Sensor element and method for manufacturing a sensor element

Abstract

A sensor element is provided that can reduce the peeling of the odorant receptor layer from the substrate and achieve high yield. The sensor element (1) includes: a substrate (11) that is rectangular in plan view, having a cover portion (12) whose substrate surface (11A) is covered by an insulating film, and a non-cover portion (13) surrounded by the cover portion and whose substrate surface is not covered by the insulating film; a first electrode (15) and a second electrode (16) disposed on the substrate surface in the non-cover portion; and an odorant receptor layer (19) comprising a conductive carbon material and a resin composition and in contact with the substrate surface in the non-cover portion, the first electrode and the second electrode, wherein the first electrode and the second electrode are disposed in a recess (13A) provided in the non-cover portion, and the substrate surface in the non-cover portion, the first surface of the first electrode for contacting the odorant receptor layer, and the second surface of the second electrode for contacting the odorant receptor layer are disposed flush with each other.

Description

Technical Field

[0001] This disclosure relates to sensor elements and methods for manufacturing sensor elements. Background Technology

[0002] In the humidity sensor described in Patent Document 1, a comb-shaped electrode is formed on an insulating substrate made of a ceramic plate. Furthermore, a rectangular annular frame made of the same material as the insulating substrate (ceramic) is joined to surround the comb-shaped electrode formed on the insulating substrate. A method is also described in which a humidity-sensitive film is formed by coating a humidity-sensitive liquid onto the area enclosed by the frame and the surface of the insulating substrate and then drying it.

[0003] [Existing Technical Documents] (Patent Documents) Patent Document 1: Japanese Patent Application Publication No. 2005-114357 Summary of the Invention (The problem that the invention aims to solve) Previously, when forming a functional film with a specified function in the area enclosed by the frame and the surface of the insulating substrate, the following problems existed: the functional film would peel off from the insulating substrate due to deformation of the functional film caused by drying, vibration during transportation, vibration during the sensor substrate cutting process, etc., resulting in a decrease in yield.

[0004] One aspect of this disclosure is to provide a sensor element and a method for manufacturing the sensor element that can reduce the peeling of the odorant receptor layer from the substrate and achieve high yield.

[0005] (Technical means used to solve the problem) To address the aforementioned problems, one aspect of the sensor element disclosed herein includes: a substrate that is rectangular in top view, having a covered portion whose substrate surface is covered by an insulating film, and a non-covered portion surrounded by the covered portion and whose substrate surface is not covered by the insulating film; a first electrode and a second electrode disposed on the substrate surface in the non-covered portion; and an odorant receptor layer comprising a conductive carbon material and a resin composition, and in contact with the substrate surface in the non-covered portion, the first electrode, and the second electrode, wherein the first electrode and the second electrode are disposed within a recess provided in the non-covered portion, wherein the substrate surface in the non-covered portion, a first surface of the first electrode in contact with the odorant receptor layer, and a second surface of the second electrode in contact with the odorant receptor layer are disposed flush with each other.

[0006] A method for manufacturing a sensor element according to one aspect of this disclosure includes: a via forming step, forming a pair of vias at two end edges of a substrate that is rectangular in plan view; an electrode placement step, placing a first electrode and a second electrode on the front side of the substrate and placing metal wiring on the back side of the substrate; a flushing step, printing a pattern of photocurable resin on the front side of the substrate and curing it by light irradiation, and then removing the photocurable resin until the top surfaces of the first electrode and the second electrode are exposed, so that the substrate surface of the substrate is flush with the top surfaces of the first electrode and the second electrode; a solder resist step, forming a cover portion covered by an insulating film on the portion other than the vias on the front side of the substrate and the non-cover portion for placing the first electrode and the second electrode; a slurry preparation step, preparing a slurry composed of a conductive carbon material and a resin composition; a coating step, coating the slurry onto the non-cover portion; and a drying step, drying the slurry coated on the non-cover portion to form an odorant receptor layer.

[0007] (Invention effect) According to one aspect of this disclosure, the first electrode and the second electrode are configured to be flush with the substrate surface in the uncovered portion of the substrate, so that the surface of the thinner odor substance receptor layer can be formed flat, thereby reducing the peeling of the odor substance receptor layer from the substrate and achieving a high yield. Attached Figure Description

[0008] Figure 1 This is a perspective view of an example of a sensor element according to the first embodiment of this disclosure.

[0009] Figure 2 It has not been installed yet. Figure 1 The top view of the sensor element in front of the pins and odorant receptor layer shown.

[0010] Figure 3 It is along Figure 2 A cross-sectional view along the middle III-III direction.

[0011] Figure 4 yes Figure 2 An explanatory diagram illustrating an example of the size scheme for the sensor element shown.

[0012] Figure 5 Is with Figure 4 An explanatory diagram illustrating an example of the dimensional scheme for the surface opposite the non-covered portion.

[0013] Figure 6 This is an illustrative diagram illustrating an example of a method for manufacturing a sensor element.

[0014] Figure 7 This is an illustrative diagram illustrating an example of a method for manufacturing a sensor element.

[0015] Figure 8 This is an explanatory diagram of an example of an electrode in the non-covered portion of the sensor element according to the second embodiment.

[0016] Figure 9 This is an explanatory diagram of an example of an electrode in the non-covered portion of the sensor element according to the third embodiment.

[0017] Figure 10 This is an explanatory diagram of an example of an electrode in the non-covered portion of the sensor element according to the fourth embodiment.

[0018] Figure 11 This is a top view schematic diagram of a configuration example of the sensor element in Comparative Example 1.

[0019] Figure 12 This is a top view schematic diagram of a configuration example of the sensor element in Comparative Example 2.

[0020] Figure 13 A table showing the evaluation results of Examples 1-4 and Comparative Examples 1 and 2 is presented. Detailed Implementation

[0021] [First Implementation] The first embodiment of this disclosure will be described below, but this disclosure is not limited thereto. In addition, unless otherwise specifically indicated in this specification, the expression of numerical range "A to B" means "A or more and B or less".

[0022] [Simplified configuration of sensor element 1] The following combination Figures 1-5 The general structure of sensor element 1 will be described. Figure 1 This is a perspective view of an example of sensor element 1. Figure 2 This is a top view of the sensor element 1 before the metal pins 18 and the odorant receptor layer 19 are installed. Figure 3 It is along Figure 2 A cross-sectional view along the middle III-III direction. Figure 4 This is an explanatory diagram of the dimension scheme of sensor element 1. Figure 5 Is with Figure 4 The diagram illustrates an example of the dimensional scheme of the surface opposite to the non-covered portion 13. Here, as an example, the sensor element 1 is, for example, a chemiluminescence type odor sensor element.

[0023] like Figure 1As shown, the sensor element 1 includes: a substrate 11 that is generally rectangular when viewed from above, a cover portion 12 that covers the surface of the substrate 11 by a solder resist that serves as an insulating film, a non-cover portion 13 that is circular when viewed from above, a first electrode 15, a second electrode 16, a pair of through holes 17, metal pins 18, and an odorant receptor layer 19.

[0024] The substrate 11 can be a glass epoxy resin substrate commonly used in electronic circuits. The surface roughness of the substrate surface 11A of the substrate 11 is preferably an arithmetic mean roughness Ra of less than 10 [μm]. Here, the substrate 11 is not limited to being formed of epoxy resin, but can also be formed of phenolic resin or polyimide resin. This helps to suppress the peeling of the odorant receptor layer 19 from the surface of the substrate 11.

[0025] The following combination Figures 2-5 The first electrode 15, the second electrode 16, and the uncovered portion 13 will be described. The first electrode 15 and the second electrode 16 are metal wires that function as electrodes to measure changes in the conductivity of the odorant receptor layer 19.

[0026] like Figure 2 and Figure 3 As shown, the non-covered portion 13 opens into the portion of the covered portion 12, which is covered by an insulating film, i.e., solder resist, coated on the surface of the substrate 11, corresponding to the central portion of the substrate 11, and forms a circle when viewed from above, with the substrate surface 11A exposed within this circle. Therefore, the center of the bottom surface of the circular non-covered portion 13 when viewed from above is located approximately at the center of the long and short sides of the substrate 11. Furthermore, the non-covered portion 13 defines a coating area for applying the slurry of the resin composition forming the odorant receptor layer 19 to the substrate surface 11A.

[0027] Furthermore, the thickness of the covering portion 12 is 50 μm to 500 μm, preferably 100 μm to 400 μm, and more preferably 100 μm to 200 μm. Therefore, the depth of the non-covering portion 13, in other words, the thickness of the insulating film surrounding the non-covering portion 13, is 50 μm to 500 μm, preferably 100 μm to 400 μm, and more preferably 100 μm to 200 μm.

