JP5383991B2 - Capacitance sensor and manufacturing method thereof - Google Patents

Description

  The present invention is used for applications such as PDAs, handheld terminals and other portable information terminals, copiers, facsimile and other office equipment, smartphones, mobile phones, portable game devices, electronic dictionaries, car navigation systems, small PCs, various home appliances, etc. The present invention relates to a capacitance sensor having a well-defined electrode group and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, an apparatus in which XY coordinates can be input by bringing an operator's finger into contact with an electrostatic capacity method has been put into practical use. As such a conventional example, for example, in Patent Document 1, a plurality of first electrodes extending in parallel to each other are provided on the surface of the film body, and the back surface of the film body is provided with respect to the first electrode group. A plurality of parallel second electrodes extending in a direction perpendicular to each other and outputting a current value corresponding to the capacitance between the first electrode group and the second electrode group A sensor is disclosed.

  However, in the actual mass production of the capacitance sensor 101, instead of providing the first electrode group and the second electrode group on the front and back surfaces of the film body alone, (1) a conductive film is previously formed on one surface. Two commercially available transparent films are prepared, and the first transparent film 102 is patterned by etching the conductive film to form the first electrode group 105, and the second transparent film 104 is patterned by etching the conductive film. After the second electrode group 106 is formed, these are stacked with the transparent adhesive layer 103 so that the electrode forming surfaces face in the same direction (see FIGS. 10 and 11), or (2) the first The first transparent film 102 on which the electrode group 105 is formed and the second transparent film 104 on which the second electrode group 106 is formed are bonded together with the electrode formation surface inside (FIG. 1). Reference) to have.

Japanese Patent No. 3426847

  However, the capacitance sensor 101 having the configurations (1) and (2) using a commercially available transparent film in which a conductive film is formed on one side in advance has the following problems.

  When the first transparent film 102 in which the first electrode group 105 is formed and the second transparent film 104 in which the second electrode group 106 is formed are bonded together by pressing with a pressure roll or a press, Since the first transparent film 102 and the second transparent film 104 change in size due to the pressure, the respective dimensions of the electrodes of the first electrode group 105 and the respective electrodes of the second electrode group 106 formed on them. There is a problem that crazy will occur.

  Further, when an ITO film is used as the first electrode group 105 and the second electrode group 106, heating is performed for the purpose of crystallization, but when heating is performed after bonding as in (1) and (2) above, Since the exposed second electrode group 106 needs to be sufficiently crystallized, the heating temperature is inevitably increased. As a result, the dimensions of the first transparent film 102 and the second transparent film 104 also change, and deviations occur between the respective electrodes of the first electrode group 105 and between the respective electrodes of the second electrode group 106. End up.

  In addition, there is another problem that the bonding accuracy itself of the first transparent film 102 on which the first electrode group 105 is formed and the second transparent film 104 on which the second electrode group 106 is formed is extremely low. .

  Therefore, when a very fine electrode group is required for the capacitance sensor, it is extremely difficult to manufacture.

  Accordingly, the present invention provides a capacitance sensor in which an extremely fine electrode group is formed with high accuracy in consideration of the problems of the prior art as described above.

The manufacturing method of the capacitance sensor of the present invention is made of a resin of any one of polycarbonate, polyamide, polyetherketone, acrylic, polyethylene terephthalate, and polybutylene terephthalate, and a conductive film is formed on one side. A pair of transparent films is prepared, and the transparent films are bonded to each other so that the conductive film is on the outside, and then the one conductive film is patterned by etching to form a plurality of electrodes arranged in parallel. One electrode group is formed, and the other conductive film is patterned by etching to form a second electrode group composed of a plurality of electrodes arranged in parallel and orthogonal to the first electrode group. Configured.

According to the present invention, after the material is bonded to the transparent film between the conductive film is formed on one surface of a resin described above, the patterning the conductive film first electrode group 5 and the second electrode Since the process order of obtaining the group 6 does not cause a problem as in the prior art, it is possible to obtain a capacitance sensor in which an extremely fine electrode group is formed with high accuracy.

  Hereinafter, the configuration of the capacitance sensor 1 according to the present invention will be described in detail based on the embodiments shown in the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a capacitance sensor according to the present invention. In the figure, the capacitance sensor 1 includes a first transparent film 2, a second transparent film 4 that is entirely bonded to the back surface of the first transparent film 2 with a transparent adhesive layer 3, A first electrode group 5 composed of a plurality of electrodes arranged in parallel to the surface of the first transparent film 2; a plurality of electrodes arranged in parallel to the back surface of the second transparent film 4; A first electrode group 5 and a second electrode group 6 orthogonal to the first electrode group 5.

