Method for manufacturing a pressure measuring device

Abstract

To provide a method for manufacturing a pressure measuring device with which it is possible to perform characterization while the thermal capacity of an object whose temperature is to kept constant by characterization is small.SOLUTION: Provided is a method for manufacturing a pressure measuring device 21 comprising pressure-receiving diaphragms 31, 33, a pressure sensor chip 43, an inner space 46 in which a sensor case 54 is installed, and a body 22. This method includes a first step for manufacturing lead pipes 52, 53 that are connected between the pressure sensor chip 43 and the lead pipes 35, 36, and a second step for connecting one ends of the lead pipes 52, 53 to the pressure sensor chip 43. Also included are a third step for accommodating the pressure sensor chip 43 in the sensor case 54, mounting the sensor case 54 to a circuit board 68, and electrically connecting the pressure sensor chip 43 and the circuit board 68 together, and a fourth step for carrying out characterization of the pressure sensor chip 43. Also included is a fifth step for connecting the lead pipes 52, 53 connected to the pressure sensor chip 43 and pressure guide paths 35, 36 together after characterization, and installing the sensor case 54 in the inner space 46 of the body 22.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a pressure measuring device including a pressure sensor.

Background Art

[0002] Industrial pressure gauges include sensor elements made of Si or the like for detecting pressure, as described in Patent Document 1 and Patent Document 2, for example. After the manufacturing process is completed, this type of pressure gauge is subjected to correction called characterization and then sent to the next process. Characterization is performed to remove the influence of the surrounding environment such as the surrounding temperature and pressure.

[0003] As shown in FIG. 21, the pressure measuring device shown in Patent Document 1 includes a sensor header 2 that houses a sensor element 1, a metal body 3 that supports the sensor header 2, a cover 4, and the like. In this pressure measuring device 5, the sensor element 1 is housed in the sensor header 2 to protect the sensor element 1 from an external corrosive environment such as a measurement medium. Further, the sensor header 2 is included in a metal body 3 formed of stainless steel or the like. Oil 7 is enclosed in the pressure transmission path 6 in the metal body 3 as a pressure transmission medium that transmits pressure to the sensor element 1. The sensor element 1 is electrically connected to an external output pin 9 of the cover 4 via wiring 8 in the sensor header 2.

[0004] The sensor header 2 of the pressure measuring device 5 shown in Patent Document 1 is fixed by welding to the metal body 3 and the cover 4. In this pressure measuring device 5, the characterization of the sensor element 1 is performed by connecting a characterization substrate (not shown) to the external output pin 9 after welding the sensor header 2 to the metal body 3 and the cover 4.

[0005] In Patent Document 2, as shown in FIG. 22, between the metal body 11 and the sensor header 12 A pressure measuring device 14 is described in which a part 13 for body connection is interposed. The part 13 for body connection has a cylinder 15 inserted into the pressure guiding hole 11a of the metal body 11 and the pressure guiding hole 12a of the sensor header 12, and a flange 16 sandwiched between the metal body 11 and the sensor header 12, and is welded to the metal body 11 and the sensor header 12 by resistance welding. A signal processing board 17 is connected to the sensor header 12.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In the pressure measuring device 5 described in Patent Document 1, the sensor element 1 is characterized after the sensor header 2 is welded to the metal body 3 and the cover 4. Therefore, when performing the characterization, the temperatures of the metal body 3, the cover 4, etc. must be kept at the same temperature as the sensor element. That is, in the pressure measuring device 5 shown in Patent Document 1, the equipment for performing the characterization becomes large-sized, and since the heat capacity of the object for keeping the temperature constant in the characterization is large, a long time is required for temperature stabilization, and there is a problem that the number of processes decreases when performing the characterization in batch processing.

[0008] On the other hand, in the pressure measuring device 14 shown in Patent Document 2, before welding the sensor header 12 to the metal body 11 with the body connection part 13, by connecting the sensor header 12 to the signal processing substrate 17, it is possible to perform characterization with the sensor header alone (in a state where the heat capacity is small). However, when the sensor header 12 is welded to the metal body 11 by the body connection part 13 after the characterization, since the resistance welding electrode interferes with the substrate 17, resistance welding cannot be performed. Therefore, also in the pressure measuring device 14 shown in Patent Document 2, the process of welding the sensor header 12 to the metal body 11 by resistance welding with the body connection part 13 must be performed prior to the characterization, and the characterization must be performed in a state where the heat capacity of the object whose temperature is made constant during the characterization becomes large.

[0009] An object of the present invention is to provide a method for manufacturing a pressure measuring device capable of performing characterization in a state where the heat capacity of an object whose temperature is made constant during the characterization is small.

