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 upper and lower contacts 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. A pressure-sensitive resistor 41 in which the value of resistance changes according to pressure is formed on the first contact pattern 21. 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 brought into contact with a top face and side face of the pressure-sensitive resistor 41, and is subsequently 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 between the upper and lower contacts due to assembly. [Means for solving the problem]

[0006] The present invention is a pressure sensor in which the resistance value changes depending on the pressing force. Made of synthetic resin A first contact pattern and a first wiring pattern connected to the first contact pattern are formed directly on the upper surface of the substrate, a pressure-sensitive resistor whose resistance value changes depending on pressure is formed by directly stacking the first contact pattern on the upper surface of the first contact pattern, a second contact pattern is formed by directly stacking the first contact pattern 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 stacking the second wiring pattern so as to be in direct contact with the upper surface and side surface or the side surface of the pressure-sensitive resistor, and is then led out to the upper surface of the substrate. The pressure-sensitive resistor is formed larger than the first contact pattern and the second contact pattern, and the size of the second contact pattern formed on the pressure-sensitive resistor having a surface rougher than the substrate is formed to have an area larger than the size of the first contact pattern, so that the second contact pattern covers the entire upper surface of the first contact pattern. It is characterized by: According to the present invention, a pressure sensor can be constructed by forming various patterns on a single substrate, which reduces the number of components and the thickness, and also eliminates the risk of misalignment between the first and second contact patterns 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 located above and below it are conductive only at the points where they face each other directly above and below the resistor (resistance changes occur), so the resistance value can be easily adjusted by adjusting the area of ​​the first and second contact patterns (reducing the opposing area increases the resistance value).

[0009] In addition to the above features, the present invention further provides a method for manufacturing a semiconductor device, comprising: All of them, By printing on the substrate directly Layered It is a printed layer that It is characterized by: This allows various patterns to be formed easily and accurately on a single board, reducing the number of parts, manufacturing costs, and thickness, and also eliminating the risk of misalignment between the first and second contact patterns due to assembly. [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 between the upper and lower contacts due to assembly, thereby obtaining a pressure sensor with stable product characteristics. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a schematic cross-sectional view of a pressure-sensitive sensor 1-1. [Figure 2] FIG. 2 is a schematic plan view of the pressure sensor 1-1. [Figure 3] FIG. 2 is a plan view showing a specific example of the pressure-sensitive sensor 1-1. [Figure 4] FIG. 2 is a schematic cross-sectional view of a pressure-sensitive sensor 1-2. [Figure 5] FIG. 2 is a schematic plan view of the pressure sensor 1-2. 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 AA in Fig. 2) of a pressure-sensitive sensor 1-1 according to a first embodiment of the present invention, and Fig. 2 is a schematic plan view of the pressure-sensitive sensor 1-1. As shown in these figures, the pressure-sensitive sensor 1-1 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 a pressure-sensitive resistor (pressure-sensitive resistive layer, pressure-sensitive resistive pattern) 41 on the first contact pattern 21, the resistance value of which changes with pressure, forming a second contact pattern 51 on the pressure-sensitive resistor 41 at a position opposite the first contact pattern 21, and further forming a second wiring pattern 61 connected to the second contact pattern 51 in contact with the top and side surfaces of the pressure-sensitive resistor 41 and then extending it 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 1-1 can be used.

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

[0014] Next, 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 various other shapes), and the linear first wiring pattern 31 is formed so as to connect to part of its outer periphery.

[0015] Next, a pressure-sensitive resistor 41 is formed on the substrate 10 by screen printing a carbon paste so as to cover the entire upper surface of the first contact pattern 21 and a part of the first wiring pattern 31 connected thereto. In this example, the pressure-sensitive resistor 41 is circular (it may have various other shapes) and is formed larger than the first contact pattern 21 and the second contact pattern 51 described below. The carbon paste is made of a conductive paint made by mixing a synthetic resin that remains flexible even when hardened, carbon powder, and a solvent.

[0016] Next, 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 (although it may have various other shapes), and a linear second wiring pattern 61 is formed so as to connect to part of its outer periphery. The second contact pattern 51 is formed with a larger area than the first contact pattern 21, so as to cover the entire upper surface of the first contact pattern 21. The second wiring pattern 61 is formed so as to contact the side surface of the pressure-sensitive resistor 41 from the upper surface of the pressure-sensitive resistor 41 and be drawn out onto the substrate 10.

[0017] The pressure-sensitive sensor 1-1 is completed by the above manufacturing method. Note that the above manufacturing procedure is only one example, and it goes without saying that various other manufacturing procedures may be used for manufacturing.

