Method for manufacturing pressure sensor assembly

Abstract

To manufacture a pressure sensor assembly at low cost by welding a pipe and a metal body connected to a pressure sensor chip by resistance welding so as to heighten the reliability of the pipe connection.SOLUTION: Provided is a method for manufacturing a pressure sensor assembly 51 comprising: a first and a second lead pipe 52, 53 connected to a first and a second pressure guide path leading from a first and a second pressure transmission chamber of a pressure measuring device to an inner space; and a pressure sensor chip 43 connected to the first and second lead pipes 52, 53, said method including a first step in which a first and a second washer 37, 38 are joined to crank-shaped first and second tubes 41, 42 to create the first and second lead pipes 52, 53. Also included is a second step in which the first and second lead pipes 52, 53 are joined to the pressure sensor chip 43 by being bypassed through a sensor case 54. Also included are a third step in which the pressure sensor chip 43 is joined to the fitting face of the sensor case 54 and a fourth step in which the pressure sensor chip 43 and the sensor case 54 are wired together.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a pressure sensor assembly including a pressure conductor that connects a sensor chip to a body of a pressure measuring device. [Background technology]

[0002] Conventionally, a pressure sensor chip made of Si or the like is used in the pressure detection section of an industrial pressure gauge. The pressure sensor chip is, for example, housed in a ceramic sensor case shown by reference numeral 1 in FIG. 20 to eliminate the influence of contamination and humidity. In FIG. 20, reference numeral 2 denotes the pressure sensor chip, 3 denotes a lid that closes the opening of the sensor case 1, and 4 denotes a pipe for directing pressure to the pressure sensor chip 2. An example of a conventional pressure gauge equipped with such a pressure detection section is a pressure measuring device described in Patent Document 1.

[0003] The pressure measuring device disclosed in Patent Document 1 has a configuration in which a sensor case 1 (sensor header) is enclosed in a metal body 5 made of stainless steel or the like, as shown in Fig. 21. By accommodating the sensor case 1 in the metal body 5 in this way, the pressure sensor chip 2 can be protected from an external corrosive environment such as the measurement medium. The pressure measuring device 6 shown in Fig. 21 uses two pipes 4 to guide pressure from the metal body 5 to the pressure sensor chip 2 in the sensor case 1.

[0004] The pipe 4 is connected to a pressure guide passage 8 that opens into an internal space 7 of the metal body 5. The pressure guide passage 8 extends to a pressure transmission chamber 9 in the metal body 5 and is filled with a pressure transmission medium 10. The pressure transmission chamber 9 has a barrier diaphragm 11 formed as part of its wall, which contacts the measurement medium (not shown).

[0005] In a conventional pressure measuring device 6 as shown in Patent Document 1, there was a problem with the connection between the metal body 5 and the pipe 4 on the sensor case 1 side. From the viewpoint of environmental resistance, it is desirable to use a reliable welded structure for the connection between the pipe 4 and the metal body 5. If the pipe 4 and the metal body 5 are connected by adhesive, a mechanism for completely isolating them from the external environment is required because the adhesive has low resistance to humidity, acid, alkali, etc. and the adhesive strength is easily deteriorated. When using a welding method to connect the pipe 4 and the metal body 5, it is necessary to weld a washer (not shown) for resistance welding to the end of the pipe 4, as this is a proven method for ensuring strength and is also highly productive. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-92489 Summary of the Invention [Problem to be solved by the invention]

[0007] However, when welding the straight pipe 4 to the metal body 5, the electrodes used for resistance welding interfere with the sensor case 1, making it difficult to ensure a working area necessary for welding. In addition, the pitch between the two pressure guide holes in the pressure sensor chip 2 is narrow at a few millimeters, so it is difficult to resistance weld the pipe 4 to the metal body 5 with this pitch due to the constraints of the washer shape. In other words, if the pipes 4 are connected to the two pressure guide holes formed with this pitch and washers are welded to the ends of these pipes 4, the washers will interfere with each other. If the pitch between the two pressure guide holes in the pressure sensor chip 2 is widened, the pressure sensor chip 2 will become larger and the manufacturing costs will increase.

