KR102519263B1 - Touch panel module - Google Patents

Abstract

The present invention relates to a touch panel module, and more particularly, to a touch panel including a plurality of sensing patterns and wiring patterns and a plurality of bonding pads connected thereto and at least partially covered with an overcoat layer; An anisotropic conductive film having conductive balls; and a flexible printed circuit board having a plurality of tag pads connected to the exposed portions of the bonding pads by pressing the anisotropic conductive film through the pressed conductive balls, wherein the thickness of the anisotropic conductive film is expressed by the following equation By satisfying 1, the pressure applied to the bonding pad of the touch panel during bonding between the touch panel and the flexible printed circuit board is reduced, and thus the occurrence of cracks in the bonding pad is reduced. Accordingly, the present invention relates to a touch panel module capable of significantly reducing touch defects.

Description

Touch panel module {TOUCH PANEL MODULE}

The present invention relates to a touch panel module.

A touch panel is a device capable of sensing information input by a touch method. The touch panel includes: 1) cathode ray tube (CRT), liquid crystal display (LCD), light-emitting diode (LED), field emission display (FED) ), a plasma display panel (PDP, Plasma Display Panel), an electro luminescence device (ELD), etc. installed in an image display device, so that the user can input touch information while viewing the image display device. (Touch Window)', or 2) it can be implemented in the form of a 'simple input device' that is formed on the surface of an electronic device without interlocking with an image display device and allows a user to simply input touch information. there is.

On the other hand, since the touch panel should be able to detect information input by a touch method in the form of an electrical signal, a 'sensing pattern' for detecting a touch stimulus and a 'printing' for transmitting a signal change on the touch pattern It is configured in a form including 'circuit board'.

Here, the sensing pattern and the printed circuit board may be electrically connected to each other by connecting a bonding pad connected to the sensing pattern and a tag pad formed on the printed circuit board with an anisotropic conductive film interposed therebetween. At this time, there is a problem in that a crack is generated in the bonding pad due to pressure applied to the bonding pad, and thus a touch failure occurs.

Korean Patent Publication No. 2015-0120113 discloses a touch panel capable of preventing cracks from occurring in a bonding process.

Korean Patent Publication No. 2015-0120113

An object of the present invention is to provide a touch panel module in which the occurrence of cracks in the bonding pad during bonding between the bonding pad of a touch panel and a printed circuit board is reduced.

1. A touch panel including a plurality of sensing patterns and wiring patterns and a plurality of bonding pads connected thereto and at least partially covered with an overcoat layer;

An anisotropic conductive film having conductive balls; and

A flexible printed circuit board having a plurality of tag pads connected to exposed portions of the bonding pads through pressurized conductive balls by pressing the anisotropic conductive film; and

A touch panel module in which the thickness of the anisotropic conductive film before pressing satisfies Equation 1 below:

[Equation 1]

Thickness of anisotropic conductive film before pressing = (1/2×H1-1/2×H2)+2(1-α)r + β

(Wherein, H1 is the height of the tag pad and is 24 to 30 μm, H2 is the height of the overcoat layer on the bonding pad and is 3 to 7 μm, α is the pressing ratio of the conductive balls and is 0.4 to 0.6, and r is the conductive ball is 5 to 10 μm as the radius of and β is r to r+3 as a correction factor).

2. The touch panel module according to 1 above, wherein the bonding pad and the tag pad have a width and a pitch of 0.1 to 3 mm.

3. The touch panel module according to 1 above, wherein the bonding pad includes a metal core and non-metal oxide coating layers stacked on and under the metal core.

4. The touch panel module according to 1 above, wherein a separation layer, an adhesive layer, and a base film are sequentially positioned under the bonding pad.

5. The touch panel module according to 1 above, wherein the anisotropic conductive film has a storage modulus of 1 to 40 MPa.

6. In the above 1, H1 in Equation 1 is 26 to 28 μm, H2 is the height of the overcoat layer on the bonding pad and is 4 to 6 μm, α is the pressing ratio of the anisotropic conductive film and is 0.4 to 0.6, r is the radius of the conductive ball and is 5 to 10 μm, and β is a correction factor of r to r + 3.

