TWI492357B - Touch panel and circuit structure thereof - Google Patents

Description

Touch panel and its circuit structure

The present invention relates to a circuit structure, and more particularly to a circuit structure of a touch panel.

As electronic devices become more compact and lighter, display screens for display electronic devices are becoming lighter and thinner, and display screens with touch functions typically include a display module (such as liquid crystal). The display module and a touch panel are disposed on the display module. The touch panel generally includes at least one sensing substrate, a flexible printed circuit (FPC), and a control circuit, wherein the flexible circuit board is electrically connected to the sensing substrate, and the control circuit is coupled to The flexible circuit board is electrically connected so that the touch panel can perform touch signal sensing and control through the control circuit. Generally, the electrical connection between the flexible circuit board and the sensing substrate is connected through a conductive adhesive, wherein the conductive adhesive is disposed between the connection pad of the flexible circuit board and the connection pad of the sensing substrate. Thereby electrical conduction is performed. The conductive adhesive has conductive particles, and the conductive particles are distributed between the connection pads of the flexible circuit board and the connection pads of the sensing substrate, and the fracture deformation rate of the conductive particles is related to whether the sensing circuit and the control circuit on the sensing substrate are successfully electrically connected. For related sensing and control operations. The control circuit can be, for example, a printed circuit board (PCB) or an integrated circuit disposed on the flexible circuit board.

However, since the connection pad is usually formed of an opaque material such as metal, the fracture deformation rate of the conductive particles in the conductive paste is not easily observed after the flexible circuit board and the sensing substrate are bonded, and the electrical connection is successful. Whether it is difficult to judge. To be able to determine the success of the electrical connection after each completed sample, the sample will be sent to the sample further. Electrical detection. However, if each sample after the completion of the connection is 100% detectable, the detection method will have one more electrical detection process step and is more complicated. Therefore, it is desirable to have a simple and easy detection method and device structure that can be used to improve the deficiencies of the prior art.

In view of the deficiencies in the prior art, the applicant of the case, after careful experimentation and research, and a perseverance, finally conceived the "touch panel and its circuit structure" in this case, which can overcome the shortcomings of the prior art. Description.

In view of the deficiencies of the prior art, the present invention provides a display screen structure that allows the rate of fracture deformation of conductive particles to be observed, and thus can be used to determine the success or failure of electrical connections.

According to the above concept, the present invention provides a touch panel including a sensing substrate, a first connection pad, a flexible circuit board, a second connection pad, and a conductive paste. The first connection pad is disposed on the sensing substrate, and the second connection pad is disposed on the flexible circuit board, wherein one of the first connection pad and the second connection pad has a through hole. The conductive adhesive is disposed between the first connection pad and the second connection pad for electrically connecting the sensing substrate and the flexible circuit board. The conductive adhesive has a plurality of conductive particles, at least one of the conductive particles is located Inside the through hole.

According to the above concept, the present invention provides a touch panel structure including a first connection pad and a second connection pad, and a conductive paste. One of the first connection pad and the second connection pad has a through hole. The conductive paste is disposed between the first connection pad and the second connection pad, the conductive paste has a plurality of conductive particles, wherein at least one of the conductive particles is located in the through hole, and a fracture deformation rate thereof is through the through hole And was detected.

According to the above concept, the present invention provides a method for manufacturing a touch panel, comprising: providing a sensing substrate having a first connection pad and a flexible circuit board having a second connection pad, wherein the first connection One of the pad and the second connection pad includes a through hole. A conductive paste having a plurality of conductive particles is disposed between the first connection pad and the second connection pad. Pressing the sensing substrate and the flexible circuit board to make the first connection pad and the second connection The pads are electrically connected to each other through the conductive paste, and at least one of the conductive particles falls within the through hole. Whether the fracture deformation rate of the conductive particles in the through hole is suitable is detected through the through hole.

