pressure sensor

Abstract

To provide a pressure sensitive sensor that can achieve a reduction in thickness and the number of components, and avoids the possibility that displacement between constituents occurs due to assembly.SOLUTION: A first contact pattern 21 and a first wiring pattern 31 connected with the first contact pattern 21 are formed on a substrate 10. An insulating layer 71 having an opening 73 exposing a part of the first contact pattern 21 is formed on the first contact pattern 21. A pressure-sensitive resistor 41 in which the value of resistance changes according to pressure is formed on the insulating layer 71 including the opening 73. A second contact pattern 51 is formed at a position on the pressure-sensitive resistor 41 opposite to the first contact pattern 21. A second wiring pattern 61 connected with the second contact pattern 51 is led out onto the substrate 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure sensor whose resistance value changes in response to a pressing force. [Background technology]

[0002] Conventionally, a pressure sensor whose resistance value changes depending on the pressing force has been configured, for example as shown in Patent Document 1, by stacking a lower circuit board with a lower electrode and an upper circuit board with an upper electrode via a spacer, with the upper and lower electrodes facing each other within an opening in the spacer, and pressing the upper circuit board on the back side of the upper electrode to lower it so that the upper electrode abuts against the lower electrode, and changing the resistance value between the upper and lower electrodes depending on the magnitude (contact area) of the abutment force (load). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-45629 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as mentioned above, conventional pressure sensors are constructed using two circuit boards and a spacer, which increases the number of parts and makes the product thicker.Furthermore, there is a risk that the position of the opening in the spacer or the upper electrode may become misaligned relative to the lower electrode due to misalignment when assembling the two circuit boards and the spacer.

[0005] The present invention has been made in consideration of the above points, and its purpose is to provide a pressure sensor that can reduce the number of parts and the thickness, and that does not have the risk of misalignment occurring between the components due to assembly. [Means for solving the problem]

[0006] The present invention relates to a pressure-sensitive sensor whose resistance value changes in response to pressure, in which a first contact pattern and a first wiring pattern connected to the first contact pattern are formed directly on the upper surface of a single substrate, an insulating layer having an opening that exposes a portion of the first contact pattern is formed by laminating directly on the upper surface of the first contact pattern, a pressure-sensitive resistor whose resistance value changes in response to pressure is formed by laminating directly on the upper surface of the insulating layer including the opening, a second contact pattern is formed by laminating directly on the upper surface of the pressure-sensitive resistor in a position facing the first contact pattern, and a second wiring pattern connected to the second contact pattern is formed by laminating so as to be in direct contact with the upper surface and side or side of the pressure-sensitive resistor and the upper surface and side or side of the insulating layer, and is then led out to the upper surface of the substrate. The pressure-sensitive resistor is filled in the opening of the insulating layer and is formed so as to cover at least a part of the surface of the insulating layer from the opening to the surrounding area. It is characterized by the following. According to the present invention, a pressure-sensitive sensor can be constructed by forming various patterns on a single substrate, which reduces the number of components and the thickness, and there is no risk of misalignment occurring between the first and second contact patterns, pressure-sensitive resistor, or insulating layer due to assembly. Furthermore, because there is no space between the first and second contact patterns using a spacer as in the past, the resistance value begins to change with the application of only a light force, making it suitable for use as a pressure-sensitive sensor that requires a characteristic in which the resistance value begins to change with a light force and then changes further as the pressure increases. Furthermore, since the thickness of the pressure-sensitive resistor is thin, the first and second contact patterns are conductive only at the parts that face each other above and below (directly above and directly below) through the opening in the insulating layer (resistance value changes), and therefore, by adjusting the area and shape of the opening, the resistance value can be easily and accurately adjusted (for example, reducing the area of ​​the opening increases the resistance value).

[0007] Also According to the present invention, a pressure-sensitive resistor is filled inside the opening provided in the insulating layer, so that the thickness of the pressure-sensitive resistor can be increased accordingly, and the resistance value of the pressure-sensitive resistor can be increased accordingly, resulting in a pressure-sensitive sensor with high resolution.