[0028] [Composition of Odor Receptor Layer 19] Odor receptor layer 19 refers to the layer that adsorbs odor substances. The resin composition forming odor receptor layer 19 comprises a resin (A) and a conductive carbon material (C). Additionally, if desired, the resin composition forming odor receptor layer 19 may also contain a surfactant (B).

[0029] Resin (A) is not particularly limited and can be polyurethane resin, polyepoxyalkylene resin, acrylic resin, fluorinated resin, vinyl polymer resin, silicone resin, polyamide resin and polyester resin, etc.

[0030] The surfactant (B) functions as a dispersant for the conductive carbon material (C) described later. The surfactant (B) can be appropriately selected from known surfactants within the range of functions described above. Examples of surfactants (B) include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. The resin (A) may or may not be miscible with the surfactant (B).

[0031] Conductive carbon materials (C) refer to materials with a volume resistivity of 0.1 [Ω]. Carbon materials of cm or less. The above resin composition is in which conductive carbon material (C) is dispersed in resin (A). The conductive carbon materials (C) contact each other to form conductive paths, thereby making the resin composition conductive. Examples of conductive carbon materials (C) include carbon black, carbon nanotubes, and graphene. The shape of the conductive carbon material (C) is preferably fibrous or spherical.

[0032] The resin composition forming the odorant receptor layer 19 may also contain other components besides the resin (A) and the conductive carbon material (C). Examples of other components include a solvent (D). From the viewpoint of improving the compatibility between the resin (A) and the surfactant (B) included as desired, improving the dispersibility of the conductive carbon material (C) in the resin composition, or improving the coatability of the resin composition, the solvent (D) may be mixed into the resin composition. Examples of solvents (D) include N-methyl-2-pyrrolidone, propylene glycol monomethyl ether acetate, ethyl butyrate, butyl butyrate, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, and xylene.

[0033] By mixing resin (A), conductive carbon material (C), solvent (D) as needed, and surfactant (B) as needed, and then uniformly mixing using a stirrer, a resin composition forming the odorant receptor layer 19 can be prepared into a slurry. If solvent (D) is added, the solvent (D) is distilled off from the resin composition. The solvent (D) can be distilled off either from the uniformly mixed resin composition or from the coating film generated during the manufacture of the sensor element, as described later.

[0034] [The configuration of the first electrode 15 and the second electrode] like Figure 3As shown, the first electrode 15 and the second electrode 16 are disposed in the recess 13A provided in the uncovered portion 13, and the substrate surface 11A in the uncovered portion 13, the top surface (first surface) of the first electrode 15 for contacting the odorant receptor layer 19, and the top surface (second surface) of the second electrode 16 for contacting the odorant receptor layer 19 are disposed flush with each other. Specifically, it is configured such that the height difference between the top surface (first surface) of the first electrode 15 for contacting the odorant receptor layer 19 and the top surface (second surface) of the second electrode 16 for contacting the odorant receptor layer 19 and the substrate surface 11A is approximately zero, for example, the height difference does not exceed ±0.1 [μm] to ±10 [μm].

[0035] As a result, the odorant receptor layer 19 coated on the uncovered portion 13 comes into contact with the bottom surface of the uncovered portion 13, the top surface of the first electrode 15, and the top surface of the second electrode 16. Consequently, the coating surface of the odorant receptor layer 19 at the uncovered portion 13 becomes flat, which can suppress the peeling of the odorant receptor layer 19.

[0036] like Figure 2 and Figure 3 As shown, through holes 17 for mounting metal leads 18 are formed at both ends of the substrate 11 along its long side and approximately at the center of the substrate 11 along its short side. Furthermore, as... Figure 3 and Figure 5 As shown, metal wiring 17A is provided on the inner peripheral surface of each through hole 17 and at the end of the surface opposite to the substrate surface 11A where the non-covered portion 13 is provided (hereinafter also referred to as the "back side"). In addition, metal wiring 21A is provided, which is connected from the back side of the substrate 11 to the first electrode 15, and is also connected to the metal wiring 17A on the back side of the substrate 11 in the through hole 17 on the opposite side of the first electrode 15 relative to the second electrode 16.

[0037] Thus, the first electrode 15 is electrically connected via metal wirings 21A and 17A to a metal pin 18 pressed and soldered into a through-hole 17 located on the opposite side of the directions opposite to those of the first electrode 15 and the second electrode 16. The second electrode 16 is electrically connected via metal wirings 21B and 17A to a metal pin 18 pressed and soldered into another through-hole 17 located on the opposite side of the directions opposite to those of the first electrode 15 and the second electrode 16. Therefore, the first electrode 15 and the second electrode 16 are electrically connected on the side of the substrate 11 opposite to the substrate surface 11A where the non-covered portion 13 is provided, to the through-hole 17 at the end of the substrate 11 opposite to the directions opposite to those of the first electrode 15 and the second electrode 16, and are electrically connected to the metal pin 18 via the through-hole 17.

[0038] In addition, such as Figure 2 The substrate 11 has four chamfered portions 23, which extend outwards along the short side from both ends of the two side edges along the long side of the substrate 11 by a predetermined length. At the base end of the inner portion of each chamfered portion 23 along the long side of the substrate 11, a roughly semi-circular chamfer is formed, the radius of which is approximately equal to the height of the chamfered portion protruding outwards along the short side. Each chamfered portion 23 is formed by forming a V-groove at its front end using a V-notch method as described later, and it connects to the chamfered portions 23 of adjacent substrates 11 (see...). Figure 6 ).

[0039] [Dimensional configuration of sensor element 1] Next, combined Figure 4 and Figure 5 An example of the dimensions of sensor element 1 will be described. For example... Figure 4 and Figure 5 As shown, the substrate 11 of the sensor element 1 is formed into a rectangle when viewed from above, with a length L1 in the long side direction and a width W1 in the short side direction. The length L1 in the long side direction is, for example, about 6 mm to 8 mm. The width W1 in the short side direction is, for example, about 4 mm to 6 mm.

[0040] Furthermore, the protrusion height W3 of each chamfered portion 23 in the short side direction is, for example, about 0.4 [mm] to 0.6 [mm]. The length L2 of the front end of each chamfered portion 23 in the long side direction is, for example, about 0.5 [mm] to 1.5 [mm]. Therefore, the width W2 of the portion of the substrate 11 for forming the non-covered portion 13 in the short side direction is the dimension obtained by subtracting the protrusion height W2 of each chamfered portion 23 from the width W1 of the substrate 11 in the short side direction.

[0041] Furthermore, the center-to-center spacing L3 of each circularly shaped through-hole 17 is formed to be approximately equal to the width W1 of the substrate 11 in the short-side direction. Additionally, each through-hole 17 is disposed on the inner side, and the distances between them and the two ends in the long-side direction of the substrate 11 are approximately equal. The center of each through-hole 17 is located on a straight line passing approximately at the center of the width W1 in the short-side direction of the substrate 11 along the long-side direction.

[0042] [Dimensioning scheme for non-covered part 13] In addition, such as Figure 4As shown, the diameter D1 of the circular non-covered portion 13, viewed from above, is 2 mm to 5 mm, preferably 2 mm to 4 mm, and more preferably 2 mm to 3 mm. When the diameter D1 of the non-covered portion 13 is less than 2 mm, the odorant receptor layer 19 may climb towards the inner sidewall of the non-covered portion 13 due to surface tension, resulting in deviation. Furthermore, when the diameter D1 of the non-covered portion 13 is greater than 5 mm, the thickness of the odorant receptor layer 19 at the center of the bottom surface of the non-covered portion 13 may become thinner due to surface tension, causing the substrate surface 11A to be exposed.

[0043] Therefore, since the non-covered portion 13 is circular when viewed from above, the odorant receptor layer 19 can also be formed to be circular when viewed from above, thereby preventing uneven film thickness of the odorant receptor layer 19 in the circumferential direction. As a result, peeling of the odorant receptor layer 19 from the substrate 11 can be further reduced. On the other hand, if the non-covered portion 13 is a deformed structure such as a rectangle when viewed from above, the surface tension caused by the covering portion 12 surrounding the non-covered portion 13 may cause deviations in the film thickness of the odorant receptor layer 19, and cracks or peeling may occur starting from that point. It is believed that this problem is caused by differences in the film thickness of the odorant receptor layer 19, and residual stress caused by uneven orientation of the conductive carbon material due to solvent flow during the drying process.