Means for Solving the Problems

[0010] In order to achieve this object, a method for manufacturing a pressure measuring device according to the present invention includes a pressure receiving diaphragm that receives the pressure of a process fluid to be measured, a pressure sensor chip that receives the pressure of a pressure transmission medium filled between the pressure receiving diaphragm and detects the pressure, an internal space where a sensor case for housing the pressure sensor chip is installed, and a body in which a pressure guiding path is formed that is formed as a part of a wall and communicates from a pressure transmission chamber that forms a part of the wall and houses a part of the pressure transmission medium to the internal space. The method for manufacturing a pressure measuring device includes: a first step of manufacturing a pressure guiding pipe connected between a pressure introduction portion of the pressure sensor chip and an opening of the pressure guiding path to the internal space; a second step of connecting one end of the pressure guiding pipe manufactured in the first step to the pressure introduction portion of the pressure sensor chip through the sensor case; a third step of housing the pressure sensor chip connected to the pressure guiding pipe in the second step in the sensor case and electrically connecting it, mounting the sensor case on a circuit board equipped with an electric circuit that generates an electric signal from a detection output of the pressure sensor chip, and electrically connecting the pressure sensor chip and the circuit board; a fourth step of performing characterization of the pressure sensor chip connected to the electric circuit in the third step; and a fifth step of connecting the other end of the pressure guiding pipe connected to the pressure sensor chip characterized in the fourth step to an opening of the pressure guiding path formed in the body to the internal space of the body and then installing the sensor case in the internal space of the body.

[0011] The method for manufacturing a pressure measuring device according to the present invention includes first and second pressure receiving diaphragms that respectively receive the pressures of first and second process fluids to be measured, and a pressure sensor chip that receives the first and second pressures of first and second pressure transmission media filled between the first and second pressure receiving diaphragms and detects a pressure difference between the first pressure and the second pressure. A method for manufacturing a pressure measuring device having an internal space for installing a sensor case that houses the pressure sensor chip, and a body in which first and second pressure transmission chambers formed as part of a wall and housing a part of the first and second pressure transmission media communicate with the internal space through first and second pressure guiding paths, the method including: a first step of manufacturing first and second pressure guiding pipes connected between first and second pressure introduction portions of the pressure sensor chip and first and second openings of the first and second pressure guiding paths formed in the body to the internal space; a second step of connecting one ends of the first and second pressure guiding pipes manufactured in the first step to the first and second pressure introduction portions of the pressure sensor chip through the sensor case; a third step of housing the pressure sensor chip connected to the first and second pressure guiding pipes in the second step in the sensor case, electrically connecting the sensor case to a circuit board on which an electric circuit for generating an electric signal from a detection output of the pressure sensor chip is mounted, and electrically connecting the pressure sensor chip and the electric circuit; a fourth step of performing characterization of the pressure sensor chip connected to the electric circuit in the third step; and a fifth step of connecting the other ends of the first and second pressure guiding pipes connected to the pressure sensor on which characterization has been performed in the fourth step to the first and second openings of the first and second pressure guiding paths formed in the body to the internal space of the body, respectively, and then installing the sensor case in the internal space of the body.

Effect of the Invention

[0012] According to the present invention, a pressure sensor assembly including a sensor case housing a pressure sensor chip and a pressure guiding pipe, and a substrate become objects for which the temperature is made constant by characterization. Therefore, it is possible to provide a method for manufacturing a pressure measuring device capable of performing characterization in a state where the heat capacity of the object to be characterized is small.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a method for manufacturing a pressure measuring device according to the present invention will be described in detail with reference to FIGS. 1 to 18. First, the pressure measuring device manufactured by the manufacturing method according to the present invention will be described. The pressure measuring device 21 shown in FIG. 1 is configured by assembling a plurality of functional components, which will be described later, to a body 22 drawn at the center in FIG. 1. The body 22 has a pressure receiving portion 23 drawn on the lower side and a detection portion 24 drawn on the upper side in FIG. 1. The body 22 according to this embodiment is formed of stainless steel.

[0015] The pressure receiving portion 23 is formed in a plate shape with the left-right direction as the thickness direction in FIG. 1. The first pipe 25 is connected to one end in the thickness direction, and the second pipe 26 is connected to the other end in the thickness direction. The inside of the first pipe 25 is filled with a first process fluid 27 that is the measurement target. The inside of the second pipe 26 is filled with a second process fluid 28 that is the measurement target. A first pressure receiving diaphragm 31 that receives the pressure of the first process fluid 27 is provided at one end of the pressure receiving portion 23 connected to the first pipe 25, and a first pressure transmission chamber 32 of which the first pressure receiving diaphragm 31 forms a part of the wall is formed. A second pressure receiving diaphragm 33 that receives the pressure of the second process fluid 28 is provided at the other end of the pressure receiving portion 23 connected to the second pipe 26, and a second pressure transmission chamber 34 of which the second pressure receiving diaphragm 33 forms a part of the wall is formed.

