig. 6(A). Fig. 6(C) is a cross-sectional view showing an enlarged portion of the protrusion. In these figures, members that are the same as or equivalent to those described in Figs. 1 to 3 are given the same reference numerals and detailed description will be omitted as appropriate.

[0033] The sensor chip 51 according to this embodiment is composed of a chip body 51a and a support member 51b that sandwich the support diaphragm 13 from one side and the other side in the thickness direction. The chip body 51a corresponds to the chip body 11a when the first embodiment is adopted, and the support member 51b corresponds to the support member 11b when the first embodiment is adopted. This sensor chip 51 is different from the sensor chips 11 and 41 shown in the first and second embodiments in the planar shape and the shape of the protrusion 35 of the support member 51b. In detail, the sensor chip 51 according to this embodiment is formed in a rectangular shape consisting of a pair of vertical side ends 31, 31 extending in the vertical direction and a pair of horizontal side ends 32, 32 extending in the horizontal direction between the pair of vertical side ends 31, 31, as shown in FIG. 6(A) when viewed from the thickness direction of the support diaphragm 13. The vertical side ends 31 and the horizontal side ends 32 are connected to each other so as to form a right angle 52.

[0034] The protrusion 35 of the sensor chip 51 according to this embodiment is formed in a rectangular shape when viewed from the thickness direction of the support diaphragm 13. The surface of the protrusion 35 provided on the support member 51b facing the support diaphragm 13 is formed as an inclined surface 35a that is inclined so that the thickness of the protrusion 35 gradually decreases from the base 34 toward the protruding end of the protrusion 35, as shown in Fig. 6(C).

[0035] When atmospheric pressure is introduced into the detection pressure chamber 26 while the reference pressure chamber 25 is in a vacuum state, the support diaphragm 13 to which the sensor chip 51 is bonded elastically deforms to become convex toward the reference pressure chamber 25, as shown by the two-dot chain line in Fig. 6(B). In this embodiment, the support diaphragm 13 thus deformed is pressed against the inclined surface 35a of the protrusion 35. Therefore, the stress generated in the support diaphragm 13 by contact with the sensor chip 51 at this time is dispersed along the inclined surface 35a. In this embodiment, the inclined surface 35a corresponds to the stress dispersion portion 36 described above. Therefore, when the support diaphragm 13 is displaced, it comes into contact with the stress distribution portion 36 (inclined surface 35a) of the sensor chip 51, and this contact distributes the stress generated in the support diaphragm 13. Therefore, even in this embodiment, it is possible to provide a pressure sensor that can improve the strength required for practical use. [Explanation of symbols]

[0036] 11, 41, 51...sensor chip, 12...pressure sensor, 13...support diaphragm, 14...package for accommodating chip, 24...sensor chip accommodating space, 25...reference pressure chamber, 26...detection pressure chamber, 28...detection portion, 31...vertical end, 32...horizontal end, 33...rounded portion, 34...base, 35...protrusion, 35a...inclined surface, 36...stress distribution portion, 42...chamfered portion, 51...sensor chip.

Claims

1. a package having a space for accommodating a sensor chip; a support diaphragm fixed to the package so as to divide the sensor chip accommodating space into two spaces; a sensor chip for detecting pressure, which is overlapped and fixed to the central portion of the support diaphragm; the sensor chip is provided with a stress dispersion portion at a portion against which the displaced support diaphragm is pressed, the stress dispersion portion is formed in a shape that disperses stress generated in the support diaphragm when the support diaphragm is pressed against the stress dispersion portion, the sensor chip is formed in a rectangular shape having a pair of vertical side ends extending in a vertical direction when viewed in a thickness direction of the support diaphragm, a pair of horizontal side ends extending in a horizontal direction between the pair of vertical side ends, and a rounded portion that is curved so as to be convex toward the outside of the sensor chip and connects the vertical side ends and the horizontal side ends, The pressure sensor according to claim 1, wherein the stress dispersion portion is constituted by the rounded portion.

2. A package having a space for accommodating a sensor chip; a support diaphragm fixed to the package so as to divide the sensor chip accommodating space into two spaces; a sensor chip for detecting pressure, which is overlapped and fixed to the central portion of the support diaphragm; the sensor chip is provided with a stress dispersion portion at a portion against which the displaced support diaphragm is pressed, the stress dispersion portion is formed in a shape that disperses stress generated in the support diaphragm when the support diaphragm is pressed against the stress dispersion portion, the sensor chip is formed in a rectangular shape having a pair of vertical side ends extending in a vertical direction, a pair of horizontal side ends extending in a horizontal direction between the pair of vertical side ends, and a chamfered portion extending in a direction inclined with respect to the vertical side ends and the horizontal side ends and connecting the vertical side ends and the horizontal side ends when viewed in a thickness direction of the support diaphragm; The pressure sensor according to claim 1, wherein the stress dispersion portion is constituted by the chamfered portion.

3. A package having a space for accommodating a sensor chip; a support diaphragm fixed to the package so as to divide the sensor chip accommodating space into two spaces; a sensor chip for detecting pressure, which is overlapped and fixed to the central portion of the support diaphragm; the sensor chip is provided with a stress dispersion portion at a portion against which the displaced support diaphragm is pressed, the stress dispersion portion is formed in a shape that disperses stress generated in the support diaphragm when the support diaphragm is pressed against the stress dispersion portion, the sensor chip is formed in a rectangular shape when viewed in a thickness direction of the support diaphragm, and has a base portion fixed to the support diaphragm and a protrusion portion protruding laterally from the base portion so as to generate a gap between the base portion and the support diaphragm, a surface of the protrusion facing the support diaphragm is an inclined surface that is inclined such that the thickness of the protrusion gradually decreases from the base toward the protruding end of the protrusion, The pressure sensor according to claim 1, wherein the stress dispersion portion is constituted by the inclined surface.

4. The pressure sensor according to any one of claims 1 to 3, the package, the support diaphragm, and the sensor chip constitute a detection unit of a diaphragm vacuum gauge; The pressure sensor is characterized in that the support diaphragm is formed so as to divide the sensor chip accommodating space into a reference pressure chamber maintained in a vacuum state and a detection pressure chamber into which a pressure to be detected is introduced.

Images