[0008] An object of the present invention is to provide a pressure sensor assembly which is inexpensive and which has high reliability for the pipe connection by welding a pipe connected to a pressure sensor chip to a metal body by resistance welding. [Means for solving the problem]

[0009] In order to achieve this object, the method for producing a pressure sensor assembly according to the present invention is a method for producing a pressure sensor assembly comprising a pressure transmission chamber having a pressure-receiving diaphragm provided in a pressure measuring device so as to receive the pressure of a process fluid to be measured and a pressure guiding tube connected to a pressure guiding path leading from the pressure transmission chamber, which contains a part of a pressure transmission medium, to an internal space of the pressure measuring device, and a pressure sensor chip connected to the pressure guiding tube to receive the pressure of the pressure transmission medium and detect the pressure, the method comprising the steps of: a first step of forming the pressure guiding tube by processing a thin tube into a crank shape and joining the two with one end of the thin tube inserted into a washer; a second step of, after the first step, passing the other end of the pressure guiding tube manufactured in the first step through a sensor case having a first opening formed on one end surface and a second opening formed on the other end surface from the first opening through the second opening, and holding the pressure sensor chip outside the sensor case in the vicinity of the second opening, and joining the other end of the pressure guiding tube to a pressure introducing portion of the pressure sensor chip; a third step of, after the second step, joining the pressure sensor chip to a wall surface of the sensor case in the vicinity of the first opening; and a fourth step of, after the third step, connecting a terminal of the pressure sensor chip to a conductive portion of the sensor case.

[0010] The present invention may further comprise, in the method for manufacturing the pressure sensor assembly, a fifth step of solder-sealing between the first opening and the pressure guiding tube after the fourth step.

[0011] The present invention relates to a method for manufacturing a pressure sensor assembly, the method including a sixth step of sealing the second opening of the sensor case with a cover member after the fifth step or between the fourth step and the fifth step. Effect of the Invention

[0012] According to the present invention, a pressure sensor assembly having a high reliability of the pipe connection can be manufactured inexpensively by welding the pressure guiding tube connected to the pressure sensor chip to the metal body by resistance welding. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of a pressure measuring device including a pressure sensor assembly according to the present invention. [Diagram 2] FIG. 2 is a perspective cross-sectional view of the pressure measuring device. [Diagram 3] FIG. 3 is an exploded perspective view showing the body and the resin case of the pressure measuring device with the body and the resin case cut away. [Figure 4] FIG. 4 is a perspective cross-sectional view of the pressure sensor assembly. [Diagram 5] FIG. 5 is an enlarged cross-sectional view showing a joint between the sensor case and the pressure sensor chip and the thin tube. [Figure 6] FIG. 6 is an enlarged cross-sectional view showing a joint between the washer and the thin tube. [Figure 7] FIG. 7 is a perspective cross-sectional view of the sensor case. [Figure 8] FIG. 8 is a plan view of the pressure sensor assembly and the substrate. [Figure 9] FIG. 9 is a perspective view of the pressure sensor assembly and the substrate. [Figure 10] FIG. 10 is a flow chart for explaining a method for manufacturing a pressure sensor assembly according to the present invention. [Figure 11] FIG. 11 is a front view of the impulse tube for explaining the first step. [Figure 12] FIG. 12 is a front view of the main part for explaining the second step. [Figure 13] FIG. 13 is a cross-sectional view of a main part for explaining the third step. [Figure 14] FIG. 14 is a perspective cross-sectional view showing an example of a sensor case. [Figure 15] FIG. 15 is a perspective view of a main part for explaining the fourth step. [Figure 16] FIG. 16 is a cross-sectional view of a main part for explaining the fifth step. [Figure 17] FIG. 17 is a cross-sectional view of a main part for explaining the sixth step. [Figure 18] FIG. 18 is a flowchart for explaining another example of a method for manufacturing a pressure sensor assembly. [Figure 19] FIG. 19 is a perspective cross-sectional view illustrating a procedure for welding the washer to the body. [Figure 20] FIG. 20 is a cross-sectional view of a conventional sensor case. [Figure 21] FIG. 21 is a cross-sectional view showing the configuration of a conventional pressure measuring device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] An embodiment of a manufacturing method for a pressure sensor assembly according to the present invention will be described in detail below with reference to Figures 1 to 19. First, a pressure measuring device that uses a pressure sensor assembly 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 parts, described below, to a body 22 depicted in the center of Fig. 1. The body 22 has a pressure receiving portion 23 depicted on the lower side of Fig. 1 and a detection portion 24 depicted on the upper side. The body 22 in this embodiment is formed from stainless steel.