[0016] As shown in FIG. 2, the first pressure transmission chamber 32 and the second pressure transmission chamber 34 communicate with the pressure chamber 44 (see FIG. 5) of the pressure sensor chip 43 via a first pressure conduction path 35 and a second pressure conduction path 36 formed in the body 22, first and second washers 37 and 38 of the detection unit 24 described later, and first and second capillary tubes 41 and 42. The pressure transmission system from the first and second pressure transmission chambers 32 and 34 to the pressure chamber 44 is filled with a pressure transmission medium 45 (see FIGS. 1 and 5). The pressure transmission medium 45 filled in the pressure transmission system including the first pressure transmission chamber 32 corresponds to the "first pressure transmission medium" in the present invention, and the pressure transmission medium 45 filled in the pressure transmission system including the second pressure transmission chamber 34 corresponds to the "second pressure transmission medium" in the present invention. The pressure sensor chip 43 receives the pressure of the pressure transmission medium 45 filled between the first and second pressure receiving diaphragms 31 and 33 and detects the pressure.

[0017] The detection unit 24 of the body 22 is formed in a cylindrical shape and opens in a direction opposite to the pressure receiving unit 23. An internal space 46 of the body 22 is formed in the detection unit 24. The opening portion of the detection unit 24 has a cover 47 (see FIG. 1) attached thereto and is closed by the cover 47. As shown in FIG. 3, the first and second pressure conduction paths 35 and 36 open at the inner bottom of the detection unit 24, respectively. The first and second pressure conduction paths 35 and 36 are formed inside the body 22 so as to communicate from the first and second pressure transmission chambers 32 and 34 to the internal space 46 of the body 22.

[0018] A first washer 37 is mounted at the opening end of the first pressure conduction path 35 communicating with the internal space 46, as shown in FIG. 2. A second washer 38 is mounted at the opening end of the second pressure conduction path 36 communicating with the internal space 46. The first and second washers 37 and 38 are each formed in a disc shape by stainless steel and are welded to the body 22.

[0019] At the central portions of the first and second washers 37 and 38, as shown in FIG. 6, convex portions 37a and 38a facing the inside of the first and second pressure guiding paths 35 and 36 are provided, and through holes 48 and 49 are formed. As shown in FIG. 4, the other end of the first thin tube 41, one end of which is connected to the pressure sensor chip 43, is inserted and joined into the through hole 48 of the first washer 37. The other end of the second thin tube 42, one end of which is connected to the pressure sensor chip 43, is inserted and joined into the through hole 49 of the second washer 38.

[0020] The first thin tube 41 and the second thin tube 42 are each formed of stainless steel and are each bent into a crank shape. The crank shape means that, as shown in FIG. 4, with respect to the first straight portions 41a and 42a including the other ends (the lower ends in FIG. 4) of the first and second thin tubes 41 and 42, the second straight portions 41b and 42b including one ends of the first and second thin tubes 41 and 42 are offset by a predetermined length in a direction orthogonal to the longitudinal direction of the first and second thin tubes 41 and 42.

[0021] The joining of the first and second thin tubes 41 and 42 to the first and second washers 37 and 38 is performed by welding the outer peripheral portions of the tips of the thin tubes 41 and 42 to the opening edges of the through holes 48 and 49 opening to the convex portions 37a and 38a. This welding is performed so that, as shown in FIG. 6, the welding portion 50 seals the first and second washers 37 and 38 and the first and second thin tubes 41 and 42 in a liquid-tight manner.

[0022] The first thin tube 41 welded to the first washer 37 and the second thin tube 42 welded to the second washer 38 constitute a part of the pressure sensor assembly indicated by reference numeral 51 in FIG. 4. The first washer 37 and the first thin tube 41 constitute a first pressure guiding tube 52 that is connected to the first pressure guiding path 35 and guides the pressure of the pressure transmission medium 45 to the pressure sensor chip 43. The second washer 38 and the second thin tube 42 constitute a second pressure guiding tube 53 that is connected to the second pressure guiding path 36 and guides the pressure of the pressure transmission medium 45 to the pressure sensor chip 43.

