TW201633638A - Method of manufacturing connector, method for connecting electronic component, and connector - Google Patents

Abstract

In order to ensure the adhesive strength of an electronic component through the formation of a fillet and to prevent the contamination of a support, the adhesion of a board and an increase in contact resistance of the electronic component, which are caused by a binder resin, this method comprises: an adhesive disposing step for disposing, on a circuit board 2 having optical transparency, a circuit-connecting adhesive 6 containing a photopolymerization initiator; and a press-bonding step in which an electronic component 5 is disposed on the circuit board 2 by means of the circuit-connecting adhesive 6 and the circuit-connecting adhesive 6 is cured while the electronic component 5 is being hot-pressed against the circuit board 2, wherein the circuit-connecting adhesive 6 has a melt viscosity of 4,000 pa.s or less at a heating temperature in the press-bonding step.

Description

Manufacturing method of connector, connection method of electronic component, connector

The present invention relates to a method for producing a connector in which an electronic component is connected to a transparent substrate via an adhesive for connecting a circuit containing a photopolymerization initiator, and an adhesive for connecting a circuit containing a photopolymerization initiator. A method of connecting electronic components to a transparent substrate, and a connector manufactured using the same.

The present application claims priority on the basis of Japanese Patent Application No. 2014-212108, filed on Jan.

In the case of connecting a rigid substrate such as a glass substrate or a glass epoxy substrate to an electronic component such as a flexible substrate or an IC wafer, an anisotropic property is obtained by forming a film of a binder resin in which conductive particles are dispersed. The conductive film serves as an adhesive. When the connection terminal of the flexible substrate and the connection terminal of the rigid substrate are connected as an example, as shown in FIG. 6(A), the two connection terminals of the flexible substrate 51 and the rigid substrate 54 are formed. Between the regions 52 and 55, an anisotropic conductive film 53 is disposed, and an appropriate buffer material 50 is disposed, and is thermally pressurized from above the flexible substrate 51 by the thermocompression bonding tool 56. Thus, as shown in FIG. 6(B), the adhesive resin exhibits fluidity, flows out from the connection terminal 52 of the flexible substrate 51 and the connection terminal 55 of the rigid substrate 54, and is in the anisotropic conductive film 53. The conductive particles are sandwiched between the two connection terminals and And it is squashed.

As a result, the connection terminal 52 of the flexible substrate 51 and the connection terminal 55 of the rigid substrate 54 are electrically connected to each other via the conductive particles, and in this state, the adhesive resin is cured. The conductive particles that are not present between the two connection terminals 52, 55 are dispersed in the adhesive resin to maintain electrical insulation. Thereby, electrical conduction is achieved only between the connection terminal 52 of the flexible substrate 51 and the connection terminal 55 of the rigid substrate 54.

Further, on the side surface of the rigid substrate 54, the adhesive resin overflows between the rigid substrate 54 and the flexible substrate 51, and a ferret is formed between the connection surface with the flexible substrate 51, thereby achieving the bonding strength. improve.

In recent years, for example, in the connection between a glass substrate of a liquid crystal panel and a flexible substrate, the thinning of the glass substrate has progressed, and as the liquid crystal screen is enlarged relative to the outer frame of the electronic device, the outer edge portion of the screen is called The narrow frame of the narrowing of the frame portion is constantly developing. Therefore, in the connection method using the thermosetting type anisotropic conductive film, the thermal shock temperature is high, and the thermal shock to the glass substrate or the flexible substrate is large. Further, when the temperature is lowered to the normal temperature after the connection of the anisotropic conductive film, the adhesive shrinks due to the temperature difference, and warpage may occur in the thinned glass substrate. Therefore, there are concerns about problems such as display unevenness or poor connection of the flexible substrate.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-26577

Therefore, a method of connecting an anisotropic conductive film using a thermosetting adhesive is also used instead of the ultraviolet curable adhesive. For the use of UV-curing adhesives In the connection method, the adhesive softens and flows by heat, and is heated only to a temperature sufficient for "capturing the conductive particles between the glass substrate and the electrodes of the flexible substrate", and the adhesive is cured by ultraviolet irradiation.

In the connection method using the ultraviolet curable adhesive, it is not necessary to apply high heat in order to cure the adhesive resin, and it is possible to prevent problems such as deformation due to thermal shock to the glass substrate or the flexible substrate.

In recent years, with the increase in the size of displays in portable electronic devices and the like, lightweight and flexible plastic substrates have been used. The plastic substrate is less resistant to thermal shock than the glass substrate or the like, and is required to be connected at a lower temperature and a lower pressure in the connection step using the ultraviolet curable adhesive.

Here, by performing the low-temperature connection using the ultraviolet curable adhesive, on the one hand, thermal shock can be prevented at a low temperature, and on the other hand, the flow of the adhesive of the adhesive is insufficient, and the intrusion of conductive particles occurs at the terminal portion. Insufficient, and there is a lack of reliability. Therefore, the ultraviolet curable adhesive needs to lower the viscosity of the binder resin itself.

However, when the viscosity of the adhesive resin is lowered, when an electronic component such as a flexible substrate is mounted and pressed by a thermocompression bonding tool, the melted adhesive resin overflows from the side surface of the substrate and flows back to the back side of the substrate. After that. Further, since the binder resin flows into the back surface of the substrate, the support table of the support substrate is stained, and the substrate is damaged when the substrate attached to the support table is peeled off.

If the melt viscosity of the binder resin is increased in order to prevent the overflow of the binder resin, the formation of the ribbon is inhibited, and the strength is insufficient. Further, under low temperature and low pressure conditions, insufficient press-fitting of electronic components such as flexible substrates causes an increase in on-resistance.

Moreover, this problem is not only the use of photohardenable anisotropic conductive adhesives. It may also occur in the case of a shape, and in the case of using a thermosetting type and a light or thermosetting anisotropic conductive adhesive.

