JP2002285135A - Anisotropic electroconductive adhesive and connecting structure using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic electroconductive adhesive capable of easily peeling from an electrode and making unnecessary the disposal of electronic parts or electric and electronic equipment, and a connecting structure using the same. SOLUTION: This anisotropic electroconductive adhesive is obtained by dispersing electroconductive fine particles 2 and insulating resin fine particles 3 in an adhesive resin binder 1. Since the insulating resin fine particles 3 are soluble in a general-purpose solvent and fine and thereby have excellent dispersibility in a resin, the insulating resin fine particles 3 are surely readily soluble because the Tg is <=160 deg.C during hot-pressing. Thereby, the adhesive can simply be peeled from the electrode to repair electronic parts even when the positional shift, etc., of the electrode occurs during connecting operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display.
(Hereinafter referred to as LCD) and electrical connection between tape carrier package (hereinafter referred to as TCP), electrical connection between TCP and printed circuit board (hereinafter referred to as PCB), flexible circuit board (hereinafter referred to as FPC) , Chips
Anisotropic conductive adhesive used for electrical connection between opposing flip chip bumps and electrodes of a liquid crystal circuit board in an on-glass (hereinafter referred to as COG) connection method and a connection structure using the same It is about.

[0002]

2. Description of the Related Art In recent years, a direct chip attach method using a bare chip such as a flip chip has been adopted as a high-density mounting method of a semiconductor element. In the flip chip method (flip chip mounting), an anisotropic conductive adhesive is interposed between the electrodes of the wiring board and the flip chip, which are opposed to each other, and this is heated and pressurized. The flip chip is electrically connected to the flip chip.

[0003] As a material of the anisotropic conductive adhesive, a thermosetting resin composition having excellent connection reliability is mainly used. In addition to the anisotropic conductive adhesive, an anisotropic conductive film adhesive in which conductive fine particles are mixed and dispersed in a thermosetting resin composition may be used instead. Such an anisotropic conductive adhesive or an anisotropic conductive film adhesive is used for the conductive connection between the LCD and the lead of the TCP, and the conductive connection between the bump portion of the opposite flip chip and the electrode of the liquid crystal circuit board in the COG connection method. Used for connection etc.

[0004]

As described above, conventional anisotropic conductive adhesives mainly contain a thermosetting resin composition, and have an extremely strong adhesive strength after being cured by heating and pressing. In the case where a connection failure typified by misalignment of the electrode occurs during the connection work, it is extremely difficult to peel off the electrode. For this reason, there is a problem that the electronic component cannot be repaired (repaired) and the electronic component must be discarded as it is. Furthermore, even if a failure occurs in the conductive connection portion after the market distribution of the electric / electronic device equipped with the electronic component, the electronic component cannot be repaired, so that the electric / electronic device itself has to be discarded. . In recent years, it is necessary to eliminate such a problem as much as possible because of the strong demand for recyclability for global environmental protection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has an anisotropic conductive adhesive capable of facilitating separation from an electrode and suppressing disposal of electronic components and electric / electronic devices, and a connection structure using the same. It is intended to provide.

[0006]

According to the first aspect of the present invention, in order to achieve the above object, conductive fine particles and insulating resin fine particles are dispersed in an adhesive resin binder. The insulating resin fine particles can be dissolved in a general-purpose solvent, and the resin having a glass transition point of 160 ° C. or less can be used. Also, 0.
A film can be formed or cured at a wavelength of from 01 to 400 nm.

Further, in order to achieve the above object, the first and second electric joints facing each other are connected by an anisotropic conductive adhesive. The conductive adhesive is the anisotropic conductive adhesive according to claim 1, 2, or 3, and the anisotropic conductive adhesive is 0.01 to
A film is formed at a wavelength of 400 nm, and the film is heated and pressurized to electrically connect the first and second electric joints.