7. The touch panel module according to 1 above, wherein the thickness of the anisotropic conductive film before pressing is 21 to 35 μm.

8. An image display device including the touch panel module of any one of 1 to 7 above.

The touch panel module of the present invention has a thickness of the anisotropic conductive film that can reduce the pressure applied to the bonding pad of the touch panel during bonding between the touch panel and the flexible printed circuit board, while allowing the connection to be sufficiently made. As a result, cracks in the bonding pad are less likely to occur, thereby significantly reducing touch defects.

1 is an assembly view of a touch panel module according to an embodiment of the present invention.
2 and 3 are cross-sectional views of a connection portion between a touch panel and a flexible printed circuit board in a touch panel module according to an embodiment of the present invention.

The present invention includes a touch panel including a plurality of sensing patterns and wiring patterns and a plurality of bonding pads connected thereto and at least partially covered with an overcoat layer; An anisotropic conductive film having conductive balls; and a flexible printed circuit board having a plurality of tag pads connected to the exposed portions of the bonding pads by pressing the anisotropic conductive film through the pressed conductive balls, wherein the thickness of the anisotropic conductive film is expressed by the following equation By satisfying 1, the pressure applied to the bonding pad of the touch panel during bonding between the touch panel and the flexible printed circuit board is reduced, and thus the occurrence of cracks in the bonding pad is reduced. Accordingly, the present invention relates to a touch panel module capable of significantly reducing touch defects.

Hereinafter, the present invention will be described in detail.

The touch panel 100 according to the present invention includes a plurality of sensing patterns 110 , wiring patterns 120 and bonding pads 130 .

The detection pattern 110 serves to generate a signal when a user touches, so that the controller can recognize the touch coordinates.

Any conductive material can be used as the sensing pattern 110 without limitation, and for example, indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), aluminum zinc oxide (AZO), gallium Zinc Oxide (GZO), Florin Tin Oxide (FTO), Indium Tin Oxide-Silver-Indium Tin Oxide (ITO-Ag-ITO), Indium Zinc Oxide-Silver-Indium Zinc Oxide (IZO-Ag-IZO), Indium Zinc Tin metal oxides selected from the group consisting of oxide-silver-indium zinc tin oxide (IZTO-Ag-IZTO) and aluminum zinc oxide-silver-aluminum zinc oxide (AZO-Ag-AZO); metals selected from the group consisting of gold (Au), silver (Ag), copper (Cu), molybdenum (Mo), and APC (Ag, Pd, Cu alloy); nanowires of a metal selected from the group consisting of gold, silver, copper and lead; carbon-based materials selected from the group consisting of carbon nanotubes (CNT) and graphene; and a material selected from conductive polymer materials selected from the group consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI). These can be used individually or in mixture of 2 or more types.

The sensing pattern 110 may include a plurality of first patterns, a plurality of second patterns, and an insulating layer interposed therebetween in order to reduce electrical resistance.

The sensing pattern 110 may be formed of ITO, silver nanowire (AgNW), or a metal mesh as an example, and the first pattern is formed of a transparent metal oxide such as ITO, and an upper portion of the ITO electrode layer is formed to further lower the electrical resistance. The second pattern may be formed using metal or AgNW.

In addition, the structure of the sensing pattern 110 will be described from the point of view of the touch sensor method.

The structure of the sensing pattern 110 is preferably an electrode pattern structure used in a capacitance method, and a mutual-capacitance method or a self-capacitance method may be applied.

In the case of a mutual-capacitance method, it may be a lattice electrode structure of a horizontal axis and a vertical axis. A bridge electrode may be included at the intersection of the first pattern and the second pattern, or the first pattern and the second pattern may be formed to be electrically separated from each other.

In the case of a self-capacitance method, it may be an electrode layer structure in which capacitance change is read using one electrode at each point.

The wiring pattern 120 enables electrical signals to be transmitted between the aforementioned electrode pattern and the flexible printed circuit board 300 to be described later. To this end, one end of the wiring pattern 120 is connected to the electrode pattern, and the other end is connected to the bonding pad 130 .

The wiring pattern 120 may be formed of the material exemplified as the material of the sensing pattern 110 .