The present invention has been made in an effort to solve the above problems, and an object of the invention is to provide an adhesive strength for securing an electronic component formed by a thin ribbon, and to prevent contamination of a support table due to a binder resin or an increase in connection resistance of a substrate and an electronic component. A method of manufacturing a connector, a method of connecting electronic components, and a connector manufactured using the same.

In order to solve the above problems, the method for producing a connector of the present invention has the following steps: an adhesive disposing step of disposing a circuit connecting adhesive containing a photopolymerization initiator on a circuit board having light transmissivity; In the step of disposing the electronic component on the circuit board, the electronic component is placed on the circuit board, and the electronic component is heated and pressed against the circuit board, and the circuit connecting adhesive is cured; and the circuit connection is followed by The melt viscosity of the agent at the heating temperature in the above crimping step is 4000 Pa. s below.

Moreover, the method of connecting an electronic component according to the present invention has the following steps: an adhesive disposing step of disposing a circuit connecting adhesive containing a photopolymerization initiator on a light-transmitting circuit substrate; and a crimping step, Interposing the above-mentioned circuit-connecting adhesive, disposing an electronic component on the circuit board, heating and pressing the electronic component toward the circuit board, and curing the circuit-connecting adhesive; and the circuit-connecting adhesive is as described above The melt viscosity at the heating temperature in the crimping step is 4000 Pa. s below.

Further, the connection system of the present invention is produced by the above-described production method.

According to the invention, the melt viscosity at the heating temperature of the formal crimping step is set at 4000 Pa. s or less, so that the conductive particles can be sufficiently pressed by the exclusion of the binder resin. Son, so that good conduction reliability can be obtained. Moreover, according to the present invention, the overflow width W of the thin strip formed between the circuit board and the electronic component is also suitable, and the connection strength between the circuit board and the electronic component can be improved, and the contamination of the support table can be prevented.

1‧‧‧Touch sensor

2‧‧‧Transparent film

3‧‧‧Connecting terminal

4‧‧‧Construction Department

5, 51‧‧‧Flexible substrate

6, 53‧‧‧ anisotropic conductive film

7, 52, 55‧‧‧ connection terminals

8‧‧‧ Coverage

9‧‧‧Substrate

10‧‧‧Wiring pattern

12‧‧‧The outer edge

20, 56‧‧‧Hot crimping tools

21‧‧‧Strip

22, 50‧‧‧ cushioning materials

23‧‧‧UV illuminator

24‧‧‧Support desk

54‧‧‧Rigid substrate

Fig. 1 is a cross-sectional view showing an example of a method of manufacturing a connecting body to which the present invention is applied.

Fig. 2 is a perspective view showing an example of a method of manufacturing a connecting body to which the present invention is applied.

Fig. 3 is a side view showing one form of an anisotropic conductive film.

Fig. 4 is a cross-sectional view schematically showing a formal crimping step.

Fig. 5 is a plan view schematically showing the areal density distribution of the conductive particles of the bonded body.

Fig. 6 is a cross-sectional view showing a conventional method of manufacturing a connector, wherein (A) is an exploded cross-sectional view and (B) is a cross-sectional view at the time of final pressure bonding.

Hereinafter, a method of manufacturing a connector to which the present invention is applied, a method of connecting electronic components, and a connector will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below, and various modifications can be made without departing from the spirit and scope of the invention. Further, the drawings are schematic, and there is a case where the ratio of each size is different from the actual one. The specific dimensions and the like are judged based on the following description. Further, of course, the drawings also include portions in which the relationship or ratio of the dimensions is different from each other.

Applying the connection system of the present invention to a circuit board having light transmissivity, intervening in the opposite direction A conductive connecting agent is connected to an electronic component such as a flexible substrate, and can be used, for example, in a television or a PC, a smart phone, a mobile phone, a game machine, an audio-visual device, an input terminal, a wearable terminal, or a vehicle. A display device such as a monitor or a touch panel, and a substrate of all other electronic devices. In such a substrate, from the viewpoints of fine pitch, light weight, and the like, a flexible substrate on which an IC chip or various circuits are formed is directly mounted on a circuit board having light transmissibility, that is, a so-called COF (chip on film), COG (chip on glass), FOF (film on film), FOG (film on glass). Further, as a bonding film for bonding various substrates to an IC chip or a flexible substrate or the like, an anisotropic conductive film (ACF: anisotropic conductive film) in which "conductive particles are dispersed in a binder resin layer" is often used. .

Hereinafter, as an example of a connector to which the present invention is applied, a touch sensor 1 incorporated as an input device to various monitors will be described. As the touch sensor 1, a film in which an electrode pattern or a substrate such as a plastic is formed is generally used, or an electrode pattern is formed on both surfaces of a substrate.

In the transparent film 2 to be a substrate, the electrode patterns to be the sensor portions are formed in a matrix shape, and the electrode pattern intervening wiring patterns are connected to the connection terminals 3 formed on the outer edge portion of the transparent film 2. Further, as shown in FIGS. 1 and 2, the flexible substrate 5 of the touch sensor 1 is connected to a configuration portion 4 in which a plurality of connection terminals 3 are connected in parallel, and the flexible substrate 5 is controlled by position detection. Connector.