[0023] As shown in Fig. 4, the pressure sensor assembly 51 includes first and second washers 37 and 38 joined to the other ends of the first and second capillary tubes 41 and 42, and a sensor case 54 and a pressure sensor chip 43 joined to one ends of the first and second capillary tubes 41 and 42. The first and second capillary tubes 41 and 42 extend from the first and second washers 37 and 38 in a direction opposite to the pressure receiving portion 23 of the body 22, and are bent so that the distance between these two capillary tubes 41 and 42 becomes narrower between the first and second washers 37 and 38 and the sensor case 54. The distance between the first and second capillary tubes 41 and 42 becomes wider on the other end side welded to the first and second washers 37 and 38, and becomes narrower on the one end side joined to the sensor case 54.

[0024] The sensor case 54 is formed in a bottomed rectangular tube shape by a ceramic material, and a cover member 55 formed by a ceramic material or a metal material is joined thereto. The pressure sensor chip 43 is formed in a cubic shape by stacking a plurality of plate-like members made of silicon in the thickness direction, and is housed in the sensor case 54. As shown in Figs. 7(A) and (B), the sensor case 54 is formed in a bottomed rectangular tube shape having a flat bottom surface on one end surface 54a, and is open in a direction opposite to the pressure receiving portion 23 of the body 22. A first through hole 56 and a second through hole 57 are opened in the one end surface 54a of the sensor case 54.

[0025] As shown in Fig. 7(B), a chip insertion hole 58 is opened in the other end surface 54b of the sensor case 54. The chip insertion hole 58 is closed by the cover member 55. This cover member 55 is formed in a plate shape and is fixed to the other end surface 54b of the sensor case 54 by brazing or seam welding or the like in a state of closing the chip insertion hole 58. The operation of joining this cover member 55 to the sensor case 54 is performed so as to be hermetically sealed in a state where the inside of the sensor case 54 is filled with vacuum or N2.

[0026] The sensor case 54 according to this embodiment is formed with a bottom wall 61, a mounting seat 62 located on the opening side of the chip insertion hole 58 from the bottom wall 61, and a wiring base 63 located near the opening of the chip insertion hole 58. On the mounting seat 62, a flat mounting surface 62a (see FIG. 7(B)) to which the pressure sensor chip 43 is adhered is formed. On the wiring base 63, a conductive portion 66 composed of a plurality of bonding pads 65 electrically connected to the pressure sensor chip 43 by a plurality of wires 64 (see FIG. 15) is provided. These bonding pads 65 are electrically connected by wiring (not shown) in the sensor case 54 to a plurality of electrode pads 67 (see FIG. 7(A)) provided on one end surface 54a of the sensor case 54.

[0027] The electrode pads 67 according to this embodiment are disposed at both ends in a direction orthogonal to the direction in which the first through hole 56 and the second through hole 57 are arranged on the bottom wall 61 (the direction in which the first capillary tube 41 and the second capillary tube 42 are arranged). These electrode pads 67 are soldered on top of soldering lands 69 formed on a substrate 68 (see FIG. 3). By performing this soldering, the sensor case 54 is electrically connected (mounted) to the soldering lands 69 in a state where the sensor case 54 is placed on the substrate 68. In this embodiment, the substrate 68 corresponds to the "circuit board" in the present invention.

[0028] As shown in FIG. 3, the substrate 68 is formed in a disk shape. The substrate 68 is formed with two circular through holes 70, 70 through which the first and second washers 37, 38 can pass, and a slit 71 connecting these through holes 70. As shown in FIG. 2, the through holes 70 are formed at positions on the substrate 68 facing the open ends of the first and second pressure guiding paths 35, 36.

[0029] The operation of overlapping the sensor case 54 on the substrate 68 is performed by passing the first and second washers 37, 38 through the through holes 70, 70 and passing the first and second capillary tubes 41, 42 through the slits 71. Further, an electric circuit 72 (see FIGS. 8 and 9) that generates an electric signal from the detection output of the pressure sensor chip 43 and a connector terminal 73 for external connection are mounted on the substrate 68. Although not shown, a wiring pattern that electrically connects the soldering land 69 and the electric circuit 72 and a wiring pattern that electrically connects the electric circuit 72 and the connector terminal 73 are formed on the substrate 68. The positions where the electric circuit 72 and the connector terminal 73 are mounted are not limited to the illustrated positions and can be changed as appropriate.

[0030] The substrate 68 according to this embodiment is supported by a resin case 81 (see FIG. 3) and is supported by the body 22 via the resin case 81. The resin case 81 is formed in a bottomed cylindrical shape that can be accommodated in the internal space 46 of the body 22. The resin case 81 is formed with a mounting surface 82 on which the substrate 68 is placed, a claw piece 83 for placing and locking the substrate 68 on the mounting surface 82, and two through holes 84, 84 for passing the first and second washers 37, 38.