[0044] Furthermore, the inventors have discovered that by forming the uncovered portion 13 into a circle with a diameter D1 of 2 mm or more and 5 mm or less when viewed from above, and by controlling the thickness of the insulating film surrounding the uncovered portion 13 to be 50 μm or more and 500 μm or less as described above, it is possible to further reduce the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0045] [Dimensioning scheme for the first electrode 15 and the second electrode 16] The first electrode 15 and the second electrode 16 are formed to be circular when viewed from above, and their diameters are 0.1 mm or more and 1 mm or less, preferably 0.2 mm or more and 0.9 mm or less, and more preferably 0.4 mm or more and 0.6 mm or less. The first electrode 15 and the second electrode 16 are arranged such that they face each other in the diameter direction of the uncovered portion 13, separated by the center position of the bottom surface of the uncovered portion 13, and are separated from each other by a first distance L12 or more in the long side direction of the substrate 11. The first distance L12 is a distance of 0.4 mm or more and 1.8 mm or less, preferably a distance of 0.6 mm or more and 1.6 mm or less. For example, the first distance L12 is 1.1 mm.

[0046] Furthermore, the first electrode 15 and the second electrode 16 are configured such that they are separated from the insulating film constituting the inner wall of the covered portion 12, which surrounds the uncovered portion 13, by a second distance L11 or more. The second distance L11 is a distance of 0.1 mm or more and 0.8 mm or less, preferably a distance of 0.2 mm or more and 0.7 mm or less. For example, the second distance L11 is 0.5 mm. In addition, the first electrode 15 and the second electrode 16, which are circular when viewed from above, are arranged on a straight line passing through the center of the bottom surface of the uncovered portion 13, which is circular when viewed from above, and are arranged at a point symmetrical position with respect to the center of the bottom surface of the uncovered portion 13.

[0047] Therefore, the first electrode 15 and the second electrode 16 are separated from each other by a first distance L12 or more, which increases the resistance value between the first electrode 15 and the second electrode 16, thereby improving the accuracy of odor substance recognition. Furthermore, the first electrode 15 and the second electrode 16 are separated from the insulating film surrounding the uncovered portion 13 in the covering portion 12 by a second distance L11 or more, thus avoiding the portion of the odor substance receptor layer 19 that thickens due to surface tension. As a result, peeling of the odor substance receptor layer 19 near the inner sidewall of the uncovered portion 13 can be suppressed, further reducing peeling of the odor substance receptor layer 19 from the first electrode 15 and the second electrode 16.

[0048] Furthermore, the top surface (first surface) of the first electrode 15 that contacts the odorant receptor layer 19 and the top surface (second surface) of the second electrode 16 that contacts the odorant receptor layer 19 are circular when viewed from above. Therefore, the first electrode 15 and the second electrode 16 can be reliably separated from the insulating film in the covering portion 12 that surrounds the non-covering portion 13 by a second distance L11 or more, thereby further reducing the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0049] [Manufacturing method of sensor element 1] Next, combined Figure 6 and Figure 7 An example of a method for manufacturing sensor element 1 will be described. Figure 6 and Figure 7 This is an illustrative diagram illustrating an example of a method for manufacturing a sensor element. Here, in this embodiment, for example, a glass cloth substrate epoxy resin copper-clad laminate (hereinafter referred to as "laminate") 31 with a thickness of approximately 1 mm is used. Furthermore, features such as... are designed on this laminate 31. Figure 4 and Figure 5 Sensor element 1 is shown.

[0050] The number of sensor elements 1 designed on the laminate 31 can be arbitrary. Hereinafter, we will take the case of manufacturing multiple sensor elements 1 in a manner that designs multiple rows in the longitudinal direction and multiple columns in the transverse direction on the laminate 31 as an example for explanation. Here, the side of the laminate 31 with the non-covered portion 13 is sometimes referred to as the front side, and the side of the laminate 31 opposite to the side with the non-covered portion 13 is referred to as the back side.

[0051] [Wiring pattern design] Figure 6 The front side of laminate 31 is shown. Figure 7 The back side of laminate 31 is shown. (As shown) Figure 6 As shown, on the front side of the laminate 31, Figure 4 The wiring pattern of the first electrode 15 and the second electrode 16 of the sensor element 1, which has a width of W1 and a length of L1, is designed to have multiple rows along the longitudinal direction and multiple columns along the transverse direction. Furthermore, as shown... Figure 7 As shown, on the back side of the laminate 31, at the location where the through hole 17 is formed at the end opposite to the direction of the first electrode 15 and the second electrode 16, a circular conductive part, namely a metal wiring 17A with a diameter of 1 mm, is designed.

[0052] Furthermore, a metal wiring 21A is designed to connect from the back side of the substrate 31 to the first electrode 15, and also to the metal wiring 17A located on the back side of the substrate 31 in a through-hole 17 on the opposite side of the first electrode 15 relative to the second electrode 16. Additionally, a metal wiring 21B is designed to connect from the back side of the substrate 31 to the second electrode 16, and also to the metal wiring 17A located on the back side of the substrate 31 in a through-hole 17 on the opposite side of the second electrode 16 relative to the first electrode 15.

[0053] [Through-hole forming process] To mount metal pins 18 on the substrate 11 of sensor element 1, holes with a diameter of, for example, 0.6 mm are formed in the portions of each metal wiring 17A that serve as circular conductive portions on the back side of the laminate 31, using an NC drilling machine, to serve as through holes. Then, chemical plating is performed first, followed by copper sulfate plating, thereby creating through holes 17 with a copper plating layer of 25 μm thickness.

[0054] [Pattern Forming Process] Next, a metal wiring pattern is created connecting the back of the laminate 31 to the first electrode 15 and the second electrode 16. A photosensitive dry film resist is applied to both sides of the laminate 31 using a roller laminator (e.g., pressure 0.4 [MPa], temperature 110 [°C], lamination speed 0.4 [m / min]).

[0055] Subsequently, in a UV exposure machine, the photosensitive dry film resist is irradiated from the UV exposure side with an 85 mJ / cm² light source, separated by a front negative photomask and a back negative photomask. 2 The photosensitive dry film resist was removed from the unexposed areas using ultraviolet light (wavelength 355 nm) and then using a 5% by weight sodium carbonate aqueous solution at 35°C. Afterwards, the exposed copper foil, now free of photosensitive dry film resist, was etched away using a ferric chloride aqueous solution. The exposed areas were then cleaned with a 10% by weight sodium hydroxide aqueous solution at 35°C to remove the photosensitive dry film resist.

[0056] The pattern used here with a negative photomask on the front side is such that... Figure 4 The circular portions of the first electrode 15 and the second electrode 16 of the sensor element 1, designed in this way, can form a pattern of multiple rows vertically and multiple columns horizontally. Furthermore, the pattern of the negative photomask on the back is such that the circular portions, for example, with a diameter of 1 mm, and the outlines of each metal wiring 21A, 21B are aligned. Figure 5 The positions of each through hole 17 in the sensor element 1 shown are arranged in a pattern of multiple rows vertically and multiple columns horizontally.

[0057] [Flattening process of substrate surface with first electrode 15 and second electrode 16] Next, a pattern of UV-curable epoxy resin is printed on the front side of the laminate 31, excluding the through holes, and pre-dried by heating, followed by irradiation with, for example, 600 mJ / cm². 2 The epoxy resin on the front side of the laminate 31 is cured using ultraviolet light (wavelength 355 nm). Then, the epoxy resin is removed by etching until the top surfaces of the first electrode 15 and the second electrode 16 are exposed, followed by surface polishing. For example, the surface is polished using a non-woven polishing wheel to smooth it. Thus, the substrate surface on the front side of the laminate 31 is flush with the top surfaces of the first electrode 15 and the second electrode 16, thereby... Figure 3 As shown, the first electrode 15 and the second electrode 16 are disposed in the recess 13A provided in the non-covered portion 13.

[0058] [Solder Resistance Process] Next, a pattern of two-component alkaline-developable solder resist ink is printed on the front side of the laminate 31, excluding the areas with through holes 17 and the areas in the circular non-covered portion 13 where the first electrode 15 and the second electrode 16 are disposed. Then, the laminate 31 is pre-dried by heating at 80°C for 30 minutes, and then irradiated with 600 mJ / cm² ink. 2 The solder resist ink was exposed to ultraviolet light (wavelength 355 nm) and unexposed areas were removed using a 1% sodium carbonate aqueous solution at 35°C. Afterwards, the ink was heated at 150°C for 60 minutes to cure the solder resist.