The bonding pad 130 serves to transfer the touch signal of the sensing pattern 110 transmitted through the wiring pattern 120 to the flexible printed circuit board 300 .

The bonding pad 130 may be formed of the material exemplified as the material of the sensing pattern 110, and may have a single-layer structure or a stacked structure of two or more layers.

As a more specific example, in the case of a single layer structure, it may be a single layer of metal among the above-described conductive materials, and in the case of a multi-layer laminated structure, metal oxides (conductive non-metal coating layer) are formed on, below or above the metal (metal core). It may be a laminated structure, but is not limited thereto.

In the bonding pad 130 , for example, the width of the unit bonding pad 130 and the pitch between the bonding pads 130 may be independently 0.1 mm to 3 mm. If the width is within the above range, it is possible to form a precise pattern while reducing the area of the bezel. Preferably, the width may be 1 to 2 mm, and the pitch may be 0.1 to 0.3 mm.

The height of the bonding pad 130 is not particularly limited, and may be, for example, 0.1 to 1 μm, but is not limited thereto.

At least a portion of the bonding pad 130 is covered with the overcoat layer 140 .

The overcoat layer 140 disperses the pressure applied to the bonding pad 130 when connected to the bonding pad 130 through the conductive ball 210 of the flexible printed circuit board 300, thereby preventing cracks in the bonding pad 130. play a role in reducing incidence.

The overcoat layer 140 covers at least a portion of the bonding pad 130 .

When cracks occur in the bonding pad 130, in particular, cracks occur more easily in the case of the edge portion of the bonding pad 130. The overcoat layer 140 covers at least a portion of the bonding pad 130, so that the edge portion can be protected, thereby reducing the occurrence of cracks.

The at least part is not particularly limited as long as it can cover the edge portion of the bonding pad 130, but more specifically, it may cover an area ratio satisfying Equation 2 below:

[Equation 2]

0.2 ≤ A'/A ≤ 0.98

In the formula, A is the total area of the bonding pad 130, and A' is the area of the portion of the bonding pad 130 that is not covered by the overcoat layer 140.

Equation 2 is an area ratio between the bonding pad 130 and the portion of the bonding pad 130 that is not covered by the insulating layer, and by satisfying Equation 2, the bonding pad 130 is effectively electrically connected without deterioration in conductivity can be performed, and at the same time, cracks of the bonding pad 130 can be remarkably reduced by protecting the edge portion to disperse the pressure applied from the outside.

In the present invention, when the area ratio of Equation 2 is less than 0.2, there is a problem that the tag pad 310 is not sufficiently contacted when bonding, and when it exceeds 0.98, the bonding pad 130 is not sufficiently protected and is subjected to bending stress In this case, cracks may easily occur in the rim. The area ratio of Equation 2 may be preferably 0.2 to 0.98, more preferably 0.3 to 0.95, and the above-described effect is further improved within the above range.

The overcoat layer 140 may have, for example, a thickness of 3 μm to 7 μm on the bonding pad 130 . When the thickness of the bonding pad 130 is within the above range, the connection between the bonding pad 130 and the tag pad 310 through the conductive ball 210 is sufficiently made, and the pressure applied to the bonding pad 130 can be buffered. . Preferably, it may be 4 μm to 6 μm.

The material of the overcoat layer 140 may be used without particular limitation as long as it can be used as an insulating layer in the art, and for example, an inorganic insulating material such as silicon oxide or silicon nitride or an organic insulating material such as a photocurable resin composition. etc. can be used.

Components of the touch panel 100 , such as the plurality of sensing patterns 110 , wiring patterns 120 , and bonding pads 130 described above, may be positioned on the base film 150 .

As the base film 150, those commonly used as transparent films for optics may be used without limitation, but among them, it is preferable to use a film having excellent flexibility, transparency, thermal stability, retardation uniformity, isotropy, and the like. Specific examples include polyacrylate, polymethacrylate (eg PMMA), polyimide, polyamide, polyamic acid, polyvinyl alcohol, polyolefin (eg PE, PP), polystyrene, polynorbornene, polymaleimide , polyazobenzene, polyester (e.g., PET, PBT), polyarylate, polyphthalimidine, polyphenylene phthalamide, polyvinyl cinnamate, polycinnamate, coumarin-based polymer, chalcone-based polymer, aromatic acetylene-based polymer , phenyl maleimide copolymers, copolymers thereof, and blends thereof.