  The material of the first transparent film 2 and the second transparent film 4 may be any material as long as it is transparent. For example, engineering plastics such as polycarbonate (PC), polyamide, or polyether ketone An acrylic film, a polyethylene terephthalate (PET) film, or a polybutylene terephthalate film can be used. The thicknesses of the first transparent film 2 and the second transparent film 4 are not particularly limited. However, in order to reduce the thickness of the capacitance sensor, it is preferable to select one that is as thin as possible within a range where stable mass production is possible. .

  The transparent adhesive layer 3 is selected from a transparent and reliable material such as acrylic pressure sensitive adhesive, UV adhesive, thermoplastic adhesive, thermosetting adhesive, and the like.

  The first electrode group 5 and the second electrode group 6 are composed of conductive films. As the material of the conductive film, a metal oxide film such as tin oxide, indium oxide, antimony oxide, zinc oxide, cadmium oxide, indium tin oxide (ITO), or antimony-doped tin oxide (ATO), or these metals A composite film mainly composed of an oxide, or a metal such as gold, silver, copper, tin, nickel, aluminum, or palladium, a transparent polymer containing a conductive filler, or a conductive polymer such as polyethylenedioxythiophene (PEDOT). There is a thin film. As a method for forming the conductive film, for example, a vacuum deposition method, sputtering, ion plating, CVD method, roll coater method, or the like can be used. The first electrode group 5 and the second electrode group 6 are formed in an electrode pattern by etching away only unnecessary portions as will be described later.

  The electrode patterns of the first electrode group 5 and the second electrode group 6 are parallel to each other as shown in FIG. A plurality of strip electrodes having a minimum electrode width of 10 to 200 μm are arranged, and the first electrode group 5 and the second electrode group 6 are formed to be orthogonal to each other. In addition, in FIG. 2, although the strip | belt-shaped electrode is drawn by equal width, it is not limited to this shape, A well-known electrode shape is possible. For example, it is possible to form a band-like electrode in which rhombuses as shown in FIG. 9 are continuous.

  The feature of the present invention is that the first electrode group 5 and the second electrode group 6 are located on the outer sides of the first transparent film 2 and the second transparent film 4, respectively. By adopting such a stacking order, after the transparent film having the conductive film formed on one side is bonded, the conductive film is patterned to form the first electrode group 5 and the second electrode group 6. Can be obtained. That is, it is positioned between the electrodes of the first electrode group 24, between the electrodes of the second electrode group 25, and between the first electrode group 24 and the second electrode group 25 by bonding. There will be no deviation.

  Further, when an ITO film is used as the first electrode group 5 and the second electrode group 6, since any electrode group is exposed, a high temperature is not required for crystallization. Therefore, the first transparent film 2 and the second transparent film 4 do not change in size due to crystallization, and are positioned between the electrodes of the first electrode group 24 and between the electrodes of the second electrode group 25. Misalignment does not occur.

  In the case of the capacitance sensor 1 having the configuration shown in FIG. 1, protective layers 32 and 33 may be provided on the outermost surface in order to protect the exposed first electrode group 5 and the second electrode group 6. Good (see FIG. 3). The protective layers 32 and 33 are made of a transparent material. For example, a transparent plastic film may be bonded or a transparent polymer may be applied. Further, a transparent adhesive layer for mounting on a window panel or an LCD panel may also serve as the protective layers 32 and 33. The protective layers 32 and 33 are formed so as to expose the connection terminal portions, respectively. 3 in FIG. 3 is a connection terminal portion of the second electrode group 6.

  Further, a thickness adjusting layer 30 may be provided between the first transparent film 2 and the second transparent film 4. As described above, in the implementation of a capacitance sensor using a film as a base material, a commercially available transparent film having a conductive film previously formed on one side is conventionally used. Therefore, the freedom degree of the thickness of the capacitance sensor is low. By providing the thickness adjusting layer 30, the thickness of the capacitance sensor can be arbitrarily set. A transparent material is selected as the material of the thickness adjusting layer 30. For example, a transparent plastic film capable of obtaining a desired thickness can be bonded to at least one of the first transparent film 2 and the second transparent film 4, or a transparent polymer can be applied. .

