JP2007198858A - Pressure detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance detection precision of pressure while simplifying manufacture for a pressure detector. <P>SOLUTION: A sensor part 3 of the pressure detector 1 in the present invention includes a substrate 15 provided with a pressure detecting electrode 8 in one side, and a diaphragm 2 made of an electronic-conductive inorganic compound, layered on the substrate 15 to be opposed with a prescribed gap 7 with respect to the pressure detecting electrode 8 in the one side, and functioned as a pressure detecting electrode in the other side paired with the pressure detecting electrode 8 in the one side. That is, the pressure detecting electrode and a lead part for the electrode are not required to be provided on the diaphragm in the sensor part 3, because a diaphragm 2 main body is formed of the electronic-conductive material, and the manufacture for the pressure detector 1 is simplified thereby. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure detector.

A resistance change type pressure detector that detects pressure based on a change in resistance value corresponding to deformation of a diaphragm provided with a resistor has been proposed (for example, see Patent Document 1).
In addition, a capacitance-type pressure detector that detects pressure based on a change in capacitance between one electrode facing each other across a predetermined gap and the other electrode on the diaphragm, etc. Is also known (see, for example, Patent Document 2).

  Here, as illustrated in FIG. 7, a conventional capacitive pressure detector 81 includes a substrate 83 having one pressure detection electrode 82 and another pressure detection electrode 84, for example, made of alumina. For example, the diaphragm 85 and the spacer layer 87 interposed between the substrate 83 and the diaphragm 85 to form the gap 86 are laminated and integrated.

Further, the board 83 of the pressure detector 81 is provided with terminal portions 88 and 89 for external connection for connecting to an external device side. The external connection terminal portions 88 and 89 are, for example, interlayer connection portions (vias) 90 and 91, terminal portions 92 of the spacer layer 87, and one and the other pressure detection electrodes 82 and 84 via wiring patterns 93 and 94. Are connected to each.
Japanese Unexamined Patent Publication No. 63-292032 JP-A-57-4531

  By the way, the diaphragm 85 of the above-described conventional pressure detector 81 has a base material made of alumina, that is, an insulating material. For this reason, the wiring pattern 94 described above is used as a lead portion for connection in order to connect the other pressure detection electrode 84 to the terminal portion 89 for external connection via the terminal portion 92 and the interlayer connection portion 91 of the spacer layer 87. It is necessary to provide Therefore, the pressure detector having such a configuration is required to be improved because it is subjected to layout restrictions in the wiring of the conductor pattern and inevitably increases the number of manufacturing processes.

  Thus, it is conceivable to apply a metal to the base material of the diaphragm. However, when the pressure to be detected is large, there is a possibility that plastic deformation or the like may occur in the metal diaphragm. On the other hand, the diaphragm 85 is warped in the diaphragm body after firing due to a difference in firing shrinkage between the alumina base portion and the pressure detecting electrode 84 which is a sintered body of a conductive paste, for example. There are concerns about the occurrence.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a pressure detector capable of simplifying the manufacturing while suppressing the occurrence of warpage that may occur in the manufacturing process of the diaphragm.

  In order to achieve the above object, a pressure detector according to the present invention includes a substrate provided with one pressure detection electrode, and the substrate facing the one pressure detection electrode with a predetermined gap therebetween. And a diaphragm made of an inorganic compound having an electronic conductivity that functions as the other pressure detection electrode and the other pressure detection electrode.

  According to this invention, since the diaphragm main body is formed of a material having electronic conductivity, there is no need to provide an electrode for pressure detection or a lead portion of this electrode on the diaphragm, and the manufacturing of the pressure detector is simplified. Can be achieved. In addition, according to the present invention, since the entire diaphragm is formed of a single material, even if residual stress acts on the diaphragm main body due to the shrinkage of the material during the manufacturing process, warping is caused by this. The occurrence is suppressed. In addition, according to the present invention, by appropriately setting the components of the material constituting the inorganic compound, the mechanical strength and elasticity satisfying the specifications as a diaphragm, as well as heat resistance and chemical stability (weather resistance) Can be given.

  Further, the pressure detector of the present invention has an electronic conductivity which is laminated on the diaphragm so as to face the diaphragm with a predetermined gap instead of the substrate and also functions as the one pressure detection electrode. It has the 2nd diaphragm made from the inorganic compound which has, It is characterized by the above-mentioned.