The thickness of the base film may be, for example, 10 to 200 μm, preferably 10 to 100 μm, but is not limited thereto.

The touch panel 100 according to the present invention may further include an adhesive layer 160 and a separation layer 170 sequentially stacked between the base film 150 and the bonding pad 130 .

The material of the adhesive layer 160 is not particularly limited in the present invention, and may be a commonly used acrylic or epoxy resin.

The thickness of the adhesive layer 160 is not particularly limited, and may be, for example, 1 to 50 μm, preferably 1 to 20 μm.

The separation layer 170 is a layer for separation from the carrier substrate, and the touch panel 100 is manufactured by forming the separation layer 170 and the above-described pattern, pad, etc. on the carrier substrate, and the base film 150 is adhered. And it may include such a configuration through a separation process from the carrier substrate.

The separation layer 170 may be a polymer organic film, for example, a polyimide-based polymer, a polyvinyl alcohol-based polymer, a polyamic acid-based polymer, or a polyamide-based polymer. , polyethylene-based polymer, polystylene-based polymer, polynorbornene-based polymer, phenylmaleimide copolymer-based polymer, polyazobenzene-based polymer, polyphenylene phthalamide (polyphenylenephthalamide)-based polymer, polyester-based polymer, polymethyl methacrylate-based polymer, polyarylate-based polymer, cinnamate-based polymer, coumarin-based polymer, It may be made of a polymer such as a phthalimidine-based polymer, a chalcone-based polymer, an aromatic acetylene-based polymer, or a cycloolefn polymer, but is not limited thereto. These can be used individually or in mixture of 2 or more types.

The thickness of the separation layer 170 is not particularly limited, and may be, for example, 1 to 50 μm, preferably 1 to 20 μm.

Also, if necessary, a protective layer 180 may be further positioned on the separation layer 170 .

The protective layer 180 serves to protect the separation layer 170 and the aforementioned sensing pattern 110 , wiring pattern 120 , and bonding pad 130 .

As the protective layer 180, a polymer known in the art may be used without limitation, and for example, an organic insulating layer material may be used without limitation.

Also, the protective layer 180 may be made of an inorganic material. For example, it may be an inorganic oxide or an inorganic nitride. Examples of the inorganic oxide include silicon oxide, alumina, and titanium oxide, and examples of the inorganic nitride include silicon nitride and titanium nitride. In terms of implementing high transmittance, it may be preferably silicon oxide.

One side of the anisotropic conductive film 200 is connected to the bonding pad 130 of the touch panel 100 and the other side is connected to the tag pad 310 of the flexible printed circuit board 300 .

The anisotropic conductive film 200 includes conductive balls 210 .

As the conductive ball 210, metal particles, metal-coated resin particles, and the like can be used.

Examples of the metal particles include nickel, cobalt, silver, copper, gold, palladium, and solder particles. These can be used individually or in mixture of 2 or more types.

The surface of the metal particle may be coated with gold, palladium, etc. for the purpose of preventing surface oxidation.

Metal-coated resin particles are made by adding metals such as nickel, silver, solder, copper, gold, palladium, etc. to the surface of resins such as styrene-divinylbenzene copolymer, benzoguanamine resin, crosslinked polystyrene resin, acrylic resin, and styrene-silica composite resin. It may be coated, but is not limited thereto. These can be used individually or in mixture of 2 or more types.

The size of the conductive ball 210 is not particularly limited, and may have, for example, a radius of 5 μm to 10 μm.

The conductive balls 210 may be included in, for example, 1 to 15% by weight of the total weight of the anisotropic conductive film 200, but are not limited thereto.

In addition, the anisotropic conductive film 200 may include resins such as phenoxy resins, unsaturated polyester resins, saturated polyester resins, urethane resins, butadiene resins, polyimide resins, polyamide resins, and polyolefin resins; photopolymerizable monomers and photoinitiators known in the art; Alternatively, a thermal polymerizable monomer and a thermal initiator may be further included.

