TWI653151B - Method for fabricating touch sensor - Google Patents

Abstract

The present invention relates to a method for manufacturing a touch sensor that suppresses surface non-uniformity for manufacturing a flexible substrate of the touch sensor and uses a heat-sensitive adhesive to be flexible The substrate is attached to or detached from the carrier substrate during the peeling of the carrier substrate. The method for manufacturing a touch sensor according to the present invention comprises: preparing a base film including a conductive layer; attaching a protective film to the base film, and thereafter attaching the base film to a carrier a substrate; and the protective film is peeled off from the base film in a state in which a viscosity between the base film and the carrier substrate is increased and a viscosity between the base film and the protective film is reduced.

Description

Method of manufacturing a touch sensor

The invention relates to a touch sensor. In particular, the present invention relates to a method for fabricating a touch sensor that suppresses surface non-uniformity of a flexible substrate used to fabricate the touch sensor and uses a thermal adhesive to Defect generation is suppressed during attachment or detachment of the flexible substrate to or from the carrier substrate.

Various electronic devices employ a touch input mode that is considered a next-generation input technology. In this regard, many research and developments have been actively made to provide a touch sensor that can be applied to various environments and accurately recognize input information by touch.

For example, since an electronic device having a touch display has focused on an ultra-lightweight and low-power thin-film flexible display having improved portability as a next-generation display, there is a touch that can be applied to a display. One of the sensors is in demand.

A flexible display is prepared on a flexible substrate that can be bent, folded or curled without impairing its properties, and the flexible display can be in the form of a flexible LCD, a flexible OLED, electronic paper, or the like .

In order to apply the touch input mode to this flexible display, a touch sensor having good bending, recovery, flexibility and stretchability is required.

The touch sensor can be manufactured by using a flexible substrate comprising a nano-sized diamond powder incorporated in a polyethylene naphthalate resin to have excellent dimensional stability and low moisture transmission rate. (Korean Patent No. 10-1078059).

Moreover, one of the flexible substrates for the touch sensor can be made of a novel and improved polyarylate resin having one of the side chains to be introduced (Korean Patent Application Laid-Open No. 10-1992-0012125).

However, such a flexible substrate using a high heat resistant resin to suppress dimensional change is difficult to control the phase difference, and its application is limited to the preparation of a touch sensor.

Meanwhile, when a film other than the high heat resistant resin is used to solve the difficulty of controlling the phase difference, curling can be generated by heat treatment to cause unevenness in the film surface even after attaching the film to a carrier substrate This is also the case.

The non-uniformity of the film surface can degrade the accuracy of subsequent processes, thereby resulting in poor properties of a device and low production yield.

It is an object of the present invention to provide a method for fabricating a touch sensor by using a heat sensitive adhesive that inhibits defect generation during attachment or detachment of a carrier substrate.

Another object of the present invention is to provide a second thermal bonding by using one of a first adhesive for attaching a protective film and a heat-treated conductive film, and for attaching the conductive film to a glass. Method for manufacturing a touch sensor, which can minimize the second heat generated during peeling of the protective film by a difference in adhesion strength between the first and second adhesives The peeling defect of the sensitive adhesive from the conductive film.

Yet another object of the present invention is to provide a method for fabricating a touch sensor by attaching a protective film to a metal oxide layer prior to the glass attachment and patterning process, which inhibits the surface Inhomogeneity.

Still another object of the present invention is to provide a method for manufacturing a touch sensor, which comprises preparing a flexible substrate using a material capable of easily controlling a phase difference and attaching a protective substrate and a bonding agent. a protective film to reduce the heat generated after heat treatment Curl, thereby improving surface unevenness.

Yet another object of the present invention is to provide a method for fabricating a touch sensor that inhibits surface non-uniformity without the use of a high heat resistant resin to maintain the accuracy of subsequent procedures.

The object of the present invention is not limited to the foregoing objects, and other objects not mentioned in the present invention will be understood from the following description by those skilled in the art.