[0031] Around the through hole 84, two circular protrusions 85, 85 protruding downward from the bottom wall 81a of the resin case 81 in FIG. 3, that is, in the direction facing the pressure receiving portion 23 of the body 22, and two cylindrical bodies 86, 86 protruding from the bottom wall 81a of the resin case 81 in the direction opposite to the pressure receiving portion 23 are provided. The circular protrusion 85 is fitted into a circular recess 87 formed so as to surround the first and second pressure guiding paths 35, 36 in the body 22. A recess 88 for passing the first and second capillary tubes 41, 42 is formed in the cylindrical body 86.

[0032] With the first and second washers 37, 38 welded to the body 22 in a state where the substrate 68 is mounted on the resin case 81, the substrate 68 is fixed to the body 22 in a state where the thickness direction of the substrate 68 is the vertical direction in FIG. 1. The vertical direction in FIG. 1 is the direction in which the open ends of the first and second pressure guiding paths 35, 36 are directed.

[0033] As shown in FIG. 4, the pressure sensor chip 43 is formed with a first hole 91 into which one end of the first capillary 41 is inserted and a second hole 92 into which one end of the second capillary 42 is inserted. As shown in FIG. 5, the pressure sensor chip 43 according to this embodiment is adhered to the mounting seat 62 of the sensor case 54 by an adhesive 93 (see FIG. 5). The pressure sensor chip 43 is configured to detect the pressure difference between the pressure of the pressure transmission medium 45 transmitted to the first hole 91 and the pressure of the pressure transmission medium 45 transmitted to the second hole 92. The first hole 91 and the second hole 92 serve as the pressure introduction portion 94 (see FIG. 5) of the pressure sensor chip 43. In this embodiment, the first hole 91 corresponds to the "first pressure introduction portion" in the present invention, and the second hole 92 corresponds to the "second pressure introduction portion" in the present invention.

[0034] The first and second through holes 56, 57 of the sensor case 54 are formed so as to be through holes penetrating the bottom wall 61. The hole diameters of the first and second through holes 56, 57 are such that one ends of the first and second capillaries 41, 42 can pass through. One end of the first capillary 41 passes through the first through hole 56 and is inserted into the first hole 91 of the pressure sensor chip 43, communicating with the pressure sensor chip 43. One end of the second capillary 42 passes through the second through hole 57 and is inserted into the second hole 92 of the pressure sensor chip 43, communicating with the pressure sensor chip 43.

[0035] As shown in Fig. 5, the first and second capillary tubes 41 and 42 are adhered to the pressure sensor chip 43 with an adhesive 95. As this adhesive 95, an epoxy-based adhesive can be used. The inside of the sensor case 54 is in a state where the epoxy-based adhesive does not absorb moisture. This state is a vacuum state or a state filled with an inert gas such as N2 gas. In order to keep the inside of the sensor case 54 in such an inert state, the portions of the first and second capillary tubes 41 and 42 passing through the first and second through-holes 56 and 57 of the sensor case 54 are sealed by soldering. The soldering is performed so that the solder 96 wets and spreads over the entire area around the first and second through-holes 56 and 57.

[0036] The first and second through-holes 56 and 57 of the sensor case 54 are subjected to a metallization process so that this soldering can be performed. Also, on the first and second capillary tubes 41 and 42, soldering plating is applied to the portions to be soldered to the first and second through-holes 56 and 57. This soldering plating is Au plating with Ni as the base.

[0037] Next, a method for manufacturing the pressure measuring device 21 configured as described above will be described with reference to the flowchart shown in Fig. 10. The pressure measuring device 21 is completed by performing the first to fifth steps S1 to S6 of the flowchart shown in Fig. 10.

[0038] (First step) In the first step S1, two linear capillary tubes 101 as shown in Fig. 11(A) are prepared. Soldering plating is applied in advance to at least a part of these capillary tubes 101 (the portions to be soldered to the first and second through-holes 56 and 57). In addition, a metallization process is applied in advance to the portions where the first and second through-holes 56 and 57 of the sensor case 54 are joined to the cover member 55.

[0039] Then, as shown in Fig. 11(B), the two capillary tubes 101 are processed into a crank shape to form a first capillary tube 41 and a second capillary tube 42. Next, the other end of the first capillary tube 41 is inserted into the first washer 37, and they are joined by welding. Also, the other end of the second capillary tube 42 is inserted into the second washer 38, and they are joined by welding. By welding the first and second washers 37 and 38 to the first and second capillary tubes 41 and 42 in this way, a first pressure guiding tube 52 and a second pressure guiding tube 53 are manufactured.

