Sulfide detection sensor

Abstract

Provided is a vulcanization detection sensor capable of accurately and easily detecting the degree of vulcanization. The vulcanization detection sensor (10) has: an insulating substrate (1) in the shape of a rectangular parallelepiped; a resistor body (2) formed so as to be in close contact with the surface of the insulating substrate (1); a vulcanization detection conductor (3) formed so as to be in close contact with the surface of the resistor body (2); a protective layer (4) that is non-permeable to vulcanization gas and formed so as to cover a portion of the vulcanization detection conductor (3); and a pair of electrode portions (6) formed at both end portions of the insulating substrate (1) and connected to the resistor body (2) and the vulcanization detection conductor (3), the vulcanization detection conductor (3) being composed of a metal having a lower electrical resistance value than the resistor body (2), and having an exposed portion (3a) that is not covered by the protective layer (4) and exposed to the outside.

Description

TECHNICAL FIELD

[0001] The present application relates to a sulfidation detection sensor that detects the amount of sulfidation accumulated in a sulfidation environment. BACKGROUND

[0002] As an internal electrode of an electronic component such as a chip resistor, an Ag (silver)-based electrode material having a low resistivity is generally used, but since silver is exposed to a sulfidation gas to become silver sulfide, and silver sulfide is an insulator, a failure such as a wire breakage of the electronic component occurs. Therefore, in recent years, a method of adding Pd (palladium), Au (gold) to Ag to form an electrode that is not easily sulfidated, or a method of forming an electrode in a structure in which a sulfidation gas does not easily reach, and the like, have been taken to cope with sulfidation.

[0003] However, even if such a method of coping with sulfidation is taken for an electronic component, in a case where the electronic component is exposed to a sulfidation gas for a long time, or is exposed to a high concentration of a sulfidation gas, since it is difficult to completely prevent a wire breakage, it is necessary to detect the electronic component before the wire breakage occurs so as to prevent a failure from occurring at an unexpected time.

[0004] Therefore, up to now, a sulfidation detection sensor as described in Patent Document 1 has been proposed, which detects the degree of sulfidation accumulated in an electronic component, and can detect a danger before a failure such as a sulfidation breakage of the electronic component occurs. The sulfidation detection sensor described in Patent Document 1 is configured such that a sulfidation detection conductor mainly made of Ag is formed on an insulating substrate, a protective film that is transparent and has a sulfidation gas permeability is formed so as to cover the sulfidation detection conductor, and end surface electrodes connected to the sulfidation detection conductor are formed at both end portions of the insulating substrate.

[0005] After the sulfidation detection sensor thus configured is mounted on a circuit substrate together with other electronic components, when the circuit substrate is used in an environment containing a sulfidation gas, the sulfidation gas permeates the protective film of the sulfidation detection sensor to come into contact with the sulfidation detection conductor, and thus the color of the sulfidation detection conductor changes in correspondence with the concentration of the sulfidation gas and the elapsed time. Further, as sulfidation progresses, silver constituting the sulfidation detection conductor becomes silver sulfide, and thus the resistance value of the sulfidation detection sensor gradually increases, and eventually a wire breakage occurs. Thus, by visually observing the color change of the sulfidation detection conductor through the protective film, or by detecting light reflected from the sulfidation detection conductor after light is irradiated onto the upper surface of the sulfidation detection sensor, or by detecting a change in the resistance value of the sulfidation detection conductor, it is possible to detect the degree of sulfidation.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT DOCUMENTS

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-250611

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, the color change of the sulfidation detection conductor caused by the sulfidation gas is subtle, and it is difficult to accurately detect the degree of sulfidation by visual inspection by an operator. Even if the degree of sulfidation is detected based on the light reflected by the sulfidation detection conductor, a large-scale device for detection is additionally required.

[0011] Further, in the case where the change in the resistance value of the sulfidation detection conductor is detected, since the sulfidation detection conductor is a conductor mainly composed of Ag or the like having a low resistivity, the resistance value of the sulfidation detection conductor changes little during the time from the sulfidation to the disconnection, and it is difficult to accurately detect the degree of sulfidation based on the change in the resistance value of the sulfidation detection conductor during this time. SUMMARY

[0012] The present application has been achieved in view of the actual situation of such prior art, and aims to provide a sulfidation detection sensor capable of accurately and easily detecting the degree of sulfidation.