[0015] 1, the pressure-receiving section 23 is formed in a plate shape with its thickness direction being the left-right direction, and one end in the thickness direction is connected to a first pipe 25, and the other end in the thickness direction is connected to a second pipe 26. The inside of the first pipe 25 is filled with a first process fluid 27 to be measured. The inside of the second pipe 26 is filled with a second process fluid 28 to be measured. One end of the pressure-receiving section 23 that is connected to the first piping 25 is provided with a first pressure-receiving diaphragm 31 that receives the pressure of the first process fluid 27, and a first pressure transmission chamber 32 is formed in which this first pressure-receiving diaphragm 31 forms part of the wall. 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 section 23 that is connected to the second pipe 26, and a second pressure transmission chamber 34 is formed in which this second pressure-receiving diaphragm 33 forms part of the wall.

[0016] As shown in Fig. 2, the first pressure transmission chamber 32 and the second pressure transmission chamber 34 are connected to a pressure chamber 44 (see Fig. 5) of a pressure sensor chip 43 via a first pressure guide path 35 and a second pressure guide path 36 formed in the body 22, first and second washers 37, 38 of the detection unit 24 described below, and first and second capillaries 41, 42. The pressure transmission system from the first and second pressure transmission chambers 32, 34 to the pressure chamber 44 is filled with a pressure transmission medium 45 (see Figs. 1 and 5). The pressure sensor chip 43 detects pressure by receiving the pressure of the pressure transmission medium 45 filled between the first and second pressure receiving diaphragms 31, 33.

[0017] The detection portion 24 of the body 22 is formed in a cylindrical shape and opens in the direction opposite to the pressure-receiving portion 23. An internal space 46 of the body 22 is formed within the detection portion 24. A cover 47 (see FIG. 1) is attached to and closes the opening of the detection portion 24. 3, first and second pressure guide paths 35, 36 are respectively opened to the inner bottom of detection portion 24. First and second pressure guide paths 35, 36 are formed inside body 22 so as to communicate from first and second pressure transmission chambers 32, 34 to internal space 46 of body 22.

[0018] 2, a first washer 37 is attached to the open end of the first pressure passage 35 that communicates with the internal space 46. A second washer 38 is attached to the open end of the second pressure passage 36 that communicates with the internal space 46. The first and second washers 37, 38 are each made of stainless steel and formed into a disk shape, and are welded to the body 22.

[0019] As shown in Fig. 6, the first and second washers 37, 38 are provided at their centers with protrusions 37a, 38a facing the insides of the first and second pressure guide paths 35, 36, and also have through holes 48, 49. As shown in Fig. 4, one end of a first capillary tube 41, which will be described later, is inserted into and joined to the through hole 48 of the first washer 37. One end of a second capillary tube 42, which will be described later, is inserted into and joined to the through hole 49 of the second washer 38.

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

[0021] The first and second capillaries 41, 42 are joined to the first and second washers 37, 38 by welding the outer peripheries of the tips of the capillaries 41, 42 to the opening edges of the through holes 48, 49 that open into the protrusions 37a, 38a. This welding is performed so that the welds 50 provide a liquid-tight seal between the first and second washers 37, 38 and the first and second capillaries 41, 42, as shown in Fig. 6.