  Further, a dielectric constant adjusting layer 31 may be provided between the first transparent film 2 and the second transparent film 4. As described above, in the implementation of a capacitance sensor using a film as a base material, a commercially available transparent film having a conductive film previously formed on one side is conventionally used. Therefore, the freedom degree of the dielectric constant of the base material of the capacitance sensor is low. By providing the dielectric constant adjusting layer 31 as described above, the dielectric constant of the substrate of the capacitance sensor can be arbitrarily set. The dielectric constant adjusting layer 31 is made of a transparent material. For example, a transparent plastic film capable of obtaining a desired dielectric constant is bonded to at least one of the first transparent film 2 and the second transparent film 4, or a transparent polymer is applied. it can.

  In addition, the capacitance sensor 1 of the present invention may form a lower resistance routing circuit around the sensor. In that case, the material may be a conductive paste printing layer such as silver paste or carbon paste, or a conductive layer. A metal layer formed by plating, a pattern etching layer of a metal thin film, or the like is used.

  Hereinafter, a method for manufacturing a capacitance sensor according to the present invention will be described in detail based on the embodiments shown in the drawings.

  6 is a cross-sectional view showing a process of forming the first electrode group of the capacitance sensor of FIG. 1, and FIG. 7 is a cross-sectional view showing a process of forming the second electrode group of the capacitance sensor of FIG. is there. In these figures, the manufacturing method of the capacitance sensor 1 is a set of transparent films 12 and 13 having conductive films 10 and 11 formed on one side (see FIG. 6a). After the conductive films 10 and 11 are bonded to each other (see FIG. 6b), the first electrode group 24 including a plurality of electrodes arranged in parallel by patterning the one conductive film 10 by etching. (See FIGS. 6c to 6h), and the second conductive film 11 is patterned by etching to form a plurality of electrodes arranged in parallel and orthogonal to the first electrode group 24. The electrode group 25 is formed (see FIG. 7).

  As shown in FIGS. 6a and 6b, at the stage where the transparent films 12 and 13 are bonded together, the conductive films 10 and 11 formed on the transparent films 12 and 13 are not yet patterned. Of course, the bonding is performed between the electrodes of the first electrode group 24, between the electrodes of the second electrode group 25, and between the first electrode group 24 and the second electrode group 25. No effect on position accuracy.

  In order to form the first electrode group 24, first, a resist film 14 is formed on the entire surface of the one conductive film 10 (see FIG. 6c). The resist film 14 is formed by coating the conductive film 10 with a photocurable or photolytic photosensitive resist solution. As the material of the photosensitive resist film 14, for example, an acrylic, polyvinyl cinnamate-based, synthetic rubber-based, or novolac-based photocurable or photodegradable photosensitive resist material is used. In FIG. 6 b, the other conductive film 11 is covered with a re-peelable protective film 22, but it cannot be covered after forming the resist film 14, so that the resist film 14 is formed. Coat in advance. The protective film 22 protects the other conductive film 11 in each step after development described later.

  Next, the exposure light 18 is transmitted through the non-mask portion of the photomask 16 to expose the resist film 14 in a desired pattern (see FIG. 6d). In this case, in the photomask 16, when a photocurable material is used for the resist film 14, a portion corresponding to the pattern of the first electrode group 24 to be formed transmits light. Further, in the photomask 16, when a photolytic material is used for the resist film 14, a portion corresponding to the pattern of the first electrode group 24 to be formed shields light. As the exposure light 18 used for exposure, sunlight, mercury lamp, xenon lamp, arc lamp, argon laser light or the like is used.

  Next, the exposed resist film 14 is developed, and the resist film (see FIG. 6e) of the exposed (or not) portion is removed to obtain a resist pattern 20 (see FIG. 6f). When the resist film 14 is a photo-curing type, development is performed by selectively removing uncured portions by using sodium carbonate or the like as a developer. Further, when the resist film 14 is of a photolytic type, it is performed by selectively removing the decomposed portion by using sodium metasilicate as a developing solution. Since the resist pattern 20 obtained by the photo process can be formed very finely, it can have a dimension corresponding to an electrode group pattern having a minimum electrode width of 10 to 200 μm.

  Next, the conductive film 10 is etched. At this time, the portion of the conductive film 10 covered with the resist pattern 20 remains without being etched (see FIG. 6 g), and the patterned conductive film 10 becomes the first electrode group 24. As an etching agent, for example, an alkaline etching solution such as ammonium persulfate, ammonium, or ammonium chloride or an acidic etching solution such as cupric chloride, ferric chloride, chromic acid / sulfuric acid mixture, hydrogen peroxide solution / sulfuric acid mixture, or the like is used. .