[0013] Solution to Problem

[0014] To achieve the above object, the sulfidation detection sensor of the present application is characterized by having: an insulating substrate of a rectangular parallelepiped shape; a resistor body provided on a main surface of the insulating substrate; a sulfidation detection conductor provided on the resistor body and sulfidated by a sulfidation gas; a protection layer of non-permeability to the sulfidation gas provided so as to cover a part of the sulfidation detection conductor; and a pair of electrode portions provided at both end portions of the insulating substrate and connected to the resistor body and the sulfidation detection conductor, the sulfidation detection conductor being composed of a metal having a lower resistance value than the resistor body and having an exposed portion exposed to the outside without being covered by the protection layer.

[0015] In the sulfidation detection sensor thus configured, the pair of electrode portions is always made conductive by the resistor body, and when continuously sulfidated by being exposed to an environment containing the sulfidation gas, the sulfidation detection conductor provided on the resistor body is sulfidated from the exposed portion exposed to the outside without being covered by the protection layer, and as the sulfidation progresses to the inside covered by the protection layer, the current path flowing between the pair of electrode portions changes according to the degree of sulfidation of the sulfidation detection conductor. Thus, the resistance value of the resistor body is continuously changed according to the degree of sulfidation of the sulfidation detection conductor, and the degree of sulfidation can be accurately and easily detected.

[0016] In the sulfurization detection sensor of the above structure, the sulfurization detection conductor can be formed to cover the entire resistance body, but if the resistance body is configured to have an adjustment region not covered by the sulfurization detection conductor, an adjustment groove for adjusting the resistance value is formed in the adjustment region, and the adjustment region is covered by a portion of the protective layer, then not only can the initial resistance value of the resistance body be increased by the adjustment groove, but a sulfurization detection sensor with good temperature characteristics (TCR) can also be achieved.

[0017] Further, in the sulfurization detection sensor of the above structure, the sulfurization detection conductor can be composed of a single material, but if the sulfurization detection conductor is composed of a first sulfurization detection conductor and a second sulfurization detection conductor composed of different materials with different gas selectivity, and each of the first and second sulfurization detection conductors has an exposed portion, the degree of sulfurization can be accurately detected regardless of the type of sulfurization gas contained in the use environment.

[0018] That is, sulfurization gas has different reactivity depending on the type of metal that constitutes the sulfurization detection conductor, for example, silver (Ag) easily reacts with hydrogen sulfide (H2S) but has low reactivity with sulfur dioxide (SO2), and nickel (Ni) easily reacts with sulfur dioxide (SO2) but has low reactivity with hydrogen sulfide (H2S), so if one of the first and second sulfurization detection conductors is composed of Ag and the other is composed of Ni, a multi-type sulfurization detection sensor that can correspond to different types of sulfurization gas can be achieved. In addition, copper (Cu) is a material that easily reacts with both hydrogen sulfide (H2S) and sulfur dioxide (SO2), so even if only copper (Cu) is used, a multi-type sulfurization detection sensor can be obtained, but by combining a material with high reactivity with the target sulfurization gas, which has different gas selectivity from the Ag material and the Ni material, the detection accuracy can be improved compared to the case where only copper (Cu) is used to form the sulfurization detection conductor.

[0019] In this case, preferably, the resistance body has an exposed region not covered by the first and second sulfurization detection conductors, and an intermediate protective layer is provided on the exposed region, and the exposed portion of the first sulfurization detection conductor and the exposed portion of the second sulfurization detection conductor are arranged in positions sandwiching the intermediate protective layer.

[0020] Further, in the sulfurization detection sensor of the above structure, the resistance body and the sulfurization detection conductor can be metal glaze formed into a thick film using screen printing or the like, but if these resistance body and sulfurization detection conductor are metal films formed into a thin film using sputtering or the like, film thickness deviation of the resistance body and the sulfurization detection conductor will not occur, and the detection accuracy can be improved.