[0022] The first capillary tube 41 welded to the first washer 37 and the second capillary tube 42 welded to the second washer 38 form part of a pressure sensor assembly indicated by the reference numeral 51 in FIG. The first washer 37 and the first capillary 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 capillary 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 the first and second washers 37, 38 joined to one ends of the first and second capillaries 41, 42, and a sensor case 54 and a pressure sensor chip 43 joined to the other ends of the first and second capillaries 41, 42. The first and second capillaries 41, 42 extend from the first and second washers 37, 38 in the opposite direction to the pressure receiving portion 23 of the body 22, and are bent so that the gap between the first and second washers 37, 38 and the sensor case 54 becomes narrow. The gap between the first and second capillaries 41, 42 is wider at one end side welded to the first and second washers 37, 38, and narrower at the other end side joined to the sensor case 54.

[0024] The sensor case 54 is made of a ceramic material and has a bottomed rectangular cylinder shape, to which a cover member 55 made of a ceramic material or a metal material is joined. The pressure sensor chip 43 is made of a plurality of silicon plate members stacked in the thickness direction to form a cube shape, and is housed in the sensor case 54. 7(A) and (B), the sensor case 54 is formed in a bottomed rectangular cylinder shape with one end surface 54a being a flat bottom surface, and opens in the direction opposite to the pressure-receiving portion 23 of the body 22. A first through hole 56 and a second through hole 57, which serve as a "first opening" according to the present invention, are opened in the one end surface 54a of the sensor case 54.

[0025] 7(B), the other end surface 54b of the sensor case 54 has a tip insertion hole 58, which serves as a "second opening" according to the present invention. The tip insertion hole 58 is closed by a cover member 55. The 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 in a state in which the cover member 55 closes the tip insertion hole 58. The operation of joining the cover member 55 to the sensor case 54 is performed so that the inside of the sensor case 54 is hermetically sealed while being vacuum or filled with N2.

[0026] The sensor case 54 in 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 stand 63 located near the opening of the chip insertion hole 58. The mounting seat 62 is formed with a flat mounting surface 62a (see FIG. 7B) to which the pressure sensor chip 43 is attached. In this embodiment, the mounting surface 62a of the mounting seat 62 corresponds to the "wall surface in the vicinity of the first opening" according to the present invention. The wiring base 63 is provided with a conductive portion 66 consisting of a plurality of bonding pads 65 electrically connected to the pressure sensor chip 43 by a plurality of wires 64 (see FIG. 15). These bonding pads 65 are electrically connected to a plurality of electrode pads 67 (see FIG. 7A) provided on one end surface 54a of the sensor case 54 by wiring (not shown) within the sensor case 54.

[0027] In this embodiment, the electrode pads 67 are arranged at both ends of the bottom wall 61 in a direction perpendicular to the direction in which the first through hole 56 and the second through hole 57 are aligned (the direction in which the first capillary 41 and the second capillary 42 are aligned). These electrode pads 67 are soldered to soldering lands 69 formed on a substrate 68 (see FIG. 3). By this soldering, the sensor case 54 is electrically connected (mounted) to the soldering lands 69 in a state in which it is placed on the substrate 68.

[0028] The substrate 68 is formed in a disk shape as shown in Fig. 3. 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 to each other. The through hole 70 is formed in the substrate 68 at a position facing the open ends of the first and second pressure guide paths 35, 36 as shown in Fig. 2.

[0029] The sensor case 54 is placed on the substrate 68 by passing the first and second washers 37, 38 through the through holes 70, 70 and passing the first and second thin tubes 41, 42 through the slits 71. The substrate 68 is also equipped with 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. Although not shown, the substrate 68 is formed with 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. The positions at which the electric circuit 72 and the connector terminal 73 are mounted are not limited to those shown in the drawings 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 cylindrical shape with a bottom 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 tab 83 for mounting 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 therethrough.

[0031] Around the through hole 84, there are provided two circular protrusions 85, 85 protruding downward in Fig. 3 from the bottom wall 81a of the resin case 81, i.e., in a direction toward 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 a direction opposite to the pressure-receiving portion 23. The circular protrusions 85 fit into a circular recess 87 formed in the body 22 so as to surround the first and second pressure guide paths 35, 36. The cylindrical body 86 is formed with a recess 88 for passing the first and second capillaries 41, 42 through.