[0040] (Second Step) The second step following the first step S1 is performed using the bonding jig 102 shown in Fig. 12. The bonding jig 102 has a pipe restraint portion 103 for restraining the first and second pressure guiding tubes 52 and 53, a chip restraint portion 104 for restraining the pressure sensor chip 43, and a support portion 105 for supporting these pipe restraint portion 103 and chip restraint portion 104. In the second step S2, one end of the first pressure guiding tube 52 is passed through the sensor case 54 from the first through hole 56 of the sensor case 54 so as to pass through the chip insertion hole 58. Also, one end of the second pressure guiding tube 53 is passed through the sensor case 54 from the second through hole 57 of the sensor case 54 so as to pass through the chip insertion hole 58. Then, the first and second pressure guiding tubes 52 and 53 and the sensor case 54 are held by the bonding jig 102 so that this state is maintained.

[0041] At this time, a clearance of a predetermined width is ensured between the sensor case 54 and the tips of the first and second pressure guiding tubes 52 and 53. The second straight portions 41b and 42b of the first capillary tube 41 and the second capillary tube 42 are formed to be longer than the overall length of the sensor case 54 (the length from one end face 54a to the other end face 54b) so that this clearance can be widened. Next, the pressure sensor chip 43 is held by the bonding jig 102 in a state of being located outside the sensor case 54 and near the opening portion of the chip insertion hole 58. At this time, the tips of the first and second pressure guiding tubes 52 and 53 are inserted into the first and second holes 91 and 92 by a predetermined length. Thereafter, the adhesive 95 is injected into the openings of the first and second holes 91, 92 and cured. When the adhesive 95 cures, one ends of the first and second pressure guiding tubes 52, 53 and the pressure introduction portion 94 of the pressure sensor chip 43 are joined. After the adhesive 95 has cured, the assembly consisting of the first and second pressure guiding tubes 52, 53, the sensor case 54, and the pressure sensor chip 43 is removed from the bonding jig 102.

[0042] (Third step) After the second step S2, in the third step S3, the pressure sensor chip 43 is joined to the mounting surface 62a of the sensor case 54. That is, first, as shown in Fig. 13(A), the adhesive 93 is applied to the mounting surface 62a of the sensor case 54. Then, as shown in Fig. 13(B), the pressure sensor chip 43 is inserted into the sensor case 54 and bonded to the mounting surface 62a via the adhesive 93. Thereafter, as shown in Fig. 14, the terminal 107 of the pressure sensor chip 43 and the bonding pad 65 (conductive portion 66) of the sensor case 54 are connected by a wire 64 to electrically connect the pressure sensor chip 43 and the sensor case 54. Then, as shown in Fig. 15, the space between the first and second through holes 56, 57 of the sensor case 54 and the first and second pressure guiding tubes 52, 53 is sealed with solder 96.

[0043] Next, as shown in Fig. 16, a cover member 55 is joined to the other end face 54b of the sensor case 54 to seal the chip insertion hole 58 with the cover member 55. At this time, the sensor case 54 and the first and second pressure guiding tubes 52, 53 are loaded into a joining device (not shown), and the interior of the sensor case 54 is made inert, and the cover member 55 is attached to the sensor case 54 by brazing or seam welding. After the openings (the first and second through holes 56, 57) on one end face 54a and the opening (chip insertion hole 58) on the other end face 54b of the sensor case 54 are sealed in this way, as shown in Figs. 17(A) and (B), the pressure sensor assembly 51 consisting of the sensor case 54 and the first and second pressure guiding tubes 52, 53 is attached to the substrate 68.

[0044] This mounting operation is performed by passing the first and second washers 37, 38 through the through-holes 70 of the substrate 68, passing the first and second capillary tubes 41, 42 through the slits 71, and soldering the sensor case 54 to the substrate 68. At this time, an electric circuit 72 and a connector terminal 73 for external connection are also soldered to the substrate 68. By performing soldering in this way, the pressure sensor chip 43 and the substrate 68 (electric circuit 72 and connector terminal 73) are electrically connected. Then, the substrate 68 is locked to the resin case 81 and assembled. When assembling the substrate 68 to the resin case 81, while visually checking the first and second washers 37, 38 through the through-holes 70 of the substrate 68, the position of the substrate 68 is adjusted so that the first and second washers 37, 38 enter the through-holes 84 of the resin case 81.

