JP2007163299A - Pressure sensor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a pressure detection precision of pressure detectors, while simplifying their manufacture. <P>SOLUTION: A sensor part 3 of a pressure detector 1 is provided with a substrate 15 provided with a first electrode 8 for pressure detection; a diaphragm 2 provided with a second electrode 9 for pressure detection, facing the first electrode 8 for pressure detection on both sides of a gap 7 on the substrate 15; and a spacer layer 25 interposed between the substrate 15 and the diaphragm 2 and constituted of a solid body of an insulating ceramic paste, having an opening part 37 made of curved surfaces in which inner wall surfaces 25a are bulged within a region, in which the first and second electrodes 8 and 9 for pressure detection are face each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pressure detector and a manufacturing method thereof.

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, a conventional manufacturing method in the latter capacitance type pressure detector will be described with reference to FIGS.
As shown in FIG. 7 a, for example, on an unfired substrate (base material) 97 including one pressure detection electrode 58 connected to a terminal portion 66 via an interlayer connection portion (via) 61 on a green sheet 65. The peripheral portion including the pressure detection electrode 58 is pressurized and flattened, and a sublimation material 74 that is sublimated below the firing temperature of the green sheet 65 is printed on the flattened portion.

  On the other hand, as shown in FIG. 7a, for example, a protective tape for preventing cracking of the sheet is formed on the side of the terminal portion 93 connected via the interlayer connection portion (via) 92 on the green sheet 91 having a thickness of about 25 μm. 94 is affixed and a sheet-like member 90 having a rectangular through-hole 96 corresponding to the gap is prepared, and this sheet-like member 90 is superimposed on the substrate 97 side.

  Next, as shown in FIG. 7 b, after the protective tape 94 is peeled off from the sheet-like member 90, the green sheet 62 on which the other pressure detection electrode 59 is printed is placed on the sheet-like member 90 on the upper part of the substrate 97. While aligning, the pressure members 75 and 72 are used for pressure bonding.

Next, as shown in FIG. 7c, after the sublimation material 74 is sublimated by heat treatment at a relatively lower temperature than the firing temperature of the green sheet on the laminated body that has been pressure-bonded to each other, the green sheets 65, 62, 91 of each layer are further sublimated. A firing process is performed to form the ceramic layers 97, 98, and 99 obtained by sintering the ceramics. As a result, a capacitance type pressure detector that detects a change in capacitance between one pressure detection electrode 58 and the other pressure detection electrode 59 provided in the diaphragm 52 with each other across the gap 95. (Sensor part 53) is manufactured.
Japanese Unexamined Patent Publication No. 63-292032 JP-A-57-4531

However, such a conventional method for manufacturing a pressure detector has the following problems.
That is, since the green sheet 91 laminated on the substrate 97 for forming the gap has a through hole in the central portion and becomes a thin component having a thickness of about 25 μm as described above, It is difficult to handle.

  Further, in the conventional manufacturing method, since the amount of gap formed between the electrodes is set by the thickness of the green sheet 91 described above, it is natural that the sheet 91 is thinly formed to narrow the gap. There is. That is, in the conventional manufacturing method in which the gaps are formed by laminating the sheets 91 having through holes, it is difficult to set the gaps narrower to increase the amount of change in capacitance, and thus to increase the pressure detection accuracy. It has become.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a pressure detector that can improve the pressure detection accuracy while simplifying the manufacturing and a manufacturing method thereof.

  In order to achieve the above object, a pressure detector according to the present invention includes a predetermined gap between a substrate on which a first pressure detection electrode is provided and the first pressure detection electrode on the substrate. A diaphragm having a second pressure detection electrode disposed opposite to each other, and is interposed between the substrate and the diaphragm, and the first and second pressure detection electrodes are mutually connected. And a spacer layer having an opening made of a curved surface with an inner wall surface bulging in an opposing region portion.

  Moreover, the manufacturing method of the pressure detector of the present invention is a manufacturing method for manufacturing the pressure detector of the above-mentioned invention, and avoids the portion where the first pressure detecting electrode is provided and is not fired. A step of forming the spacer layer on the substrate by a printing method; and the first pressure detection electrode and the second pressure detection electrode on the unfired substrate on which the spacer layer is laminated are opposed to each other. And laminating the diaphragm on the spacer layer so as to be disposed in the same manner.

