JP6052434B2 - Method for manufacturing piezoelectric sensor - Google Patents

Description

  The present invention relates to a method of manufacturing a piezoelectric sensor that detects that a pressure is applied.

  Conventionally, in a display device including a touch panel, a piezoelectric sensor may be provided in order to detect not only a touch position on one main surface (operation surface) of the touch panel but also a pressing amount on the operation surface.

  For example, Patent Document 1 discloses a plate-like piezoelectric sensor in which a first detection electrode and a second detection electrode are provided on both surfaces of a piezoelectric sheet (piezoelectric film). For example, the piezoelectric sensor is bonded to the other main surface opposite to the operation surface of the touch panel.

  When the piezoelectric sheet (piezoelectric film) is pressed through the touch panel by pressing the operation surface of the touch panel, a voltage is generated between the first detection electrode and the second detection electrode of the piezoelectric sheet. This piezoelectric sensor can detect the amount of pressing on the operation surface by detecting the voltage.

International Publication No. 2012/137897

  Preferably, the first detection electrode and the second detection electrode are protected by covering with an insulator. Therefore, the inventor attaches a piezoelectric film on the first detection electrode of the substrate part in which the first detection electrode and the second detection electrode are formed on the same surface and are separated from each other, folds the substrate part, and performs the second detection. A method of manufacturing a piezoelectric sensor has been developed by attaching an electrode to a piezoelectric film and sandwiching the piezoelectric film between the first detection electrode and the second detection electrode.

  However, in the piezoelectric sensor having such a structure, when the substrate portion is folded and the piezoelectric film is sandwiched between the two detection electrodes, a plurality of minute bubbles may be generated between the detection electrodes and the piezoelectric film.

  In this case, the pressure is relieved by the plurality of minute bubbles, and the pressure is not sufficiently transmitted to the piezoelectric film, or the piezoelectric film and each detection electrode are partially separated by the plurality of minute bubbles. That is, the plurality of minute bubbles prevent a sufficient voltage from being generated in the piezoelectric sensor.

  Therefore, the piezoelectric sensor having such a structure has a problem that the pressure cannot be detected with high accuracy.

  The objective of this invention is providing the manufacturing method of the piezoelectric sensor which can detect a press accurately.

The present invention relates to a method for manufacturing a piezoelectric sensor including a piezoelectric film, a substrate portion, and a pusher. This method for manufacturing a piezoelectric sensor includes at least a preparation process, a first application process, a second application process, a mounting process , a first press process , and a second press process .

  The preparing step prepares a substrate portion on which the first detection electrode and the second detection electrode are formed.

  A 1st sticking process sticks a piezoelectric film on the 1st detection electrode of a board | substrate part.

  In the second attaching step, the second detection electrode is attached to the piezoelectric film, and the piezoelectric film is sandwiched between the first detection electrode and the second detection electrode.

  In the mounting step, the pusher is mounted on the main surface opposite to the piezoelectric film in a part of the region of the substrate portion sandwiching the piezoelectric film. The pusher is a member that transmits stress from the operation plate to the piezoelectric film.

In the first pressing step, the substrate portion and the presser in a state where the piezoelectric film is sandwiched are pressed.
In the second pressing step, the substrate portion in a state where the piezoelectric film is stuck on the first detection electrode is pressed prior to the second sticking step.

  In this manufacturing method, in the first pressing step, a plurality of minute bubbles between the first detection electrode and the piezoelectric film are discharged from between the first detection electrode and the piezoelectric film to the outside, A plurality of minute bubbles between the piezoelectric film can be discharged to the outside from between the second detection electrode and the piezoelectric film.

  That is, in this manufacturing method, a plurality of minute bubbles that prevent a sufficient voltage from being generated in the piezoelectric sensor can be greatly reduced.

  In particular, in the first pressing step, the press pressure applied to one main surface of the region of the substrate portion where the pusher is mounted is applied to the one main surface of the region of the substrate portion where the pusher is not mounted. Higher than the pressure.

  Therefore, a plurality of minute bubbles between the two detection electrodes and the piezoelectric film in the region of the substrate portion on which the pusher is mounted and the surrounding region can be moved to the outside.

  That is, a plurality of minute bubbles between the first detection electrode and the piezoelectric film and a space between the second detection electrode and the piezoelectric film in the mounting region of the pusher that transmits stress to the piezoelectric film and the surrounding region. The plurality of minute bubbles can be greatly reduced.

Therefore, according to the piezoelectric sensor manufactured by this manufacturing method, it is possible to detect the press with high accuracy.
Moreover, the manufacturing method including the second pressing step can discharge a plurality of minute bubbles between the first detection electrode and the piezoelectric film to the outside from between the first detection electrode and the piezoelectric film.
That is, in the manufacturing method described above, it is possible to further reduce a plurality of minute bubbles that prevent a sufficient voltage from being generated in the piezoelectric sensor.
Therefore, according to the piezoelectric sensor manufactured by this manufacturing method, pressing can be detected with higher accuracy.

Further, in this method of manufacturing a piezoelectric sensor, the preparing step includes preparing a substrate portion in which the first detection electrode and the second detection electrode are formed side by side on the same surface,
In the second attaching step, it is preferable that the substrate portion is folded, the second detection electrode is attached to the piezoelectric film, and the piezoelectric film is sandwiched between the first detection electrode and the second detection electrode.

Moreover, it is preferable that the manufacturing method of this piezoelectric sensor includes an electrode formation process. Electrode formation step, the shape formed the first detection electrode and the second detection electrode on the substrate portion.