The anisotropic conductive film 200 may have, for example, a storage modulus of 1 to 40 MPa. When the storage modulus is within the above range, parameters described later may be satisfied. The storage modulus may be the storage modulus at 20 to 150 °C.

The flexible printed circuit board 300 is electrically connected to the bonding pad 130 of the touch panel 100 and serves to electrically connect the electrode pattern and the controller.

Specifically, the flexible printed circuit board 300 may include a substrate, a tag pad 310, and an integrated circuit, and the tag pad 310 presses the anisotropic conductive film 200 to form a pressurized conductive ball 210. Through this, it is connected to the exposed portion of the bonding pad 130 .

When the tag pad 310 of the flexible printed circuit board 300 is connected to the exposed portion of the bonding pad 130 through the conductive ball 210, the integrated circuit applies a driving signal to the bonding pad 130, and Coordinates and numbers of touch inputs applied to the touch panel 100 and gesture operations may be determined using touch signals acquired through the pad.

Specifically, the integrated circuit includes a driving circuit for applying a driving signal to the sensing pattern 110, a capacitance sensing circuit for detecting a change in capacitance generated in the sensing pattern 110, and an output signal of the capacitance sensing circuit. It may include an analog-to-digital conversion circuit for converting into a digital value, an arithmetic circuit for determining a touch input using data converted into a digital value, and the like.

The tag pad 310 may be formed of the material exemplified as the material of the sensing pattern 110 .

In the tag pad 310, for example, the width of the unit tag pad 310 and the pitch between the tag pads 310 may be independently 0.1 mm to 3 mm, preferably within the range of the bonding pad 130. It may have the same width as the width and the same pitch as the pitch between the bonding pads 130 .

The touch panel module of the present invention cracks the bonding pad 130 according to specifications such as the height of the tag pad 310, the height of the overcoat layer, and the pressure ratio of the conductive balls 210 (thickness ratio before and after pressure). A specific thickness value of the anisotropic conductive film 200 capable of reducing , is calculated, and a main feature is that the thickness of the anisotropic conductive film 200 before pressing has the corresponding thickness value. The thickness value satisfies Equation 1 below.

[Equation 1]

Thickness of anisotropic conductive film before pressing = (1/2×H1-1/2×H2)+2(1-α)r + β

(Wherein, H1 is the height of the tag pad and is 24 to 30 μm, H2 is the height of the overcoat layer on the bonding pad and is 3 to 7 μm, α is the pressing ratio of the conductive balls and is 0.4 to 0.6, and r is the conductive ball is 5 to 10 μm as the radius of and β is r to r+3 as a correction factor).

The present inventors variously changed the thickness of the anisotropic conductive film 200 before pressing within the range of the specific specifications and checked whether or not cracks occurred in the bonding pad 130, and thus cracked the bonding pad 130. A relationship between each specification that can be suppressed and the thickness of the anisotropic conductive film 200 was derived.

When the thickness of the anisotropic conductive film 200 before pressing is within the range of Equation 1, the bonding pad 130 of the touch panel 100 and the tag pad 310 of the flexible printed circuit board 300 are sufficiently connected. The occurrence of cracks in the bonding pad 130 may be reduced. The thickness of the anisotropic conductive film 200 after pressing may be substantially the same as the diameter of the conductive balls after pressing.

The thickness of the anisotropic conductive film 200 before pressing satisfies the range of Equation 1 above and may be, for example, 21 to 35 μm, and preferably 21 to 25 μm when the radius of the conductive ball is 5 μm. And, when the radius of the conductive ball is 10 μm, it may be 29 to 35 μm, but is not limited thereto.

In addition, the present invention provides an image display device including the touch panel module.

The touch panel module of the present invention can be applied to various image display devices such as an electroluminescent display device, a plasma display device, and a field emission display device as well as a general liquid crystal display device.

Hereinafter, preferred embodiments are presented to aid understanding of the present invention, but these embodiments are only illustrative of the present invention and do not limit the scope of the appended claims, and embodiments within the scope and spirit of the present invention It is obvious to those skilled in the art that various changes and modifications to the are possible, and it is natural that these variations and modifications fall within the scope of the appended claims.