  That is, according to the present invention, a gap between electrodes for pressure detection can be formed by a spacer layer formed by using a printing method or the like, for example, regardless of lamination of sheets having through holes. As a result, the gap can be narrowed to increase the rate of change in capacitance, and the pressure detection sensitivity can be increased. Further, in the present invention, it is not necessary to handle a thin sheet for forming a gap, so that the manufacturing process can be simplified.

  Therefore, according to the present invention, it is possible to provide a pressure detector capable of improving the pressure detection accuracy while simplifying the manufacturing and a manufacturing method thereof.

The best mode for carrying out the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view showing a structure of a pressure detector according to the first embodiment of the present invention, and FIG. 2 is a diagram showing in detail a gap portion included in the pressure detector of FIG. .
As shown in FIGS. 1 and 2, the pressure detector 1 of this embodiment includes a sensor unit 3 having a diaphragm 2 for sensing pressure, and a package unit 5 attached to the main board (motherboard or the like) side of equipment. It is a separated structure type pressure sensor mainly composed of

  Further, the pressure detector 1 of this embodiment includes a terminal portion 16 on the sensor portion 3 side connected to a terminal portion 10 and a first pressure detection electrode 8 described later via an interlayer connection portion (via) 11, The terminal portion 17 on the package portion 5 side is joined to each other via a joining material 18 made of tin-antimony alloy solder. Further, the bonding material 18 may be made of 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 -You may apply the brazing material which consists of germanium alloys. The sensor unit 3 includes, for example, a ceramic substrate 15 having a thickness of 0.5 mm on which a first pressure detection (capacitance detection) electrode 8 is provided, and a first pressure detection electrode 8 on the substrate 15. For example, a diaphragm 2 having a thickness of, for example, 40 μm, provided with a second pressure detection electrode 9 disposed so as to be opposed to each other with a gap 7 interposed therebetween, and between the substrate 15 and the diaphragm 2. And an opening (space portion) 37 having a curved surface in which an inner wall surface (side wall surface) 25a bulges in a region where the first and second pressure detection electrodes 8 and 9 face each other. And a spacer layer 25 having. The opening 37 of the spacer layer 25 has a rectangular cross section, and is a through hole that opens on both the substrate 15 side and the diaphragm 2 side (through the spacer layer 25 itself in the thickness direction). Through-hole).

  The pressure detector 1 of the present embodiment configured as described above includes a first pressure detection electrode 8 that faces each other with a gap 7 formed as a sealed space between the substrate 15 and the diaphragm 2, and a pressure This is a capacitance type pressure detector that detects pressure based on a change in capacitance between the second pressure detection electrode 9 on the diaphragm 2 that is elastically deformed when the pressure is applied.

  The insulating layers constituting the substrate 15 and the diaphragm 2 provided in the pressure detector 1 are formed by ceramic layers 12 and 14 obtained by firing alumina green sheets 32 and 34, respectively. Examples of the constituent material of the ceramic layers 12 and 14 include aluminum nitride, boron nitride, silicon carbide, silicon nitride, borosilicate glass and lead ceramic borosilicate glass, and a glass ceramic obtained by adding an inorganic ceramic filler such as alumina. 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 first and second pressure detection electrodes 8, 9 are made of an alloy with tungsten and molybdenum. Moreover, in the pressure detector 1 of this embodiment, when the diaphragm 2 deform | transforms excessively, in order to prevent that the 1st and 2nd electrodes 8 and 9 for pressure detection contact and short-circuit. A short prevention film 20 made of alumina ceramic, which is an electrically insulating material, is coated on the first pressure detection electrode 8. The first and second pressure detection electrodes 8 and 9 may be made of copper, silver, nickel, or an alloy thereof. Moreover, the sheet | seat prevention film | membrane 20 can be comprised using materials other than an alumina ceramic, if it is an electrically insulating material which can endure the baking temperature of the above-mentioned alumina green sheets 32 and 34. FIG.