  In this manufacturing method, a substrate portion on which a first detection electrode and a second detection electrode are formed is prepared.

  Moreover, in this invention, it is preferable that a board | substrate part is a flexible printed circuit board. Since the flexible printed board is flexible and can be greatly deformed, the board portion is easily folded back in the second attaching step.

  In the present invention, the piezoelectric sensor preferably has a piezoelectric film formed of a chiral polymer.

  In this manufacturing method, the piezoelectric sensor can reliably detect the displacement of the piezoelectric film with high sensitivity.

  In the present invention, the chiral polymer is preferably polylactic acid.

  In this manufacturing method, the piezoelectric sensor can reliably detect the displacement of the piezoelectric film with high sensitivity.

  In the present invention, the polylactic acid is preferably L-type polylactic acid.

  In this manufacturing method, the piezoelectric sensor can reliably detect the displacement of the piezoelectric film with high sensitivity.

  According to the piezoelectric sensor manufactured by the manufacturing method of the present invention, it is possible to detect the press with high accuracy.

It is a top view of the display apparatus 10 provided with the piezoelectric sensor 100 which concerns on embodiment of this invention. It is sectional drawing of the AA line shown in FIG. It is a top view of the piezoelectric sensor 100 shown in FIG. It is sectional drawing of the BB line shown in FIG. FIG. 4 is an exploded plan view of a sensor unit 16 of the piezoelectric sensor 100 shown in FIG. 3. It is sectional drawing at the time of the pressing force detection of the principal part of the display apparatus 10 shown in FIG. It is a flowchart which shows the manufacturing method of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. It is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. FIG. 15A is a diagram illustrating a result of measuring the thickness of the sensor unit 16 of the piezoelectric sensor 100 that has not undergone the pressing processes of S5, S7, and S9 illustrated in FIG. FIG. 15B is a diagram illustrating a result of measuring the thickness of the sensor unit 16 of the piezoelectric sensor 100 that has undergone the pressing steps S5, S7, and S9 illustrated in FIG. It is a flowchart which shows the 1st modification of the manufacturing method of the piezoelectric sensor 100 shown in FIG. It is a flowchart which shows the 2nd modification of the manufacturing method of the piezoelectric sensor 100 shown in FIG. FIG. 18 is a plan view showing a manufacturing process of the piezoelectric sensor 100 shown in FIG. 17. FIG. 18 is a plan view showing a manufacturing process of the piezoelectric sensor 100 shown in FIG. 17. FIG. 18 is a plan view showing a manufacturing process of the piezoelectric sensor 100 shown in FIG. 17. FIG. 18 is a plan view showing a manufacturing process of the piezoelectric sensor 100 shown in FIG. 17.

  Hereinafter, a piezoelectric sensor according to an embodiment of the present invention will be described. FIG. 1 is a plan view of a display device 10 including a piezoelectric sensor 100 according to an embodiment of the present invention. 2 is a cross-sectional view taken along line AA shown in FIG.

  The display device 10 includes an operation plate 12, a spacer 14A, a spacer 14B, a detection plate 15, a plate-shaped sensor unit 16, a columnar pusher 17, and a columnar cushion 21. The display device 10 includes a piezoelectric sensor 100 having a pusher 17, a sensor unit 16, and a detection plate 15, which will be described in detail later. Further, the display device 10 includes a housing 11 having a size that is portable. The display device 10 is, for example, a tablet or a smartphone.

  The housing 11 has a rectangular parallelepiped shape with the top surface opened. As shown in FIGS. 1 and 2, the casing 11 is fitted with an operation plate 12 so as to close the opening surface of the casing 11. The operation plate 12 is a laminated body in which a liquid crystal panel, a touch panel, and a cover glass are laminated. One main surface of the operation plate 12 (specifically, one main surface of the outermost cover glass) serves as the operation surface 101. The operation plate 12 is made of a material having translucency.

  As shown in FIGS. 1 and 2, the operation plate 12, the pusher 17, the sensor unit 16, the detection plate 15, and the cushion 21 are arranged in this order from the operation surface 101 side in the housing 11. .

  Hereinafter, the longitudinal direction of the operation surface 101 is referred to as the X direction, the short direction of the operation surface 101 is referred to as the Y direction, and the direction perpendicular to the operation surface 101 (that is, the thickness direction of the housing 11) is referred to as the Z direction. Sometimes called.

  The spacer 14 </ b> A is disposed in the vicinity of the first side surface parallel to the X direction among the side surfaces of the housing 11. The spacer 14 </ b> B is disposed in the vicinity of the second side surface (side surface facing the first side surface) of the housing 11. The spacer 14 </ b> A and the spacer 14 </ b> B are disposed at a substantially central portion in the X direction of the housing 11. The material of the spacer 14A and the spacer 14B is, for example, PET resin.

  The material of the detection plate 15 is SUS (stainless steel). The detection plate 15 is supported inside the housing 11 by spacers 14 </ b> A, 14 </ b> B, and a cushion 21 so that the main surface on the operation surface 101 side of the detection plate 15 is parallel to the operation surface 101 of the operation plate 12. .

  Therefore, spaces are formed between the detection plate 15 and the operation plate 12 and between the detection plate 15 and the bottom surface inside the housing 11. The detection plate 15 is disposed at a substantially central portion in the X direction of the housing 11. The longitudinal direction of the detection plate 15 is parallel to the Y direction.