[0009] In addition to the above features, the present invention further provides a method for manufacturing a semiconductor device, comprising: forming a first contact pattern, a first wiring pattern, an insulating layer, a pressure-sensitive resistor, and a second contact pattern and a second wiring pattern in a manner such that: All of them, By printing on the substrate directly Formed by laminating It is a printed layer It is characterized by the fact that This allows various patterns to be formed easily and accurately on a single substrate, reducing the number of parts, manufacturing costs, and thickness. It also eliminates the risk of misalignment during assembly in the positions of the first and second contact patterns and the openings in the insulating layer. [Effects of the Invention]

[0010] According to the present invention, it is possible to reduce the number of parts and the thickness, and it is also possible to eliminate the risk of misalignment occurring between the components during assembly, thereby obtaining a pressure sensor with stable product characteristics. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of a pressure-sensitive sensor 1. FIG. [Figure 2] FIG. 2 is a schematic plan view of the pressure-sensitive sensor 1. [Figure 3] 3A to 3C are explanatory diagrams of a method for manufacturing the pressure-sensitive sensor 1. [Figure 4] 3 is an explanatory diagram of the operation of the pressure-sensitive sensor 1. FIG. [Figure 5] 1 is a plan view showing a specific example of a pressure-sensitive sensor 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic cross-sectional view (a schematic cross-sectional view along the line AA in Fig. 2) of a pressure-sensitive sensor 1 according to one embodiment of the present invention, and Fig. 2 is a schematic plan view of the pressure-sensitive sensor 1. As shown in these figures, the pressure-sensitive sensor 1 is configured by forming a first contact pattern 21 and a first wiring pattern 31 connected to the first contact pattern 21 on a substrate 10, forming an insulating layer 71 having an opening 73 on the first contact pattern 21, forming a pressure-sensitive resistor (pressure-sensitive resistive layer, pressure-sensitive resistive pattern) 41 whose resistance value changes in response to pressure on the insulating layer 71 including the opening 73, forming a second contact pattern 51 on the pressure-sensitive resistor 41 at a position facing the first contact pattern 21, and further, bringing a second wiring pattern 61 connected to the second contact pattern 51 into contact with the top and side surfaces of the pressure-sensitive resistor 41 and the top and side surfaces of the insulating layer 71, and then extending the second wiring pattern 61 onto the substrate 10. In the following explanation, "up" refers to the direction when looking from the substrate 10 toward the surface on which the first contact pattern 21 etc. is formed, and "down" refers to the opposite direction, but this is not intended to limit the direction in which the pressure sensor 1 can be used.

[0013] Next, the configuration of the pressure-sensitive sensor 1 will be described together with its manufacturing method. Figure 3 is an explanatory diagram of the manufacturing method of the pressure-sensitive sensor 1. First, a substrate 10 shown in Figure 3(a) is prepared. The substrate 10 is made of a flexible synthetic resin film, and in this example, a polyethylene terephthalate (PET) film is used.

[0014] 3(a), a first contact pattern 21 and a first wiring pattern 31 are simultaneously formed on the substrate 10 by screen printing a conductive paste (silver paste in this example). In this example, the first contact pattern 21 is circular (it may have any other shape), and a linear first wiring pattern 31 (it may have any other shape) is formed so as to connect to part of its outer periphery.

[0015] Next, as shown in FIG. 3(b), an insulating layer 71 is formed by screen printing a resin paste so as to cover the upper surface of the first contact pattern 21 and a portion of the first wiring pattern 31 connected thereto. In this example, the insulating layer 71 is circular (it may be of various other shapes) and has a circular opening 73 (it may be of various other shapes) in its center. The outer diameter of the insulating layer 71 is larger than the outer diameter of the first contact pattern 21, and the inner diameter of the opening 73 is smaller than the outer diameter of the first contact pattern 21. Therefore, the entire outer periphery of the first contact pattern 21 is covered by the insulating layer 71, and the first contact pattern 21 is exposed throughout the entire interior of the opening 73.

[0016] 3(c), the pressure-sensitive resistor 41 is formed on the insulating layer 71 by screen printing a carbon paste. In this example, the pressure-sensitive resistor 41 is circular (it may have various other shapes), and its outer shape (outer diameter) is larger than that of the first contact pattern 21 and smaller than that of the insulating layer 71. The carbon paste is made of a conductive paint that is a mixture of a synthetic resin that remains flexible even when hardened, carbon powder, and a solvent.

[0017] The thickness of the pressure-sensitive resistor 41 is greater than the thickness (for example, 10 μm) of the insulating layer 71. The pressure-sensitive resistor 41 fills the interior of the opening 73 of the insulating layer 71, and therefore the thickness of the pressure-sensitive resistor 41 is greater at the portion of the opening 73 by the depth of the opening 73. That is, in this embodiment, the pressure-sensitive resistor 41 is formed so as to fill the interior of the opening 73 of the insulating layer 71 and to cover a portion of the surface of the insulating layer 71 from the opening 73 to the surrounding area.