Here, the spacer layer 25 constituting the gap (gap) 7 between the first and second pressure detection electrodes 8 and 9 will be described.
That is, the spacer layer 25 (after firing) is formed of a sintered body (ceramic layer) of a ceramic paste obtained by adding an organic binder to the same material as the green sheets 32 and 34 described above. For example, it has a thickness of about 5 μm to 50 μm. Specifically, as shown in FIG. 2, the spacer layer 25 is made of a paste printed on the unfired substrate 35 by using a screen printing method while avoiding the portion where the first pressure detection electrode 8 is provided. It is a sintered body, and the non-printing area becomes the opening 37. Accordingly, the edge of the opening 37 is deformed due to the fluidity of the paste and is sintered after being deformed. Therefore, as described above, the inner wall surface 25a of the opening 37 becomes a bulged curvature surface.

  Further, in the pressure detector 1 of the present embodiment in which the amount of the gap 7 can be adjusted according to the thickness of paste printing as described above, unlike the case where the spacer layer is formed of, for example, a green sheet, the thickness can be paste printed. Correspondingly, the amount of the gap 7 can be reduced to an amount of about 5 μm to 20 μm, for example.

Here, the dielectric constant of the gap in the gap 7 is ε (F / m), the individual surface areas of the first and second pressure detection electrodes 8 and 9 are S (m ² ), and the amount of the gap 7 is d ( m), the capacitance C (F) between the electrodes is expressed by the following formula (1).
C = εS / d Formula (1)

  Therefore, in the pressure detector 1 of the present embodiment that can be formed to make the gap 7 narrower, as is clear from the relationship of the above formula (1), the gap 7 is narrowed to obtain the absolute value of the capacitance as a large value. Thus, the accuracy (sensitivity) of pressure detection can be increased, and the pressure detector main body can be reduced in size and thickness.

Next, the manufacturing method of the pressure detector 1 of the present embodiment configured as described above will be described based on FIGS. 3a to 3i in addition to the above-described FIGS.
As shown in FIG. 3a, 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 base material serving as a base material of the substrate 15) 35 including the first pressure detection electrode 8 that was interlayer-connected to the terminal portion 16 via the connection portion 11 was produced. Further, the surface of the first pressure detection electrode 8 on the substrate 35 was coated with an anti-short film 20 by printing an alumina ceramic paste.

  Next, as shown in FIG. 3b, the first pressure detection electrode 8 and its peripheral portion were flattened (fluttering treatment). After the flattening process, as shown in FIG. 3C, the alumina ceramic paste is exposed to the portion where the first pressure detection electrode 8 is provided and the substrate 35 of the interlayer connection portion 11 by screen printing. As a result, printing was performed on the unfired substrate 35 with a thickness of, for example, about 5 μm to 20 μm, thereby forming an unfired spacer layer 45.

  Subsequently, as shown in FIG. 3d, a terminal portion 10 was formed by printing, for example, a conductive paste on the surface of the portion of the interlayer connection portion (via) 11 exposed on the substrate 35 and in the vicinity thereof. Thereafter, as shown in FIG. 3e, a sublimation material 24 such as theobromine that sublimates at a predetermined heating temperature (about 250 ° C.) was filled into the opening 37 of the spacer layer 45 formed on the substrate 35 by printing.

  Further, as shown in FIG. 3f, the first pressure detection electrode 8 and the second pressure detection electrode are sandwiched between the sublimation material 24 (and the short prevention film 20) filled in the opening 37 of the spacer layer 45. A green sheet 32 of 3 mm square and 40 μm thickness formed by printing the second pressure detecting electrode 9 is laminated on the substrate 35 on which the spacer layer 25 is laminated so that the electrode 9 is opposed to the substrate 9. Then, as shown in FIG. 3 g, these were pressure-bonded using the pressure members 25 and 22.

  Next, as shown in FIG. 3h, a heating temperature of 250 ° C. is used to sublimate the sublimation material 24 with respect to the unfired substrate (base material) 35 on which the green sheets 32 including the second pressure detection electrodes 9 are laminated. Heat treatment was performed. Next, when the green sheets 34 and 32 and the insulating ceramic paste 45 are made of a material mainly composed of alumina, for example, the heating temperature is set to about 1600 ° C. to 1800 ° C., the unfired substrate 35, the spacer layer 25, The laminated body in which the green sheets 32 including the two pressure detection electrodes 9 were laminated together was fired in a reducing atmosphere. Thereby, the spacer layer 25 and the ceramic layers 12 and 14 sintered as a ceramic layer from the alumina ceramic paste were formed, and the respective layers were fired and integrated.