According to an aspect of the present invention, a method for manufacturing a touch sensor is provided, the method comprising: preparing a base film including a conductive layer; attaching a protective film to the base film, and thereafter The base film is attached to a carrier substrate; and a viscosity between the base film and the carrier substrate is increased and a viscosity between the base film and the protective film is reduced. The protective film was peeled off.

Attaching the protective film to the base film allows the surface curl of the base film to be relieved prior to attaching the base film to the carrier substrate.

The attachment of the protective film to the base film can be performed using a first adhesive, and the attachment of the base film to the carrier substrate can be performed using a second adhesive other than the first adhesive.

The first adhesive may be a heat curable or UV curable adhesive selected from the group consisting of polyesters, polyethers, urethanes, epoxies, polyoxyxides, and acrylate materials.

The second binder may be a one-temperature-sensitive adhesive exhibiting a viscosity of one side of the crystalline polymer and exhibiting viscosity at a temperature equal to or higher than the melting point of the side chain crystalline polymer.

The heat-sensitive adhesive may include one of crosslinked polymers obtained by adding a metal chelate to the side chain crystalline polymer and thereafter performing a crosslinking reaction.

The side chain crystalline polymer may be crystallized at a temperature lower than one of the melting points thereof and may have flexibility at a temperature equal to or higher than one of the melting points thereof.

The side chain crystalline polymer may include acrylic acid (meth) ester having a straight chain alkyl group having 16 or more carbon atoms, acrylic acid (meth) ester having one alkyl group of 1 to 6 carbon atoms, and a polar group. One of the copolymers is obtained by polymerization of a monomer.

The metal chelate may be tris(acetonitrile)aluminum.

The attachment of the protective film to the base film can be performed using a binder having a _Tg of less than 0, and the attachment of the base film to the carrier substrate can be performed using a heat sensitive adhesive, thereby The viscosity between the base film and the carrier substrate is selectively increased by the action of raising a temperature.

This increase in temperature for increasing the viscosity between the base film and the carrier substrate reduces the bonding strength of the adhesive for attaching the protective film to the base film.

After the protective film is peeled off, the conductive layer may be patterned to form a laminated structure, after which the base film is peeled off from the carrier substrate.

The conductive layer may be formed of a metal oxide selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc zinc oxide (IZTO), aluminum zinc oxide (AZO), and oxidation. Gallium zinc (GZO), fluorine-doped 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 oxide-silver-indium zinc oxide (IZTO-Ag-IZTO) and aluminum oxide zinc-silver-alumina zinc (AZO-Ag-AZO).

The base film may include a thermoplastic resin.

The base film may comprise a cyclic olefin polymer (COP).

The method for manufacturing a touch sensor according to the present invention has the following effects:

First, the use of a heat sensitive adhesive can inhibit the generation of defects during attachment or stripping of a carrier substrate.

Second, attaching a protective film to a metal oxide layer prior to the glass attachment and patterning process can inhibit surface non-uniformities.

Third, the method can suppress surface non-uniformity without using a high heat resistant resin to maintain the accuracy of subsequent procedures.

Fourth, the method can be easily applied to a conventional procedure because the protective film is removed after improving surface unevenness.

21‧‧‧ base film

22‧‧‧Metal oxide conducting layer

23‧‧‧Protective film

24‧‧‧Binder

25‧‧‧ Carrier substrate

S101‧‧‧Steps

S102‧‧‧Steps

S103‧‧‧Steps

S104‧‧‧Steps

S105‧‧‧Steps

S106‧‧‧Steps

S107‧‧‧Steps

1 is a flow chart showing one of the procedures for fabricating a touch sensor in accordance with the present invention.

2a through 2d are cross-sectional views of a procedure for fabricating a touch sensor in accordance with the present invention.

Figure 3 is a graph showing the change in bond strength versus temperature for one of the heat sensitive adhesives used in the present invention.