[0045] (Fourth step) After the third step S3, in the fourth step, the characterization of the pressure sensor chip 43 connected to the electric circuit 72 is performed. The characterization can be performed in a state where an assembly composed of the pressure sensor assembly 51 and the substrate 68 is assembled to the resin case 81. When assembling the substrate 68 to the resin case 81, while visually checking the first and second washers 37, 38 through the through-holes 70 of the substrate 68, the position of the substrate 68 is adjusted so that the first and second washers 37, 38 enter the through-holes 84 of the resin case 81, and the substrate 68 is locked to the resin case 81.

[0046] The characterization is performed using the pressurizing device 111 shown in FIG. 18. The pressurizing device 111 includes a support table 114 having mounting seats 112, 113 for mounting the first and second washers 37, 38, a first pin 115 stacked on the first washer 37, a second pin 116 stacked on the second washer 38, and a pressing mechanism 117 that presses the first and second pins 115, 116 toward the support table 114. The support table 114 is formed with a first pressure guiding hole 118 for applying fluid pressure to the first washer 37 and a second pressure guiding hole 119 for applying fluid pressure to the second washer 38.

[0047] Characterization is performed by holding the pressure sensor assembly 51 and the substrate 68 in the pressurizing device 111, connecting a measurement device (not shown) for characterization or the like to the connector terminal 73, and applying a predetermined fluid pressure to the first and second pressure guiding holes 118 and 119 with the entire pressurizing device 111 including the pressure sensor assembly 51 set to a predetermined inspection temperature. By performing this characterization, the linearity, temperature identification, static pressure characteristics, etc. of the sensor output of the pressure sensor chip 43 are corrected, and the influence of the surrounding environment such as the surrounding temperature and pressure can be removed.

[0048] (Fifth step) After performing the characterization in the fourth step, in the fifth step, after connecting the other ends of the first and second pressure guiding tubes 52 and 53 to the body 22, the sensor case 54 is installed in the internal space 46 of the body 22. In this fifth step, the resin case 81 is inserted into the internal space 46 of the body 22, the circular protrusion 85 of the resin case 81 is fitted into the circular recess 87 of the body 22, and the convex portions 37a and 38a of the first and second washers 37 and 38 are inserted into the first and second pressure guiding paths 35 and 36.

[0049] Thereafter, the first and second washers 37 and 38 are welded to the body 22. This welding is performed by placing the body 22 on the lower electrode 121 and pressing the upper electrode 122 against the first and second washers 37 and 38 for resistance welding as shown in FIG. 19. The upper electrode 122 is formed in a rod shape and is overlapped with the first and second washers 37 and 38 through the through hole 84 of the resin case 81 and the through hole 70 of the substrate 68. A slit 123 is formed at the tip of the upper electrode 122 for passing the first and second thin tubes 41 and 42. After the first and second washers 37 and 38 are welded to the body 22, the pressure transmission medium 45 is filled into the pressure transmission path from the first and second pressure transmission chambers 32 and 34 to the inside of the pressure sensor chip 43. This filling is performed using filling holes (not shown) extending from the first and second pressure transmission chambers 32 and 34 to the outside of the body 22. By filling the pressure transmission medium 45 in this way, the manufacturing of the pressure measuring device 21 is completed.

[0050] In the method for manufacturing the pressure measurement device 21 according to this embodiment, the pressure sensor assembly 51 including the sensor case 54 housing the pressure sensor chip 43 and the first and second pressure guiding pipes 52 and 53, and the substrate 68 are objects for which the temperature is made constant in the characterization. For this reason, it becomes possible to perform the characterization in a state where the heat capacity of the object to be characterized is small. As a result, it is possible to reduce the size of the facility for performing the characterization, and since the heat capacity of the object for which the temperature is made constant in the characterization is small, the time required for temperature stabilization becomes short, and the number of processes can be increased when performing the characterization in batch processing.

[0051] In the above-described embodiment, the method for manufacturing the pressure measurement device 21 that detects the differential pressure between the pressure of the first process fluid 27 and the pressure of the second process fluid 28 has been described. However, the manufacturing method of the present invention can also be applied to a pressure measurement device in the case where the detected pressure is one, such as an absolute pressure sensor or a gauge pressure sensor. The pressure measurement device having one detected pressure can be configured, for example, as shown in FIG. 20. In FIG. 20, members that are the same as or equivalent to those described with reference to FIGS. 1 to 19 are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

[0052] The pressure sensor chip 43 of the pressure measurement device 131 shown in FIG. 20 constitutes, for example, an absolute pressure sensor, has a vacuum chamber 132, and one pressure guiding pipe (the first pressure guiding pipe 52) is connected thereto. In the body 133 of this pressure measurement device 131, one pressure receiving diaphragm (the first pressure receiving diaphragm 31), one pressure transmission chamber (the first pressure transmission chamber 32), and one pressure guiding path (the first pressure guiding path 35) are provided. The substrate 68 and the resin case 81 can be made common with the parts of the pressure measurement device 21 when adopting the first embodiment, and the same ones as those shown in the first embodiment can be used. Note that circular recesses 87 are formed at two locations in the body 133 so that the resin case 81 can be attached thereto. According to the present invention, even when the detected pressure is one, it is possible to manufacture a pressure measuring device capable of performing characterization in a state where the heat capacity of the object to be characterized is small.