  The main surface opposite to the operation surface 101 of the sensor unit 16 is attached to the main surface of the detection plate 15 on the operation surface 101 side. The sensor unit 16 is arranged inside the housing 11 so that the main surface on the operation surface 101 side of the sensor unit 16 is parallel to the operation surface 101 of the operation plate 12. Although details will be described later, the sensor unit 16 is attached to the detection plate 15 and constitutes a part of the piezoelectric sensor 100 (see FIG. 3 described later).

  The pusher 17 is disposed between the operation plate 12 and the sensor unit 16 so as to contact the operation plate 12 and the sensor unit 16. The pusher 17 is disposed at a substantially central portion of the detection plate 15 in the Y direction. The pusher 17 transmits stress from the operation plate 12 to the detection plate 15 and the sensor unit 16. The material of the pusher 17 is, for example, PET resin.

  The cushion 21 is disposed between the bottom surface inside the housing 11 and the detection plate 15 so as to contact the bottom surface inside the housing 11 and the detection plate 15. The cushion 21 is disposed at a substantially central portion of the detection plate 15 in the Y direction. The cushion 21 is made of a material softer than the pusher 17. The material of the cushion 21 is, for example, a foamable film.

  The cushion 21 is disposed at substantially the same position as the pusher 17 when viewed from the Z direction (in plan view), and has substantially the same shape and size as the pusher 17. That is, the cushion 21 overlaps the pusher 17 when viewed from the Z direction (direction perpendicular to the main surface of the detection plate 15).

  The cushion 21 supports the detection plate 15 and presses the detection plate 15 against the pusher 17 via the sensor unit 16. Thereby, even if the operation plate 12 is warped, the pressure applied to the pusher 12 can be reliably transmitted to the detection plate 15 without creating a gap between the operation plate 12 and the pusher 17.

  Next, the configuration of the piezoelectric sensor 100 will be described in detail.

  FIG. 3 is a plan view of the piezoelectric sensor 100 shown in FIG. 4 is a cross-sectional view taken along line BB shown in FIG. FIG. 5 is an exploded plan view of the sensor unit 16 of the piezoelectric sensor 100 shown in FIG. FIG. 5A is a plan view of the piezoelectric film 31 of the sensor unit 16. FIG. 5B is a plan view of the sensor unit 16 in a state where the substrate unit 36 and the substrate unit 37 are opened and the piezoelectric film 31 is removed.

  As shown in FIGS. 3 and 4, the piezoelectric sensor 100 includes a detection plate 15, a sensor unit 16, a pusher 17, a component mounting unit 38, and a circuit component 39. Has been placed. The component mounting unit 38 is a part of the flexible printed circuit board 30. The flexible printed circuit board 30 includes a substrate unit 36 and a substrate unit 37 that constitute a part of the sensor unit 16, and a component mounting unit 38. The material of the flexible printed circuit board 30 is a resin such as polyimide.

  On the front main surface of the component mounting portion 38, a first terminal 32 and a second terminal 33, which are conductor patterns, are formed. Further, a circuit component 39 is surface-mounted on the front main surface of the component mounting portion 38. The circuit component 39 is connected to the first detection electrode 34 and the second detection electrode 35 via the first terminal 32 and the second terminal 33.

  The pusher 17 is attached to the main surface on the operation surface 101 side in a part of the area of the sensor unit 16 with, for example, an adhesive.

  The main surface opposite to the operation surface 101 of the sensor unit 16 is adhered to the main surface on the operation surface 101 side of the detection plate 15 with an adhesive layer 90 so that the longitudinal direction thereof is the Y direction. The pressure-sensitive adhesive layer 90 is made of, for example, an epoxy adhesive.

  As shown in FIGS. 3 to 5, the sensor unit 16 includes a piezoelectric film 31, an adhesive layer 91 and an adhesive layer 92, a first detection electrode 34, a second detection electrode 35, a substrate unit 36, and a substrate unit 37. Prepare. As described above, the flexible printed board 30 includes the board part 36 and the board part 37 that constitute a part of the sensor part 16 and the component mounting part 38.

  The first detection electrode 34, the second detection electrode 35, the piezoelectric film 31, the substrate portion 36, and the substrate portion 37 each have a flat main surface and a back main surface that are flat and face each other in the thickness direction. In addition, the upper side surface in FIG. 4 is referred to as a front main surface and the lower side surface is referred to as a back main surface.

  As shown in FIG. 4, the substrate portion 37, the second detection electrode 35, the adhesive layer 91, the piezoelectric film 31, the adhesive layer 92, the first detection electrode 34, and the substrate portion 36 are arranged in this order from the front main surface side. It is laminated over the back main surface side.

  Specifically, the second detection electrode 35 is laminated on the front main surface of the piezoelectric film 31 via the adhesive layer 91, and the substrate portion 37 is further laminated on the front main surface of the second detection electrode 35. Further, the first detection electrode 34 is laminated on the back main surface of the piezoelectric film 31 via the adhesive layer 92, and the substrate portion 36 is further laminated on the back main surface of the first detection electrode 34.

  As shown in FIG. 5, the outer shape of each of the second detection electrode 35, the first detection electrode 34, the piezoelectric film 31, the substrate portion 37, and the substrate portion 36 in a plan view is a substantially rectangular shape. Here, the outer shapes of the substrate portion 37 and the substrate portion 36 are slightly larger than the outer shape of the piezoelectric film 31.

  As shown in FIGS. 3 and 5, the substrate unit 36 and the substrate unit 37 are part of the flexible printed circuit board 30. In the flexible printed circuit board 30, a slit 18 </ b> A is provided at a position that partitions the substrate unit 37 and the substrate unit 36.