[0018] Next, as shown in FIG. 2, a second contact pattern 51 and a second wiring pattern 61 are simultaneously formed on the substrate 10, including the upper surface of the pressure-sensitive resistor 41, by screen-printing silver paste. In this example, the second contact pattern 51 is circular (it may have various other shapes), and a linear second wiring pattern 61 (it may have various other shapes) is formed so as to connect to a portion of its outer periphery. The second contact pattern 51 is formed in a position opposite the first contact pattern 21. The outer diameter of the second contact pattern 51 is formed to have an area larger than the inner diameter of the opening 73 in the insulating layer 71. The second wiring pattern 61 is formed so as to contact the side surface of the pressure-sensitive resistor 41 from the upper surface thereof, and further contact the side surface of the insulating layer 71 from the upper surface thereof, and extend onto the substrate 10.

[0019] The above manufacturing method completes the pressure-sensitive sensor 1. It goes without saying that the above manufacturing procedure is only one example, and various other manufacturing procedures may be used for manufacturing.

[0020] In the pressure-sensitive sensor 1 configured as described above, the pressure-sensitive resistor 41 is interposed between the first and second contact patterns 21, 51 via the opening 73 in the insulating layer 71, thereby generating a predetermined resistance value between the first and second contact patterns 21, 51. Note that unless at least a portion of the second contact pattern 51 is positioned directly above the first contact pattern 21 via the opening 73, they will not be electrically connected to each other. Therefore, at least a portion of the second contact pattern 51 must be positioned directly above the first contact pattern 21 via the opening 73.

[0021] When the substrate 10 is placed on a base (not shown) and the second contact pattern 51 is pressed from above with a finger or a pressing object such as a key top, the flexible pressure-sensitive resistor 41 is compressed, its thickness decreases, and the carbon particles in the pressure-sensitive resistor 41 come into strong contact with each other, increasing the contact area between the carbon particles, thereby reducing the resistance between the first and second contact patterns 21, 51. On the other hand, as the pressure is gradually released, the thickness of the pressure-sensitive resistor 41 returns to its original thickness due to its elastic restoring force, and the resistance increases. In other words, the resistance between the first and second contact patterns 21, 51 varies depending on the magnitude of the pressing force (pressure), thereby obtaining different outputs corresponding to the pressing force and enabling the magnitude of the pressing force to be detected.

[0022] In this case, since there is no space provided by a spacer between the first contact pattern 21 and the second contact pattern 51 as in the past, the resistance value starts to change with just a light force being applied, making it suitable for use as a pressure-sensitive sensor 1 that requires the resistance value to start changing with a light force and continue to change as the pressing force increases.

[0023] Furthermore, the pressure-sensitive sensor 1 is provided with an insulating layer 71, which acts as a cushion and provides greater rubber-like elasticity when the pressure-sensitive sensor 1 is pressed down. This allows the resistance value to change more linearly in response to the strength of the pressing force, improving the resolution of the output value according to the pressing force.

[0024] 4 is a diagram showing the current path when a voltage is applied between the first and second contact patterns 21 and 51. As shown in the figure, the current flows through the path of the first wiring pattern 31, the first contact pattern 21, the pressure-sensitive resistor 41, the second contact pattern 51, and the second wiring pattern 61.

[0025] At this time, because the thickness of the pressure-sensitive resistor 41 is thin, current flows between the first and second contact patterns 21, 51 when a voltage is applied only in a portion X of the surface where the first and second contact patterns 21, 51 face each other vertically (directly above and directly below) within the opening 73 of the insulating layer 71 of the entire pressure-sensitive resistor 41. In other words, the resistance value between the first and second wiring patterns 31, 61 is the resistance value due only to the portion X directly above the opening 73 of the pressure-sensitive resistor 41, assuming that the resistance values ​​of the first and second wiring patterns 31, 61 and the first and second contact patterns 21, 51 are zero.

[0026] In other words, the first and second contact patterns 21, 51 are conductive only at the portions that face each other above and below (directly above and directly below) through the opening 73 provided in the insulating layer 71 (resistance changes occur), and therefore, by adjusting the area and shape of the opening 73, it is possible to easily and accurately adjust the resistance (for example, reducing the area of ​​the opening 73 increases the resistance).