The transparent film 2 which becomes the base of the touch sensor 1 can be reinforced by, for example, PET (polyethylene terephthalate), polycarbonate, or a polyimide film adhered to the PET film, or A film made of a transparent synthetic resin such as a cycloolefin-based resin composition film obtained by dispersing an elastomer or the like with a cycloolefin-based resin. As an electrode pattern constituting the sensor portion, an organic guide can be used. A transparent conductive material mainly composed of an electrical polymer. For example, a composition containing at least a polythiophene derivative polymer, a water-soluble organic compound, and a dopant material may be mentioned. A slurry composed of such an organic conductive polymer is used as a printing ink, and is directly patterned by screen printing, for example, whereby an electrode pattern having a specific shape can be formed on the surface of the transparent film 2. Alternatively, after the organic conductive polymer is applied to both surfaces of the transparent film 2, the layer of the organic conductive polymer is locally deteriorated by a transparent printing ink containing an acid or an alkaline agent, whereby an electrode pattern can also be formed. . Further, various methods such as gravure printing and inkjet printing can be used for patterning the electrode pattern. Further, a photolithography method in which a specific pattern is formed by exposing a surface of a substrate coated with a photosensitive material in a pattern may be used. That is, as long as a transparent conductive material containing an organic conductive polymer as a main component can be formed as an electrode pattern, a method other than the above method can be used.

The plurality of connection terminals 3 connected to the respective electrode patterns via the wiring pattern can be formed, for example, by a known method such as sputtering or vacuum deposition to produce an ITO transparent conductive film, or by using a known method such as sputtering or vacuum deposition. The silver paste is directly patterned by screen printing, or etched copper foil or the like. The plurality of connection terminals 3 are formed substantially in a rectangular shape, for example, and are formed by arranging a plurality of outer edges of the transparent film 2 and a direction orthogonal to the longitudinal direction as shown in FIG. 2, thereby constituting the flexible substrate 5 for connection. The mounting portion 4.

When the structure 4 and the flexible substrate 5 are connected, an anisotropic conductive film (ACF) 6 is used as a conductive adhesive. The anisotropic conductive film 6 contains conductive particles in the binder resin as described below, and the connection terminals 7 of the flexible substrate 5 and the connection terminals 3 formed on the transparent film 2 are electrically connected to each other via conductive particles.

[Flexible substrate]

The flexible substrate 5 connected to the mounting portion 4 of the transparent film 2 is connected to a position not shown. The measuring controller is a connector that connects the connection terminal 3 provided for each of the electrode patterns constituting the sensor portion to the controller. As shown in FIG. 2, the flexible substrate 5 is formed with a plurality of connection terminals 7 for connecting to the connection terminals 3 of the transparent film 2, on one surface 9a of the flexible substrate 9 such as polyimide. The connection terminal 7 is formed by, for example, patterning a copper foil or the like, and is subjected to a plating treatment such as nickel plating or gold plating on the surface, and is formed into a substantially rectangular shape, for example, orthogonal to the longitudinal direction, similarly to the connection terminal 3 . A plurality of directions are formed. The width of the connection terminal 7 and the width of the connection terminal 3, and the interval between the adjacent connection terminals 7 and the interval between the adjacent connection terminals 3 are arranged in substantially the same pattern, and the connection terminal 7 is separated from the connection terminal 3. The anisotropic conductive film 6 overlaps.

[coverage layer]

Further, the flexible substrate 5 is provided with a cover layer 8 in the vicinity of the connection terminal 7. The cover layer 8 protects other wiring patterns formed on the one surface 9a of the substrate 9 connected to the transparent film 2, and an adhesive layer is provided on one surface of the insulating base film, and the adhesive layer is attached to the substrate 9 One side 9a.

In the touch sensor 1, the outer peripheral portion of the connecting portion 7 in which the connecting portion 3 of the transparent film 2 is provided with the connection terminal 3 or the flexible substrate 5 is narrowed is provided, and as shown in FIG. The connection of the anisotropic conductive film 6 is performed by covering a portion of the cover layer 8 near the outer edge of the flexible substrate 5. Thereby, the touch sensor 1 ensures the reliability of the electrical and mechanical connection of the transparent film 2 and the flexible substrate 5.

[Anisotropic Conductive Film]

The anisotropic conductive film 6 is a photocurable adhesive which is fluidized by thermal compression by the following thermocompression bonding tool 20, and the conductive particles 16 are connected to each of the transparent film 2 and the flexible substrate 5. The terminals 3 and 7 are crushed, and are irradiated with light to be cured in a state where the conductive particles 16 are crushed. Thereby, the anisotropic conductive film 6 electrically and mechanically connects the transparent film 2 and the flexible substrate 5.

The anisotropic conductive film 6 is formed by dispersing the conductive particles 16 in the binder resin 15 (adhesive) as shown in FIG. 3, and applying the thermosetting adhesive material composition to the base film 17. Formed into a film shape.

The base film 17 is formed by, for example, applying a stripping agent such as poly(ethylene terephthalate), OPP (oriented polypropylene), PMP (poly-4-methylpentene-1), or PTFE (polytetrafluoroethylene) to polyfluorene.

The binder rouge 15 is not particularly limited as long as it is photocurable, and a radical polymerization type, a cationic polymerization type, or the like can be used. Hereinafter, the radical polymerization type binder resin will be described.

The radical polymerizable binder resin contains a film-forming resin, a radical curable compound, and a radical polymerization initiator. As the film-forming resin, a thermoplastic elastomer such as a phenoxy resin, an epoxy resin, a polyester resin, a polyurethane resin, a polyamide or EVA can be used. Among these, in terms of heat resistance and adhesion, it is preferred to use a bisphenol A type phenoxy resin synthesized from bisphenol A and epichlorohydrin.

The radically polymerizable compound can be appropriately selected from (meth) acrylate which is used in the field of an adhesive or the like. Further, in the present specification, the (meth) acrylate system means acrylate and methacrylate.