Example

(One) bonding pad, tag pad, anisotropic conductive film Specifications

A polyethylene terephthalate substrate film having a thickness of 20 μm, an acrylic adhesive layer having a thickness of 5 μm, a cycloolefin-based separation layer having a thickness of 10 μm, an acrylic protective layer having a thickness of 5 μm, a bonding pad of 900 Å ITO, 1500 Å APC, and 1200 Å ITO. An acrylic overcoat layer was used as the layered structure and the overcoat layer.

As the anisotropic conductive film, CP937CM/AM (Dexerial, storage modulus 1 to 40 MPa at a temperature of 20 to 150 ° C) was used, and a flexible printed circuit board was used as a polyimide film with a tag pad in which silver was laminated on copper. .

Detailed specifications are shown in Table 1 below.

division Specifications division Specifications Width of bonding pad and tag pad 2mm Challenge ball radius
(r) 5 μm or 10 μm Pitch of bonding pad and tag pad 0.2mm tag pad height
(H1) 27㎛ Conductive ball pressurization rate
(α) 0.4 to 0.6 Height of the overcoat layer on the bonding pad
(H2) 5㎛ correction factor
(β) 8㎛ (conductive ball radius is 5㎛),
12㎛ (conductive ball radius is 10㎛)

(2) bonding Experiment

Bonding of the flexible printed circuit board was performed at 150° C. and a pressure of 0.5 MPa to 1 MPa for 10 seconds while changing the thickness of the anisotropic conductive film, and it was confirmed whether cracks occurred in 20 bonding pads.

r=5 Anisotropic conductive film thickness (㎛) bonding crack r=10 Anisotropic conductive film thickness (㎛) bonding crack 20 2/20 28 1/20 21 0/20 29 0/20 23 32 25 35 26 uncompressed 36 uncompressed

(3) Derivation of equation

Based on the experimental results of (2) above, the thickness of the anisotropic conductive film before pressing, which can prevent bonding cracks and non-bonding, was obtained, and the thickness of the anisotropic conductive film before pressing was derived through the relationship between the specifications. Equation 1 below was derived by applying the possible dummy thickness as a β value through experiments.

[Equation 1]

The thickness of the anisotropic conductive film before pressing = (1/2×H1-1/2×H2)+2(1-α)r+β.

100: touch panel 110: detection pattern
120: wiring pattern 130: bonding pad
140: overcoat layer 150: base film
160: adhesive layer 170: separation layer
180: protective layer 200: anisotropic conductive film
210: conductive ball 300: flexible printed circuit board
310: tag pad

Claims (8)

a touch panel including a plurality of sensing patterns and wiring patterns and a plurality of bonding pads connected thereto and at least some of which are covered with an overcoat layer;
An anisotropic conductive film having conductive balls; and
A flexible printed circuit board having a plurality of tag pads pressed on the anisotropic conductive film and connected to an exposed portion of the bonding pad through a pressed conductive ball;
The thickness of the anisotropic conductive film before pressing satisfies Equation 1 below,
Each of the plurality of bonding pads and the plurality of tag pads has a width of 1 to 2 mm and a pitch of 0.1 to 0.3 mm, a touch panel module:
[Equation 1]
Thickness of anisotropic conductive film before pressing = (1/2×H1-1/2×H2)+2(1-α)r + β
(Wherein, H1 is the height of the tag pad and is 26 to 28 μm, H2 is the height of the overcoat layer on the bonding pad and is 4 to 6 μm, α is the pressing ratio of the anisotropic conductive film and is 0.4 to 0.6, and r is the conductivity 5 to 10 μm as the radius of the ball, and β is r to r+3 as a correction factor).
delete The touch panel module of claim 1 , wherein the bonding pad includes a metal core and non-metal oxide coating layers stacked on and under the metal core.
The touch panel module according to claim 1, wherein a separation layer, an adhesive layer, and a base film are sequentially positioned under the bonding pad.
The touch panel module of claim 1 , wherein the anisotropic conductive film has a storage modulus of 1 to 40 MPa.
delete The touch panel module according to claim 1 , wherein a thickness of the anisotropic conductive film before pressing is 21 to 35 μm.
An image display device comprising the touch panel module of claim 1.

Images