  According to the present invention, since it is not necessary to provide a pressure detection electrode or a lead portion of this electrode for any of the pair of diaphragms, the pressure detector can be manufactured more simply. In addition, according to the present invention, since electrical connection with the external device side is easily realized, the degree of freedom in component layout is increased, which can contribute to, for example, downsizing of the pressure detector.

In the present invention, the electrical conductivity of the diaphragm may be at least 1.0 × 10 ⁴ Ω ⁻¹ · m ⁻¹ or more in order to ensure that the above-described diaphragm functions as an electrode for pressure detection. desirable.

  As described above, according to the present invention, it is possible to provide a pressure detector capable of simplifying the manufacturing while suppressing the occurrence of warpage that may occur in the manufacturing process of the diaphragm.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a sectional view showing a structure of a pressure detector according to the first embodiment of the present invention.
As shown in the figure, the pressure detector 1 of this embodiment mainly includes a sensor unit 3 having a diaphragm 2 for sensing pressure, and a package unit 5 attached to the main board (such as a motherboard) side of equipment. This is a separated structure type pressure sensor.

  In addition, the pressure detector 1 of this embodiment is connected to one of the pressure detection electrodes 8 and the diaphragm 2 to be described later via the wiring pattern 8b, the terminal portion 10, and the interlayer connection portions (vias) 8a and 9a. Terminal portions 16a and 16b on the sensor portion 3 side for external connection and terminal portions 17a and 17b on the package portion 5 side are joined to each other via a joining material 18 made of tin-antimony alloy solder. The bonding material 18 includes conductive resin such as silver epoxy, lead-tin alloy solder, tin-silver-copper alloy solder, brazing material made of Ag-Cu alloy, brazing material made of gold-tin alloy, or gold- A brazing material made of a germanium alloy may be applied.

  The sensor unit 3 described above includes a substrate 15 having one pressure detection electrode 8, a diaphragm 2, and a spacer layer 11 interposed between the substrate 15 and the diaphragm 2 to form a gap (airtight space) 7. Is constructed by laminating and integrating. That is, the diaphragm 2 is laminated on the substrate 15 via the spacer layer 11 so as to face one pressure detection electrode 8 on the substrate 15 with the gap 7 interposed therebetween. It is comprised with the inorganic compound which has an electronic conductivity which functions also as the other pressure detection electrode of a pair.

  A gap 7 formed as an airtight space between the substrate 15 and the diaphragm 2 is used to detect a capacitance between one pressure detection electrode 8 and the diaphragm 2. That is, the pressure detector 1 of the present embodiment is a capacitance type pressure detector, and functions as one pressure detection electrode 8 on the substrate 15 and the other pressure detection electrode, and pressure is applied thereto. The pressure is detected based on a change in capacitance between the diaphragm 2 and the diaphragm 2 that is elastically deformed.

  Moreover, the insulating layer which comprises the said board | substrate 15 and the spacer layer 11 with which such a pressure detector 1 is provided is each formed with the ceramic layers 14 and 30 which baked the alumina green sheet. Examples of the constituent material of the ceramic layers 14 and 30 include aluminum nitride, boron nitride, silicon carbide, silicon nitride, borosilicate glass, and borosilicate glass or glass ceramic in which an inorganic ceramic filler such as alumina is added. It is also possible to use a low-temperature fired ceramic. The main body portion of the package portion 5 is also formed of an alumina ceramic material. As a constituent material of the main body portion of the package portion 5, a glass ceramic obtained by adding an inorganic ceramic filler such as alumina to aluminum nitride, boron nitride, silicon carbide, silicon nitride, borosilicate glass or lead borosilicate glass is used. It is also possible to apply a low-temperature fired ceramic, organic resin, or the like.

  The one pressure detection electrode 8 described above is formed by firing a conductive paste in which an alloy of tungsten and molybdenum is formed into a paste. The pressure detecting electrode 8 may be formed by firing a paste made of copper, silver, nickel, or an alloy thereof. Moreover, in the pressure detector 1 of this embodiment, when the diaphragm 2 is deformed excessively, in order to prevent the diaphragm 2 and one pressure detection electrode 8 from contacting (short-circuiting), electrical insulation is provided. The surface of one pressure detection electrode 8 is covered with a short-circuit prevention film 20 made of alumina ceramic, which is a conductive material. The sheet preventing film 20 may be made of a material other than alumina ceramic as long as it is an electrically insulating material that can withstand the firing temperature of the constituent material of the substrate 15.