Hereinafter, a preferred embodiment of a method for manufacturing a touch sensor according to the present invention will be described in detail below.

The features and advantages of the method for fabricating a touch sensor in accordance with the present invention will be apparent from the following detailed description of the embodiments.

1 is a flow chart showing a procedure for fabricating a touch sensor in accordance with the present invention.

2a through 2d are cross-sectional views of a procedure for fabricating a touch sensor in accordance with the present invention.

A method for manufacturing a touch sensor according to the present invention is characterized in that a flexible substrate is prepared using a material capable of easily controlling a phase difference and a protective film is formed by a protective substrate and an adhesive. The curl generated after the heat treatment is alleviated, thereby improving surface unevenness.

In the method, a first adhesive is used to attach a protective film to a heat-treated conductive film, and a second heat-sensitive adhesive is used to attach the conductive film and a glass by the first and the first The adhesive strength difference between one of the two adhesives at one temperature minimizes the peeling defect of the second heat-sensitive adhesive self-conductive film generated during the peeling of the protective film.

Specifically, the method for manufacturing a touch sensor according to the present invention comprises the steps of: preparing a thermoplastic resin film comprising a metal oxide conductive layer; subjecting the film to heat treatment for conductivity improvement; a protective film attached to the heat-treating conductive film; attaching the conductive film to a glass carrier substrate using a heat-sensitive adhesive; peeling off the protective film; patterning the conductive layer to form a laminated structure; and peeling the laminated structure from the glass . Thereby, a laminated structure including a patterned electrode layer on a flexible substrate can be finally produced.

In the step of attaching the protective film to the heat-treated conductive film, a protective film composed of a protective substrate and an adhesive is attached to the heat-treated conductive film (which is a laminated layer of a metal oxide and a thermoplastic resin) Especially on its metal oxide layer.

This attachment of the protective film allows to alleviate uneven curl on the surface of the film produced during the heat treatment, whereby the conductive film having a uniform surface can be attached to the glass carrier substrate in a subsequent step.

Moreover, the peeling step of the protective film is performed by heating, the heat is reduced to reduce the viscosity between the adhesive for the protective film and the metal oxide layer, and the viscosity between the heat-sensitive adhesive and the thermoplastic resin is increased. Minimize peel defects.

A method for fabricating a touch sensor in accordance with the present invention will be described in greater detail below.

A base film 21 including a metal oxide conductive layer 22 is prepared (S101), followed by heat treatment for conductivity improvement (S102).

The metal oxide can be selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), Fluorine-doped 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 sulfide-silver - Indium zinc tin oxide (IZTO-Ag-IZTO) and aluminum oxide zinc-silver-alumina zinc (AZO-Ag-AZO), but not Limited to this.

The base film 21 may comprise a thermoplastic resin, preferably a cyclic olefin polymer (COP).

For example, a cyclic olefin polymer (COP) may be a polymer obtained from a cyclic monomer such as norbornene, which is suitable for use in the preparation of a flexible substrate due to comparison with other olefin polymers. It has good transparency, heat resistance and chemical resistance as well as low birefringence and hygroscopicity.

In addition to the cycloolefin polymer (COP), the base film 21 may be made of any one selected from the group consisting of thermoplastic elastomers, styrene materials, olefin materials, polyolefins, and polyaminocarboxylic acids. Ester thermoplastic elastomer, polyamide, synthetic rubber, polydimethyl siloxane (PDMS), polybutadiene, polyisobutylene, poly(styrene-butadiene-styrene), polyurethane , polyvinyl chloride, polymethacrylate, polypropylene, polycarbonate, polyarylate, polyfluorene, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyoxyl And a mixture of one of them.

The base film can be used as a retardation film for the purpose of reducing the pattern visibility of the touch sensor or improving the optical properties of a display.

As shown in Fig. 2a, the base film 21 has a curl produced by heat treatment for conductivity improvement.