  The slit 18 </ b> A extends in parallel with the long side of the substrate unit 37 (or the long side of the substrate unit 36). In the flexible printed circuit board 30, connecting portions 18B are provided on both sides of the slit 18A in the direction in which the slit 18A extends. Each connecting portion 18 </ b> B connects the substrate portion 37 and the substrate portion 36. Note that the slit 18A and the two connecting portions 18B are not necessarily provided, and may have other shapes.

  A second detection electrode 35 is formed on the back main surface of the substrate portion 37, and a first detection electrode 34 is formed on the front main surface of the substrate portion 36. That is, the first detection electrode 34 and the second detection electrode 35 are formed side by side on the same surface of the flexible printed circuit board 30.

  As shown in FIG. 4, the piezoelectric film 31 is attached to the front main surface of the first detection electrode 34 with an adhesive layer 92. The piezoelectric film 31 is attached to the back main surface of the second detection electrode 35 with an adhesive layer 91.

  The pressure-sensitive adhesive layer 91 and the pressure-sensitive adhesive layer 92 may be made of a conductive pressure-sensitive adhesive.

  As shown in FIG. 5, one end of the first terminal 32 is connected to the first detection electrode 34. On the other hand, the other end of the first terminal 32 is connected to the circuit component 39. One end of the second terminal 33 is connected to the second detection electrode 35. On the other hand, the other end of the second terminal 33 is connected to the circuit component 39.

  Accordingly, the first detection electrode 34 and the second detection electrode 35 are electrically connected to the circuit component 39 via the first terminal 32 and the second terminal 33, respectively.

  Next, the configuration of the piezoelectric film 31 will be described in detail.

The piezoelectric film 31 is molecularly oriented in a direction 19 that forms about 45 ° with respect to the long and short sides. The piezoelectric film 31 is a film mainly composed of L-type polylactic acid (PLLA). PLLA is a chiral polymer whose main chain has a helical structure, and has a property of expressing piezoelectricity by being oriented in a predetermined axial direction. This piezoelectricity is represented by a piezoelectric tensor component d ₁₄ with the film thickness direction as the first axis and the PLLA molecule orientation direction as the third axis.

In the piezoelectric film 31 having the piezoelectric tensor component d ₁₄ is a direction intersecting the long sides and short sides in the front main surface and rear main surface, specifically about 45 ° direction with respect to the long sides and short sides, By setting the direction in which the PLLA molecules are oriented, the pressing force from the thickness direction can be detected.

  However, the angle of the direction 19 in the piezoelectric film 31 is not limited to an accurate 45 ° with respect to the long side and the short side, and can be any angle close to 45 °. As the angle in the direction 19 is closer to 45 ° with respect to the long side and the short side, the pressing force from the thickness direction can be detected more efficiently.

  Accordingly, the term “approximately 45 °” as used in the present invention refers to an angle within a predetermined range centered on 45 °, for example, about 45 ° ± 10 °. These specific angles may be appropriately determined according to the overall design based on the use of the displacement sensor, the characteristics of each part, and the like.

  The piezoelectric film 31 is not limited to a film mainly composed of PLLA, and may be a film mainly composed of D-type polylactic acid (PDLA) or polyvinylidene fluoride (PVDF). However, the piezoelectricity of the piezoelectric film 31 mainly composed of a chiral polymer such as PLLA or PDLA is not expressed by the polarization of ions like ferroelectrics such as PVDF and PZT, and is characteristic of molecules. It is derived from the spiral structure.

  Therefore, the chiral polymer does not need to exhibit piezoelectricity by poling treatment like other polymers such as PVDF and piezoelectric ceramics using a piezoelectric crystal thin film, and PVDF or the like has a piezoelectric constant over time. Although fluctuations are observed and in some cases the piezoelectric constant may be significantly reduced, the piezoelectric constant of the chiral polymer is very stable over time.

  Furthermore, the chiral polymer does not generate pyroelectricity that occurs in other ferroelectric piezoelectric materials. Therefore, the piezoelectric film 31 mainly composed of a chiral polymer can obtain a detection voltage corresponding only to the pressing force without depending on the temperature at the detection position at the time of pressing detection.

  In addition, since the chiral polymer is a polymer and has flexibility, it is not damaged by a large displacement unlike piezoelectric ceramics. Therefore, the piezoelectric film 31 mainly composed of a chiral polymer is not damaged even if the displacement amount is large, and the displacement amount can be reliably detected.

Since PLLA has a very low relative dielectric constant of about 2.5, the piezoelectric output constant (= piezoelectric g constant, g = d / ε ^T ) is large when d is a piezoelectric constant and ε ^T is a dielectric constant. Value. Here, the piezoelectric g constant of PVDF having a dielectric constant ε ₃₃ ^T = 13 × ε ₀ and a piezoelectric tensor component d ₃₁ = 25 pC / N is g ₃₁ = 0.2172 Vm / N from the above formula.

On the other hand, when the piezoelectric g constant of PLLA having a piezoelectric tensor component d ₁₄ = 10 pC / N is converted to g ₃₁ , d ₁₄ = 2 × d ₃₁ , so that d ₃₁ = 5 pC / N, and the piezoelectric g constant Is g ₃₁ = 0.2258 Vm / N. Therefore, sufficient sensor sensitivity similar to PVDF can be obtained with PLLA having a piezoelectric tensor component d ₁₄ = 10 pC / N.

The inventor of the present invention has experimentally obtained PLLA with d ₁₄ = 15 to 20 pC / N. If the PLLA film is used, the piezoelectric sensor 100 can be configured with very high sensitivity.