[0059] Here, the cover portion 12 can also be formed by applying a resist film to a substrate to cure the resist in a specified area and removing the uncured portion.

[0060] [Surface treatment process] Next, the laminate 31 is degreased, micro-etched, and acid-washed, and then immersed in a catalyst-gathering solution at 25°C for 5 minutes, followed by rinsing with pure water. Afterward, the laminate 31 is immersed in a displacement-type gold plating solution at 85°C for 5 minutes to form a displacement gold film with a thickness of 0.05 μm on the copper foil, thereby obtaining a substrate in which the copper foil is partially covered by gold plating.

[0061] [Longitudinal hole 33 of substrate 11] Next, along the two side edges of each adjacent sensor element 1 in the transverse direction of the laminate 31, a longitudinal hole 33 with a width of, for example, about 1 mm is made inward from the two ends in the long side direction into the inner part of a specified length, for example, about 1 mm, using an NC vertical milling machine.

[0062] [V-notch process for substrate] Next, a V-notch cutter is used to cut V-notches according to the dimensions of H1 in the longitudinal direction and W1 in the transverse direction, so that the sensor elements 1 can be cut off one by one. The remaining thickness after V-notch processing is set to about 0.3 mm.

[0063] [Slurry preparation process] Next, a slurry is prepared by mixing a conductive carbon material and a resin composition. The mixing ratio of the conductive carbon material and the resin composition can be appropriately set according to the required sensitivity and detection specificity of the odorant receptor layer 19. In addition to the conductive carbon material and the resin composition, the slurry may also contain solvents, additives, and surfactants.

[0064] [Coating Process] Next, the slurry is applied from the nozzle to each non-covered portion 13 of the laminate 31. For example, by using a SUS metal needle nozzle (e.g., inner diameter 0.1 mm, outer diameter 0.23 mm) in an IMAGE MASTER 350PCSmart manufactured by Musashi Engineering Co., Ltd., the desired coating shape can be obtained.

[0065] [Drying Process] Next, the slurry coated on each non-covered portion 13 of the laminate 31 is dried to form the odorant receptor layer 19. The drying method of the slurry is not particularly limited, for example, it can be heated at 100°C for 1 hour under normal pressure, and then heated at 100°C for 1 hour under reduced pressure in a vacuum dryer.

[0066] [Pin 18 Installation] Finally, the metal leads 18 are inserted into the fabricated through-holes 17 and soldered. For example, IC terminals with a diameter of 0.6 mm and a length of 5 mm can be used as leads 18. Thus, on each laminate 31, multiple rows are fabricated vertically and multiple columns horizontally. Figure 1 Sensor element 1 is shown.

[0067] As detailed above, in the sensor element 1 of this embodiment, the first electrode 15 and the second electrode 16 are arranged flush with the substrate surface 11A in the uncovered portion 13 of the substrate 11. As a result, the surface of the thinner odor substance receptor layer 19 can be formed flat, thereby reducing the peeling of the odor substance receptor layer 19 from the substrate 11 and achieving a high yield.

[0068] Since the substrate 11 is made of a resin containing any one of epoxy resin, phenolic resin and polyimide, it is possible to further reduce the peeling of the odorant receptor layer 19 from the substrate 11.

[0069] Since the non-covered portion 13 is circular when viewed from above, the odorant receptor layer 19 can also be formed to be circular when viewed from above, thereby preventing uneven film thickness of the odorant receptor layer 19 in the circumferential direction. As a result, peeling of the odorant receptor layer 19 from the substrate 11 can be further reduced.

[0070] The first electrode 15 and the second electrode 16 are spaced at least a first distance L12 apart, which increases the resistance between them and improves the accuracy of odor substance recognition. Furthermore, the first electrode 15 and the second electrode 16 are spaced at least a second distance L11 apart from the insulating film surrounding the uncovered portion 13 in the covering portion 12, thus avoiding the portion of the odor substance receptor layer 19 that thickens due to surface tension. As a result, peeling of the odor substance receptor layer 19 from the first electrode 15 and the second electrode 16 can be further reduced.

[0071] The top surface (first surface) of the first electrode 15 and the top surface (second surface) of the second electrode 16 are circular when viewed from above. As a result, the first electrode 15 and the second electrode 16 can be reliably separated from the insulating film in the covering portion 12 that surrounds the non-covering portion 13 by a second distance L11 or more, thereby further reducing the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0072] The inventors of this disclosure have discovered that by forming the uncovered portion 13 into a circle with a diameter of 2 mm or more and 5 mm or less when viewed from above, and by controlling the thickness of the insulating film surrounding the uncovered portion 13 to be 50 μm or more and 500 μm or less, it is possible to further reduce the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0073] The first electrode 15 and the second electrode 16 are separated by a first distance L12 of 0.4 mm or more and 1.8 mm or less, preferably by a first distance L12 of 0.6 mm or more and 1.6 mm or less. Furthermore, the first electrode 15 and the second electrode 16 are separated from the insulating film surrounding the non-covered portion 13 in the covering portion 12 by a second distance L11 of 0.1 mm or more and 0.8 mm or less, preferably by a second distance L11 of 0.2 mm or more and 0.7 mm or less. This further reduces the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0074] The first electrode 15 and the second electrode 16 are electrically connected to metal leads 18 on the side of the substrate 11 opposite to the substrate surface 11A where the uncovered portion 13 is provided. This prevents unnecessary metal wiring from being arranged on the substrate surface 11A in the uncovered portion 13, thereby further reducing the peeling of the odorant receptor layer 19 from the first electrode 15 and the second electrode 16.

[0075] [Second Implementation] Next, combined Figure 8 The sensor element 41 according to the second embodiment will be described. Figure 8 This is an explanatory diagram of an example of electrodes 42 and 43 on the bottom surface of the non-covered portion 13 of the sensor element 41 in the second embodiment. Here, for ease of explanation, components that have the same function as those described in the first embodiment will be given the same reference numerals and will not be described again.

[0076] The configuration of the sensor element 41 in the second embodiment is substantially the same as that of the sensor element 1 in the first embodiment. However, as Figure 8 As shown, a first electrode 42 and a second electrode 43 are provided on the bottom surface of the non-covered portion 13 of the sensor element 41, in place of the first electrode 15 and the second electrode 16.

[0077] The first electrode 42 and the second electrode 43 are formed to be circular in plan view, with a diameter of 0.4 mm or more and 2 mm or less, preferably 0.5 mm or more and 1.9 mm or less, and more preferably 0.8 mm or more and 1.2 mm or less. For example, they are formed to be circular in diameter 1 mm in plan view. The first electrode 42 and the second electrode 43 are arranged such that they face each other in the diameter direction of the non-covered portion 13, separated by the center position of the bottom surface of the circular non-covered portion 13 in plan view, and are separated from each other by a third distance L22 or more in the long side direction of the substrate 11. The third distance L22 is a distance of 0.2 mm or more and 1.2 mm or less, preferably a distance of 0.3 mm or more and 1.1 mm or less. For example, the third distance L22 is 0.6 mm.

[0078] Furthermore, the first electrode 42 and the second electrode 43 are configured such that they are separated from the insulating film constituting the inner wall of the covered portion 12, which surrounds the uncovered portion 13, by a fourth distance L21 or more. The fourth distance L21 is a distance of 0.1 mm or more and 0.5 mm or less, preferably a distance of 0.2 mm or more and 0.4 mm or less. For example, the fourth distance L21 is 0.2 mm. In addition, the first electrode 42 and the second electrode 43, which are circular in plan view, are arranged on a straight line passing through the center of the bottom surface of the uncovered portion 13, which is circular in plan view, along the long side direction, and are arranged at a point symmetrical position with respect to the center of the bottom surface of the uncovered portion 13.

[0079] Therefore, the first electrode 42 and the second electrode 43 are separated from each other by a third distance L22 or more, which increases the resistance value between the first electrode 42 and the second electrode 43, thereby improving the accuracy of odor substance recognition. Furthermore, regarding the first electrode 42 and the second electrode 43, since each electrode 42, 43 is separated from the insulating film surrounding the uncovered portion 13 in the covering portion 12 by a fourth distance L21 or more, the portion of the odor substance receptor layer 19 that thickens due to surface tension can be avoided. As a result, peeling of the odor substance receptor layer 19 near the inner sidewall of the uncovered portion 13 can be suppressed, thereby further reducing peeling of the odor substance receptor layer 19 from the first electrode 42 and the second electrode 43.