Here, the diaphragm 2 provided in the sensor unit 3 of the pressure detector 1 according to the present embodiment will be described.
The diaphragm 2 is made of an inorganic compound (including a semiconducting inorganic material) having electronic conductivity as described above, and for example, TiC, WC, TiN, ZrC, VC, NbC, TaC, Cr ₃ C ₂ , Mo _2. C, W ₂ C, ZrN, VN, NbN, TaN, Cr ₂ N, TiB ₂ , ZrB ₂ , HfB ₂ , VB ₂ , NbB ₂ , TaB ₂ , CrB, CrB ₂ , Mo ₂ B, MoB, Mo ₂ B _{5, W 2 B 5, LaB} 6, TiSi 2, ZrSi 2, NbSi 2, TaSi 2, CrSi 2, etc. _{Mo 5 Si 3, MoSi 2,} WSi 2 are exemplified.

  The material of the diaphragm 2 made of an inorganic compound having electron conductivity described above includes, for example, titanium carbide based on sintering TiC, WC, TiN, etc. and metal powder such as Ni, Co, Fe, Cr, Mo, and carbonization. Tungsten and titanium nitride cermets can also be applied. In the case of such a cermet, it is desirable to contain about 5 to 20% by volume of metal powder in consideration of the mechanical strength and elasticity of the diaphragm 2 to be produced.

Moreover, in order to make the diaphragm 2 function reliably as an electrode for pressure detection, the electrical conductivity of the diaphragm 2 (an inorganic compound having electronic conductivity) is at least 1.0 × 10 ⁴ Ω ⁻¹ · m ⁻¹ ( S / m) or more is desirable.

Next, a manufacturing method of the pressure detector 1 of the present embodiment configured as described above will be described based on FIGS. 2a to 2h in addition to FIG. 1 described above.
As shown in FIG. 2a, a green sheet 34 having a thickness of 0.5 mm is perforated, filled with a conductive material made of an alloy of tungsten and molybdenum, and printed with a conductive paste. An unfired substrate (a substrate serving as a base material of the substrate 15) including the terminal portion 10 and the unfired pressure detection electrode 38 which are interlayer-connected to the terminal portions 16a and 16b via the connection portions (vias) 8a and 9a. Material) 35 was produced. Further, the surface of the unfired pressure detection electrode 38 on the substrate 35 was coated with an anti-short film 20 by printing an alumina paste made of alumina ceramic.

  Next, as shown in FIG. 2b, a flattening process (fluttering process) was performed on one of the unfired pressure detection electrodes 38 on the unfired substrate 35 and its peripheral portion.

  Further, as shown in FIG. 2c, for example, a protective tape 52 for preventing cracking of the sheet is formed on the side of the terminal portion 10 connected via the interlayer connection portion (via) 51 on the green sheet 50 having a thickness of about 25 μm. Is prepared, and a sheet-like member 54 having a rectangular through hole 53 corresponding to the gap 7 is prepared, and the sheet-like member 54 is attached to the substrate 35 side as shown in FIG. The protective tape 52 was peeled off. Thereby, the unfired spacer layer 31 having the recesses 37 was formed.

  Thereafter, as shown in FIG. 2e, a sublimation material 24 such as theobromine that sublimates at a predetermined heating temperature (about 250 ° C.) was filled in the recess 37 of the spacer layer 31 formed on the substrate 35 by printing.

  Next, as shown in FIG. 2f, the above-described inorganic compound paste 9 having electron conductivity is applied on the unfired substrate 35 in which the sublimation material 24 is filled in the recesses 37 by a screen printing method to a thickness of, for example, 20 μm. I printed it.

  Next, as shown in FIG. 2 g, the unfired substrate 35 on which the paste 9 was printed was subjected to a heat treatment at a heating temperature of 250 ° C. in order to sublimate the sublimation material 24. Subsequently, the heating temperature is set to, for example, about 1600 ° C. to 1800 ° C., and the laminated body in which the unfired substrate 35, the spacer layer 31, and the paste 9 are laminated is baked in a reducing atmosphere, and the layers are baked and integrated. .