  Furthermore, as shown in FIG. 4h, the sensor part 3 including the diaphragm 2 manufactured through such a baking process and the separately prepared package part 5 are soldered to each other with the terminal parts 16 and 17 between them. As a result, the capacitance type pressure detector 1 shown in FIG. 1 was obtained.

  As described above, according to the pressure detector 1 and the manufacturing method thereof of the present embodiment, the gap is formed by the spacer layer 25 formed by using the screen printing method, for example, regardless of the lamination of the sheets provided with the through holes. 7 can be formed, the gap can be narrowed to increase the rate of change in capacitance, and the pressure detection sensitivity can be increased. Moreover, in the manufacturing method of the pressure detector 1 of this embodiment, since it is unnecessary to handle a thin sheet for forming a gap, the manufacturing process can be simplified.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. 4 and 5, the same components as those described in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.
In the manufacturing method of the pressure detection device according to this embodiment, the steps shown in FIG. 3c and the steps shown in FIG. 3d among the manufacturing steps of the pressure detector 1 of the first embodiment shown in FIGS. The manufacturing process shown in FIG. 4 is added between these processes.

  That is, in this embodiment, as shown in FIG. 3c, the insulating ceramic is avoided by avoiding the portion where the first pressure detection electrode 8 is provided (and the portion exposed on the substrate 35 of the interlayer connection portion 11). After the paste is screen-printed on the unfired substrate 35 to a thickness of, for example, about 20 μm to form a (unfired) spacer layer 45, the spacer layer 45 is further formed on the spacer layer 45 as shown in FIG. A step of forming a (non-fired) spacer layer 46 by screen printing the same paste material as the insulating ceramic paste to a thickness of about 10 μm, for example, was added.

  As a result, as shown in FIG. 5, after firing, a spacer layer 27 having a laminated structure in which the spacer layer 25 and the spacer layer 26 in which the alumina ceramic paste was sintered as a ceramic layer was laminated in two stages was obtained. .

  Here, as shown in FIG. 5, in the gap 48 formed by the spacer layer 27 having a two-layer structure, even when the diaphragm 2 is elastically deformed relatively large, the outer shape portion of the deformed diaphragm 2 (imaginary line) The portion indicated by 8a comes into contact with the inner wall surface (side wall surface) 25a formed of the bulged curvature surface in the lower spacer layer 25.

  Therefore, according to the pressure detector of the present embodiment, the damage that can be applied to the diaphragm is reduced compared to the structure of another structure in which the outer shape part of the elastically deformed diaphragm is in contact with the edge part, etc. The durability of the vessel body could be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. 6a and 6b. 6A and 6B, the same components as those described in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.
The manufacturing method of the pressure detection device according to this embodiment is that of the second embodiment in which the manufacturing process shown in FIG. 4 is added to the manufacturing process of the pressure detection device of the first embodiment shown in FIGS. In the manufacturing method of the pressure detection device, a manufacturing process in which the unfired substrate 35 shown in FIGS. 3f and 3g and the green sheet 32 on which the second pressure detection electrode 9 is laminated are aligned and pressure-bonded to each other. Instead, the manufacturing process shown in FIGS. 6a and 6b is applied.

  That is, as shown in FIG. 6 a, tungsten, on a non-fired substrate 35 in which a sublimation material 24 is filled in a rectangular opening 41 formed by a (non-fired) spacer layer 48 having a two-layer structure. A conductive paste 49 made of molybdenum was printed (metalized printing) by a screen printing method. Furthermore, as shown in FIG. 6b, on the conductive paste 49 printed on the surface of the unfired substrate 35, the same as that used for forming the spacer layers of the first and second embodiments is further provided. The material ceramic paste 42 was printed using a screen printing method to a thickness of 20 μm.

  Thereafter, in substantially the same manner as in the first embodiment, heat treatment for sublimating the sublimation material 24 and sintering the paste-printed green spacer layer 44, conductive paste 49, and insulating ceramic paste 42 are performed. The pressure detector was produced by performing a baking process.