[0021] In this case, preferably, if the insulating substrate is composed of an alumina substrate, and the resistor is a Ni-Cr metal film formed on the surface of the alumina substrate by sputtering, the adhesion to the alumina substrate is improved by Cr in the metal film, and the adhesion to the vulcanization detection conductor (Ag, Cu, Ni, etc.) is improved by Ni.

[0022] Further, in the vulcanization detection sensor of the above structure, preferably, the protective layer is composed of an inner coating layer composed of a glass material formed on the vulcanization detection conductor, and an outer coating layer composed of a resin material formed on the inner coating layer, and the electrode portion covers the end portion of the vulcanization detection conductor and is in close contact with the outer coating layer. When configured in this way, since the adhesion of the electrode portion to the outer coating layer composed of a resin material is improved, the vulcanization of the end portion of the vulcanization detection conductor covered by the electrode portion can be suppressed, and in addition, since the inner coating layer that does not transmit the vulcanization gas is provided below the outer coating layer composed of a resin material, the portion of the vulcanization detection conductor covered by the protective layer can be prevented from being vulcanized by the reaction with the vulcanization gas that has transmitted the outer coating layer.

[0023] Effects of Invention

[0024] The vulcanization detection sensor according to the present application can accurately and easily detect the degree of vulcanization. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a plan view of the vulcanization detection sensor according to the first embodiment.

[0026] Figure 2 is a sectional view along the line II-II of Figure 1 .

[0027] Figure 3 is a plan view showing a manufacturing process of the vulcanization detection sensor.

[0028] Figure 4 is a sectional view showing a manufacturing process of the vulcanization detection sensor.

[0029] Figure 5 is an explanatory diagram showing a change in the current path in the vulcanization detection sensor.

[0030] Figure 6 is an explanatory diagram showing the relationship between the elapsed time and the resistance value in the vulcanization detection sensor.

[0031] Figure 7 is a plan view of the vulcanization detection sensor according to the second embodiment.

[0032] Figure 8 is a sectional view along the line VIII-VIII of Figure 7 .

[0033] Figure 9 is a plan view of a vulcanization detection sensor according to a third embodiment.

[0034] Figure 10 is a sectional view taken along the X-X line of Figure 9

[0035] Figure 11 is a plan view of a vulcanization detection sensor according to a fourth embodiment.

[0036] Figure 12 is a sectional view taken along the XII-XII line of Figure 11 DETAILED DESCRIPTION

[0037] Next, embodiments of the application will be described with reference to the drawings.

[0038] Figure 1 is a plan view of a vulcanization detection sensor according to a first embodiment of the application, Figure 2 is a sectional view taken along the II-II line of Figure 1 Figure 1 and Figure 2 As shown in FIGS. 1 and 2, the vulcanization detection sensor 10 according to the first embodiment mainly includes an insulating substrate 1 in a rectangular parallelepiped shape, a resistor body 2 formed to be in close contact with a surface of the insulating substrate 1, a vulcanization detection conductor 3 formed to be in close contact with a surface of the resistor body 2, a protection layer 4 formed to cover a part of the vulcanization detection conductor 3, a pair of back electrodes 5 formed at both end portions in a length direction of the back surface of the insulating substrate 1, and a pair of electrode portions 6 formed at both end portions in the length direction of the insulating substrate 1.

[0039] The insulating substrate 1 is obtained by dividing a large-size substrate described later into a plurality of pieces along longitudinal and lateral division grooves, and the large-size substrate is an alumina substrate in which alumina is a main component (purity: 96%).

[0040] The resistor body 2 is composed of a Ni-Cr metal film formed as a thin film on a surface of the insulating substrate (alumina substrate) 1 by sputtering, vapor deposition, or the like. The resistor body 2 is formed in a rectangular shape on the entire surface of the insulating substrate 1, and both end portions of the resistor body 2 are connected to the pair of electrode portions 6, respectively.

[0041] ​​​The sulfuration detection conductor 3 is composed of a metal film such as Cu, Ag, or Ni formed as a thin film on the surface of the resistor 2 by sputtering, vapor deposition, or the like. The resistance of this metal film is significantly lower than that of the metal film constituting the resistor 2 (e.g., several kilo-ohms for the resistor and tens of milli-ohms for the sulfuration detection conductor). The sulfuration detection conductor 3 is formed in a rectangular shape over the entire surface of the resistor 2, and both ends of the sulfuration detection conductor 3 are connected to a pair of electrodes 6.