[0018] In the pressure-sensitive sensor 1-1 configured as described above, the pressure-sensitive resistor 41 is interposed between the first and second contact patterns 21 and 51, thereby generating a predetermined resistance value between the first and second contact patterns 21 and 51. Note that unless at least a portion of the second contact pattern 51 is positioned directly above the first contact pattern 21, 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, and this is the embodiment in which this is the case.

[0019] 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.

[0020] As mentioned above, it is more preferable that the thickness of the pressure-sensitive resistor 41 is thicker, because this increases the resistance between the first and second contact patterns 21, 51 when the pressure-sensitive sensor 1-1 is not pressed, and also increases the range of change in the resistance when the pressure-sensitive sensor 1-1 is pressed. Therefore, in the pressure-sensitive sensor 1-1, the thickness of the pressure-sensitive resistor 41 is made thicker than the thicknesses of the first and second contact patterns 21, 51, but the present invention is not limited to this, and the thickness of the pressure-sensitive resistor 41 may be the same as or thinner than the thicknesses of the first and second contact patterns 21, 51.

[0021] Furthermore, because the thickness of the pressure-sensitive resistor 1 is thin, when a voltage is applied between the first and second contact patterns 21, 51, electricity flows, i.e., the only part of the pressure-sensitive resistor 41 that acts as a resistor is the part of the surface where the first and second contact patterns 21, 51 face each other (overlap) vertically. In this embodiment, since the first contact pattern 21 is smaller than the second contact pattern 51, only the part of the pressure-sensitive resistor 41 that faces directly above the surface of the first contact pattern 21 acts as a resistor. Therefore, to obtain a high resistance value, it is sufficient to reduce the area of ​​at least one of the first and second contact patterns 21, 51 (in this example, the first contact pattern 21). In this case, it is preferable to make the area of ​​the other contact pattern (in this example, the second contact pattern 51) larger than that of one of the contact patterns (the first contact pattern 21), thereby reliably preventing the occurrence of any portion where the other contact pattern (the second contact pattern 51) does not face the one of the contact patterns (the first contact pattern 21) due to printing errors between the two.

[0022] As described above, the resistance value of the pressure-sensitive sensor 1-1 is determined by the area of ​​the smaller contact pattern (first contact pattern 21). However, as in this embodiment, the contact pattern (first contact pattern 21) printed directly on the substrate 10 is made smaller than the contact pattern (second contact pattern 51) printed on the pressure-sensitive resistor 41 because the contact pattern (first contact pattern 21) formed on the substrate 10 with a smooth surface can be printed with higher accuracy than the contact pattern (second contact pattern 51) formed on the pressure-sensitive resistor 41 with a rough surface, and it is expected that the accuracy of the resistance value determined by the area of ​​the smaller contact pattern (first contact pattern 21) can be further improved.

[0023] Furthermore, as in this pressure-sensitive sensor 1-1, it is preferable that the pressure-sensitive resistor 41 be formed with an outer shape larger than the first and second contact patterns 21, 51 so as to be reliably located between the opposing surfaces of the first and second contact patterns 21, 51.

[0024] 3 is a plan view showing one specific example of a pressure-sensitive sensor 1-1. 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-like shape. The first and second contact patterns 21 and 51, the 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. 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 at their tips. This allows a voltage to be easily applied between the first and second contact patterns 21 and 51 to obtain an output.

[0025] Fig. 4 is a schematic cross-sectional view (sectional view taken along the line BB in Fig. 5) of a pressure-sensitive sensor 1-2 according to a second embodiment of the present invention, and Fig. 5 is a schematic plan view of the pressure-sensitive sensor 1-2. In the pressure-sensitive sensor 1-2 shown in these figures, parts that are the same as or correspond to those of the pressure-sensitive sensor 1-1 shown in Figs. 1 to 3 are given the same reference numerals (however, the reference numerals are given the suffix "-2"). Note that matters other than those described below are the same as those in the embodiment shown in Figs. 1 to 3.

[0026] This pressure-sensitive sensor 1-2 differs from the pressure-sensitive sensor 1-1 in that the first contact pattern 21-2 is larger than the second contact pattern 51-2 and the pressure-sensitive resistor 41-2, and the pressure-sensitive resistor 41-2 is formed so as to cover at least a part of the periphery (outer periphery) of the first contact pattern 21-2. As in the first embodiment, the pressure-sensitive resistor 41-2 is positioned over the entire area where the first contact pattern 21-2 and the second contact pattern 51-2 face each other directly above and below.