[0032] With the substrate 68 attached to the resin case 81, the first and second washers 37, 38 are welded to the body 22, whereby the substrate 68 is fixed to the body 22 with the thickness direction of the substrate 68 being the up-down direction in Fig. 1. The up-down direction in Fig. 1 is the direction in which the open ends of the first and second pressure guide paths 35, 36 are oriented.

[0033] As shown in Fig. 4, the pressure sensor chip 43 is formed with a first hole 91 into which the other end of the first capillary tube 41 is inserted, and a second hole 92 into which the other end of the second capillary tube 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 with 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. Therefore, the first hole 91 and the second hole 92 become a pressure introduction portion 94 (see Fig. 5) of the pressure sensor chip 43.

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

[0035] As shown in FIG. 5, the first and second capillaries 41, 42 are bonded to the pressure sensor chip 43 by an adhesive 95. An epoxy adhesive can be used as the adhesive 95. The inside of the sensor case 54 is in a state where the epoxy 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 capillaries 41, 42 that pass through the first and second through holes 56, 57 of the sensor case 54 are sealed by soldering. The soldering is performed so that the solder 96 spreads over the entire area around the first and second through holes 56, 57.

[0036] The first and second through holes 56, 57 of the sensor case 54 are metallized to enable this soldering. Furthermore, the first and second capillaries 41, 42 are plated for soldering at the portions to be soldered to the first and second through holes 56, 57. This plating for soldering is Au plating on a Ni base.

[0037] Next, a procedure for assembling the pressure measuring device 21 will be described, including a method for manufacturing the pressure sensor assembly configured as described above. When assembling the pressure measuring device 21, first, the pressure sensor assembly 51 is manufactured. The pressure sensor assembly 51 is completed by carrying out the first step S1 to the sixth step S6 shown in the flowchart in FIG.

[0038] (1st step) In the first step S1, two straight thin tubes 101 as shown in Fig. 11(A) are prepared. At least a portion of these thin tubes 101 (portions to be soldered to the first and second through holes 56, 57) is plated in advance for soldering. Note that the portions of the sensor case 54 where the first and second through holes 56, 57 and the cover member 55 are joined are metallized in advance.

[0039] 11(B), the two capillaries 101 are each processed into a crank shape to form a first capillary tube 41 and a second capillary tube 42. Next, one end of the first capillary tube 41 is inserted into a first washer 37 and these are joined by welding. Also, one end of the second capillary tube 42 is inserted into a second washer 38 and these 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 manner, a first impulse guiding tube 52 and a second impulse guiding tube 53 are produced.

[0040] (2nd process) The second step following the first step S1 is performed using a 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, 53, a chip restraint portion 104 for restraining the pressure sensor chip 43, and a support portion 105 for supporting the pipe restraint portion 103 and the chip restraint portion 104. In the second step S2, the other end of the first pressure guiding tube 52 is passed through the sensor case 54 from the first through hole 56 to the chip insertion hole 58. Also, the other end of the second pressure guiding tube 53 is passed through the sensor case 54 from the second through hole 57 to the chip insertion hole 58. Then, the first and second pressure guiding tubes 52, 53 and the sensor case 54 are held by the bonding jig 102 so as to maintain this state.

[0041] At this time, a predetermined clearance is secured between the sensor case 54 and the tips of the first and second pressure guiding tubes 52, 53. In order to ensure this clearance is large, the second straight portions 41b, 42b of the first capillary tube 41 and the second capillary tube 42 are formed to be longer than the entire length of the sensor case 54 (the length from one end face 54a to the other end face 54b). Next, the pressure sensor chip 43 is held by the bonding jig 102 in a state where it is located outside the sensor case 54 and near the opening of the chip insertion hole 58. At this time, the tips of the first and second pressure guiding tubes 52, 53 are inserted into the first and second holes 91, 91 by a predetermined length. Thereafter, adhesive 95 is injected into the openings of the first and second holes 91, 92 and allowed to harden. As the adhesive 95 hardens, the other ends of the first and second pressure guiding tubes 52, 53 are joined to the pressure introducing portion 94 of the pressure sensor chip 43. After the adhesive 95 has hardened, 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] (3rd step) After the second step S2, in the third step S3, the pressure sensor chip 43 is bonded to the mounting surface 62a of the sensor case 54. That is, first, as shown in FIG. 13(A), an 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. The step of bonding the pressure sensor chip 43 to the sensor case 54 can also be performed after bonding the first and second pressure guiding tubes 52, 53 to the pressure sensor chip 43 without passing them through the sensor case 54. In this case, as shown in FIG. 14, a slit 106 is required in the sensor case 54 for inserting the first straight portions 41a, 42a and the bent portions 41c, 42c of the first and second thin tubes 41, 42.