Specific examples of the radically polymerizable compound include epoxy acrylate, isomeric cyanuric acid EO modified diacrylate, tricyclodecane dimethanol diacrylate, and dimethylol-tricyclodecane II. Acrylate, polyethylene glycol diacrylate, urethane acrylate, 2-hydroxy acrylate Ethyl ethyl ester, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, bisphenoxyethanol fluorene diacrylate, succinic acid 2-propenyloxyethyl ester, lauryl acrylate, stearyl acrylate, isodecyl acrylate, cyclohexyl acrylate, tris(2-hydroxyethyl)isocyanuric acid triacrylate, tetrahydrofurfuryl acrylate, adjacent Diglycidyl ether acrylate, ethoxylated bisphenol A dimethacrylate, bisphenol A epoxy acrylate, and the like (meth) acrylate, etc.; Kind or more than two. Among these, acrylate or acrylate or the like is preferably used. Specific examples which can be obtained in the market include the trade name "M-315" or "M1600" manufactured by Toagosei Co., Ltd.

The photoradical polymerization initiator can be appropriately selected from known radical polymerization initiators.

As a photopolymerization type radical polymerization initiator, ethyl ketone, 1-[9-ethyl-6-(2-methylbenzylidene)-9H-carbazol-3-yl]-1- 9-oxosulfuric acid such as (0-acetamidine), benzophenone, 4,4-bis(diethylamino)benzophenone, 2,4,6-dimethylbenzophenone (thioxanthone); acetophenones such as diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin dimethyl ketal; benzoin methyl ether, Benzoin ethers such as benzoin ethyl ether and benzoin isopropyl ether; 2,4,6-trimethylbenzimidyl diphenylphosphine oxide, bis(2,6-dimethoxybenzylidene)-2,4 a fluorenylphosphine oxide such as 4-dimethylpentylphosphine oxide or bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide.

These radical polymerization initiators may be used alone or in combination of two or more. Among these, 1,1-di(t-butylperoxy)cyclohexane, bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide, and the like are preferably used. Specific examples of the product that can be obtained in the market include the trade name "IRGACURE OXE02" of BASF Japan.

Further, as an additional additive to be mixed with the circuit connecting material, a halogen monomer, an inorganic filler, an acrylic rubber, a dilute monomer such as various acrylic monomers, a filler, a softener, a colorant, a flame retardant, or the like may be contained as needed. Thixotropic agents, etc.

The decane coupling agent is not particularly limited, and examples thereof include epoxy-based, amine-based, thiol-thioether-based, and guanidine-based. By adding a decane coupling agent, the adhesion of the interface between the organic material and the inorganic material can be improved.

Further, the inorganic filler is not particularly limited, and cerium oxide, talc, titanium oxide, calcium carbonate, magnesium oxide or the like can be used. By adding an inorganic filler, the fluidity of the binder resin 15 can be controlled, thereby increasing the particle trapping rate.

The conductive particles 16 include any of the known conductive particles used in the anisotropic conductive film 6. Examples of the conductive particles 16 include particles of various metals such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, gold, or metal alloys; and metal oxides, carbon, graphite, glass, and ceramics. The surface of the particles such as plastic is coated with a metal; or the surface of the particles is coated with an insulating film. In the case where a metal is applied to the surface of the resin particle, examples of the resin particle include an epoxy resin, a phenol resin, an acrylic resin, an acrylonitrile-styrene (AS) resin, and a benzoquinone. Particles such as a benzoguanamine resin, a divinylbenzene resin, or a styrene resin.

In addition, the anisotropic conductive film 6 may be configured to provide a cover film on the side opposite to the surface on which the base film 17 is laminated, from the viewpoints of easiness of use, storage stability, and the like. Further, the shape of the anisotropic conductive film 6 is not particularly limited, and for example, it can be formed into a long strip shape that can be wound around the reel 18, and can be used by cutting a specific length.

Further, the anisotropic conductive film 6 of the present invention may be formed to contain conductive particles. An anisotropic conductive film having a multilayer structure in which an adhesive resin layer of 16 and an insulating adhesive composed of an insulating adhesive composition containing no conductive particles are laminated. Further, in addition to the anisotropic conductive film 6 to be bonded to the flexible substrate 5, a paste-like anisotropic conductive paste may be used in addition to the anisotropic conductive film 6 formed into a film shape.

[melt viscosity]

Here, the refractive conductivity of the anisotropic conductive film 6 of the present technology at the heating temperature of the thermocompression bonding tool 20 in the final crimping step of the flexible substrate 5 described below is 4000 Pa. s below. By setting the melt viscosity of the anisotropic conductive film 6 at the heating temperature of the final pressure bonding step to the range, in the final pressure bonding step using the photocurable anisotropic conductive film 6 under low temperature and low pressure, the adhesive The resin 15 also exhibits moderate fluidity, and the conductive particles 16 are sufficiently pressed by the connection terminals 3 and 7, so that the conduction reliability can be ensured.

Further, the adhesive resin 15 exhibits a moderate fluidity, whereby the side surface 2a of the transparent film 2 from which the adhesive resin protrudes from the flexible substrate 5 is moderately overflowed, and the fine tape 21 is formed by irradiation of ultraviolet light. Thereby, the contact area of the adhesive resin 15 between the transparent film 2 and the flexible substrate 5 is increased, and the adhesive resin 15 is adhered to and hardened to the substrate of the transparent film 2 or the flexible substrate 5, whereby The so-called anchoring effect is exerted, whereby the improvement of the bonding strength can be achieved.

Moreover, the anisotropic conductive film 6 of the present technology is preferably a melt viscosity at a heating temperature of the thermal bonding tool 20 in the final crimping step of the flexible substrate 5 at 1000 Pa. s above. By setting the melt viscosity of the anisotropic conductive film 6 at the heating temperature in the final pressure bonding step to this range, the adhesive resin 15 is allowed to overflow to the side 2a of the flexible substrate 5 on which the transparent film 2 protrudes. The formed fine tape 21 has an overflow width W of an appropriate length, and can achieve an increase in the adhesion strength due to an increase in the connection area with the adhesive resin 15, and also prevent the adhesive resin 15 from being self-transparent. The side 2a of the clear film 2 flows back to the back side to contaminate the support table.