[0042] The protective layer 4 is formed of an insulating material that is impermeable to sulfide gas, and has, for example, a two-layer structure comprising an inner coating layer composed of a glass material and an outer coating layer composed of a resin material. The protective layer 4 is formed at two locations other than the center and both ends of the sulfide detecting conductor 3. The center portion of the sulfide detecting conductor 3 not covered by the protective layer 4 forms an exposed portion 3a that is exposed to the outside.

[0043] The back electrode 5 is composed of a Cr-Cu or Cr-Ni-Cu metal film formed as a thin film on the back surface of the insulating substrate (alumina substrate) 1 by sputtering. A pair of back electrodes 5 are formed at both ends in the longitudinal direction of the back surface of the insulating substrate 1. Alternatively, the back electrode 5 may be formed as a thick film instead of a thin film. In this case, Ag-based paste and Cu-based paste can be screen-printed and then dried and sintered.

[0044] The electrode section 6 consists of an end surface electrode 7 with a U-shaped cross section, which provides electrical continuity between the end of the sulfuration detecting conductor 3 exposed from the protective layer 4 and the back surface electrode 5; an intermediate electrode 8 and an external electrode 9, which are sequentially formed to cover the end surface electrode 7. The end surface electrode 7 is formed by sputtering Ni / Cr on the end surface of the insulating substrate 1; the intermediate electrode 8 is formed by electrolytic plating of Ni plating; and the external electrode 9 is formed by electrolytic plating of Sn plating.

[0045] Next, use Figure 3 and Figure 4 , the manufacturing process of the thus constructed sulfuration detection sensor 10 will be described. Figure 3 (a) to (f) are top views of the large-size substrate used in the manufacturing process as viewed from the front. Figure 4 (a) to (f) are respectively along Figure 3 (a) to (f) are cross-sectional views corresponding to a single slice at the center portion in the longitudinal direction.

[0046] First, if Figure 3 (a) and Figure 4 As shown in (a), a large-sized substrate 1A is prepared from which multiple insulating substrates 1 can be made. The large-sized substrate 1A is pre-set with a primary dividing groove and a secondary dividing groove in a grid shape, and each grid divided by the two dividing grooves becomes a sheet area.Figure 3 and Figure 4 is shown as a representative of a large-size substrate 1A corresponding to one piece region, but in fact, the following each process is performed uniformly on the large-size substrate 1A corresponding to a plurality of piece regions.

[0047] That is, after sputtering Ni-Cr on the surface of the large-size substrate 1A, Cu or the like is sputtered from above to form a metal film of a double-layer structure. Then, by patterning these metal films into a rectangular shape using photolithography, as shown in Figure 3 (b) of FIG. 2A and Figure 4 (b) of FIG. 2B, the resistance body 2 adhered to the surface of the large-size substrate 1A, and the sulfidation detection conductor 3 adhered to the surface of the resistance body 2 are formed.

[0048] Next, by sputtering Cr-Cu or Cr-Ni-Cu from above the mask (mask sputtering) on the back surface of the large-size substrate 1A, as shown in Figure 3 (c) of FIG. 2A and Figure 4 (c) of FIG. 2B, the facing back surface electrodes 5 having a prescribed interval are formed on the back surface of the large-size substrate 1A.

[0049] Next, after forming a SiO2 film from the surface side of the large-size substrate 1A using a CVD (Chemical Vapor Deposition) method, a sputtering method, or screen printing a glass paste and performing drying and sintering to form an inner coating layer, an outer coating layer is formed by screen printing an epoxy resin, a phenol resin from above the inner coating layer and performing heat curing, as shown in Figure 3 (d) of FIG. 2A and Figure 4 (d) of FIG. 2B, the protective layer 4 covering the two end portions and the portion other than the central portion of the sulfidation detection conductor 3 is formed.