[0080] [Third Implementation] Next, combined Figure 9 The sensor element 51 of the third embodiment will be described. Figure 9 This is an explanatory diagram illustrating an example of electrodes 15, 16, 52, and 53 on the bottom surface of the non-covered portion 13 of the sensor element 51 in the third embodiment. Here, for ease of explanation, components that have the same function as those described in the first embodiment will be given the same reference numerals and will not be described again.

[0081] The configuration of the sensor element 51 in the third embodiment is substantially the same as that of the sensor element 1 in the first embodiment. However, as Figure 9 As shown, in addition to the first electrode 15 and the second electrode 16, the bottom surface of the non-covered part 13 of the sensor element 51 is also provided with a third electrode 52 and a fourth electrode 53.

[0082] The third electrode 52 and the fourth electrode 53 are formed to be circular in plan view, with a diameter of 0.1 mm or more and 1 mm or less, preferably 0.2 mm or more and 0.9 mm or less, and more preferably 0.4 mm or more and 0.6 mm or less. For example, they are formed to be circular in diameter of 0.5 mm in plan view. The third electrode 52 and the fourth electrode 53 are arranged such that they face each other in the diameter direction of the non-covered portion 13, separated by the center position of the bottom surface of the circular non-covered portion 13 in plan view, and are separated from each other by a first distance L12 or more in the short side direction of the substrate 11. The first distance L12 is a distance of 0.4 mm or more and 1.8 mm or less, preferably 0.6 mm or more and 1.6 mm or less. For example, the first distance L12 is 1.1 mm.

[0083] Furthermore, the third electrode 52 and the fourth electrode 53 are configured such that they are separated from the insulating film constituting the inner wall of the covered portion 12, which surrounds the uncovered portion 13, by a second distance L11 or more. The second distance L11 is a distance of 0.1 mm or more and 0.8 mm or less, preferably a distance of 0.2 mm or more and 0.7 mm or less. For example, the second distance L11 is 0.5 mm. In addition, the third electrode 52 and the fourth electrode 53, which are circular in plan view, are arranged on a straight line passing through the center of the bottom surface of the uncovered portion 13, which is circular in plan view, along the short side direction, and are arranged at a point symmetrical position with respect to the center of the bottom surface of the uncovered portion 13.

[0084] Therefore, the first electrode 15 and the second electrode 16, as well as the third electrode 52 and the fourth electrode 53, are separated from each other by a first distance L12 or more. As a result, the resistance values ​​between the first electrode 15 and the second electrode 16, and between the third electrode 52 and the fourth electrode 53, can be increased, thereby further improving the accuracy of odor substance identification.

[0085] Furthermore, the first electrode 15, the second electrode 16, the third electrode 52, and the fourth electrode 53 are all separated from the insulating film surrounding the uncovered portion 13 in the covering portion 12 by a fourth distance L21 or more. As a result, the electrodes 15, 16, 52, and 53 can be positioned to avoid the portion of the odorant receptor layer 19 that becomes thicker due to surface tension. As a result, peeling of the odorant receptor layer 19 near the inner sidewall of the uncovered portion 13 can be suppressed, thereby further reducing peeling of the odorant receptor layer 19 from the first electrode 15, the second electrode 16, the third electrode 52, and the fourth electrode 53.

[0086] [Fourth Implementation] Next, combined Figure 10 The sensor element 61 of the fourth embodiment will be described. Figure 10 This is an explanatory diagram illustrating an example of electrodes 62 and 63 on the bottom surface of the non-covered portion 13 of the sensor element 61 in the fourth embodiment. The configuration of the sensor element 61 in the fourth embodiment is substantially the same as that of the sensor element 51 in the third embodiment. However, as... Figure 10 As shown, on the bottom surface of the non-covered portion 13 of the sensor element 61, the fifth electrode 62 and the sixth electrode 63 are provided, in place of the first electrode 15, the second electrode 16, the third electrode 52 and the fourth electrode 53.

[0087] The fifth electrode 62 is formed in a generally rectangular shape when viewed from above. This is achieved by connecting the outer peripheries of the first electrode 15 and the fourth electrode 53 (which are circular when viewed from above in the third embodiment) obliquely with a straight line using the external tangent of a circle. As a result, the two ends of the fifth electrode 62 in the long axis direction are formed into a semi-circular shape when viewed from above. Similarly, the sixth electrode 63 is formed in a generally rectangular shape when viewed from above. This is achieved by connecting the outer peripheries of the third electrode 52 and the second electrode 16 (which are circular when viewed from above in the third embodiment) obliquely with a straight line using the external tangent of a circle. As a result, the two ends of the sixth electrode 63 in the long axis direction are formed into a semi-circular shape when viewed from above.

[0088] Therefore, the width of the fifth electrode 62 and the sixth electrode 63, which are approximately rectangular when viewed from above, is 0.1 mm or more and 1 mm or less, and the length is 0.8 mm or more and 3 mm or less. Preferably, the width of the fifth electrode 62 and the sixth electrode 63 is 0.2 mm or more and 0.9 mm or less, and the length is 1.1 mm or more and 2.2 mm or less. More preferably, the width of the fifth electrode 62 and the sixth electrode 63 is 0.4 mm or more and 0.6 mm or less, and the length is 1.4 mm or more and 1.8 mm or less.

[0089] Furthermore, the fifth electrode 62 and the sixth electrode 63 are arranged such that they are inclined clockwise by approximately 45 degrees along a diametrical direction relative to the long side of the substrate 11, and are positioned opposite each other across the center of the bottom surface of the non-covered portion 13, which is circular when viewed from above. The fifth electrode 62 and the sixth electrode 63 are also arranged such that they are spaced at least a fifth distance L32 from each other. The fifth distance L32 is 0.2 mm or more and 1.2 mm or less, preferably 0.3 mm or more and 1.1 mm or less. For example, the fifth distance L32 is 0.6 mm.

[0090] Furthermore, the fifth electrode 62 and the sixth electrode 63 are configured such that they are inclined clockwise by approximately 45 degrees in the diametrical direction relative to the long side of the substrate 11, and are separated from the insulating film constituting the inner wall of the cover portion 12 that surrounds the non-cover portion 13 by a sixth distance L31 or more. The sixth distance L31 is a distance of 0.5 mm or more and 0.7 mm or less.

[0091] Furthermore, the two ends of each of the fifth electrode 62 and the sixth electrode 63 are configured such that they are separated from the insulating film constituting the inner wall of the covered portion 12, which surrounds the uncovered portion 13, by a second distance L11 or more. The second distance L11 is a distance of 0.1 mm or more and 0.8 mm or less, preferably a distance of 0.2 mm or more and 0.7 mm or less. For example, the second distance L11 is 0.5 mm. In addition, the fifth electrode 62 and the sixth electrode 63, which are generally rectangular in plan view, are configured to be linearly symmetrical about a straight line that passes through the center of the bottom surface of the uncovered portion 13, which is circular in plan view, and is inclined counterclockwise by about 45 degrees with respect to the long side.

[0092] Therefore, the fifth electrode 62 and the sixth electrode 63 are spaced at least a fifth distance L32 apart, which increases the resistance between them and improves the accuracy of odor substance recognition. Furthermore, the two ends of each of the fifth electrode 62 and the sixth electrode 63 are spaced at least a second distance L11 apart from the insulating film surrounding the uncovered portion 13 in the covering portion 12. This allows the electrodes 62 and 63 to be positioned away from portions of the odor substance receptor layer 19 that thicken due to surface tension. As a result, peeling of the odor substance receptor layer 19 near the inner sidewall of the uncovered portion 13 is suppressed, further reducing peeling of the odor substance receptor layer 19 from the fifth electrode 62 and the sixth electrode 63.

[0093] Furthermore, the fifth electrode 62 can also be formed as a generally rectangular shape when viewed from above, obtained by obliquely connecting the outer peripheries of the first electrode 15 and the third electrode 52, which are circular in view in the third embodiment, with the external tangent of the circle. Furthermore, the sixth electrode 63 can also be formed as a generally rectangular shape when viewed from above, obtained by obliquely connecting the outer peripheries of the fourth electrode 53 and the second electrode 16, which are circular in view in the third embodiment, with the external tangent of the circle.

[0094] [Example] The present disclosure is further illustrated below by way of examples and comparative examples. However, the present disclosure is not limited to these examples and comparative examples. Unless otherwise specified, "%" means % by weight and "parts" means parts by weight.

[0095] The following shows the various materials used in the embodiments and comparative examples.

[0096] <Resin(A)> A1: Polyamide resin (manufactured based on Manufacturing Example 1 and Manufacturing Example 2) <Conductive Carbon Materials (C)> C1: Carbon black ("SuperC65" manufactured by MTI Corporation, primary particle size 50nm, DBP oil absorption 254cm³). 3 / 100g) Solvent (D) D1: N-methyl-2-pyrrolidone Examples 1 and 2 of the manufacture of resin (A) are shown below.