Explanation of Signs

[0053] 21... Pressure measuring device, 31... First pressure receiving diaphragm, 32... First pressure transmission chamber, 33... Second pressure receiving diaphragm, 34... Second pressure transmission chamber, 35... First pressure guiding path, 36... Second pressure guiding path, 37... First washer, 38... Second washer, 41... First capillary tube, 42... Second capillary tube, 43... Pressure sensor chip, 45... Pressure transmission medium, 46... Internal space, 51... Pressure sensor assembly, 52... First pressure guiding tube, 53... Second pressure guiding tube, 54... Sensor case, 64... Wire, 65... Bonding pad, 91... First hole, 92... Second hole, 94... Pressure introduction part, 96... Solder, 107... Terminal, 111... Pressurizing device, S1... First step, S2... Second step, S3... Third step, S4... Fourth step, S5... Fifth step.

Claims

1. A method for manufacturing a pressure measuring device, comprising a pressure-receiving diaphragm that receives the pressure of a process fluid to be measured, a pressure sensor chip that receives the pressure of a pressure transmission medium filled between the pressure-receiving diaphragm and detects the pressure, an internal space for installing a sensor case that houses the pressure sensor chip, and a body having a pressure guiding path formed through a wall portion of the pressure-receiving diaphragm and communicating from a pressure transmission chamber that houses a part of the pressure transmission medium to the internal space, a first step of manufacturing a pressure guiding tube connected between a pressure introduction portion of the pressure sensor chip and an opening of the pressure guiding path to the internal space, a second step of connecting one end of the pressure guiding tube manufactured in the first step to the pressure introduction portion of the pressure sensor chip through the sensor case, a third step of housing the pressure sensor chip connected to the pressure guiding tube in the second step in the sensor case and electrically connecting it to the sensor case, mounting the sensor case on a circuit board equipped with an electric circuit that generates an electric signal from the detection output of the pressure sensor chip, and electrically connecting the pressure sensor chip and the circuit board, a fourth step of performing characterization of the pressure sensor chip connected to the electric circuit in the third step, and a fifth step of connecting the other end of the pressure guiding tube connected to the pressure sensor chip on which characterization has been performed in the fourth step to an opening of the pressure guiding path formed in the body to the internal space of the body, and then installing the sensor case in the internal space of the body. The method for manufacturing a pressure measuring device is characterized by including the above steps.

2. A method for manufacturing a pressure measuring device, comprising first and second pressure-receiving diaphragms that respectively receive the pressures of first and second process fluids to be measured, a pressure sensor chip that receives the first and second pressures of first and second pressure transmission media filled between the first and second pressure-receiving diaphragms and detects the pressure difference between the first pressure and the second pressure, an internal space for installing a sensor case that houses the pressure sensor chip, and a body having first and second pressure guiding paths formed through a wall portion of the first and second pressure-receiving diaphragms and communicating from first and second pressure transmission chambers that house parts of the first and second pressure transmission media to the internal space. A first step of manufacturing first and second pressure guiding tubes connected between first and second pressure introduction portions of the pressure sensor chip and first and second openings to the internal space of the first and second pressure guiding paths formed in the body; A second step of connecting one ends of the first and second pressure guiding tubes manufactured in the first step to the first and second pressure introduction portions of the pressure sensor chip through the sensor case; A third step of housing the pressure sensor chip connected to the first and second pressure guiding tubes in the second step in the sensor case, electrically connecting the sensor case, mounting the sensor case on a circuit board equipped with an electric circuit that generates an electric signal from the detection output of the pressure sensor chip, and electrically connecting the pressure sensor chip and the electric circuit; A fourth step of performing characterization of the pressure sensor chip connected to the electric circuit in the third step; A fifth step of connecting the other ends of the first and second pressure guiding tubes connected to the pressure sensor chip subjected to characterization in the fourth step to the first and second openings to the internal space of the body of the first and second pressure guiding paths formed in the body, respectively, and then installing the sensor case in the internal space of the body. A method of manufacturing a pressure measuring device, characterized by including the above steps.

Images