[0050] Next, after the large-size substrate 1A is once divided into a narrow strip-shaped substrate 1B along a first division groove, Ni / Cr is sputtered on the division surface of the narrow strip-shaped substrate 1B, as shown in Figure 3 (e) of FIG. 2A and Figure 4 (e) of FIG. 2B, the end surface electrode 7 connecting between the sulfidation detection conductor 3 and the back surface electrode 5 is formed on the two end portions of the narrow strip-shaped substrate 1B. This end surface electrode 7 is connected not only to the end portion of the sulfidation detection conductor 3 exposed from the protective layer 4, but also to the end surface of the resistance body 2 covered by the sulfidation detection conductor 3.

[0051] Next, after the narrow strip-shaped substrate 1B is twice divided into a plurality of piece-shaped substrates 1C along a second division groove, electrolytic plating is performed on these piece-shaped substrates 1C, and an intermediate electrode 8 composed of a plated Ni layer, and an external electrode 9 formed of a plated Sn layer are sequentially formed. Thus, as shown in Figure 1 (f) of FIG. 2A and Figure 5of FIG. 1 (f), electrode portions 6 composed of end face electrodes 7, intermediate electrodes 8 and outer electrodes 9 are formed at both end portions of the sheet-like substrate 1C, and the completion Figure 6 , 2 of the vulcanization detection sensor 10 shown in FIG. 1 (a).

[0052] Figure 5 is a explanatory view showing a change in current path in the case where the vulcanization detection sensor 10 according to the present embodiment is disposed in a vulcanization gas environment, Figure 5 is a explanatory view showing a relationship between elapsed time and resistance value in the case where the vulcanization detection sensor 10 is disposed in a vulcanization gas environment.

[0053] In an initial state before the vulcanization detection sensor 10 is exposed to a vulcanization gas, since the entire surface of the resistance body 2 is covered with the vulcanization detection conductor 3, both end portions of these resistance body 2 and the vulcanization detection conductor 3 are connected to a pair of electrode portions 6, and thus, as shown by an arrow X1 of (a) of FIG. 1, a current flowing between the pair of electrode portions flows through the vulcanization detection conductor 3, in which the resistance value of the vulcanization detection conductor 3 is significantly smaller than the resistance value of the resistance body 2. Figure 6

[0054] When the vulcanization detection sensor 10 is disposed in an environment containing a vulcanization gas, since the exposed portion 3a of the vulcanization detection conductor 3 exposed to the outside is not covered with the protective layer 4 and comes into contact with the vulcanization gas, vulcanization starts from the exposed portion 3a and then progresses to the inside of the vulcanization detection conductor 3 covered with the protective layer 4 over time. Thus, as shown by an arrow X2 of (b) of FIG. 1, the current path changes to: from the unvulcanized portion of one side of the vulcanization detection conductor 3, via the resistance body 2, to the unvulcanized portion of the other side, and in conjunction therewith, the resistance value between the pair of electrode portions changes as shown in (c) of FIG. 1. Figure 6 Figure 7 That is, the resistance value of the vulcanization detection sensor 10 increases in a gentle curve until the time (T1) when the exposed portion 3a of the vulcanization detection conductor 3 is vulcanized, and then increases linearly as the vulcanization progresses to the inside of the vulcanization detection conductor 3, and reaches a fixed value (the resistance value of the resistance body 2) at the time (T2) when the entire vulcanization detection conductor 3 is vulcanized. Thus, within a threshold value indicated by a symbol S in (d) of FIG. 1, the resistance value of the resistance body 2 continuously changes as the degree of vulcanization of the vulcanization detection conductor 3, and thus, the degree of vulcanization can be accurately and easily detected. Figure 8

[0055] ​​​As described above, in the sulfidation detection sensor 10 according to the first embodiment, by the resistor 2 formed on the insulating substrate 1, it is possible to ensure that the pair of electrode portions 6 is always in conduction, and when sulfidation occurs when exposed to an environment containing a sulfidation gas, after sulfidation starts from the exposed portion 3a of the sulfidation detection conductor 3 that is not covered by the protective layer 4 and exposed to the outside, the sulfidation progresses to the inside covered by the protective layer 4, and thus the current path flowing between the pair of electrode portions 6 changes according to the degree of sulfidation of the sulfidation detection conductor 3. Thus, it is possible to continuously change the resistance value of the resistor 2 according to the degree of sulfidation of the sulfidation detection conductor 3, and it is possible to accurately and easily detect the degree of sulfidation.