10‧‧‧Touch panel of the present invention

100‧‧‧Sensor substrate

40‧‧‧Circuit structure

200‧‧‧Sensor Department

201‧‧‧Wire Department

2031‧‧‧Light conductive layer

206‧‧‧Flexible circuit board

205‧‧‧ conductive adhesive

2041‧‧‧metal layer

217‧‧‧Control circuit

20410,20411,20412‧‧‧through hole

2011, 2061‧‧‧ connection pads

Dir1‧‧‧ first inspection direction

2053‧‧‧Electrical particles

Dir2‧‧‧ second inspection direction

42‧‧‧Conductive adhesive

41‧‧‧Connecting mat

422‧‧‧ lower surface

421‧‧‧ upper surface

46‧‧‧Connecting mat

44‧‧‧Flexible circuit board

47‧‧‧Sensor substrate

441‧‧‧through hole

48‧‧‧Light conductive layer

49‧‧‧metal layer

R‧‧‧Projection Intersection Area

1 is a schematic view of a touch panel of a first preferred embodiment of the present invention; FIG. 2 is a schematic view showing a cross section of a touch panel according to a first preferred embodiment of the present invention; and FIG. 3 is a schematic view showing cracking of conductive particles after assembly; FIG. 4(a) is a schematic view showing a first step of fabricating the touch panel according to a second preferred embodiment of the present invention; and FIG. 4(b) is a second preferred embodiment of the present invention. FIG. 4 is a schematic view showing a third step of fabricating the touch panel according to a second preferred embodiment of the present invention; and FIG. 5 is a schematic cross-sectional view showing a circuit structure of a third preferred embodiment of the present invention; And a sixth figure: a schematic diagram of a method of manufacturing the touch panel of the present invention.

The invention is fully described in the following examples, which can be understood by those skilled in the art. However, the implementation of the present invention is not limited by the following embodiments, and those skilled in the art can still rely on the present invention. Other embodiments are intended to be included within the scope of the invention.

Please refer to the first figure and the second figure, which are schematic diagrams of the touch panel 10 according to the first preferred embodiment of the present invention, wherein the second figure is a schematic view along the line AA in the first figure. The touch panel 10 includes a sensing substrate 100 , a sensing portion 200 , a wire portion 201 , a flexible circuit board 206 , a conductive paste 205 , and a control circuit 217 . The sensing substrate 100 can be a transparent substrate, such as a glass substrate, but is not limited thereto. The sensing portion 200 includes a plurality of polygonal transparent sensing units to form an x-axis sensing circuit and a y-axis sensing circuit. Can be indium tin oxide (ITO) The wire portion 201 includes a plurality of wires for electrically connecting the corresponding sensing units. The wire portion 201 extends to the edge of the substrate and is electrically connected to the flexible circuit board 206. Each of the wires includes a corresponding one. The connection pad 2011 is located at the junction of the wire portion 201 and the flexible circuit board 206. Each of the connection pads 2011 is a multi-layer structure comprising a light-transmissive conductive layer 2031 and a metal layer 2041, wherein each A metal layer 2041 has at least one through hole 20410, respectively. The flexible circuit board 206 also has a plurality of connection pads 2061 respectively corresponding to the connection pads 2011 on the sensing substrate 100. The conductive adhesive 205 is disposed between the connection pads 2061 and the connection pads 2011 for electrically conducting the sensing substrate 100. And a flexible circuit board 206; wherein the conductive paste 205, such as an anisotropic conductive film (ACF), comprises a plurality of conductive particles 2053. When the conductive particles are pressed and ruptured, the vertical connection pad 2061 and the connection pad 2011 are electrically connected, so that the control circuit 217 electrically connected to the flexible circuit board 206 can perform touch detection and Drive operation. For example, when a certain position or some positions of the sensing substrate 100 are touched, the x-axis sensing circuit and the y-axis sensing circuit transmit the information of the x-axis coordinate and the y-axis coordinate to the control as shown in the first figure. Circuit 217 is used for position detection.

In this embodiment, since the metal layer 2041 of each of the connection pads 2011 has at least one through hole 20410, and the sensing substrate 100 and the light-transmitting conductive layer 2031 are both translucent, each conductive particle 2053 in the conductive paste 205 The rate of rupture deformation will be detected via vias 20410. For example, in the second figure, the light reaches the conductive paste 205 from the first viewing direction Dir1 through the sensing substrate 100, the light-transmitting conductive layer 2031, and the via hole 20410, so that the crack deformation state of the conductive particle 2053 can be observed. In general, the preferred fracture deformation rate of each conductive particle is in the range of 20% to 80%. In particular, although the connection pad structure of the present embodiment is applied to the sensing substrate 100 of the touch panel 10, the improved structure can also be applied to substrates of other electronic devices, for example, for a liquid crystal display module. The glass substrate. In addition, in this example, the control circuit 217 includes an integrated circuit (IC), but in other embodiments, it may be a printed circuit board electrically connected to the flexible circuit board 206 (Print Circuit Board) , PCB) or any combination of other active and passive components.