  Further, as shown in FIG. 2h, the terminal portions are joined to each other by soldering the sensor portion 3 including the diaphragm 2 manufactured through the firing process and the package portion 5 separately manufactured. Thus, the capacitance type pressure detector 1 shown in FIG. 1 was obtained.

  As described above, according to the pressure detector 1 of the present embodiment, the diaphragm 2 body is formed of a material having electronic conductivity, so that the electrode for pressure detection and the lead portion of this electrode are mounted on the diaphragm 2. The pressure detector 1 can be easily manufactured. According to the pressure detector 1 of the present embodiment, since the entire diaphragm 2 is formed of a single material, even if residual stress acts on the diaphragm main body due to firing shrinkage of the material during the manufacturing process, It is possible to suppress warping caused by Moreover, according to the pressure detector 1 of this embodiment, since the inorganic compound which has electronic conductivity, such as a cermet, is applied as a constituent material of the diaphragm 2, desired mechanical strength and elasticity are given to the diaphragm 2 main body. Can be granted. Accordingly, it is possible to prevent the diaphragm from being plastically deformed at the time of pressure detection.

2C and FIG. 2D, the manufacturing method shown in FIG. 3A and FIG. 3B is applied in place of the manufacturing method of forming the unfired spacer layer 31 for forming the gap 7 using the sheet-like member 54. Also good.
That is, as shown in FIG. 3a, first, the alumina ceramic paste 32 is avoided by a screen printing method from a portion where one pressure detection electrode 8 is provided and a portion where the interlayer connection portion 9a is exposed on the substrate 35. Then, printing is performed on the unfired substrate 35 to a thickness of, for example, about 5 μm to 20 μm to form an unfired spacer layer 36. Next, as shown in FIG. 3b, the substrate of the interlayer connection (via) 9a The terminal portion 33 may be formed by printing, for example, a conductive paste on the surface of the portion exposed on the surface 35 and in the vicinity thereof.

Further, in place of the step of screen printing the inorganic compound paste 9 having electron conductivity shown in FIG. 2f, as shown in FIG. 4, a sintered body obtained by separately firing the inorganic compound having electron conductivity as shown in FIG. The (diaphragm) 39 and the substrate 15 having the spacer layer 11 baked separately in the same manner may be joined (stacked and integrated) using a metallization method or the like. This manufacturing method is useful when the constituent materials of the spacer layer 11 and the substrate 15 and the firing temperature of the inorganic compound having electron conductivity are greatly different.
Further, similarly to the sintered body 39, the substrate 15 having the spacer layer 11 that is separately fired may be joined (laminated and integrated) using low-melting glass.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6a to 6c. In FIGS. 5 and 6a to 6c, components having the same functions as the components described in the first embodiment are given the same reference numerals and description thereof is omitted.

  That is, as shown in FIG. 5, the pressure detector 41 according to this embodiment includes a sensor unit 43 having a pair of diaphragms 42a and 42b for sensing pressure from two different directions (arrows X1 and X2 directions) This is a separate structure type pressure sensor composed of a package portion 5 attached to the main board side of the kind.

  The pair of diaphragms 42 a and 42 b are opposed to each other with a spacer layer 60 having a gap (airtight space) 47 interposed therebetween, and are arranged in a standing posture with respect to the surface of the package unit 5. The diaphragms 42a and 42b are made of the same material as the diaphragm 2 of the first embodiment, that is, an inorganic compound having electron conductivity, and each also functions as one or the other pressure detection electrode. To do. Therefore, such a pressure detector 41 has a static electricity between a diaphragm 42a that elastically deforms when pressure is applied from the direction of the arrow X1 and a diaphragm 42b that elastically deforms when pressure is applied from the direction of the arrow X2. It is a capacitance-type pressure detector that detects pressure based on a change in capacitance.

  As a manufacturing method of the pressure detector 41 of the present embodiment configured as described above, as shown in FIG. 6A, first, for example, alumina having an opening 62 corresponding to the gap 47 in the center and pre-baked. As shown in FIG. 6b, the ceramic spacer member 61 and the diaphragm substrates 44a and 44b that were separately fired in a process different from the manufacturing process of the spacer member 61 were joined together.

  For these joining, joining using a brazing material made of an Ag-Cu alloy, a brazing material made of a gold-tin alloy, a brazing material made of a gold-germanium alloy, a glass sealing material, an epoxy resin, or the like may be applied. it can.