  Next, the resist pattern 20 covering the first electrode group 24 is removed, and the protective film 22 covering the other conductive film 11 is peeled off (see FIG. 6h). For removing the resist pattern 20, for example, an aqueous solution of sodium hydroxide or potassium hydroxide is used.

  Next, following the first electrode group 24, the second electrode group 25 orthogonal to the first electrode group 24 is formed. First, after the already formed first electrode group 24 is covered with a protective film 23, a resist film 15 is formed on the entire surface of the other conductive film 11 (see FIGS. 7a and 7b). FIG. 7b is a cross-sectional view of FIG. 7a cut along the line AA, and the following steps (FIGS. 7c to g) will be described with reference to the cross section of the line AA. The material and the formation method of the resist film 15 are the same as those of the resist film 14 described above. The protective film 23 is the same as the protective film 22 described above.

  Next, the exposure light 19 is transmitted through the non-mask portion of the photomask 17 to expose the resist film 15 in a desired pattern (see FIG. 7c). At this time, the photomask 17 is easily positioned with respect to the already formed first electrode group 24. Therefore, the finally obtained electrostatic capacitance sensor 1 has excellent positional accuracy between the first electrode group 24 and the second electrode group 25. The photomask 17 and exposure light 19 are the same as those of the photomask 16 and exposure light 18 described above.

  Next, the exposed resist film 15 is developed, and the resist film in the exposed (or not) portion is removed to obtain a resist pattern 21 (see FIG. 7e). The developer used for developing the resist film 15 is the same as that used for developing the resist film 14 described above.

  Next, the conductive film 11 is etched. At this time, the portion of the conductive film 11 covered with the resist pattern 21 remains without being etched (see FIG. 7 f), and the patterned conductive film 11 becomes the second electrode group 25. The etching solution used for etching the conductive film 11 is the same as that for the etching of the conductive film 10 described above.

  Next, the resist pattern 21 covering the second electrode group 25 is removed, and finally the protective film 23 covering the first electrode group 24 is peeled off (see FIG. 7g). An electrostatic capacitance sensor 1 as shown in FIG.

  6 and 7, the resist patterns 20 and 21 are formed by a photo process, but may be printed by using a printing resist material. A resist pattern formed by a photo process and a printed resist pattern may be used in combination.

  6 and 7, the first electrode group 24 is formed and then the second electrode group 25 is formed. The manufacturing process of the capacitance sensor 1 according to the present invention is not limited to this. It is not limited. For example, when using a photo-curing type photoresist material or printing a resist pattern as described above, the transparent films 12 and 13 having the conductive films 10 and 11 formed on one side as shown in FIG. After bonding them together, the conductive films 10 and 11 on both sides are covered with the resist patterns 20 and 21, respectively, and then the conductive films 10 and 11 on both sides are etched together to form the capacitance sensor 1. The first electrode group 24 and the second electrode group 25 can be formed simultaneously, and the number of steps can be reduced (see FIG. 8).

<Example 1>
A pair of commercially available PET films (thickness 38 μm) with a conductive film made of ITO formed on one side by a sputtering method, and a transparent acrylic film with a thickness of 25 μm so that the conductive films are on the outside It bonded together with the acid adhesive.

  Next, the one conductive film was patterned by etching to form a first electrode group composed of a plurality of electrodes arranged in parallel. That is, first, the entire surface of the other conductive film is covered with a protective film, and then a photo-curable dry film resist is bonded to the entire surface of the one conductive film, and then ultraviolet light is transmitted through the non-masked portion of the photomask. Then, a portion corresponding to the pattern of the first electrode group of the dry film resist is exposed. Next, the exposed dry film resist is developed with sodium carbonate, and the dry film resist in the portion not exposed to light is removed to obtain a resist pattern. Next, the conductive film is etched with ferric chloride. At this time, the portion of the conductive film covered with the resist pattern remains without being etched. Next, the resist pattern covering the patterned conductive film is removed with 3% sodium hydroxide, and further, the protective film covering the other conductive film is peeled off, whereby an electrode having a width of 20 μm at the finest detail. However, the 1st electrode group formed with the equal pitch of 50 micrometers was obtained.