The process of the process device of the touch panel 10 has various parameters in the manufacturing process, and the setting of various parameters has an opportunity to affect the fracture deformation rate of the conductive particles 2053. The pressure parameter is the main influence factor. When the pressure parameter of the process is larger, the deformation amount of the conductive particles is increased, that is, the flattened portion is pressed, so that the contact area of the conductive portion is increased, and the contact impedance is smaller; When the pressure is too small, the contact area is insufficient, the contact resistance is too large, and the conduction is poor.

The third figure is a top view of the second figure and a schematic diagram of the breakdown of the conductive particles after assembly. In the third figure, when the process equipment is processed, the conductive paste 205 between the connection pad 2011 and the connection pad 2061 is subjected to appropriate pressure to cause the conductive particles 2053 to undergo crack deformation. The conductive particles 2053 are subjected to pressure deformation at the overlapping area of the connection pad 2011 and the connection pad 2061, and the diameter of the conductive particles 2053 is greater than the thickness of the metal layer 2041 when it is not pressed, so that it is located in the through hole 20410. The conductive particles 2053 are also broken and deformed during the pressing process, so that the detecting instrument can observe the cracking of the conductive particles 2053 located in the through hole 20410 through the through hole 20410 in the Dir1 direction, thereby judging whether the overall pressing result is normal. .

In a preferred embodiment, the thickness of the metal layer 2041 is smaller than the diameter of the conductive particles 2053. For example, the thickness of the metal layer 2041 is about 0.15-0.5 microns, and the diameter of the conductive particles 2053 is about 3-6 microns. Therefore, the conductive particles 2053 in the through hole 20410 can still be pressed to generate a fracture deformation, and an electrical connection condition of the conductive particle 2053 can be observed and determined, and the electrical connection condition includes, for example, whether an impedance characteristic is low impedance. In order to judge the successful electrical connection. The electrical connection state of the conductive particles in the other through holes can also be determined in the same manner.

In another preferred embodiment, the through holes 20410, 20411, and 20412 are both larger than the diameter of the conductive particles 2053. The metal layer 2041 and the connection pad 2061 are bonded to each other by heating or pressing the conductive paste 205. When the particles 2053 are properly heated or pressurized, the conductive particles 2053 generate a fracture deformation, so that the metal layer 2041 is electrically connected to the connection pad 2061 on the flexible circuit board 206, wherein the fracture deformation rate is 20% to 80%. range.

In the third figure, the typical length PL of the metal layer 2041 of the contact pad 2011 is about 500-1200 micrometers, and the width PW is about 100-200 micrometers. The through holes 20410, 20411, 20412 have a specific shape, which may be a shape of a circle, a triangle, a rectangle, a polygon, or the like, or any combination thereof. The cross-sectional area of the via hole 20410 is greater than the maximum cross-sectional area of each of the conductive particles 2053.

In the third figure, a plurality of conductive particles 2053 are distributed in the vias 20410. When the plurality of conductive particles 2053 are properly heated or pressurized, most of the conductive particles 2053 exhibit a ruptured state to electrically connect the connection pads 2011 connected in the vertical direction with the connection pads 2061. As described above, the defect rate of each of the conductive particles 2053 can be observed by the through hole 20410. The judgment of the fracture deformation rate can be judged by using a graphical sample of various degrees of cracking of the conductive particles.

Please refer to FIG. 4( a ), which is a schematic diagram of a first step of fabricating the touch panel 10 according to a second preferred embodiment of the present invention. The fourth figure (a) contains a top view and a front view. First, a sensing portion 200 (not shown) and a light-transmitting conductive layer 2031 are simultaneously formed on the sensing substrate 100, and an embodiment thereof may be formed by using an indium tin oxide or other transparent conductive layer by evaporation or sputtering. The substrate 100 is sensed.