  6 is a cross-sectional view of the main part of the display device 10 shown in FIG. 1 when a pressing force is detected. In addition, in FIG. 6, in order to demonstrate a mode that the operation board 12, the sensor part 16, and the detection board 15 bend, these bending is emphasized and shown.

  The user presses the operation surface 101 of the operation plate 12 as shown in FIG. As a result, the sensor unit 16 and the detection plate 15 of the piezoelectric sensor 100 are pressed in the thickness direction from the operation plate 12 via the pusher 17, and are bent in the thickness direction to generate charges in the piezoelectric film 31.

  That is, between the first detection electrode 34 and the second detection electrode 35, the detection voltage having a voltage value corresponding to the magnitude of the pressing force (the amount of expansion of the piezoelectric film 31) is a voltage polarity corresponding to the direction of the pressing force. It occurs in. This detection voltage is input to the circuit component 39 via the first terminal 32 and the second terminal 33 as a press detection signal (see FIG. 3).

  Next, an example of a method for manufacturing the piezoelectric sensor 100 will be described. FIG. 7 is a flowchart showing a manufacturing method of the piezoelectric sensor 100 shown in FIG. 8-13 is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG.

  In the implementation, a plurality of piezoelectric sensors 100 are manufactured in a lump. However, in this embodiment, a scene in which one piezoelectric sensor 100 is manufactured will be described in order to simplify the description.

  First, as shown in FIG. 8, a sheet-like flexible printed circuit board (FPC) 3 having a copper foil 50 attached to the entire surface of one main surface is prepared (S1). In the implementation, the flexible printed circuit board 3 may be formed with copper foil on the entire main surface in order to provide the sensor unit 30 with a shield electrode layer that shields noise.

  Next, as shown in FIG. 9, a conductor pattern is formed on one main surface of the flexible printed circuit board 3 by etching or the like (S2). Accordingly, the first detection electrode 34 connected to the first terminal 32 and the second detection electrode 35 connected to the second terminal 33 are formed side by side on the same surface of the flexible printed circuit board 3.

  Next, the flexible printed circuit board 3 is punched with a press die to form the flexible printed circuit board 30 having the shape shown in FIG. 10 (S3). Thereby, the flexible printed circuit board 30 on which the first terminal 32, the second terminal 33, the slit 18A, the connecting portion 18B, the first detection electrode 34, the second detection electrode 35, the substrate portion 36, and the substrate portion 37 are formed is prepared. The

  Next, as shown in FIG. 11, the piezoelectric film 31 is stuck on the first detection electrode 34 of the substrate portion 36 with a conductive adhesive (S4).

  Here, when the piezoelectric film 31 is stuck on the first detection electrode 34 of the substrate portion 36 with an adhesive, a plurality of minute bubbles may be generated between the first detection electrode 34 and the piezoelectric film 31. In particular, a plurality of minute bubbles are easily captured in the pressure-sensitive adhesive layer 92.

  Next, as shown in FIG. 11, the substrate portion 36 with the piezoelectric film 31 attached on the first detection electrode 34 is pressed using, for example, a roller press laminator device (S5).

  Next, as shown in FIG. 12, the substrate portion 37 is folded, the second detection electrode 35 is attached to the piezoelectric film 31 with an adhesive, and the piezoelectric film 31 is interposed between the first detection electrode 34 and the second detection electrode 35. (S6). Since the flexible printed board 30 is flexible and can be greatly deformed, the board portion 37 is easily folded back.

  Since the flexible printed circuit board 30 is folded, the flexible printed circuit board 30 is formed with one flexible printed circuit board 30, and this manufacturing method can reduce the dimensional variation of the electrode pattern. Further, when the circuit element is mounted on the flexible printed circuit board 30, electrical connection with the circuit element is easy.

  Here, when the substrate portion 37 is folded and the second detection electrode 35 is attached to the piezoelectric film 31 with an adhesive, a plurality of minute bubbles may be generated between the second detection electrode 35 and the piezoelectric film 31. . In particular, a plurality of minute bubbles are easily captured in the pressure-sensitive adhesive layers 91 and 92 (see FIG. 4).

  Next, as shown in FIG. 12, the sensor unit 16 with the piezoelectric film 31 sandwiched between the first detection electrode 34 and the second detection electrode 35 is pressed using, for example, a roller press laminator device (S7). ).

  Next, as shown in FIG. 13, the main surface of the pusher 17 on the side opposite to the piezoelectric film 31 in a part of the area of the substrate portions 36 and 37 (that is, the sensor portion 16) sandwiching the piezoelectric film 31. For example, it is mounted with an adhesive (S8).

  Next, as shown in FIG. 13, the substrate portions 36 and 37 (that is, the sensor portion 16) and the pusher 17 with the piezoelectric film 31 interposed therebetween are pressed using, for example, a roller press laminator device (S9).

  Next, as shown in FIG. 14, the main surface opposite to the operation surface 101 of the sensor unit 16 is attached to the main surface of the detection plate 15 on the operation surface 101 side with an adhesive (S10). Thereby, the sensor part 16 is affixed on the detection board 15 with an adhesive agent, and the composite_body | complex of the sensor part 16 and the detection board 15 is created. This adhesive is preferably an acrylic conductive adhesive. Note that an adhesive or pressure-sensitive adhesive having no conductivity can also be used.

  Finally, as shown in FIG. 3, the circuit component 39 is surface-mounted on the front main surface of the component mounting portion 38 (S11). Accordingly, the first detection electrode 34 and the second detection electrode 35 are connected to the circuit component 39 via the first terminal 32 and the second terminal 33.