  Next, the other conductive film was patterned by etching to form another electrode group composed of a plurality of electrodes arranged in parallel and orthogonal to the first electrode group. That is, first, the first electrode group already formed is covered with a protective film, and then a photo-curable dry film resist is bonded to the entire surface of the other conductive film, and then ultraviolet light is applied to the non-masked portion of the photomask. The portion corresponding to the pattern of the second electrode group of the dry film resist is exposed through light. Next, the exposed dry film resist is developed with sodium carbonate, and the dry film resist in the portion not exposed to light is removed to obtain a resist pattern. Next, the conductive film is etched with ferric chloride. At this time, the portion of the conductive film covered with the resist pattern remains without being etched. Next, the resist pattern that covers the patterned conductive film is removed with 3% sodium hydroxide, and finally the protective film that covers the first electrode group is peeled off, so that the width is 20 μm at the finest. The 2nd electrode group in which the electrode of this was formed was obtained.

  Further, after the first electrode group and the second electrode group are crystallized by heating, a transparent silicon-based self-adhesive rubber layer having a thickness of 50 μm as a protective layer on the surface having the first electrode group Is applied so that only the connection terminal portion is exposed, and a transparent acrylic UV curable resin is applied as a protective layer to the surface having the second electrode group so as to expose only the connection terminal portion, and is cured by UV irradiation. I let you. Thereafter, the outer shape was cut to a predetermined size to obtain a capacitance sensor.

<Comparative Example 1>
Except for using the same two commercially available transparent films with ITO film as in Example 1, patterning each ITO film, and then laminating the films to obtain a laminated structure as in prior art (1). Same as 1.

<Comparative example 2>
Except for using the same two commercially available transparent films with ITO film as in Example 1, patterning each ITO film, and then laminating the films to obtain a laminated structure as in prior art (2). Same as 1.

  The electrostatic capacitance sensor of Example 1 has an equal pitch of 50 μm between the electrodes of the first electrode group and between the electrodes of the second electrode group, and the first electrode group and the second electrode group. The positional accuracy between the electrode groups was 20 μm. On the other hand, the capacitance sensors of Comparative Example 1 and Comparative Example have different pitches between the electrodes of the first electrode group and between the electrodes of the second electrode group. The positional accuracy between this electrode group and the second electrode group was extremely coarse, 400 μm.

  It is to be noted that, by appropriately combining any of the various embodiments, the effects possessed by them can be produced. Although the present invention has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such changes and modifications are to be understood as included within the scope of the present invention as long as they do not depart from the scope of the present invention.

It is sectional drawing which shows one Example of the electrostatic capacitance sensor which concerns on this invention. It is a perspective exploded view showing one example of the capacitance sensor shown in the present invention. It is sectional drawing which shows one Example of the electrostatic capacitance sensor which concerns on this invention. It is sectional drawing which shows one Example of the electrostatic capacitance sensor which concerns on this invention. It is sectional drawing which shows one Example of the electrostatic capacitance sensor which concerns on this invention. It is sectional drawing which shows the process in which one electrode group of the electrostatic capacitance sensor of FIG. 1 is formed. It is sectional drawing which shows the process in which the other electrode group of the electrostatic capacitance sensor of FIG. 1 is formed. It is sectional drawing which shows the process in which both the electrode groups of the electrostatic capacitance sensor of FIG. 1 are formed simultaneously. It is the elements on larger scale which show one Example of the electrode shape of the electrostatic capacitance sensor which concerns on this invention. It is sectional drawing which shows the example of the electrostatic capacitance sensor which concerns on a prior art. It is sectional drawing which shows another example of the electrostatic capacitance sensor which concerns on a prior art. It is a perspective exploded view of the capacitance sensor of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Capacitance sensor 2,102 1st transparent film 3,103 Transparent adhesive layer 4,104 2nd transparent film 5,105 1st electrode group 6,106 2nd electrode group 10,11 Conductive film 12, 13 Transparent film 14, 15 Resist film 16, 17 Photo mask 18, 19 Exposure light 20, 21 Resist pattern 22, 23 Protective film 24, 25 Electrode group 30 Thickness adjusting layer 31 Dielectric constant adjusting layer 32, 33 Protecting layer 34 Connection terminal

Claims (1)

Prepare a set of transparent films made of polycarbonate, polyamide, polyetherketone, acrylic, polyethylene terephthalate, or polybutylene terephthalate resin and having a conductive film on one side. After bonding the conductive films so that the conductive film is on the outside, the first conductive film is patterned by etching to form a first electrode group composed of a plurality of electrodes arranged in parallel, and the other conductive film A method of manufacturing a capacitance sensor, comprising: forming a second electrode group formed of a plurality of electrodes arranged in parallel by patterning a conductive film by etching and orthogonal to the first electrode group.

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