Here, the first and second electric joints in the claims include at least various electric and electronic devices.
It includes an LCD, a TCP, a PCB, an FPC, a COG, a COF substrate, a liquid crystal circuit substrate, and the like used for a communication terminal or a computer device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 and FIG. A large number of conductive fine particles 2 and insulating resin fine particles 3 are dispersed in an adhesive resin binder 1 and applied between glass substrates 4 and 5 which are opposing electric joints. A film is formed at a wavelength of 0.01 to 400 nm and heated and pressurized, thereby electrically connecting the electrodes of the glass substrate 4 and the substrate 5 to each other.

The adhesive resin binder 1 is based on the premise that the insulating resin fine particles 3 are not dissolved. Therefore, a solventless photo-curable resin, a radical polymerization initiator, an epoxy resin, a latent curing agent, a known filler And silane coupling agents. The photo-curable resin may be any liquid resin that is polymerized and cured by irradiation with ultraviolet rays or electron beams.

[0011] Types include photopolymer oligomers such as epoxy acrylate oligomer, urethane acrylate oligomer, polyether acrylate oligomer, polyester acrylate oligomer, trimethylolpropane triacrylate, polyethylene glycol diacrylate, polyalkylene glycol diacrylate, and pentaerythritol acrylate. 2-cyanoethyl acrylate, cyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, 2 (2-ethoxyethoxy) ethyl acrylate, 2-ethoxyethyl acrylate, 2-ethylhexyl acrylate, n-hexyl acrylate, 2-hydroxy Ethyl acrylate, hydroxypropyl acrylate, Seo isobornyl acrylate, isodecyl acrylate, isooctyl acrylate, n-
Acrylic acid such as photopolymerizable monofunctional group such as lauryl acrylate, 2-methoxyethyl acrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, and polyfunctional acrylate monomer Esters and the like, and t-butylaminoethyl methacrylate, cyclohexyl methacrylate, dicyclopentenyloxyethyl methacrylate, 2-hydroxyethyl methacrylate, isobornyl methacrylate, isodecyl methacrylate, n-lauryl acrylate, stearyl methacrylate, Photopolymerizable monofunctional groups such as decyl methacrylate and glycidyl methacrylate, and polyfunctional methacrylate monomers Is photopolymerization type resin represented by said methacrylic acid ester.

These resins can be used alone or as a mixture as needed. In addition, since the photopolymerizable oligomer has a high viscosity, one kind of low-viscosity photopolymerizable acrylate monomer is used for adjusting the viscosity.
More than one species can be mixed. Examples of the radical polymerization initiator used in the photopolymerizable resin include known benzophenones, ketones such as acetophenone, and derivatives thereof, benzoin ethers such as benzoin ethyl ether and isopropyl benzoin ethyl ether, and benzyl ketals such as benzyl and hydroxycyclohexyl phenyl ketone. Kind,
Thioxanthones, bisimidazoles, phosphorus compounds and the like. Sensitizers such as amines, sulfur compounds and phosphorus compounds may be added to these photoinitiators at any ratio as needed.

The light for curing may be a commonly used ultraviolet ray or electron beam, and more specifically, a light having a wavelength peak of 0.0.
Ultraviolet light or an electron beam of 1 to 400 nm can be used. Specifically, the dominant wavelength is 365 nm,
03, a high-pressure mercury lamp that efficiently irradiates ultraviolet rays of 313 nm, a metal halide lamp that emits an ultraviolet spectrum over a wide range of 200 to 400 nm, an electrodeless lamp,
The laser beam or the electron beam can be generated by an EB curing device having an acceleration energy of less than 1 MeV.

The epoxy resin to be mixed with the adhesive resin binder is not particularly limited, but is a liquid bis-A or bis-F type epoxy resin whose viscosity can be adjusted.
Solid epoxy resins and epoxy resins other than bisphenol can be used. Preferably, a type of epoxy resin containing less chlorine, which is harmful to electronic components, is preferable. As a curing agent that reacts with the epoxy resin, dicyanamide,
Commonly used latent curing agents such as dibasic acid dihydrazides, imidazoles, imidazole / epoxy adducts, and boron trifluoride / amine complexes can be used.