In particular, in the low-temperature pressure bonding step in which the heating temperature of the thermocompression bonding tool 20 is 100° C. or less in the final pressure bonding step, the refractive index at the heating temperature is set to 1000 Pa. . Above s and 4000Pa. In the following, it is possible to secure the conduction reliability and the adhesion strength to the flexible substrate 5, and also to suppress thermal shock to the transparent film 2 or the flexible substrate 5, thereby preventing deformation and the like.

[manufacturing steps]

Next, the manufacturing steps of the touch sensor 1 will be described. The manufacturing step of the touch sensor 1 has an adhesive arrangement step of disposing the anisotropic conductive film 6 on the structure 4 of the transparent film 2, and a formal crimping step of isotropic conduction. In the film 6, the flexible substrate 5 is placed on the transparent film 2, and the flexible substrate 5 is heated and pressed against the transparent film 2, and ultraviolet light is irradiated to cure the anisotropic conductive film 6.

[temporary attachment step]

First, the anisotropic conductive film 6 is temporarily attached to the transparent film 2 (adhesive arrangement step). The method of temporarily attaching the anisotropic conductive film 6 is performed on the connection terminal 3 of the transparent film 2, and the anisotropic conductive film 6 is disposed such that the adhesive resin 15 is on the side of the connection terminal 3. After the adhesive resin 15 is placed on the connection terminal 3, the adhesive resin 15 is transferred to the transparent film 2 from the base film 17 side by heating and pressurization using a thermocompression bonding tool, and the base film 17 is self-adhesive. The resin 15 was peeled off.

[Alignment step / temporary crimping step]

Then, the transparent substrate 6 and the connection terminal 7 of the flexible substrate 5 are opposed to each other with the adhesive resin 15 interposed therebetween, and the flexible substrate 5 is aligned, and the flexible substrate 2 is placed on the transparent film 2 5, under the low temperature and low pressure of the binder resin 15 exhibiting fluidity Temporary crimping of the flexible substrate 5. Thereby, the warpage of the transparent film 2 is suppressed to the minimum, and damage to the flexible substrate 5 due to heat is not caused.

[Formal crimping step]

Then, as shown in FIG. 4, the flexible substrate 5 is heated and pressed against the transparent film 2, and is irradiated with ultraviolet light, whereby it is electrically and mechanically connected (formal pressure bonding step). In the final pressure bonding step, the thermocompression bonding tool 20 is heated to a low temperature at which the binder resin 15 flows, and the conductive particles 4 are sandwiched between the connection terminal 7 of the flexible substrate 5 and the transparent film 2 The specific pressure between the connection terminals 3 is pressurized. Further, on the hot pressing surface of the thermocompression bonding tool 20, a cushioning material 22 composed of a sheet-like elastic agent such as ruthenium rubber is interposed.

Further, in the final pressure bonding step, ultraviolet light is irradiated from the back side of the transparent film 2 by the ultraviolet ray irradiator 23. The ultraviolet rays emitted from the ultraviolet illuminator 23 penetrate the transparent support table 24 such as glass supporting the transparent film 2, and are irradiated to the binder resin 15.

As the ultraviolet ray irradiator 23, an LED lamp, a mercury lamp, a metal halide lamp or the like can be used. Further, the ultraviolet ray irradiator 23 is disposed on the back side of the support table 24, and starts at the same time as the start of the heating pressing of the flexible substrate 5 by the thermocompression bonding tool 20, or a predetermined time from the start of the heating pressing, and starts. Irradiation of ultraviolet light. Thereby, the ultraviolet ray irradiator 23 is irradiated with ultraviolet rays to cure the adhesive resin 15 at the time point, that is, the pressure is lowered by the heat pressing of the thermocompression bonding tool 20, and the connection by the transparent film 2 is used. The conductive particles 16 are interposed between the terminal 3 and the connection terminal 7 of the flexible substrate 5, and the adhesive resin 15 overflows to the side surface of the transparent film 2.

Thereby, the touch panel 1 in which the flexible substrate 5 is electrically and mechanically connected to the transparent film 2 and provided with the thin strip 21 and then increased in strength is formed.

Here, as described above, the melt viscosity of the anisotropic conductive film 6 at the heating temperature by the thermocompression bonding tool 20 is set at 4000 Pa. s below. Therefore, according to the present technology, the adhesive resin 15 exhibits a moderate fluidity in the formal crimping step at a low pressure of less than 10 MPa, for example, 3 to 5 MPa, etc., and can be sufficiently pressed by the connection terminals 3, 7. Conductive particles 16.

On the other hand, if the anisotropic conductive film 6 is heated by the thermocompression bonding tool 20, the melt viscosity is higher than 4000 Pa. s, the fluidity of the binder resin 15 is low, and the removal of the binder resin between the connection terminals 3 and 7 is insufficient, so that the press-fitting of the conductive particles 16 is insufficient, and the conduction reliability is impaired.

Moreover, the melt viscosity at the heating temperature of the anisotropic conductive film 6 by the thermocompression bonding tool 20 is set to 1000 Pa. s or more, the overflow width W of the adhesive resin 15 overflowing to the side surface of the transparent film 2 on which the flexible substrate 5 protrudes is an appropriate length, and an appropriate size of the thin strip 21 can be formed by irradiation of ultraviolet light, thereby improving the subsequent strength.

On the other hand, if the anisotropic conductive film 6 is heated by the thermocompression bonding tool 20, the melt viscosity is less than 1000 Pa. s, the binder resin 15 will flow back to the back surface of the transparent film 2, whereby the contamination of the transparent support table 24 may occur or the transparent film 2 may be damaged when the transparent film 2 of the support table 24 is peeled off.