[0097] [Manufacturing Example 1] (Manufacturing of Polyester Resin (PE-1)) In a reaction vessel equipped with a cooling pipe, a heating and cooling device, a thermometer, a stirrer, and a nitrogen inlet pipe, 58.2 parts of 12-hydroxystearic acid and 441.8 parts of ε-caprolactone were added. The mixture was heated to 140°C over a nitrogen atmosphere for 4 hours, then reacted for 2 hours. The reaction was stopped when the remaining amount of ε-caprolactone was below 1%. The removed resin was cooled to room temperature and then granulated to obtain polyester resin (PE-1). The number-average molecular weight (Mn) of polyester resin (PE-1) was 2600, and the acid value was 21.6 mg KOH / g.

[0098] [Manufacturing Example 2] (Manufacturing of Polyesteramide Resin (A-1)) In a reaction vessel equipped with a cooling pipe, a dehydration pipe, a heating and cooling device, a thermometer, a stirrer, and a nitrogen inlet pipe, 150 parts of xylene and 82.3 parts of a 20% aqueous solution of polyallylamine ("PAA-03" manufactured by Nittobo Medica Co., Ltd., with an average molecular weight of approximately 3,000) were added. The temperature was raised to 160°C, and the water was distilled off using the dehydration pipe. At this point, the xylene separated from the water was refluxed back into the reaction solution.

[0099] Next, 83.5 parts of the polyester resin (PE-1) obtained from Manufacturing Example 1, heated to 160°C, were added and reacted at 160°C for 2 hours. Then, the xylene was distilled off by heating at 160°C for 0.5 hours, and the resulting product was collected. The collected resin was cooled to room temperature and then granulated to obtain polyesteramide resin (A-1). The number-average molecular weight (Mn) of polyesteramide resin (A-1) was 10,200, and the acid value was 14.9 mg KOH / g.

[0100] Examples of resin composition 1 are shown below.

[0101] <Resin Composition 1> The following components were weighed in the following amounts and placed into sample vials to obtain a mixture.

[0102] 60 parts by weight of polyesteramide resin (A-1) 40 parts by weight of conductive carbon material (C1) Solvent (D1) 1900 parts by weight The mixture was stirred for 20 minutes at 2000 rpm using a planetary mixer (ARE-310 manufactured by THINKY Co., Ltd.) to obtain a slurry. Thus, resin composition 1 in this slurry form was obtained.

[0103] The following shows embodiments and comparative examples of sensor elements.

[0104] [Example 1] In the patterning process of the sensor element 1 according to the first embodiment, each electrode 15 and 16 is formed into a circle with a diameter of 0.5 mm when viewed from above. Furthermore, the first distance L12 between each electrode 15 and 16 of the sensor element 1 is formed to be 1.087 mm. In addition, through the solder resist process, the non-covered portion 13 of the sensor element 1 is formed to have a diameter of 3 mm, and the second distance L11 between each electrode 15 and 16 and the inner wall of the cover portion 12 is formed to be 0.4565 mm.

[0105] Then, in a coating process, approximately 2 μL of the aforementioned resin composition 1 was applied to the non-covered portion 13 using a SUS metal needle nozzle (e.g., inner diameter 0.1 mm, outer diameter 0.23 mm). After coating, the coated slurry was dried by a drying process, for example, by heating at 100 °C for 1 hour under normal pressure, followed by heating at 100 °C for 1 hour under reduced pressure in a vacuum dryer, thereby obtaining the sensor element of Example 1. As an example, the thickness of the odorant receptor layer 19 was 5 μm. Furthermore, the same operation was repeated 10 times, resulting in 10 sensor elements of Example 1.

[0106] [Example 2] In the patterning process of the sensor element 41 according to the second embodiment, each electrode 42 and 43 is formed into a circle with a diameter of 1 mm when viewed from above. Furthermore, the third distance L22 between each electrode 42 and 43 of the sensor element 1 is formed to be 0.587 mm. In addition, in the solder resist process, the non-covered portion 13 of the sensor element 41 is formed to have a diameter of 3 mm, and the fourth distance L21 between each electrode 42 and 43 and the inner wall of the cover portion 12 is formed to be 0.2065 mm.

[0107] Then, similarly to Example 1, about 2 [μL] of the above-described resin composition 1 was applied to the non-covered portion 13, and the applied slurry was dried to obtain the sensor element of Example 2. As an example, the thickness of the odorant receptor layer 19 was 5 [μm]. Furthermore, the same operation was repeated 10 times to obtain 10 sensor elements of Example 2.

[0108] [Example 3] In the patterning process of the sensor element 51 according to the third embodiment, each electrode 15, 16, 52, and 53 is formed into a circle with a diameter of 0.5 mm when viewed from above. Furthermore, the first distance L12 between each electrode 15 and 16 of the sensor element 51, and the first distance L12 between each electrode 52 and 53, are formed to be 1.087 mm. In addition, through the solder resist process, the non-covered portion 13 of the sensor element 51 is formed to have a diameter of 3 mm, and the second distance L11 between each electrode 15, 16, 52, and 53 and the inner wall of the covered portion 12 is formed to be 0.4565 mm.

[0109] Then, similarly to Example 1, about 2 [μL] of the above-described resin composition 1 was applied to the non-covered portion 13, and the applied slurry was dried to obtain the sensor element of Example 3. As an example, the thickness of the odorant receptor layer 19 was 5 [μm]. Furthermore, the same operation was repeated 10 times to obtain 10 sensor elements of Example 3.

[0110] [Example 4] In the patterning process of the sensor element 61 according to the fourth embodiment, the fifth electrode 62 and the sixth electrode 63 are formed into a generally rectangular shape with a width of 0.5 mm and a length of 1.6228 mm when viewed from above. The two ends of each electrode 62 and 63 in the long axis direction are formed into semi-circular arcs with a diameter of 0.5 mm. The fifth distance L32 between each electrode 62 and 63 is formed to be 0.622 mm. Furthermore, through a solder resist process, the non-covered portion 13 of the sensor element 61 is formed to have a diameter of 3 mm.

[0111] The sixth distance L31 between the long sides of each electrode 62, 63 and the inner wall of the cover portion 12 is formed to be 0.689 mm. Furthermore, the second distance L11 between the two ends of each electrode 62, 63 and the inner wall of the cover portion 12 is formed to be 0.4565 mm. Then, similarly to Example 1, approximately 2 μL of the above-described resin composition 1 is applied to the non-cover portion 13, and the applied slurry is dried to obtain the sensor element of Example 4. As an example, the thickness of the odorant receptor layer 19 is 5 μm. Furthermore, the same operation is repeated 10 times to obtain 10 sensor elements of Example 4.

[0112] [Comparative Example 1] The following combination Figure 11 The sensor element 71 of Comparative Example 1 will be described. Figure 11 This is a top view of a configuration example of sensor element 71 in Comparative Example 1. (See attached image.) Figure 11 As shown, in the sensor element 71 of Comparative Example 1, a T-shaped seventh electrode 72 and a T-shaped eighth electrode 73 are arranged opposite each other on the substrate 11 by a patterning process. The seventh electrode 72 includes a first metal wiring 72A parallel to the long side direction of the substrate 11 and a second metal wiring 72B parallel to the short side direction of the substrate 11.

[0113] The eighth electrode 73 includes a third metal wiring 73A parallel to the short side direction of the substrate 11 and a fourth metal wiring 73B parallel to the long side direction of the substrate 11. The length L42 of the second metal wiring 72B and the third metal wiring 73A, which are opposite each other, is formed to be 2.5 mm, and the distance L41 is formed to be 1.5 mm. In addition, the length L43 of the first metal wiring 72A and the fourth metal wiring 73B is formed to be 2 mm. Furthermore, the linewidth of each metal wiring 72A, 72B, 73A, and 73B is formed to be 0.3 mm.

[0114] Furthermore, through a solder resist process, the uncovered portion 76 of the sensor element 71 is formed into a rectangle with metal wires 72B and 73A as opposing sides, and each metal wire 72B and 73A is positioned further inward than the inner wall of the cover portion 12. Then, through a coating process, using a SUS metal needle nozzle (e.g., inner diameter 0.1 mm, outer diameter 0.23 mm), the resin composition 1 is coated into an ellipse that, when viewed from above, spans between each metal wire 72B and 73A and has a major axis of 1.5 mm. Then, similarly to Example 1, the slurry coated on the uncovered portion 76 is dried, thereby obtaining a sensor element of Comparative Example 1 having an odorant receptor layer 75 that is elliptical when viewed from above. As an example, the thickness of the odorant receptor layer 75 is 5 μm. Furthermore, the same operation was repeated 10 times to obtain 10 sensor elements of Comparative Example 1.