[0043] 14, the sensor case 54 becomes larger and the number of laminated ceramic sheets for forming the sensor case 54 increases, resulting in higher manufacturing costs. In addition, since the slit 106 of the sensor case 54 needs to be sealed, the width of the slit 106 is restricted, and it is not possible to form a space for the first and second washers 37 and 38 to pass through the slit 106. For this reason, the first and second washers 37 and 38 must be welded to the first and second capillaries 41 and 42 after the pressure sensor chip 43 is bonded to the sensor case 54. This welding must be performed while holding the first and second capillaries 41 and 42 including the sensor case 54, and therefore must be performed under conditions of poor workability. Moreover, there is a risk that foreign matter may get into the first and second capillaries 41 and 42 during welding, and it is not possible to inspect whether or not foreign matter has got into the first and second capillaries 41 and 42. With the method of this embodiment, foreign matter can be easily removed after welding the first and second washers 37, 38 to the first and second capillaries 41, 42, making it possible to manufacture a highly reliable pressure sensor assembly 51.

[0044] (4th step) After the third step S3, in a fourth step S4, the terminals 107 of the pressure sensor chip 43 and the bonding pads 65 (conductive portions 66) of the sensor case 54 are connected by wires 64 as shown in FIG. (5th step) After the fourth step S4 is completed, in a fifth step S5, the gaps between the first and second through holes 56, 57 (first openings) of the sensor case 54 and the first and second pressure guiding tubes 52, 53 are sealed with solder 96, as shown in FIG.

[0045] (6th step) 17, in a sixth step S6, a cover member 55 is joined to the other end surface 54b of the sensor case 54, and the tip insertion hole 58 is sealed 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 inside of the sensor case 54 is made inactive, and the cover member 55 is attached to the sensor case 54 by brazing or seam welding. In this manner, the openings (first and second through holes 56, 57) in one end face 54a of the sensor case 54 and the opening (chip insertion hole 58) in the other end face 54b of the sensor case 54 are sealed, thereby completing the manufacturing process of the pressure sensor assembly 51. Note that the sixth step S6 of joining the cover member 55 to the sensor case 54 can be performed between the fourth step S4 and the fifth step S5, as shown in FIG.

[0046] When assembling the pressure measuring device 21 using the pressure sensor assembly 51, first, the pressure sensor assembly 51 is attached to the board 68. This attachment is performed by passing the first and second washers 37, 38 through the through holes 70 of the board 68, passing the first and second capillaries 41, 42 through the slits 71, and soldering the sensor case 54 to the board 68. Thereafter, the board 68 is engaged with and assembled into the resin case 81. When assembling the board 68 to the resin case 81, the position of the board 68 is adjusted so that the first and second washers 37, 38 enter the through holes 84 of the resin case 81 while visually checking the first and second washers 37, 38 through the through holes 70 of the board 68.

[0047] After the pressure sensor assembly 51 is assembled in the resin case 81, the pressure sensor chip 43 is characterized. By performing this characterization, the linearity, temperature characteristics, 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 eliminated. Characterization is performed by connecting a pressurizing device (not shown) to the first and second pressure guiding tubes 52, 53 and connecting a measuring device (not shown) to the connector terminal 73, and maintaining the pressure sensor assembly at a predetermined inspection temperature.

[0048] After characterization, the assembly consisting of the pressure sensor assembly 51 and the resin case 81 is inserted into the internal space 46 of the body 22 and assembled to the body 22. To do this, the circular protrusion 85 of the resin case 81 is fitted into the circular recess 87 of the body 22, and the protrusions 37a, 38a of the first and second washers 37, 38 are inserted into the first and second pressure guide paths 35, 36.