Further, according to the present technology, when the heating temperature of the thermocompression bonding tool 20 is 50 ° C or lower, for example, 80 ° C or the like, the melting viscosity is set as the final pressure bonding step. It is 1000Pa. Above s and 4000Pa. In the following, it is possible to ensure the reliability of the conduction and the improvement of the adhesion strength with the flexible substrate 5, and also to suppress thermal shock to the transparent film 2 or the flexible substrate 5, thereby preventing deformation and the like.

[area density distribution of conductive particles]

Here, the touch sensor 1 manufactured by the manufacturing step exhibits a specific areal density distribution after the conductive particles 16 crimped by the thermocompression bonding tool 20, thereby improving the bonding strength and the conduction reliability. . Specifically, as shown in FIG. 5 , in the touch sensor 1 , the surface density distribution of the conductive particles 16 after connecting the transparent film 2 and the flexible substrate 5 is performed on the self-heating bonding tool 20 . The density of particles in the outer edge portion 12 of the outer edge of the transparent film 2 on which the flexible substrate 5 and the anisotropic film 6 are formed is set to (a), and the When the particle density on the two connection terminals 3 and 7 in the mounting portion 4 where the thermocompression bonding tool 20 is pressed is (b), a>b is obtained.

Here, the areal density distribution refers to the distribution of the density a and b of the conductive particles 16 on the same plane of the outer edge portion 12 and the configuration portion 4, and is the connection terminal between the outer edge portion 12 and the configuration portion 4. The respective particle densities a and b on the third and seventh sides are compared, and the outer edge portion 12 and the conductive particles 16 in the constitution portion 4 are sandwiched by the plane between the two connection terminals 3 and 7 on the same plane.

The main object of the present invention is to cause the adhesive resin 15 of the anisotropic conductive film 6 to flow by the heat pressing of the thermocompression bonding tool 20, and to form the thin strip 21 on the side of the transparent film 2, thereby achieving conduction reliability. With the strength of the next. Further, when the fine tape 21 is appropriately cured by ultraviolet irradiation, the flow in the outer edge portion 12 is hindered, so that the fluidity is different on the same plane, and the conductive particles 16 are deposited at the outer edge portion 12 at the most Become high density. The bonding portion of the conductive particles 16 between the two connection terminals 3 and 7 is thermally pressed by the thermocompression bonding tool 20, whereby the binder resin 15 is extruded, so that the particle density is relatively small.

By providing the density distribution of the conductive particles 16 and the anisotropic conductive film 6 between the transparent film 2 and the flexible substrate 5, the fine tape 21 using the adhesive resin 15 is appropriately formed, whereby the bonding strength can be improved. That is, according to the anisotropic conductive film 6, the conductive particles in the outer edge portion 12 The density (a) of 16 is higher than the density (b) of the conductive particles in the constitution portion 4, and it is understood from this case that the outer edge portion 12 flows and hardens more of the binder resin 15. Further, as shown in FIG. 4, the fine tape 21 is formed between the transparent film 2 and the flexible substrate 5 by the adhesive resin 15 flowing to the outer edge portion 12. Thereby, the anisotropic conductive film 6 can firmly bond the transparent film 2 and the flexible substrate 5.

Further, by providing the density distribution of the conductive particles 16, the adhesive resin 15 is appropriately discharged from the connection terminals 3 and 7 in the anisotropic conductive film 6, so that the pressure is applied by the thermocompression bonding tool 20. In addition, the conductive particles 16 can be surely interposed, and the conduction reliability can be improved.

In other words, by confirming the areal density distribution of the conductive particles 16 in the structure 4 and the outer edge portion 12, it is possible to easily check the balance between the adhesion and the functionality. That is, it is not necessary to perform a destructive inspection such as peel strength inspection, and by measuring the surface density of the particles, it is known that the reinforcing portion is the end portion of the peeling start point by the increase in the local strength of the thin strip portion, and is subjected to hot pressing. When the bonding tool 20 is pressed against the bonding portion 4, the conductive particles 16 are appropriately sandwiched between the connection terminals 3 and 7, whereby the unevenness of the conductive particles 16 is achieved, and the anisotropic conductivity is favorably maintained. Therefore, the inspection of the adhesion strength and the conduction reliability of the transparent film 2 and the flexible substrate 5 can be performed non-destructively and simply.

[other]

The above description has been made by using the flexible substrate 5 as an electronic component. However, in addition to the flexible substrate 5, the present invention can also use an IC chip or a flexible flat cable, a rigid substrate, and a tape-reel type. Substrate package (TCP) or the like.

[Examples]

Next, an embodiment of the present invention will be described. In the present embodiment, an anisotropic conductive film containing a photocurable or heat-curing type hardener is used, and a molded body sample in which the evaluation plastic substrate is connected to the evaluation flexible substrate is used. For each of the connected body samples, the conduction reliability evaluation, the measurement of the overflow width (mm) of the fine tape, the measurement of the particle areal density (pcs/200×200 μm), and the deformation evaluation of the plastic film substrate after the pressure bonding step were performed.

[Anisotropic Conductive Film]

The anisotropic conductive film used for the production of the sample of the connector of each of the examples and the comparative examples was prepared in accordance with the components (unit: parts by mass) shown in Table 1. The anisotropic conductive film of the components A to C is a photocurable adhesive, and the anisotropic conductive film of the component D is a heat-curing adhesive.

The mixed solution of the components of A to D was applied onto a PET film, and dried in an oven to form a film having a thickness of 16 μm, a width of 20 cm, and a length of 30 cm. The density of the conductive particles before the pressure bonding of the anisotropic conductive film of each of the components A to D was 20 pcs/200×200 μm.

[Flexible substrate for evaluation]

In the evaluation flexible substrate, a copper wiring pattern having a thickness of 12 μm formed by copper plating was formed on one surface of a polyimide substrate having a thickness of 25 μm. The wiring pitch is 400 μm and L/S = 1/1.