As shown in FIG. 2b, the curling can be alleviated by the step of attaching a protective film 23 composed of a protective substrate and an adhesive to the base film 21 (S103). That is, attaching the protective film to the base film allows the surface curl of the base film to be alleviated, so that the base film attached to a carrier substrate is in its uniform surface state.

In the present invention, the protective film is preferably polyethylene terephthalate (PET), but is not limited thereto.

For example, the protective film may be made of a thermoplastic resin such as a polyester resin such as polyethylene terephthalate (PET), polyethylene isophthalate, polyethylene naphthalate, and poly Butylene terephthalate; cellulose resin such as diethyl cellulose and Triacetyl cellulose; polycarbonate resin; acrylate resin, such as poly(meth)acrylate and polyethylene acrylate; styrene resin, such as polystyrene and acrylonitrile-styrene copolymer; Polyolefin resin, such as polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, and ethylene-propylene copolymer; vinyl chloride resin; guanamine resin, such as nylon and aromatic polyamine; quinone Resin; polyether oxime resin; polydiether ketone resin; polyphenylene sulfide resin; vinyl alcohol resin; vinylidene chloride resin; vinyl alcohol butyral resin; acrylic acid ester resin; polyacetal resin; One of its mixtures.

Moreover, heat curable or UV curable resins such as acrylic acid esters, urethanes, urethane acrylates, epoxy resins and enamel resins may be used.

The adhesive used in the protective film 23 may be one selected from the group consisting of polyester, polyether, urethane, epoxy resin, polyoxymethylene, and acrylate. It may be heat-curable or UV-curable. Agent.

As shown in Fig. 2c, the base film is attached to a glass carrier substrate 25 using an adhesive (S104).

The binder can be a heat sensitive adhesive.

A heat-sensitive adhesive refers to a binder having an adhesive strength that changes depending on a change in temperature.

The heat-sensitive adhesive used in one embodiment of the present invention contains a side chain crystalline polymer and exhibits viscosity at a temperature equal to or higher than the melting point of the side chain crystalline polymer.

The heat-sensitive adhesive may include one of a crosslinked polymer obtained by adding a metal chelate to a side chain crystalline polymer and thereafter performing a crosslinking reaction.

The side chain crystalline polymer may be crystallized at a temperature lower than one of its melting points and may have flexibility at a temperature equal to or higher than one of its melting points.

The side chain crystalline polymer is preferably an acrylic acid (meth) ester having a straight chain alkyl group having 16 or more carbon atoms, an alkyl (meth) ester having an alkyl group of 1 to 6 carbon atoms, and One of the copolymers is obtained by polymerization of a polar monomer.

The metal chelate is preferably selected from at least one of a coordination compound in which one of acetoacetone and a polyvalent metal is coordinated, and one of the coordination compounds of an acetoacetate and a polyvalent metal. Especially triethyl acetonide aluminum.

As shown in FIG. 2d, the protective film 23 is peeled off from the base film 21 attached to the glass as the carrier substrate 25 (S105), and the conductive layer is patterned to form a laminated structure (S106).

After the laminate structure is formed, the laminate structure is peeled off from the glass as the carrier substrate 25 (S107).

Peeling of the protective film 23 from the base film 21 attached to the glass is carried out by using a change in the bonding strength to temperature.

In particular, Figure 3 is a graph showing one of the changes in bond strength of a heat sensitive adhesive to temperature used in the present invention.

According to an embodiment of the present invention, the protective film 23 is composed of a protective substrate and a binder having a _Tg of less than 0, and a heat-sensitive adhesive is used (the bonding strength thereof increases with an increase in temperature). The attachment of the base film to the glass as the carrier substrate 25 is carried out.

Therefore, when peeling of the protective film 23 from the base film 21 of the glass as the carrier substrate 25 is performed at a temperature of 40 ° C or higher, between the adhesive for the protective film and the metal oxide layer The viscosity is reduced, and the viscosity between the heat-sensitive adhesive and the thermoplastic resin is increased (as shown in the graph of Fig. 3), thereby suppressing peeling defects.