[0049] Thereafter, the first and second washers 37, 38 are welded to the body 22. As shown in Fig. 19, this welding is performed by placing the body 22 on the lower electrode 111 and pressing the upper electrode 112 against the first and second washers 37, 38 by resistance welding. The upper electrode 112 is formed in a rod shape and is passed through the through hole 84 of the resin case 81 and the through hole 70 of the substrate 68 and overlapped on the first and second washers 37, 38. A slit 113 is formed at the tip of the upper electrode 112 to allow the first and second capillaries 41, 42 to pass therethrough. After the first and second washers 37, 38 are welded to the body 22, the pressure transmission path extending from the first and second pressure transmission chambers 32, 34 to the inside of the pressure sensor chip 43 is filled with the pressure transmission medium 45. This filling is performed using a filling hole (not shown) extending from the first and second pressure transmission chambers 32, 34 to the outside of the body 22.

[0050] The manufacturing method of the pressure sensor assembly 51 according to this embodiment is a method in which the pressure sensor chip 43 is joined to the first and second pressure guiding tubes 52, 53, each of which is composed of the first and second capillary tubes 41, 42 formed into a crank shape and the first and second washers 37, 38, in a state in which the first and second pressure guiding tubes 52, 53 are passed directly through the sensor case 54, and thereafter the pressure sensor chip 43 is joined to the sensor case 54. Therefore, it is possible to manufacture the pressure sensor assembly 51 in which the gap between the first washer 37 and the second washer 38 can be made wider without increasing the size of the pressure sensor chip 43. Therefore, according to this manufacturing method of the pressure sensor assembly, the first and second pressure guiding tubes 52, 53 connected to the pressure sensor chip 43 can be welded to the body 22 by resistance welding, thereby making it possible to inexpensively manufacture the pressure sensor assembly 51 having high reliability of the pipe connection. [Explanation of symbols]

[0051] 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, 54a...one end surface, 54b...other end surface, 56...first through hole (first opening), 57...second through hole (first opening), 58...chip insertion hole (second opening), 62a...mounting surface (wall surface), 64...wire, 65...bonding pad, 66...conductive portion, 91...first hole, 92...second hole, 94...pressure introduction portion, 96...solder, 101...thin tube, 107...terminal, S1...first step, S2...second step, S3...third step, S4...fourth step, S5...fifth step, 55...cover member, S6...sixth step.

Claims

1. a pressure transmission chamber having a pressure-receiving diaphragm provided in the pressure measuring device so as to receive the pressure of the process fluid to be measured and containing a part of a pressure transmission medium, the pressure transmission chamber having a wall including a pressure-receiving diaphragm as a part of the wall and a pressure guiding tube connected to a pressure guiding path leading from the pressure measuring device to an internal space thereof to guide the pressure of the pressure transmission medium; a pressure sensor chip connected to the pressure guiding tube to receive the pressure of the pressure transmission medium and detect the pressure, a first step of forming the impulse guiding tube by processing a thin tube into a crank shape and joining one end of the thin tube to a washer in a state where the two are inserted; a second step of, after the first step, passing the other end of the pressure guiding tube manufactured in the first step through a sensor case having a first opening formed in one end surface and a second opening formed in the other end surface from the first opening through the second opening, holding the pressure sensor chip outside the sensor case and in the vicinity of the second opening, and joining the other end of the pressure guiding tube to a pressure introducing portion of the pressure sensor chip; a third step of bonding the pressure sensor chip to a wall surface of the sensor case in the vicinity of the first opening after the second step; A method for manufacturing a pressure sensor assembly, comprising: a fourth step of connecting a terminal of the pressure sensor chip and a conductive portion of the sensor case after the third step.

2. 2. The method of claim 1, further comprising the steps of: a fifth step of solder-sealing a gap between the first opening and the pressure guiding tube after the fourth step,

3. 3. The method of manufacturing a pressure sensor assembly according to claim 2, further comprising the steps of: A method for manufacturing a pressure sensor assembly, comprising a sixth step of sealing the second opening of the sensor case with a cover member after the fifth step or between the fourth step and the fifth step.

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