[0056] Further, in the sulfidation detection sensor 10 according to the first embodiment, since the resistor 2 and the sulfidation detection conductor 3 are metal films formed as thin films using sputtering or the like, it is possible to improve the detection accuracy without causing a film thickness deviation of the resistor 2 and the sulfidation detection conductor 3. Also, since the resistor 2 is a Ni-Cr metal film formed as a thin film on the surface of the insulating substrate (alumina substrate) 1, it is possible to improve the adhesion to the alumina substrate 1 by Cr in the metal film, and it is possible to improve the adhesion to the sulfidation detection conductor 3 composed of Ag, Cu, Ni, or the like by Ni.

[0057] In addition, although Cr functions to improve the sulfidation resistance of the metal film itself, since the metal film becomes mechanically brittle when the content of Cr in the metal film increases, it is preferable that the content of Cr in the metal film composed of Ni-Cr be in the range of 40 to 60 wt%. Further, as long as the main component of the metal film is Ni-Cr, it is also possible to appropriately add titanium (Ti), tungsten (W), or the like in order to reduce the temperature characteristics (TCR) or the like, as long as it is within a range that can maintain the above-described functions.

[0058] Figure 7 is a plan view of a sulfidation detection sensor 20 according to a second embodiment of the present application, Figure 1 is a sectional view taken along the line VIII-VIII of Figure 2 , and Figure 7 and Figure 8 corresponding portions use the same reference numerals.

[0059] As shown in Figure 9 and Figure 10 , in the sulfidation detection sensor 20 according to the second embodiment, the resistor 2 is configured to have an adjustment region 2a that is not covered by the sulfidation detection conductor 3, an adjustment groove 21 for adjusting the resistance value is formed in the adjustment region 2a, and the adjustment region 2a is covered by the protective layer 4.

[0060] In the thus configured sulfuration detection sensor 20, the initial resistance value of the resistor 2 can be increased by forming the adjustment groove 21 in the adjustment region 2a, thereby achieving a sulfuration detection sensor 20 having excellent temperature characteristics (TCR). The adjustment groove 21 is not limited to the I-shaped notch shown in the figure, but may be another shape such as an L-shaped notch. Furthermore, the number of adjustment grooves 21 is not limited to the two shown in the figure, and may be increased or decreased as appropriate.

[0061] Figure 9 3 is a top view of a vulcanization detection sensor 30 according to a third embodiment of the present invention. Figure 1 It is along Figure 2 The sectional view of line XX, and Figure 9 and Figure 10 Corresponding parts are given the same reference numerals.

[0062] like Figure 11 and Figure 12 As shown, in the sulfuration detection sensor 30 according to the third embodiment, the protective layer 4 is composed of an inner coating layer 31 and an outer coating layer 32. The inner coating layer 31 is composed of a glass material formed on the sulfuration detection conductor 3, and the outer coating layer 32 is composed of a resin material formed on the inner coating layer 31. The electrode portion 6 is configured to cover the end portion of the sulfuration detection conductor 3 and to be in close contact with the outer coating layer 32.

[0063] In the thus configured sulfuration detection sensor 30, the protective layer 4 includes an outer coating layer 32 made of a resin material, thereby improving the adhesion between the outer coating layer 32 and the electrode portion 6 and suppressing sulfuration of the end portion of the sulfuration detection conductor 3 covered by the end surface electrode 7 of the electrode portion 6. However, because resin materials are gas-permeable, if the entire protective layer 4 is formed of a resin material, there is a risk that the sulfuration detection conductor 3 located directly below the protective layer 4 will be sulfurized by sulfurized gas that has permeated the protective layer 4. Therefore, by forming an inner coating layer 31 made of a glass material that is impermeable to sulfurized gas below the outer coating layer 32 made of a resin material, the sulfuration detection conductor 3 located directly below the protective layer 4 can be prevented from reacting with sulfurized gas that has permeated the outer coating layer 32 and thus sulfurizing.