[0027] Incidentally, the larger the resistance value when the pressure-sensitive sensor 1 is not being pressed, the greater the change in resistance value when it is pressed, which is preferable in terms of improving the resolution of the output value according to the pressing force. In the pressure-sensitive sensor 1, the pressure-sensitive resistor 41 is filled inside the opening 73 provided in the insulating layer 71, so the thickness of the pressure-sensitive resistor 41 is increased accordingly, and the resistance value when the pressure-sensitive resistor 41 is not being pressed can be increased accordingly. From this point of view, the pressure-sensitive sensor 1 can be made to have high resolution.

[0028] Of course, in the above-mentioned pressure-sensitive sensor 1, it is more preferable to increase the resistance value by making the thickness of the entire pressure-sensitive resistor 41, including the portion of the pressure-sensitive resistor 41 located other than the opening 73, thicker than the thickness of the first and second contact patterns 21, 51, but the present invention is not limited to this, and the thickness may be the same as or thinner than the thickness of the first and second contact patterns 21, 51.

[0029] As in this pressure-sensitive sensor 1, it is desirable that the pressure-sensitive resistor 41 be formed so that its outer dimensions are larger than the inner diameter of the opening 73 so that it can be reliably filled into the entire opening 73 of the insulating layer 71 (taking into consideration printing misalignment, etc.). In other words, it is desirable that the pressure-sensitive resistor 41 be formed so that it fills the inside of the opening 73 of the insulating layer 71 and covers at least a portion of the surface of the insulating layer 71 from the opening 73 to the surrounding area.

[0030] Similarly, it is desirable that the outer diameter dimensions of the first contact pattern 21 and the second contact pattern 51 are formed larger than the inner diameter dimensions of the opening 73 so that they face the entire opening 73 of the insulating layer 71 (taking into account printing misalignment, etc.).

[0031] Furthermore, since the outer periphery of the insulating layer 71 of the pressure-sensitive sensor 1 is formed to be larger than the outer periphery of the pressure-sensitive resistor 41, it is possible to prevent minute currents from flowing from the first wiring pattern 31 or the second wiring pattern 61, which passes directly below or directly above the pressure-sensitive resistor 41, to the other electrode pattern directly via the pressure-sensitive resistor 41, thereby more reliably preventing variations in the output voltage.

[0032] 5 is a plan view showing one specific example of the pressure-sensitive sensor 1. As shown in the figure, the substrate 10 is configured to include a sensor body forming portion 11 and an output lead portion 13 that is connected to the outer periphery of the sensor body forming portion 11 and extends in a strip shape. The first and second contact patterns 21 and 51, an insulating layer 71, a pressure-sensitive resistor 41, and portions of the first and second wiring patterns 31 and 61 connected to the first and second contact patterns 21 and 51, respectively, are printed on the sensor body forming portion 11, and the remaining portions of the first and second wiring patterns 31 and 61 are printed on the output lead portion 13, with output terminal patterns 33 and 63 printed on their tips. This makes it easy to apply a voltage between the first and second contact patterns 21 and 51 and obtain an output.

[0033] In the pressure-sensitive sensor 1, the second wiring pattern 61 is brought into contact with the top and side surfaces (outer peripheral side surfaces) of the pressure-sensitive resistor 41 and the top and side surfaces (outer peripheral side surfaces) of the insulating layer 71 before being drawn out onto the substrate 10. However, for example, by aligning a portion of the outer periphery of the second contact pattern 51 with a portion of the outer periphery of the pressure-sensitive resistor 41 and a portion of the outer periphery of the insulating layer 71 and connecting the second wiring pattern 61 at the aligned portion, the second wiring pattern 61 can be drawn out onto the substrate 10 in contact only with the side surfaces of the pressure-sensitive resistor 41 and the insulating layer 71 (without contacting the top surfaces of the pressure-sensitive resistor 41 and the insulating layer 71). Also, if the outer shape of the pressure-sensitive resistor 41 is made larger (or partially larger) than the outer shape of the insulating layer 71 so as to cover the insulating layer 71, the second wiring pattern 61 can be drawn out onto the substrate 10 in contact only with the top and side surfaces (or only the side surfaces) of the pressure-sensitive resistor 41 without coming into contact with the insulating layer 71.