The method for manufacturing a touch sensor according to the present invention can use a material capable of easily controlling a phase difference to prepare a flexible substrate and attaching a protective film composed of a protective substrate and an adhesive to alleviate The curl produced after heat treatment, thereby improving surface non-uniformity and maintaining the accuracy of subsequent procedures.

Moreover, the method of the present invention uses a first adhesive for attaching a protective film and a heat-treated conductive film, and a second heat-sensitive adhesive for attaching the conductive film to a glass, which can be used by the first And the second adhesive has a poor adhesion strength to one of the temperatures and is minimized. Peeling defects of the second heat-sensitive adhesive self-conducting film generated during peeling of the film.

Although a particular embodiment of the invention has been shown and described, it will be understood by those skilled in the art Various changes and modifications are made in the context of the spirit and scope.

Therefore, the scope of the invention should be defined by the scope of the appended claims and their equivalents.

Claims (15)

A method for manufacturing a touch sensor, comprising: preparing a base film comprising a conductive layer; attaching a protective film to the base film, and thereafter attaching the base film to a carrier substrate; And the protective film is peeled off from the base film in a state in which a viscosity between the base film and the carrier substrate is increased and a viscosity between the base film and the protective film is reduced. The method of claim 1, wherein attaching the protective film to the base film allows surface curling of the base film to be relieved prior to attaching the base film to the carrier substrate. The method of claim 1, wherein the attaching of the protective film to the base film is performed using a first adhesive, and the base film is applied to the carrier using a second adhesive other than the first adhesive. This attachment of the substrate. The method of claim 3, wherein the first binder is heat curable from one of the group consisting of polyester, polyether, urethane, epoxy, polyoxymethylene, and acrylate materials. UV curable adhesive. The method of claim 3, wherein the second binder comprises a one-chain crystalline polymer and exhibits a viscosity one of the heat-sensitive adhesives at a temperature equal to or higher than a melting point of the side chain crystalline polymer. The method of claim 5, wherein the heat-sensitive adhesive comprises one of a crosslinked polymer obtained by adding a metal chelate to the side chain crystalline polymer and thereafter performing a crosslinking reaction. The method of claim 5, wherein the side chain crystalline polymer is crystallized at a temperature lower than one of the melting points thereof and has flexibility at a temperature equal to or higher than one of the melting points. The method of claim 6 or 7, wherein the side chain crystalline polymer comprises by having 16 A copolymer of one or more carbon atoms of an alkyl (meth) acrylate having an alkyl group, an alkyl (meth) acrylate having one alkyl group of 1 to 6 carbon atoms, and a polar monomer. The method of claim 6, wherein the metal chelate is aluminum triacetate. The method of claim 1, wherein the attaching of the protective film to the base film is performed using a binder having a _Tg of less than 0, and the base film is applied to the carrier substrate using a heat-sensitive adhesive. Attached, whereby the adhesion between the base film and the carrier substrate is selectively increased by an action of raising a temperature. The method of claim 10, wherein the increase in temperature for increasing a viscosity between the base film and the carrier substrate reduces the adhesive for attaching the protective film to the base film Bond strength. The method of claim 1, wherein the conductive layer is patterned after peeling off the protective film to form a laminated structure, after which the base film is peeled off from the carrier substrate. The method of claim 1, wherein the conductive layer is formed of a metal oxide selected from the group consisting of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), Alumina zinc oxide (AZO), gallium zinc oxide (GZO), fluorine-doped 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-tin-silver-indium zinc oxide (IZTO-Ag-IZTO), and aluminum zinc oxide-silver-alumina zinc (AZO-Ag-AZO). The method of claim 1, wherein the base film comprises a thermoplastic resin. The method of claim 14, wherein the base film comprises a cyclic olefin polymer (COP).