[0115] [Comparative Example 2] The following combination Figure 12 The sensor element 81 of Comparative Example 2 will be described. Figure 12 This is a top view of a configuration example of sensor element 81 in Comparative Example 2. (See attached image.) Figure 12 As shown, the sensor element 81 of Comparative Example 2 has a configuration that is substantially the same as that of the sensor element 71 of Comparative Example 1. However, in the coating process, a SUS metal needle nozzle (e.g., inner diameter 0.1 mm, outer diameter 0.23 mm) was used to coat the resin composition 1 to cover the entire surface of the non-covered portion 76, which is rectangular in plan view. Then, as in Example 1, the slurry coated on the non-covered portion 76 was dried to obtain the sensor element of Comparative Example 2 having an odorant receptor layer 82 that is rectangular in plan view. As an example, the thickness of the odorant receptor layer 82 is 5 μm. Furthermore, the same operation was repeated 10 times to obtain 10 sensor elements of Comparative Example 2.

[0116] [Measurement of sensor elements in Examples 1-4 and Comparative Examples 1 and 2] [Measurement of voltage change] A housing was fabricated, comprising a test material receiving section with an inlet for introducing the sample (odorant) and a temperature-regulating aluminum block thermostat, a nitrogen gas tank for gas supply, a mass flow controller, and a sensing chamber. Here, the volume of the test material receiving section was designed to be five times the volume of the sensing chamber.

[0117] Leads for bringing the terminals of the sensor element to the outside are soldered to the metal pins 18 of the sensor element, and the sensor element is placed inside the sensing chamber. For the sensor element, a constant voltage power supply of 1.45V and a fixed resistor of 300Ω are connected in series at the end of the lead that leads out of the sensing chamber, and a voltmeter is connected to measure the voltage applied to the metal pins 18 of the sensor element.

[0118] Then, for each sensor element of Examples 1-4 and Comparative Examples 1 and 2, the internal temperature of the receiving part of the material to be measured was adjusted to 30°C using an aluminum block thermostat set up in the laboratory (temperature 23°C, humidity 40%), and the voltage change of the sensor element [mV] was measured. First, nitrogen gas was supplied from a nitrogen gas supply tank to the receiving part of the material to be measured at a flow rate of 1 [L / min] for 5 seconds using a mass flow controller.

[0119] Next, saturated ethanol was supplied to the receiving section of the analyte at a flow rate of 1 L / min for 7 seconds using a mass flow controller. Then, nitrogen gas was supplied from a nitrogen cylinder to the receiving section of the analyte at a flow rate of 1 L / min for 30 seconds using the same mass flow controller to remove odor substances adhering to the sensor element. During this series of operations, the voltage change [mV] was measured using a voltmeter connected to the sensor element.

[0120] Thus, for each of the 10 sensor elements in Examples 1-4 and Comparative Examples 1 and 2, the voltage change [mV] was measured, and the average of the 10 values ​​was taken as the voltage change [mV] of each sensor element. The voltage change [mV] of each sensor element in Examples 1-4 and Comparative Examples 1 and 2 was evaluated.

[0121] [Determination of coating smoothness] For each sensor element of Examples 1-4 and Comparative Examples 1 and 2, the depth between the surface of the cover portion 12 and the surface of each odor substance receptor layer 19, 75, 82 in each of the non-cover portions 13, 76 was measured using a white light interferometer. Specifically, the "center depth" between the surface of the cover portion 12 and the center surface of each odor substance receptor layer 19, 75, 82 was measured. In addition, the "outermost peripheral depth" between the surface of the cover portion 12 and the outermost peripheral surface of each odor substance receptor layer 19, 75, 82 was measured. Furthermore, the "electrode peripheral depth" between the surface of the cover portion 12 and the surfaces of each odor substance receptor layer 19, 75, 82 corresponding to the outer periphery of each electrode 15, 16, 42, 43, 52, 53, 62, 63, 72, 73 was measured.

[0122] Next, for each sensor element, the absolute values ​​[μm] of the value obtained by subtracting the "outermost peripheral depth" from the "center depth" and the absolute values ​​[μm] of the value obtained by subtracting the "electrode outer perimeter depth" from the "center depth" were calculated, and the coating smoothness was evaluated. Thus, for each of the 10 sensor elements in Examples 1-4 and Comparative Examples 1 and 2, the absolute values ​​[μm] of the value obtained by subtracting the "outermost peripheral depth" from the "center depth" and the absolute values ​​[μm] of the value obtained by subtracting the "electrode outer perimeter depth" from the "center depth" were calculated. Then, the average of the 10 calculated values ​​was used as the calculated values ​​for each sensor element in Examples 1-4 and Comparative Examples 1 and 2 to evaluate the coating smoothness.

[0123] [Measuring Resistance] For each of the 10 sensor elements in Examples 1-4 and Comparative Examples 1 and 2, the resistance value [Ω] between the metal pins 18 was measured using a ohmmeter, and the average of the 10 values ​​was taken as the resistance value [Ω] of each sensor element. Then, the resistance value [Ω] of each sensor element in Examples 1-4 and Comparative Examples 1 and 2 was evaluated.

[0124] [Evaluation Results] Figure 13 The evaluation results of “voltage change [mV]”, “coating smoothness” and “resistance value [Ω]” for the sensor elements of Examples 1 to 4 and Comparative Examples 1 and 2 are shown. Figure 13 Table 91 shows an evaluation result for Examples 1-4 and Comparative Examples 1 and 2. In Table 91, "A" indicates that the sensor element performs well in practical applications, "B" indicates that the sensor element performs well in practical applications, and "C" indicates that the sensor element performs poorly.

[0125] Specifically, in the evaluation of "voltage change [mV]", values ​​above 170 [mV] are rated "A", values ​​above 100 [mV] but less than 170 [mV] are rated "B", and values ​​less than 100 [mV] are rated "C". In the evaluation of "coating smoothness", values ​​where the absolute value [μm] of the difference between "center depth" and "outermost peripheral depth" is less than 20 [μm] and the absolute value [μm] of the difference between "center depth" and "electrode outer perimeter depth" is less than 1 [μm] are rated "A". Furthermore, in the evaluation of "coating smoothness", values ​​where the absolute value [μm] of the difference between "center depth" and "outermost peripheral depth" is less than 50 [μm] and the absolute value [μm] of the difference between "center depth" and "electrode outer perimeter depth" is less than 2 [μm] are rated "B".

[0126] Furthermore, in the evaluation of "coating smoothness", the absolute value [μm] of the value obtained by subtracting the "outermost peripheral depth" from the "center depth" is less than 100 [μm] and the absolute value [μm] of the value obtained by subtracting the "electrode peripheral depth" from the "center depth" is less than 3 [μm], which is rated as "C". If the "resistance value [Ω]" is 700 [Ω] or less, preferably 500 [Ω] or less, and more preferably 300 [Ω] or less, it can be determined that there is no problem in practical use.

[0127] [Considerations] As shown in Table 91, the sensor elements of Examples 1-4 and Comparative Examples 1 and 2 all have performance that is practically sound. It is also evident that the sensor elements of Examples 1 and 3 have superior performance in practical application compared to the sensor elements of Examples 2 and 4 and Comparative Examples 1 and 2.

[0128] [Summarize] The sensor element of aspect 1 disclosed herein comprises: a substrate that is rectangular in plan view, having a covered portion whose substrate surface is covered by an insulating film, and a non-covered portion surrounded by the covered portion and whose substrate surface is not covered by the insulating film; a first electrode and a second electrode disposed on the substrate surface in the non-covered portion; and an odorant receptor layer comprising a conductive carbon material and a resin composition, and in contact with the substrate surface in the non-covered portion, the first electrode, and the second electrode, wherein the first electrode and the second electrode are disposed in a recess provided in the non-covered portion, and the substrate surface in the non-covered portion, a first surface of the first electrode in contact with the odorant receptor layer, and a second surface of the second electrode in contact with the odorant receptor layer are disposed flush with each other.

[0129] In the sensor element of aspect 2 of this disclosure based on aspect 1, the following approach may also be adopted: the substrate is made of a resin comprising any one of epoxy resin, phenolic resin and polyimide.