[Plastic film substrate for evaluation]

The circuit board for evaluation of the anisotropic conductive film is a transparent plastic film (the thickness of the electrode is 0.1 μm) in which an ITO electrode is provided on a PET film having a thickness of 50 μm and a Cu electrode is laminated thereon. The wiring pitch is 400 μm and L/S = 1/1.

After the temporary attachment of the anisotropic conductive film to the plastic film substrate and the temporary pressure bonding of the evaluation flexible substrate, heat pressing using a thermocompression bonding tool and using an ultraviolet ray irradiator (ZUV- C30H: OMRON Co., Ltd.) UV irradiation, and formal crimping is performed to form a connector sample.

The actual crimping temperature of the thermocompression bonding tool was set to 80 ° C in Examples 1 and 2, Comparative Examples 1 and 3, and 130 ° C in Comparative Examples 2 and 4. Moreover, the final crimping pressure and time of the thermocompression bonding tool were 4 MPa and 5 seconds in each of the examples and the comparative examples, and a buffer material of 矽 rubber having a thickness of 450 μm was deposited on the hot pressing surface of the thermocompression bonding tool. . Further, the ultraviolet ray irradiator was placed on the back side of the transparent support table supporting the transparent plastic film substrate, and in addition to Comparative Example 3, ultraviolet ray irradiation was started 4 seconds after the heating and pressing of the flexible substrate by the thermocompression bonding tool was started. , irradiated for 1 second. The end of the irradiation is simultaneously with the end of the thermal pressurization using the thermocompression bonding tool. Further, the illuminance of the ultraviolet ray was set to 180 mW/cm ² (peak wavelength: 365 nm).

Then, the initial on-resistance value (Ω) and the on-resistance value (Ω) after the reliability test were measured for the connected body samples of the respective examples and comparative examples. The conditions of the reliability test were 60 ° C, 95% RH, and 100 hr. The measurement of the on-resistance value is performed by connecting a ITO electrode or a Cu electrode of a transparent plastic film substrate connected to the connection terminal of the evaluation flexible substrate to a digital multimeter, and measuring the resistance value at a flow current of 2 mA by a so-called four-terminal method. Then, the average value is set as the on-resistance value. For the reliability evaluation of conduction, set 5 Ω or less to OK, and set it to be larger. For NG.

The overflow width W of the thin strip of the connector sample is measured by measuring the width W (see FIG. 4) of the thin strip formed in the surface direction of the side surface of the plastic film substrate protruding from the flexible substrate. Then, after the connection, the connector sample is pulled up from the transparent support table, on the transparent plastic film substrate side of the connector sample (on the opposite side of the surface in contact with the hot pressing surface of the thermocompression bonding tool) or the transparent support table. If the adhesive which does not adhere to the overflow itself is confirmed to be OK, it is considered to be NG if any of the transparent plastic film substrate side of the connection sample or the transparent support itself adheres to the adhesive.

Regarding the areal density distribution of the conductive particles of the bonded body sample, the particle density in the outer edge region of the outer edge of the transparent plastic film substrate on which the self-heating crimping tool is formed is set to (a) The particle density in the pressing region of the thermocompression bonding tool was set to (b), and the particle density on the same plane was measured at 200 × 200 μm in each region.

The confirmation of the deformation of the transparent plastic film after the crimping by visual inspection is set to × when the appearance of the undulating texture in the pressing region of the thermocompression bonding tool is used, and the undulating texture is not confirmed, and the pressing region is presented. In the case of the same external appearance, it is set to ○.

[Example 1]

In Example 1, a photocurable anisotropic conductive film of Component A was used. The melt viscosity of the anisotropic conductive film of component A at a heating temperature (80 ° C) in the final crimping step is 1000 Pa. s. The continuity reliability of the connector sample of Example 1 was 5 Ω or less (OK), and the overflow width W of the ribbon was 550 μm (OK). Further, the particle density (a) in the outer peripheral region was 12.1 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 4.2 pcs/200 × 200 μm. Further, the deformation of the transparent plastic film of the bonded body sample was not confirmed.

[Embodiment 2]

In Example 2, a photocurable anisotropic conductive film of Component B was used. The melting viscosity at a heating temperature (80 ° C) in the formal crimping step of the anisotropic conductive film of the component A is 4000 Pa. s. The conduction reliability of the sample of the joint of Example 2 was evaluated to be 5 Ω or less (OK), and the overflow width W of the fine tape was 400 μm (OK). Further, the particle density (a) in the outer peripheral region was 11.1 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 4.5 pcs/200 × 200 μm. Further, the deformation of the transparent plastic film of the bonded body sample was not confirmed.

[Comparative Example 1]

In Comparative Example 1, a photocurable anisotropic conductive film of Component C was used. The melting viscosity at a heating temperature (80 ° C) in the formal crimping step of the anisotropic conductive film of component C is 10000 Pa. s. The conduction reliability of the sample of the connector of Comparative Example 1 was evaluated to be 20 Ω or more (NG), and the overflow width W of the ribbon was 200 μm (OK). Further, the particle density (a) in the outer peripheral region was 8.4 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 4.2 pcs/200 × 200 μm. Furthermore, the deformation of the transparent plastic film of the bonded body sample was not confirmed.

[Comparative Example 2]

In Comparative Example 2, a photocurable anisotropic conductive film of Component C was used. Further, in Comparative Example 2, the heating temperature in the final pressure bonding step was 130 °C. The continuity reliability of the connector sample of Comparative Example 2 was 5 Ω or less (OK), and the overflow width W of the ribbon was 350 μm (OK). Further, the particle density (a) in the outer peripheral region was 11.5 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 4.6 pcs/200 × 200 μm. Furthermore, the deformation of the transparent plastic film of the connector sample was confirmed.