[0034] As described above, the pressure-sensitive sensor 1 has the first contact pattern 21 and the first wiring pattern 31 connected to the first contact pattern 21 formed on the substrate 10, the insulating layer 71 having the opening 73 exposing a portion of the first contact pattern 21 formed on the first contact pattern 21, the pressure-sensitive resistor 41 whose resistance value changes in response to pressure formed on the insulating layer 71 including the opening 73, the second contact pattern 51 formed on the pressure-sensitive resistor 41 at a position facing the first contact pattern 21, and the second wiring pattern 61 connected to the second contact pattern 51 extended onto the substrate 10, so that the pressure-sensitive sensor 1 can be constructed by forming various patterns on a single substrate 10. This allows for a reduction in the number of parts and a thinner device, and also eliminates the risk of misalignment occurring between the first and second contact patterns 21 and 51, the pressure-sensitive resistor 41, and the insulating layer 71 during assembly.

[0035] Furthermore, the pressure-sensitive sensor 1 is formed by stacking the first contact pattern 21, the first wiring pattern 31, the insulating layer 71, the pressure-sensitive resistor 41, the second contact pattern 51, and the second wiring pattern 61 on the substrate 10 by printing, so that various patterns can be easily and accurately formed in positions on a single substrate 10, which also reduces the number of parts, reduces manufacturing costs, and makes the sensor thinner. There is also no risk of misalignment due to assembly in the positions of the first and second contact patterns 21, 51 or the opening 73 in the insulating layer 71.

[0036] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications are possible within the scope of the claims and the technical concept described in the specification and drawings. Furthermore, any shape, structure, or material not directly described in the specification and drawings is within the scope of the technical concept of the present invention as long as it achieves the functions and effects of the present invention. For example, it goes without saying that various modifications are possible to the shapes and positions of the substrate 10, first contact pattern 21, first wiring pattern 31, pressure-sensitive resistor 41, second contact pattern 51, second wiring pattern 61, insulating layer 71, and opening 73.

[0037] In the above embodiment, the pressure-sensitive resistor 41 is filled into the entire opening 73 of the insulating layer 71, but as long as the desired resistance value is obtained, it is not necessary to fill the entire opening 73, and it may be filled only in a portion.

[0038] In the above example, screen printing was used to form the various patterns, but other printing methods (e.g., offset printing, inkjet printing), and even pattern formation methods other than printing (e.g., etching) may be used. In the above embodiment, a flexible substrate is used as the substrate 10, but a hard substrate may also be used. Alternatively, a separate insulating layer or insulating film may be placed on the second contact pattern 51, and the second contact pattern 51 may be pressed from above by a pressing body.

[0039] Furthermore, the embodiments described above and shown in the drawings can be combined with each other as long as there is no contradiction in their purpose, configuration, etc. Furthermore, even a part of the description described above and the drawings can be an independent embodiment, and the embodiment of the present invention is not limited to a single embodiment combining the description described above and the drawings. [Explanation of symbols]

[0040] 10 Substrate 21 First contact pattern 31 First wiring pattern 41 Pressure-sensitive resistor 51 Second contact pattern 61 Second wiring pattern 71 Insulating layer 73 Opening

Claims

1. In a pressure sensor whose resistance value changes depending on the pressing force, forming a first contact pattern and a first wiring pattern connected to the first contact pattern directly on an upper surface of one substrate; forming an insulating layer having an opening for exposing a portion of the first contact pattern by directly laminating it on an upper surface of the first contact pattern; a pressure-sensitive resistor whose resistance value changes in response to pressure is formed by directly laminating it on the upper surface of the insulating layer including the opening; forming a second contact pattern by directly stacking it on the upper surface of the pressure-sensitive resistor at a position facing the first contact pattern; Furthermore, a second wiring pattern connected to the second contact pattern is formed by laminating it so as to be in direct contact with the upper surface and side surface or side surface of the pressure-sensitive resistor and the upper surface and side surface or side surface of the insulating layer, and is drawn out to the upper surface of the substrate; A pressure-sensitive sensor characterized in that the pressure-sensitive resistor is filled inside an opening in the insulating layer and is formed so as to cover at least a portion of the surface of the insulating layer from the opening to its surroundings.

2. A pressure-sensitive sensor according to claim 1, A pressure-sensitive sensor characterized in that the first contact pattern, the first wiring pattern, the insulating layer, the pressure-sensitive resistor, and the second contact pattern and the second wiring pattern are all printed layers formed by directly stacking them on the substrate by printing.

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