  Therefore, according to the manufacturing method of the pressure detector according to the present embodiment, the diaphragm can be obtained by using paste printing, so that the thickness of the diaphragm can be reduced compared to a manufacturing method in which green sheets are stacked. As a result, the responsiveness (deformability) of the diaphragm to the pressure was increased, and the pressure (capacitance) detection sensitivity could be further improved.

  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. In the third embodiment, the form of manufacturing the diaphragm by paste printing in the pressure detector manufactured in the second embodiment has been described. Instead, the diaphragm is manufactured in the first embodiment. It is also possible to constitute a pressure detector in which this diaphragm is formed by paste printing.

Sectional drawing which shows the structure of the pressure detector which concerns on the 1st Embodiment of this invention. The figure which shows the gap with which the pressure detector of FIG. 1 is equipped, and its surrounding structure in detail. 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 which concerns on the 1st Embodiment of this invention. Sectional drawing which shows the state by which the flattening process was performed to the 1st electrode for a pressure detection on an unbaked board | substrate, and its peripheral part. Sectional drawing which shows the state which screen-printed the insulating ceramic paste on the unbaked board | substrate after the planarization process, and formed the spacer layer. Sectional drawing which shows the state which printed the electrically conductive paste connected with an interlayer connection part on the unbaked board | substrate, and formed the terminal part. Sectional drawing which shows the state which filled the sublimation material in the opening part of the spacer layer on a non-baking board | substrate. Sectional drawing which shows the state with which the unbaked board | substrate with which the sublimation material was filled in the opening part of a spacer layer, and the green sheet on which the 2nd electrode for pressure detection was laminated | stacked were aligned. Sectional drawing which shows the state by which the green sheet and the unbaked board | substrate with which the 2nd electrode for pressure detection was laminated | stacked are crimped | bonded using the pressurization member. Sectional drawing for demonstrating the heat processing for the sublimation of the sublimation material in an unbaked board | substrate, and a baking process. Sectional drawing which shows the state just before joining the sensor part produced through the baking process, and the package part produced separately. Sectional drawing which shows the manufacturing process added in the middle of the manufacturing process of 1st Embodiment in the manufacturing method of the pressure detector which concerns on the 2nd Embodiment of this invention. Sectional drawing which shows the surrounding structure of the gap in the pressure detector obtained by adding the manufacturing process shown in FIG. 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 which concerns on the 3rd Embodiment of this invention. Sectional drawing which shows the state which printed the insulating ceramic paste further on the electrically conductive paste on the board | substrate shown to FIG. 6a. Sectional drawing which shows the state just before sticking the sheet-like member which has a rectangular through-hole on the base material side in the manufacturing method of the conventional pressure detector. Sectional drawing which shows the state immediately before crimping | bonding the base material which piled up the sheet-like member, and the green sheet | seat on which the other electrode for pressure detection was laminated | stacked using a pressurization member. Sectional drawing which shows the sensor part of the pressure detector obtained after the baking process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pressure detector, 2 ... Diaphragm, 3 ... Sensor part, 5 ... Package part, 7, 48 ... Gap, 8 ... 1st pressure detection electrode, 9 ... 2nd pressure detection electrode, 12, 14 ... Ceramic layer, 15 ... fired substrate, 25, 26, 27 ... fired spacer layer, 25a ... inner wall surface, 32, 34 ... green sheet, 35 ... unfired substrate (base material), 37, 41 ... opening Part, 42 ... insulating ceramic paste, 45, 44, 46 ... unsintered spacer layer, 49 ... conductive paste.

Claims (2)

A substrate provided with a first pressure detection electrode;
A diaphragm including a second pressure detection electrode disposed opposite to the first pressure detection electrode on the substrate with a predetermined gap therebetween;
A spacer layer interposed between the substrate and the diaphragm, and having an opening made of a curved surface with an inner wall surface bulging in a region where the first and second pressure detection electrodes face each other When,
A pressure detector. A manufacturing method for manufacturing the pressure detector according to claim 1,
Forming the spacer layer by a printing method on the unfired substrate while avoiding the portion where the first pressure detection electrode is provided;
The diaphragm is stacked on the spacer layer so that the first pressure detection electrode and the second pressure detection electrode are arranged to face each other on the green substrate on which the spacer layer is stacked. Process,
A method for manufacturing a pressure detector, comprising:

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