  The piezoelectric sensor 100 according to the present embodiment can be manufactured through the steps as described above. In the pressing step of S9, the substrate portion 36 and the substrate portion 37 (that is, the sensor portion 16) in a state where the piezoelectric film 31 is sandwiched are pressed.

  Therefore, in the pressing step of S7 and S9, a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 are discharged from between the first detection electrode 34 and the piezoelectric film 31 to the outside. A plurality of minute bubbles between the second detection electrode 35 and the piezoelectric film 31 can be discharged to the outside from between the second detection electrode 35 and the piezoelectric film 31.

  That is, in this manufacturing method, it is possible to significantly reduce a plurality of minute bubbles that prevent the piezoelectric sensor 100 from generating a sufficient voltage.

  In particular, in the pressing step of S9, the pressure of the press applied to the main surface on the operation surface 101 side in the area of the sensor unit 16 where the pusher 17 is mounted is the sensor unit 16 where the pusher 17 is not mounted. It becomes higher than the pressure of the press concerning the main surface by the side of the operation surface 101 of this area | region.

  Therefore, a plurality of minute bubbles between the detection electrodes 34 and 35 and the piezoelectric film 31 in the region of the sensor unit 16 to which the pusher 17 is attached and the surrounding region can be moved to the outside. it can.

  That is, a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 in the mounting region of the pusher 17 that transmits stress from the operation plate 12 to the detection plate 15 and the sensor unit 16 and in the surrounding region. And a plurality of minute bubbles between the second detection electrode 35 and the piezoelectric film 31 can be greatly reduced.

  Therefore, according to the piezoelectric sensor 100 manufactured by this manufacturing method, it is possible to detect the press with high accuracy.

  In the pressing step of S5, the substrate portion 36 in a state where the piezoelectric film 31 is stuck on the first detection electrode 34 is pressed prior to the step of S6. Thereby, the pressing step of S5 can discharge a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 from between the first detection electrode 34 and the piezoelectric film 31 to the outside. .

  That is, in this manufacturing method, it is possible to further reduce a plurality of minute bubbles that prevent the piezoelectric sensor 100 from generating a sufficient voltage.

  Therefore, according to the piezoelectric sensor 100 manufactured by this manufacturing method, it is possible to detect the press with higher accuracy.

  Hereinafter, the piezoelectric sensor 100 that has not undergone the pressing process of S5, S7, and S9 is compared with the sensor unit 16 of the piezoelectric sensor 100 that has undergone the pressing process of S5, S7, and S9.

  FIG. 15A is a diagram illustrating a result of measuring the thickness of the sensor unit 16 of the piezoelectric sensor 100 that has not undergone the pressing steps of S5, S7, and S9. FIG. 15B is a diagram illustrating a result of measuring the thickness of the sensor unit 16 of the piezoelectric sensor 100 that has undergone the pressing processes of S5, S7, and S9.

  Here, in FIG. 15A, a plurality of piezoelectric sensors 100 that have not undergone the pressing steps of S5, S7, and S9 are prepared, and the height Z of each point in the Y direction of the sensor unit 16 of each piezoelectric sensor 100 is shown. The experimental result which measured was shown. FIG. 15B shows an experimental result in which a plurality of piezoelectric sensors 100 that have undergone the pressing processes of S5, S7, and S9 are prepared, and the thickness Z at each point in the Y direction of the sensor unit 16 of each piezoelectric sensor 100 is measured. Is shown.

  In addition, Y1 in FIG. 15 (A) and FIG. 15 (B) has shown the range of the area | region of the sensor part 16 with which the pusher 17 is mounted | worn. Y2 in FIGS. 15A and 15B indicates a range of a region located around the region Y1. Y3 in FIGS. 15A and 15B indicates the range of the region outside the surrounding region Y2.

  According to the experiment, in the piezoelectric sensor 100 that has not undergone the pressing process, the surrounding region Y2 has been raised from the outer region Y3, whereas in the piezoelectric sensor 100 that has undergone the pressing process, such a bump has not occurred.

  From this experimental result, in the piezoelectric sensor 100 that has not undergone the pressing process, a plurality of gaps are provided between the detection electrodes 34 and 35 and the piezoelectric film 31 in the surrounding area Y2 of the area of the sensor unit 16 to which the pusher 17 is attached. It is thought that microbubbles are generated. From this experimental result, it is considered that a plurality of minute bubbles move from the periphery Y2 to the outer side Y3 through the pressing steps of S5, S7, and S9.

  That is, the first detection electrode 34 and the piezoelectric element in the peripheral region Y2 of the pusher 17 that transmits stress from the operation plate 12 to the detection plate 15 and the sensor unit 16 through the pressing steps S5, S7, and S9. It is considered that a plurality of minute bubbles between the film 31 and a plurality of minute bubbles between the second detection electrode 35 and the piezoelectric film 31 can be greatly reduced.

  Therefore, according to the piezoelectric sensor 100 manufactured by this manufacturing method, it is possible to detect the press with high accuracy.

  Moreover, the following modifications can be adopted for the manufacturing method of the piezoelectric sensor 100.

  FIG. 16 is a flowchart showing a first modification of the manufacturing method of the piezoelectric sensor 100 shown in FIG. The manufacturing method of the first modification shown in FIG. 16 is different from the manufacturing method shown in FIG. 7 in that the mounting process of the circuit component 39 shown in S11 of FIG. . In the manufacturing method of the 1st modification shown in FIG. 16, it carries out between S2 and S3.