FIG. 4(b) is a schematic diagram showing a second step of fabricating the touch panel 10 according to the second preferred embodiment of the present invention. The fourth figure (b) includes a top view and a front view. In the second step, a metal layer 2041 is formed on the light-transmissive conductive layer 2031, wherein the metal layer 2041 is opaque.

FIG. 4(c) is a schematic diagram showing a third step of fabricating the touch panel 10 according to the second preferred embodiment of the present invention. The fourth figure (c) contains a top view and a front view. In the third step, the metal layer 2041 is etched by using an etchant to form via holes 20410, 20411, and 20412, respectively, and a portion of the light-transmitting conductive portion 2031 may be exposed through the via holes 20410, 20411, and 20412. In the next step, a film-like conductive paste 205 can be disposed on the metal layer 2041. Preferably, the conductive paste is an anisotropic conductive paste, and the flexible circuit board 206 is pressed into the conductive adhesive by the process equipment. 205 is formed to bond the metal layer 2041 and the flexible circuit board 206.

Please refer to FIG. 5, which is a schematic cross-sectional view of a circuit structure 40 according to a third preferred embodiment of the present invention. The circuit structure 40 includes a conductive paste 42 and a flexible circuit board 44. The conductive adhesive 42 has an upper surface 421 , a conductive particle 420 , and a lower surface 422 for bonding a touch substrate 47 . The connection pad (or gold finger) 41 on the flexible circuit board 44 has a through hole 441 for detecting the fracture deformation rate of the conductive particles 420. The position of the through hole 441 is in the range of a projection intersection region R of the connection pad 41 and the metal layer 49. The flexible circuit board 44 has a light transmissive area at least at the through hole 441 or the entire flexible circuit board 44 is formed of a light transmissive material. The rupture condition of the conductive particles 420 is observed from the second viewing direction Dir2.

In the present embodiment, the wire portion (not shown) on the flexible circuit board 44 includes a connection pad 41. A through hole 441 can be formed in the connection pad 41. When the flexible circuit board 44, the conductive paste 42, and the sensing substrate 47 are pressed together, the fracture deformation rate of the conductive particles 420 can pass through the second viewing direction Dir2. Hole 441 is used for observation. Similarly, the connection pad 46 on the sensing substrate 47 includes a light-transmissive conductive layer 48 and a metal layer 49. Specifically, in this embodiment, the metal layer 49 is not provided with a through hole, but The through holes are modified to be connected to the connection pads 41 of the flexible circuit board 44.

In another embodiment (not shown), the connection pad 41 may be a transparent material, and the flexible circuit board 44 has a light transmissive area or the entire flexible circuit board 44 at least corresponding to the through hole 441 of the connection pad 41. It is formed of a light-transmitting material, so the connection pad 41 will not need to be boring or opening.

With the touch panel 10 or the circuit structure 40 of the present invention, the conductive particles 2053, 420 of the conductive pastes 205, 42 can be easily observed and detected, which provides proof that the conductive paste 205, 42 is electrically conductive therein after being pressed. The fracture deformation rate of the particles 2053, 420. The process equipment will first set the pressure parameters before pressing, and the pressure parameters can be gradually corrected after the previous several attempts, and then the same batch of conductive adhesives 205, 42 can be processed using the corrected pressure parameters.

Please refer to FIG. 6 , which is a schematic diagram of a method for constructing a conductive adhesive layer of a touch panel according to the present invention. The method includes: Step S101 , providing a sensing substrate 100 , 47 having a first connection pad 2011 , 46 and having a second connection a flexible circuit board 206, 44 of pads 2061, 41 wherein the first connection One of the pads 2011, 46 and the second connection pads 2061, 41 includes a through hole 20410, 441. In step S102, a conductive paste 205, 42 having a plurality of conductive particles 2053, 420 is disposed between the first connection pads 2011, 46 and the second connection pads 2061, 41. In step S103, the sensing substrates 100, 47 and the flexible circuit boards 206, 44 are pressed together, so that the first connection pads 2011, 46 and the second connection pads 2061, 41 pass through the conductive adhesives 205, 42. Electrically conductive, wherein at least one of the conductive particles falls within the through hole 20401 or the through hole 441. In step S104, it is determined whether the fracture deformation rate of the conductive particles 2053, 420 in the through hole is appropriate through the through holes 20410, 441. In step S105, if the previous step is YES, the batch of conductive pastes 205, 42 are all applied under the specific pressing conditions. If not, the first two steps are repeated under a specific specific pressing condition.