[0027] That is, the pressure-sensitive resistor 41-2 does not need to cover the entire upper surface of the first contact pattern 21-2, but may be configured to cover at least a portion of the periphery of the first contact pattern 21-2. In this way, the sizes and positions of the first contact pattern 21-2, the second contact pattern 51-2, and the pressure-sensitive resistor 41-2 can be changed in various ways. Even when the pressure-sensitive sensor 1-2 is configured in this way, the functions and effects of the present invention can be achieved.

[0028] In the above pressure-sensitive sensors 1-1, 1-2, the second wiring patterns 61, 61-2 are brought into contact with the upper and side surfaces (outer peripheral surfaces) of the pressure-sensitive resistors 41, 41-2 and then drawn out onto the substrate 10. However, it is also possible to draw out the second wiring patterns 61, 61-2 onto the substrate 10 in contact with only the side surfaces of the pressure-sensitive resistors 41, 41-2 (without coming into contact with the upper surfaces of the pressure-sensitive resistors 41, 41-2) by, for example, aligning a portion of the outer periphery of the second contact patterns 51, 51-2 with a portion of the outer periphery of the pressure-sensitive resistors 41, 41-2 and connecting the second wiring patterns 61, 61-2 to the aligned portions.

[0029] As described above, the pressure-sensitive sensors 1-1 and 1-2 are formed on the substrates 10 and 10-2 with the first contact patterns 21 and 21-2 and the first wiring patterns 31 and 31-2 connected to the first contact patterns 21 and 21-2, with the pressure-sensitive resistors 41 and 41-2 whose resistance value changes depending on pressure formed on the first contact patterns 21 and 21-2, and with the second contact patterns 51 and 51-2 formed on the pressure-sensitive resistors 41 and 41-2 at positions facing the first contact patterns 21 and 21-2. Since the pressure-sensitive sensors 1-1 and 1-2 are configured by forming first and second wiring patterns 1 and 51-2 and further extending second wiring patterns 61 and 61-2 connected to the second contact patterns 51 and 51-2 onto the substrates 10 and 10-2, the pressure-sensitive sensors 1-1 and 1-2 can be configured simply by forming various patterns on a single substrate 10 and 10-2, thereby reducing the number of parts and the thickness, and also eliminating the risk of misalignment between the first and second contact patterns 21, 51, 21-2 and 51-2 due to assembly.

[0030] Furthermore, since the pressure-sensitive sensors 1-1 and 1-2 are formed by layering the first contact patterns 21 and 21-2, the first wiring patterns 31 and 31-2, the pressure-sensitive resistors 41 and 41-2, the second contact patterns 51 and 51-2, and the second wiring patterns 61 and 61-2 by printing, various patterns can be easily and accurately formed on a single substrate 10 and 10-2, which also reduces the number of parts, manufacturing costs, and thickness. Furthermore, there is no risk of misalignment between the first and second contact patterns 21 and 21-2, 51 and 51-2 due to assembly.

[0031] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and can be modified in various ways 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 changes can be made to the shapes and positions of the substrates 10 and 10-2, first contact patterns 21 and 21-2, first wiring patterns 31 and 31-2, pressure-sensitive resistors 41 and 41-2, second contact patterns 51 and 51-2, and second wiring patterns 61 and 61-2. In the above examples, various patterns were formed using screen printing, but other printing methods (e.g., offset printing, inkjet printing), and even pattern formation methods other than printing (e.g., etching) may also be used. In the above embodiments, flexible substrates were used as the substrates 10 and 10-2, but rigid substrates may also be used.

[0032] 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]

[0033] 1-1, 1-2 Pressure sensor 10,10-2 board 21,21-2 First contact pattern 31,31-2 First wiring pattern 41,41-2 Pressure-sensitive resistor 51,51-2 Second contact pattern 61,61-2 Second wiring pattern

Claims

1. In a pressure sensor whose resistance value changes depending on the pressing force, a first contact pattern and a first wiring pattern connected to the first contact pattern are directly formed on an upper surface of a single synthetic resin substrate; a pressure-sensitive resistor whose resistance value changes in response to pressure is formed by directly laminating it on the upper surface of the first contact pattern; a second contact pattern is formed 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 of the pressure-sensitive resistor or the side surface of the pressure-sensitive resistor, and is drawn out to the upper surface of the substrate; The pressure-sensitive resistor is formed to be larger than the first contact pattern and the second contact pattern; A pressure-sensitive sensor characterized in that the size of a second contact pattern formed on the pressure-sensitive resistor, which has a surface rougher than the substrate, is formed to be larger than the size of the first contact pattern, and the second contact pattern covers the entire top surface of the first contact pattern.

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 pressure-sensitive resistor, and the second contact pattern, the second wiring pattern are all printed layers formed by directly stacking them on the substrate by printing.

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