[0064] Figure 11 4 is a top view of a sulfuration detection sensor 40 according to a fourth embodiment of the present invention. Figure 1 It is along Figure 2 The cross-sectional view of the XII-XII line, with Figure 11 and Figure 12 Corresponding parts are given the same reference numerals.

[0065] like ​ and ​As shown, in the sulfurization detection sensor 40 according to the fourth embodiment, the exposed region 2b is provided in the central portion of the resistor 2 in the length direction, and the first sulfurization detection conductor 41 and the second sulfurization detection conductor 42 are formed at two positions on the resistor 2 sandwiching the exposed region 2b. These first and second sulfurization detection conductors 41 and 42 are each formed of a metal film of a different material formed as a thin film on the surface of the resistor 2 by sputtering, vapor deposition, or the like, and, for example, the first sulfurization detection conductor 41 is a metal film of Ni, and the second sulfurization detection conductor 42 is a metal film of Ag.

[0066] A protective layer 4A that is non-permeable to sulfurization gas is formed in the central portion of the first sulfurization detection conductor 41, and an exposed portion 41a that is not covered by the protective layer 4A and is exposed to the outside is formed in the inner end portion of the first sulfurization detection conductor 41. Similarly, a protective layer 4A that is non-permeable to sulfurization gas is formed in the central portion of the second sulfurization detection conductor 42, and an exposed portion 42a that is not covered by the protective layer 4A and is exposed to the outside is formed in the inner end portion of the second sulfurization detection conductor 42. Further, an intermediate protective layer 4B that is non-permeable to sulfurization gas is formed in the exposed region 2b of the resistor 2, and the exposed portion 41a of the first sulfurization detection conductor 41 and the exposed portion 42a of the second sulfurization detection conductor 42 are disposed in facing positions sandwiching the intermediate protective layer 4B.

[0067] In the sulfurization detection sensor 40 thus configured, since the first and second sulfurization detection conductors 41 and 42 formed of different materials that are different in gas selectivity are formed on the resistor 2, and these first and second sulfurization detection conductors 41 and 42 each have the exposed portion 41a or 42a, the degree of sulfurization can be accurately detected regardless of the type of sulfurization gas contained in the use environment.

[0068] That is, the reactivity of sulfurization gas differs depending on the type of metal that constitutes the sulfurization detection conductor, and, for example, silver (Ag) readily reacts with hydrogen sulfide (H2S) but has low reactivity with sulfur dioxide (SO2), and nickel (Ni) readily reacts with sulfur dioxide (SO2) but has low reactivity with hydrogen sulfide (H2S), and thus, in a gas environment containing sulfur dioxide, sulfurization starts from the exposed portion 41a of the first sulfurization detection conductor 41 made of Ni, and in a gas environment of hydrogen sulfide, sulfurization starts from the exposed portion 42a of the second sulfurization detection conductor 42 made of Ag, and thus, a multi-type sulfurization detection sensor 40 that can correspond to different types of sulfurization gas can be realized.

[0069] In addition, copper (Cu) is a material that readily reacts with both hydrogen sulfide (H2S) and sulfur dioxide (SO2), and thus, even if only copper (Cu) is used, a plurality of types of sulfidation detection sensors can be obtained, but by combining with a material that is different in gas selectivity from the above-described Ag material and Ni material and has high reactivity with a target sulfidation gas, it is possible to improve the detection accuracy compared to the case where only copper (Cu) forms a sulfidation detection conductor.

[0070] Further, in the sulfidation detection sensor 40 according to the fourth embodiment, the resistor 2 has an exposed region 2b that is not covered by the first sulfidation detection conductor 41 and the second sulfidation detection conductor 42, and the intermediate protective layer 4B is formed so as to cover the exposed region 2b, and since the exposed portion 41a of the first sulfidation detection conductor 41 and the exposed portion 42a of the second sulfidation detection conductor 42 are disposed in facing positions sandwiching the intermediate protective layer 4B, it is possible to easily form the first sulfidation detection conductor 41 and the second sulfidation detection conductor 42 composed of different materials by sputtering (mask sputtering) Ni and Ag on the surface of the resistor 2 from above the mask.