The invention is a difficult and innovative invention, and has profound industrial value, and is submitted in accordance with the law. In addition, the present invention may be modified by those skilled in the art without departing from the scope of the appended claims.

10‧‧‧Touch panel of the present invention

100‧‧‧Sensor substrate

206‧‧‧Flexible circuit board

2031‧‧‧Light conductive layer

2041‧‧‧metal layer

205‧‧‧ conductive adhesive

20410,20411,20412‧‧‧through hole

2011, 2061‧‧‧ connection pads

Dir1‧‧‧ first inspection direction

2053‧‧‧Electrical particles

Claims (13)

A touch panel includes: a sensing substrate; a first connection pad disposed on the sensing substrate; a flexible circuit board; a second connection pad disposed on the flexible circuit board, wherein the first connection One of the pad and the second connection pad comprises a conductive layer, the conductive layer has a through hole, and the through hole is a through hole penetrating the conductive layer; and a conductive paste is disposed on the first connection pad and the first a connecting pad for electrically connecting the sensing substrate and the flexible circuit board, the conductive adhesive having a plurality of conductive particles, at least one of the conductive particles being located in the through hole, wherein the through hole is disposed in the first hole a connection pad or the second connection pad, and the flexible circuit board has a first light transmissive area corresponding to the through hole in the second connection pad, through the first light transmissive area and the The through hole in the second connection pad, whether the fracture deformation rate of the conductive particle is detected from a second direction, or the sensing substrate has a second permeable corresponding to the through hole in the first connection pad a light region passing through the second permeable region and the pass in the first connection pad Rupture deformation of the conductive particles is detected from a first direction if appropriate. The touch panel of claim 1, wherein the first connection pad comprises a metal layer, and the through hole is located in the metal layer, and the metal layer has a through portion to form the through hole. The touch panel of claim 2, wherein the first connection pad further comprises a light-transmissive conductive layer interposed between the metal layer and the sensing substrate. The touch panel of claim 1, wherein the flexible circuit board is formed of a light transmissive material. The touch panel of claim 1, wherein the sensing substrate is a glass substrate. The touch panel of claim 2, wherein the metal layer has a thickness of 0.15 to 0.5 μm, and the conductive particles have a maximum diameter of 3 to 6 μm. The touch panel of claim 1, further comprising a control circuit electrically connected to the flexible circuit board, the control circuit comprising a printed circuit board (PCB), an integrated circuit (Integrated Circuit, IC), or any combination thereof. The touch panel of claim 1, wherein the conductive paste is an anisotropic conductive film (ACF). The touch panel of claim 1, wherein a cross-sectional area of the through hole is larger than a maximum cross-sectional area of the conductive particle. The touch panel of claim 1, wherein the at least one of the conductive particles has a fracture deformation rate in the range of 20% to 80%. The touch panel of claim 1, wherein the through hole has a specific shape, which is a circle, a triangle, a rectangle, a polygon, or any combination thereof. The touch panel of claim 1, wherein the metal layer of the first connection pad has a length of 500 to 1200 micrometers and a width of 100 to 200 micrometers. A method of manufacturing a touch panel, comprising: providing a sensing substrate having a first connection pad and a flexible circuit board having a second connection pad, wherein the first connection pad and the second connection pad One of the conductive layers includes a conductive layer, the conductive layer includes a through hole, and the through hole is a through hole penetrating the conductive layer; and a conductive paste having a plurality of conductive particles is disposed on the first connection pad and the second Bonding the sensing substrate and the flexible circuit board to electrically connect the first connection pad and the second connection pad to each other through the conductive adhesive, wherein at least one of the conductive particles falls on And the flexible circuit board has a first permeable region corresponding to the through hole in the second connection pad, through the first permeable region and the second connection pad a through hole, the rupture deformation rate of the conductive particle is detected from a second direction, or the sensing substrate has a second permeable region corresponding to the through hole in the first connection pad, through the second a light transmissive area and the through hole in the first connection pad, Fracture deformation ratio of charged particles to be detected if appropriate from a first direction.