  In the mounting process, the circuit component 39 is mounted using, for example, a reflow apparatus. Therefore, when the piezoelectric film 31 is formed of a material that is easily affected by temperature, it is preferable to perform the mounting process before the attaching process of the piezoelectric film 31.

  FIG. 17 is a flowchart showing a second modification of the manufacturing method of the piezoelectric sensor 100 shown in FIG. 18-21 is a top view which shows the manufacturing process of the piezoelectric sensor 100 shown in FIG. The manufacturing method of the second modification shown in FIG. 17 is different from the manufacturing method of the first modification shown in FIG. 16 in that the process of S6 shown in FIG. 16 is deleted and the processes of S31 to S34 are added. . This will be described in detail below.

  First, as shown in FIG. 8, a sheet-like flexible printed circuit board 3 is prepared in which a copper foil 50 is attached to the entire surface of one main surface (S1). In the implementation, the flexible printed circuit board 3 may be formed with copper foil on the entire main surface in order to provide the sensor unit 30 with a shield electrode layer that shields noise.

  Next, a conductor pattern is formed on one main surface of the flexible printed circuit board 3 by etching or the like (S2). Thereby, the 2nd detection electrode 35 connected to the 2nd terminal 133 (refer FIG. 18) is formed in the front main surface of the flexible printed circuit board 3. FIG.

  Next, the circuit component 39 is surface-mounted on the front main surface of the flexible printed circuit board 3 (S21). As a result, the second detection electrode 35 is connected to the circuit component 39 via the second terminal 133.

  Next, the flexible printed circuit board 3 is punched with a press die to form the flexible printed circuit board 130 having the shape shown in FIG. 18 (S3). Thereby, the flexible printed circuit board 130 on which the second terminal 133, the second detection electrode 35, and the substrate unit 37 are formed is prepared. The second terminal 133 includes a pad P1.

  Next, as shown in FIG. 19, the piezoelectric film 31 is stuck on the second detection electrode 35 of the substrate portion 37 with a conductive adhesive (S4).

  Here, when the piezoelectric film 31 is stuck on the second detection electrode 35 of the substrate portion 37 with an adhesive, a plurality of minute bubbles may be generated between the second detection electrode 35 and the piezoelectric film 31. In particular, a plurality of minute bubbles are easily captured in the pressure-sensitive adhesive layer 92.

  Next, as shown in FIG. 19, the substrate part 37 in a state where the piezoelectric film 31 is stuck on the second detection electrode 35 is pressed using, for example, a roller press laminator device (S5).

  Next, as shown in FIG. 8, a sheet-like flexible printed circuit board 3 is prepared in which a copper foil 50 is attached to the entire surface of one main surface (S31). This step has the same contents as the above-described step S1.

  Next, a conductor pattern is formed on one main surface of the flexible printed circuit board 3 by etching or the like (S32). This step has the same contents as the step S2 described above. Thereby, the 1st detection electrode 34 connected to the 1st terminal 132 (refer FIG. 20) is formed in the front main surface of the flexible printed circuit board 3. FIG.

  Next, the flexible printed circuit board 3 is punched with a press die to form the flexible printed circuit board 230 having the shape shown in FIG. 20 (S33). This step has the same contents as the step S3 described above. However, FIG. 20 differs from FIG. 18 in that the conductor pattern is formed on the back surface of the flexible printed board 230. Thereby, the flexible printed circuit board 230 on which the first terminal 132, the first detection electrode 34, and the substrate section 36 are formed is prepared. The first terminal 132 includes a pad P2.

  Then, as shown in FIG. 21, the two flexible printed boards 130 and 230 are pasted with an adhesive so that the pads P1 and P2 are connected (S34). The pads P1 and P2 are made conductive by conductive adhesive, solder, caulking, wire bonding, or the like. As a result, the first detection electrode 34 and the second detection electrode 35 are connected to the circuit component 39 via the first terminal 132 and the second terminal 133. That is, the same sensor unit 16 as that in FIG. 12 is obtained.

  Here, when the two flexible printed boards 130 and 230 are stuck with an adhesive, a plurality of minute bubbles may be generated between the first detection electrode 34 and the piezoelectric film 31. In particular, a plurality of minute bubbles are easily captured in the pressure-sensitive adhesive layers 91 and 92 (see FIG. 4).

  Thereafter, the same steps (S7 to S10, FIGS. 13 and 14) as those in the manufacturing method shown in FIGS. 7 and 16 are performed. Therefore, explanation is omitted.

  Also in the second modified example, the piezoelectric sensor 100 of the present embodiment is manufactured through the above-described steps. In the pressing step of S7 and S9, the substrate portion 36 and the substrate portion 37 (that is, the sensor portion 16) in a state where the piezoelectric film 31 is sandwiched are pressed.

  Therefore, in the pressing step of S7 and S9, a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 are discharged from between the first detection electrode 34 and the piezoelectric film 31 to the outside. A plurality of minute bubbles between the detection electrode 35 and the piezoelectric film 31 can be discharged to the outside from between the second detection electrode 35 and the piezoelectric film 31.

  That is, also in the manufacturing method of the second modified example, it is possible to significantly reduce a plurality of minute bubbles that prevent the piezoelectric sensor 100 from generating a sufficient voltage.

  In particular, in the pressing step of S9, the pressure of the press applied to the main surface on the operation surface 101 side in the area of the sensor unit 16 where the pusher 17 is mounted is the sensor unit 16 where the pusher 17 is not mounted. It becomes higher than the pressure of the press concerning the main surface by the side of the operation surface 101 of this area | region.