[0071] In addition, in each of the above-described embodiments, a case where the resistor 2 and the sulfidation detection conductor 3 (41, 42) are formed as a thin film using sputtering or the like is described, but these resistor and sulfidation detection conductor can also be composed of a thick film formed of a metal glaze. For example, the resistor can be formed by screen printing Ag-Pd (50%) paste and then drying and sintering it, or the sulfidation detection conductor can be formed by screen printing Cu paste or Ag paste and then drying and sintering it.

[0072] Explanation of Reference Numerals

[0073] 1: Insulating substrate;

[0074] 1A: Large-size substrate;

[0075] 1B: Narrow strip-shaped substrate;

[0076] 1C: Sheet-shaped substrate;

[0077] 2: Resistor;

[0078] 2a: Adjustment region;

[0079] 2b: Exposed region;

[0080] 3: Sulfidation detection conductor;

[0081] 3a: Exposed portion;

[0082] 4, 4A: Protective layer;

[0083] 4B: Intermediate protective layer;

[0084] 5: back electrode

[0085] 6: electrode portion

[0086] 7: end surface electrode

[0087] 8: intermediate electrode

[0088] 9: outer electrode

[0089] 10, 20, 30, 40: vulcanization detection sensor

[0090] 21: adjustment groove

[0091] 31: inner coating layer

[0092] 32: outer coating layer

[0093] 41: first vulcanization detection conductor

[0094] 41a: exposed portion

[0095] 42: second vulcanization detection conductor

[0096] 42a: exposed portion

Claims

1. A sulfur detection sensor, characterized in that: have: A rectangular parallelepiped insulating substrate; a resistor provided on a main surface of the insulating substrate; a sulfide detection conductor provided on the resistor and sulfurized by sulfide gas; a sulfide gas-impermeable protective layer provided so as to cover a portion of the sulfide detection conductor; and a pair of electrodes provided at opposite ends of the insulating substrate and connected to the resistor and the sulfide detection conductor. The sulfuration detecting conductor is made of a metal having a lower resistance value than the resistor, and has an exposed portion that is not covered by the protective layer and is exposed to the outside.

2. The sulfur detection sensor according to claim 1, characterized in that: The resistor has an adjustment region not covered by the sulfuration detecting conductor, an adjustment groove for adjusting the resistance value is formed in the adjustment region, and the adjustment region is covered by a portion of the protective layer.

3. The sulfur detection sensor according to claim 1, characterized in that: The sulfuration detection conductor includes a first sulfuration detection conductor and a second sulfuration detection conductor. The first sulfuration detection conductor and the second sulfuration detection conductor are made of different materials having different gas selectivities. The first sulfuration detection conductor and the second sulfuration detection conductor each have the exposed portion.

4. The sulfur detection sensor according to claim 3, characterized in that: The resistor has an exposed area not covered by the first and second sulfuration detecting conductors, and an intermediate protective layer is provided on the exposed area. The exposed portion of the first and second sulfuration detecting conductors are arranged so as to sandwich the intermediate protective layer.

5. The sulfur detection sensor according to any one of claims 1 to 4, characterized in that: The resistor and the sulfuration detection conductor are each composed of a metal film formed into a thin film.

6. The sulfur detection sensor according to claim 5, characterized in that: The insulating substrate is composed of an alumina substrate, and the resistor is a Ni—Cr metal film formed on the surface of the alumina substrate by sputtering.

7. The sulfur detection sensor according to any one of claims 1 to 4, characterized in that: The protective layer includes an inner coating layer formed of a glass material formed on the sulfide detection conductor and an outer coating layer formed of a resin material formed on the inner coating layer. The electrode portion covers an end portion of the sulfide detection conductor and is in close contact with the outer coating layer.

8. The sulfur detection sensor according to claim 5, characterized in that: The protective layer includes an inner coating layer formed of a glass material formed on the sulfide detection conductor and an outer coating layer formed of a resin material formed on the inner coating layer. The electrode portion covers an end portion of the sulfide detection conductor and is in close contact with the outer coating layer.

9. The sulfur detection sensor according to claim 6, characterized in that: The protective layer includes an inner coating layer formed of a glass material formed on the sulfide detection conductor and an outer coating layer formed of a resin material formed on the inner coating layer. The electrode portion covers an end portion of the sulfide detection conductor and is in close contact with the outer coating layer.

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