[Comparative Example 3]

In Comparative Example 3, a heat-curable anisotropic conductive film of the component D was used. The melting viscosity at a heating temperature (80 ° C) in the final crimping step of the anisotropic conductive film of component D is 1000 Pa. s. The continuity reliability of the sample of the connector of Comparative Example 3 was 20 Ω or more (NG), and the overflow width W of the ribbon was 550 μm (OK). Further, the particle density (a) in the outer peripheral region was 13.5 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 5.1 pcs/200 × 200 μm. Furthermore, the deformation of the transparent plastic film of the bonded body sample was not confirmed.

[Comparative Example 4]

In Comparative Example 4, a photocurable anisotropic conductive film of Component A was used. Further, in Comparative Example 4, the heating temperature in the final pressure bonding step was set to 130 °C. The conduction reliability of the connector sample of Comparative Example 4 was evaluated to be 5 Ω or less (OK), and the overflow width W of the fine tape was 900 μm (NG). Further, the particle density (a) in the outer peripheral region was 12.9 pcs/200 × 200 μm, and the particle density (b) in the pressed region was 4.7 pcs/200 × 200 μm. Furthermore, the deformation of the transparent plastic film of the connector sample was confirmed.

As shown in Table 2, in the sample of the joint of Example 1 and Example 2, the melt viscosity at the heating temperature of the final crimping step was 1000-4000 Pa. s, therefore, the conductive particles can be sufficiently pressed by the removal of the binder resin, thereby obtaining good conduction reliability. Further, in the sample of the joint of the first embodiment and the second embodiment, the overflow width W of the fine tape was also suitable, and the connection strength between the plastic film substrate and the flexible substrate was improved. The particle density distribution of the sample of the connector according to Example 1 and Example 2 can also be confirmed. Further, in the sample of the joint of Example 1 and Example 2, the deformation of the plastic film substrate was not confirmed.

On the other hand, in the sample of the connector of Comparative Example 1, the melt viscosity at the heating temperature of the final crimping step was as high as 10,000 Pa. s, when the conductive particles are insufficiently pressed, the conduction reliability evaluation is lowered, and the gap width W of the binder resin is also small, and the connection strength is also lowered.

Further, in the sample of the connector of Comparative Example 2, the pressure-bonding temperature in the final pressure-bonding step was increased as compared with Comparative Example 1, whereby the fluidity of the adhesive resin was improved, so that the conduction reliability and the fine band were The overflow width W was observed to be improved, but the plastic film substrate after the crimping was deformed.

In the sample of the connector of Comparative Example 3 using the thermosetting anisotropic conductive film, the curing reaction was insufficient due to the low-temperature heating at 80 ° C, and the evaluation of the communication communication was found to be lowered by the reliability test.

In the sample of the connector of Comparative Example 4, the melt viscosity at 80 ° C was used as low as 1000 Pa. The anisotropic conductive film of the component A of s, the crimping temperature in the final crimping step is raised to 130 ° C, so the fluidity of the adhesive resin is excessive, the overflow width W of the fine ribbon is large, and the adhesive resin flows back. To the back of the plastic film substrate, in addition, the plastic film substrate after the crimping is deformed.

2‧‧‧Transparent film

2a‧‧‧Side of the transparent film

3‧‧‧Connecting terminal

4‧‧‧Construction Department

5‧‧‧Flexible substrate

6‧‧‧ Anisotropic conductive film

7‧‧‧Connecting terminal

20‧‧‧Hot crimping tools

22‧‧‧ cushioning material

24‧‧‧Support desk

Claims (9)

A method for producing a connector, comprising the steps of: providing an adhesive for circuit connection containing a photopolymerization initiator on a circuit board having light transmissivity; and a step of crimping The electronic component is placed on the circuit board, and the electronic component is heated and pressed against the circuit board, and the circuit connecting adhesive is cured; and the circuit connecting adhesive is bonded to the bonding device. The melt viscosity at the heating temperature in the step is 4000 Pa. s below. 1. The method of manufacturing a connector according to claim 1, wherein the adhesive for the circuit connection has a melt viscosity of 1000 Pa at a heating temperature in the crimping step. s above. The method of manufacturing a connector according to the first or second aspect of the invention, wherein the circuit substrate is a plastic film substrate, and the electronic component is heated at a temperature of 100 ° C or lower in the pressure bonding step. The method of manufacturing a connector according to the first or second aspect of the invention, wherein in the crimping step, the circuit-connecting adhesive overflows to a side surface of the circuit board on which the electronic component protrudes to form a thin strip, and After the pressure bonding step, the particle density of the conductive particles contained in the above-mentioned circuit-connecting adhesive agent in the thin band region is higher than the pressure-receiving region of the electronic component. The method of manufacturing a connector according to claim 3, wherein in the crimping step, the circuit-connecting adhesive overflows to a side surface of the circuit board on which the electronic component protrudes to form a thin strip, and After the pressure bonding step, the particle density of the conductive particles contained in the above-mentioned circuit-connecting adhesive agent in the thin band region is higher than the pressure-receiving region of the electronic component. The method of manufacturing a connector according to claim 1 or 2, wherein the circuit substrate is a sensor film of a touch panel. The method of manufacturing a connector according to claim 1 or 2, wherein the electronic component is a flexible substrate. A method for connecting electronic components, comprising the steps of: providing an adhesive for circuit connection containing a photopolymerization initiator on a circuit board having light transmissivity; and a step of crimping The electronic component is placed on the circuit board, and the electronic component is heated and pressed against the circuit board, and the circuit connecting adhesive is cured; and the circuit connecting adhesive is bonded to the bonding device. The melt viscosity at the heating temperature in the step is 4000 Pa. s below. A connector produced by the method of manufacturing a connector according to any one of claims 1 to 7.