  Thereafter, as shown in FIG. 6c, the sensor unit 3 including the diaphragms 42a and 42b laminated and integrated with the spacer layer 60 interposed therebetween and the separately prepared package unit 5 are connected to each other by soldering or the like. By joining the parts, the capacitance type pressure detector 1 shown in FIG. 5 was obtained.

  Therefore, according to the pressure detector 41 according to the present embodiment, it is not necessary to provide an electrode for pressure detection or a lead portion of this electrode for any of the pair of diaphragms. Can be manufactured. Further, according to the pressure detector 41 of the present embodiment, since the connection between the package unit 5 attached to the device side and the diaphragms 42a and 42b can be easily realized in this way, the degree of freedom in component layout is increased. This can contribute to downsizing of the pressure detector body.

  The present invention has been specifically described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, a separate structure type in which a sensor unit having a diaphragm and a package unit attached to the main board side of the devices are individually manufactured and finally joined by brazing, soldering, or the like. However, instead of this, the sensor part and the package part are integrated in advance in the initial stage of the manufacturing process so as to eliminate the need for brazing or soldering. The present invention can also be applied to a pressure detector or the like.

Sectional drawing which shows the structure of the pressure detector which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the state which printed the electrically conductive paste on the unbaked board | substrate in the manufacturing method of the pressure detector of FIG. FIG. 2B is a cross-sectional view showing a state where one of the unsintered pressure detection electrodes on the unsintered substrate of FIG. Sectional drawing which shows the state just before sticking the sheet-like member which has a rectangular through-hole with respect to the unbaking board | substrate of FIG. 2b. Sectional drawing which shows the state which peeled off the protective tape, after sticking a sheet-like member on the unbaked board | substrate of FIG. 2c. Sectional drawing which shows the state which filled the sublimation material in the recessed part on the unbaking board | substrate which stuck the sheet-like member of FIG. 2d. Sectional drawing which shows the state which printed the paste of the inorganic compound which has electronic conductivity on the unbaking board | substrate which filled the sublimation material of FIG. Sectional drawing for demonstrating the heat processing for the sublimation of the sublimation material in the unbaked board | substrate with which the paste of FIG. 2f was printed, and a baking process. Sectional drawing which shows the state just before joining the sensor part obtained through the baking process of FIG. 2g to a package part. Sectional drawing which shows the state which replaced with the process of sticking the sheet-like member of FIG. 2d, and printed the insulating paste and formed the unbaked spacer layer. Sectional drawing which shows the state which printed the electrically conductive paste in the predetermined non-printing part of the insulating paste of FIG. 3a. FIG. 2F is a cross-sectional view showing a state immediately before bonding a fired substrate and a separately fired diaphragm substrate in place of the step of printing the paste of the inorganic compound having electron conductivity in FIG. Sectional drawing which shows the structure of the pressure detector which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows the state immediately before joining the spacer member baked previously and the board | substrate for diaphragms baked separately. FIG. 6B is a cross-sectional view illustrating a sensor unit in which the spacer member and the diaphragm substrate in FIG. 6A are bonded to each other. FIG. 6B is a cross-sectional view illustrating a state immediately before the sensor unit of FIG. Sectional drawing which shows the structure of the conventional electrostatic capacitance type pressure detector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,41 ... Pressure detector, 2, 42a, 42b ... Diaphragm, 3, 43 ... Sensor part, 5 ... Package part, 7, 47 ... Gap, 8 ... One pressure detection electrode, 9 ... Electron conductivity Inorganic compound paste, 15... Substrate after firing, 35... Unfired substrate, 44a, 44b.

Claims (3)

A substrate provided with one pressure detection electrode;
Electronic conductivity that is laminated on the substrate so as to face the one pressure detection electrode with a predetermined gap therebetween, and also functions as the other pressure detection electrode paired with the one pressure detection electrode. A diaphragm made of an inorganic compound,
A pressure detector.   Instead of the substrate, a second diaphragm made of an inorganic compound that is laminated on the diaphragm so as to face the diaphragm across a predetermined gap and also functions as the one pressure detection electrode is used. The pressure detector according to claim 1, further comprising: 3. The pressure detector according to claim 1, wherein an electrical conductivity of the diaphragm is 1.0 × 10 ⁴ Ω ⁻¹ · m ⁻¹ or more.

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