  Therefore, a plurality of minute bubbles between the detection electrodes 34 and 35 and the piezoelectric film 31 in the region of the sensor unit 16 to which the pusher 17 is attached and the surrounding region can be moved to the outside. it can.

  That is, a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 in the mounting region of the pusher 17 that transmits stress from the operation plate 12 to the detection plate 15 and the sensor unit 16 and in the surrounding region. And a plurality of minute bubbles between the second detection electrode 35 and the piezoelectric film 31 can be greatly reduced.

  Therefore, according to the piezoelectric sensor 100 manufactured by the manufacturing method of the second modification, it is possible to detect the press with high accuracy.

  In the pressing step of S5, the substrate portion 36 in a state where the piezoelectric film 31 is stuck on the first detection electrode 34 is pressed prior to the step of S6. Thereby, the pressing step of S5 can discharge a plurality of minute bubbles between the first detection electrode 34 and the piezoelectric film 31 from between the first detection electrode 34 and the piezoelectric film 31 to the outside. .

  That is, in the manufacturing method of the second modified example, it is possible to further reduce a plurality of minute bubbles that prevent the piezoelectric sensor 100 from generating a sufficient voltage.

  Therefore, according to the piezoelectric sensor 100 manufactured by the manufacturing method of the second modified example, it is possible to detect the press more accurately.

  Further, in the manufacturing method of the second modified example, the bending of S6 in FIG. 7 is not performed. Therefore, in the manufacturing method of the second modified example, there is no portion where the electrode bends, and disconnection hardly occurs. Further, in the manufacturing method of the second modified example, there is no deformation in the restoring direction called spring back due to the reaction force generated by bending the flexible printed circuit board. Moreover, since it is difficult to automate the process of bending the flexible printed circuit board, the manufacturing method of the second modification can reduce the manufacturing cost.

  In the manufacturing method of the second modified example, the mounting process for mounting the circuit component 39 is performed before the attaching process of the piezoelectric film 31, but the attaching process of the piezoelectric film 31 as in the manufacturing method shown in FIG. You may go after.

  In the above-described embodiment, the planar shape of the piezoelectric film 31 is a rectangular shape, but is not limited thereto. In implementation, the planar shape of the piezoelectric film may be other planar shapes such as a square shape, a circular shape, a trapezoidal shape, a parallelogram shape, a polygonal shape of quadrilateral or more, an elliptical shape, an oval shape, or the like.

  Moreover, in the said embodiment, although the material of the detection plate 15 is SUS (stainless steel), it is not restricted to this. In implementation, the material of the detection plate 15 may be a glass plate, for example.

  Moreover, in the said embodiment, although the piezoelectric sensor 100 has the sensor part 16 and the detection board 15, it does not restrict to this. In implementation, for example, the sensor unit 16 may be attached to the operation plate 12 instead of the detection plate 15, and the piezoelectric sensor 100 may have the operation plate 12 instead of the detection plate 15.

  Finally, the description of each of the embodiments should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

DESCRIPTION OF SYMBOLS 3 ... Flexible printed circuit board 10 ... Display apparatus 11 ... Housing | casing 12 ... Operation board 14A, 14B ... Spacer 15 ... Detection board 16 ... Sensor part 17 ... Pusher 18A ... Slit 18B ... Connection part 21 ... Cushion 30 ... Flexible printed circuit board 31 ... piezoelectric film 32 ... first terminal 33 ... second terminal 34 ... first detection electrode 35 ... second detection electrodes 36, 37 ... substrate part 38 ... component mounting part 39 ... circuit component 50 ... copper foil 90 ... adhesive layer 91 , 92 ... conductive adhesive layer 100 ... piezoelectric sensor 101 ... operation surface 130, 230 ... flexible printed circuit board 132 ... first terminal 133 ... second terminals P1, P2 ... pads

Claims (7)

A preparation step of preparing a substrate portion on which the first detection electrode and the second detection electrode are formed;
A first pasting step of pasting a piezoelectric film on the first detection electrode of the substrate portion;
A second attaching step of attaching the second detection electrode to the piezoelectric film and sandwiching the piezoelectric film between the first detection electrode and the second detection electrode;
A mounting step of mounting the pusher on a main surface opposite to the piezoelectric film in a part of the region of the substrate portion sandwiching the piezoelectric film;
A first pressing step of pressing the substrate portion and the pusher in a state of sandwiching the piezoelectric film;
Prior to the second pasting step, a second pressing step of pressing the substrate portion in a state where the piezoelectric film is pasted on the first detection electrode;
A method for manufacturing a piezoelectric sensor, comprising: The preparing step prepares the substrate part in which the first detection electrode and the second detection electrode are formed on the same surface and separated from each other,
In the second attaching step, the substrate portion is folded, the second detection electrode is attached to the piezoelectric film, and the piezoelectric film is sandwiched between the first detection electrode and the second detection electrode.
The method for manufacturing a piezoelectric sensor according to claim 1. Including an electrode forming step of forming the first detection electrode and the second detection electrode on the substrate portion,
The manufacturing method of the piezoelectric sensor of Claim 1 or 2.   The method for manufacturing a piezoelectric sensor according to claim 1, wherein the substrate unit is a flexible printed circuit board.   The method for manufacturing a piezoelectric sensor according to claim 1, wherein the piezoelectric film is formed of a chiral polymer.   The method for manufacturing a piezoelectric sensor according to claim 5, wherein the chiral polymer is polylactic acid.   The method for manufacturing a piezoelectric sensor according to claim 6, wherein the polylactic acid is L-type polylactic acid.

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