[0130] In the sensor element of aspect 3 of this disclosure based on aspect 1 or 2, the following approach may also be adopted: the non-covered portion is formed to be circular when viewed from above.

[0131] In the sensor element of aspect 4 of this disclosure based on aspect 3, the following scheme may also be adopted: the first electrode and the second electrode are configured to be opposite each other in the diametrical direction of the non-covered portion and separated from each other by a first distance or more, and are configured to be separated from the insulating film surrounding the non-covered portion in the covered portion by a second distance or more.

[0132] In the sensor element of aspect 5 of this disclosure based on aspect 4, the following scheme may also be adopted: the first surface and the second surface are circular when viewed from above.

[0133] In the sensor element of aspect 6 of this disclosure based on any one of aspects 3 to 5, the following scheme may also be adopted: the non-covered portion is formed into a circle with a diameter of 2 [mm] or more and 5 [mm] or less when viewed from above, and the thickness of the insulating film surrounding the non-covered portion is 50 [μm] or more and 500 [μm] or less.

[0134] In the sensor element of aspect 7 of this disclosure based on aspect 4 or 5, the following scheme may also be adopted: the first distance is a distance of 0.4 mm or more and 1.8 mm or less, and the second distance is a distance of 0.1 mm or more and 0.8 mm or less.

[0135] In the sensor element of aspect 8 of this disclosure based on aspect 5, the following approach may also be adopted: the first surface and the second surface are formed into a circle with a diameter of more than 0.1 mm and less than 1 mm when viewed from above.

[0136] In the sensor element of aspect 9 of this disclosure based on any one of aspects 1 to 8, the following approach may also be adopted: it further comprises: a pair of through holes disposed at two ends in the long side direction of the substrate; and a pair of metal pins inserted into the pair of through holes, wherein the first electrode and the second electrode are electrically connected to the through holes at the ends of the substrate opposite to the side of the substrate surface where the non-covered portion is provided, and are electrically connected to the metal pins via the through holes.

[0137] The method for manufacturing a sensor element according to aspect 10 of this disclosure includes: a through-hole forming step, forming a pair of through holes at two end edges of a substrate that is rectangular in plan view; an electrode placement step, placing a first electrode and a second electrode on the front side of the substrate and placing metal wiring on the back side of the substrate; a flushing step, printing a pattern of photocurable resin on the front side of the substrate and curing it by light irradiation, and then removing the photocurable resin until the top surfaces of the first electrode and the second electrode are exposed, so that the substrate surface of the substrate is flush with the top surfaces of the first electrode and the second electrode; a solder resist step, forming a covering portion covered by an insulating film on the portion other than the through holes on the front side of the substrate and the non-covered portion for placing the first electrode and the second electrode; a slurry preparation step, preparing a slurry composed of a conductive carbon material and a resin composition; a coating step, coating the slurry onto the non-covered portion; and a drying step, drying the slurry coated on the non-covered portion to form an odorant receptor layer.

[0138] In the method of manufacturing a sensor element based on aspect 11 of this disclosure, which is based on aspect 10, it may also include a pin mounting step of inserting a pair of metal pins into the pair of through holes to make an electrical connection on the back side of the substrate.

[0139] In the method of manufacturing a sensor element based on aspect 12 of this disclosure, which is based on aspect 10 or 11, the following approach may also be adopted: in the solder resist process, the non-covered portion is formed to be circular when viewed from above.

[0140] In the method for manufacturing a sensor element of aspect 13 of this disclosure based on any one of aspects 10 to 12, the following approach may also be adopted: in the electrode configuration step, the first electrode and the second electrode are configured to be opposite each other in the diametrical direction of the non-covered portion and separated from each other by a first distance or more, and configured to be separated from the insulating film surrounding the non-covered portion in the covered portion by a second distance or more.

[0141] In the method for manufacturing a sensor element based on aspect 14 of this disclosure, which is based on aspect 13, the following approach may also be adopted: in the electrode configuration step, the first electrode and the second electrode are formed to be circular when viewed from above.

[0142] [Additional Notes] This disclosure is not limited to the above-described embodiments. Various changes can be made within the scope of the overall technical concept shown. Embodiments obtained by appropriately combining the technical means disclosed in each embodiment and variation are also included within the technical scope of this disclosure.

[0143] <Explanation of Figure Markers> Sensor elements 1, 41, 51, 61, 71, 81 11 substrate 11A substrate surface 12 Coverage Section 13 Non-covered sections 15, 42 First electrode 16, 43, second electrode 17 through holes 18 pins 19 Odor Receptor Layer 52 Third electrode 53. Electrode 4 62 Fifth electrode 63. The 6th electrode

Claims

1. A sensor element comprising: A rectangular substrate viewed from above has a covered portion whose surface is covered by an insulating film, and a non-covered portion surrounded by the covered portion whose surface is not covered by the insulating film. The first electrode and the second electrode are disposed on the surface of the substrate in the uncovered portion; and An odorant receptor layer comprising a conductive carbon material and a resin composition, and in contact with the substrate surface, the first electrode, and the second electrode in the uncovered portion. The first electrode and the second electrode are disposed within a recess in the non-covered portion, wherein, The substrate surface in the non-covered portion, the first surface of the first electrode in contact with the odorant receptor layer, and the second surface of the second electrode in contact with the odorant receptor layer are arranged flush with each other.

2. The sensor element according to claim 1, wherein, The substrate is made of a resin comprising any one of epoxy resin, phenolic resin and polyimide.

3. The sensor element according to claim 1 or 2, wherein, The uncovered portion is formed to appear circular when viewed from above.

4. The sensor element according to claim 3, wherein, The first electrode and the second electrode are configured to face each other in the diametrical direction of the uncovered portion and to be separated from each other by a first distance or more, and are configured to be separated from the insulating film surrounding the uncovered portion in the covered portion by a second distance or more.

5. The sensor element according to claim 4, wherein, The first and second surfaces are circular when viewed from above.

6. The sensor element according to claim 3, wherein, The uncovered portion is formed into a circle with a diameter of 2 mm or more and 5 mm or less when viewed from above, and, The thickness of the insulating film surrounding the non-covered portion is 50 μm or more and 500 μm or less.

7. The sensor element according to claim 4, wherein, The first distance is a distance of 0.2mm or more and 1.8mm or less. The second distance is a distance of 0.1 mm or more and 0.8 mm or less.

8. The sensor element according to claim 5, wherein, The first surface and the second surface are formed into a circle with a diameter of more than 0.1 mm and less than 2 mm when viewed from above.

9. The sensor element according to claim 1, further comprising: A pair of through holes are disposed at both ends along the long side of the substrate; and A pair of metal pins are inserted into a pair of through holes. The first electrode and the second electrode are electrically connected to the through hole at the end of the substrate opposite to the surface of the substrate on which the non-covered portion is provided, and are electrically connected to the metal pin through the through hole.

10. A method for manufacturing a sensor element, comprising: In the through-hole forming process, a pair of through holes are formed on two end edges of one side of a substrate that is rectangular in top view; The electrode configuration process involves configuring a first electrode and a second electrode on the front side of the substrate, and configuring metal wiring on the back side of the substrate. In the flushing process, a pattern of photocurable resin is printed on the front side of the substrate and cured by light irradiation. Then the photocurable resin is removed until the top surfaces of the first electrode and the second electrode are exposed, so that the substrate surface of the substrate is flush with the top surfaces of the first electrode and the second electrode. In the solder resist process, a covering portion covered by an insulating film is formed in the portion of the substrate other than the through-hole on the front side and the non-covered portion for the placement of the first electrode and the second electrode. The slurry preparation process involves preparing a slurry by mixing a conductive carbon material and a resin composition. The coating process involves applying the slurry to the uncovered portion; as well as The drying process involves drying the slurry applied to the uncovered portion to form an odorant receptor layer.

11. The method for manufacturing a sensor element according to claim 10, further comprising: The pin mounting process involves inserting a pair of metal pins into the pair of through holes to make an electrical connection on the back side of the substrate.

12. The method for manufacturing a sensor element according to claim 10, wherein, In the solder resist process, the non-covered portion is formed to be circular when viewed from above.

13. The method for manufacturing a sensor element according to claim 10, wherein, In the electrode configuration process, the first electrode and the second electrode are configured to face each other in the diametrical direction of the uncovered portion and to be separated from each other by a first distance or more, and to be separated from the insulating film surrounding the uncovered portion in the covered portion by a second distance or more.

14. The method for manufacturing a sensor element according to claim 13, wherein, In the electrode configuration process, the first electrode and the second electrode are formed to be circular when viewed from above.

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