As the conductive fine particles 2, Au, Ag, N
Metal particles such as i, Cu, and solder, and carbon. In addition, these and non-conductive glass, ceramic,
Au, Ag, Ni, Cu, solder, I
A conductive layer such as TO may be formed by means such as coating. When plastic is used as the nucleus or when the hot-melt metal particles are used as the conductive fine particles 2, since they exhibit deformability under heating and pressing,
The contact area with the electrode at the time of connection increases, and the reliability improves. The conductive fine particles 2 are properly used in a wide range of 0.1 to 30 parts by volume based on 100 parts by volume of the component of the adhesive. However, in order to prevent a short circuit in an adjacent circuit due to excessive conductive fine particles 2, the volume is preferably 0.2 to 15 parts by volume.
In this case, the average particle size of the conductive fine particles 2 is optimally 1 to 15 μm, though it depends on the amount of the fine particles added.

The insulating resin fine particles 3 are dissolved in ketone solvents such as acetone and MEK, hydrocarbon solvents such as toluene and xylene, ester solvents such as ethyl acetate, alcohols and ether solvents which are general-purpose solvents. A thermoplastic resin having a glass transition point (hereinafter, referred to as Tg) of 160 ° C. or lower is finely divided. Examples of the thermoplastic resin include polyester resins, acrylic resins, polyurethane resins, polystyrene resins, butyral resins, phenoxy resins, polysulfone resins, copolymers of ethylene and vinyl acetate, and copolymers of styrene and butadiene.
Species, a mixture of two or more, a silicone-modified resin (for example,
Acrylic silicone, epoxy silicone, polyimide silicone). These resins are subjected to freeze pulverization, jet mill pulverization, and chemical pulverization, and have an average particle diameter of not more than 50 μm when the anisotropic conductive adhesive is formed into a thin film.
It is used after pulverized and classified to a size of at most 20 μm, preferably at most 20 μm.

Further, in order to be blended with the anisotropic conductive adhesive,
One or more kinds of the above-mentioned thermoplastic resins may be mixed so that the adhesive strength is not reduced as much as possible. It is preferable to use a chemically pulverized phenoxy resin as a resin that can be easily repaired without reducing the adhesive strength. Further, the insulating resin fine particles 3 may be obtained by pulverizing and mixing an epoxy resin which undergoes a heat curing reaction with a curing agent. The compounding amount at this time is appropriately 1 to 50% by weight, preferably 3 to 40% by weight of the whole resin.

The anisotropic conductive adhesive includes an inorganic filler, an organic filler, a white pigment, a polymerization inhibitor, a sensitizer, a silane coupling agent, heat resistance, water absorption / adhesion, depending on the application. And an additive selected from a combination thereof. In this case, the addition amount is preferably 0.1 to 100 parts by weight based on 100 parts by weight of the resin component of the anisotropic conductive adhesive. However, in this case, care must be taken to use the additive within a range in which the type and properties of the additive do not adversely affect the reliability of the obtained circuit board or are significantly reduced.

According to the present embodiment, the insulating resin fine particles 3 of the anisotropic conductive adhesive are easily dissolved in a general-purpose solvent, and are fine, so that they are excellent in dispersion in the resin.
Because it is 60 ° C or less, it is very easy to melt. Therefore, even if a connection failure typified by a displacement of the electrode occurs during the connection work, the connection can be easily separated from the electrode, and the electronic component can be repaired. Also, even if a failure occurs in the conductive connection part after the market distribution of the electric / electronic device equipped with the electronic component, the electronic component can be repaired. Therefore, it is not necessary to immediately dispose of the electric / electronic device itself. Recyclability can be satisfied. Furthermore, since a photocurable resin is used, 0.01 to 400
can be formed or cured at wavelengths below nm.
The adhesive can be solvent-free, and is environmentally friendly in the manufacturing process.

[0020]

EXAMPLES Examples of the anisotropic conductive adhesive according to the present invention and a connection structure using the same will be described together with comparative examples. Example 1 20 g of a photopolymerizable epoxy acrylate resin (trade name 3002A, manufactured by Kyoeisha Chemical Co., Ltd.) and a monoacrylate resin (trade name IB-XA, manufactured by Kyoeisha Chemical Co., Ltd.) 20
g, initiator [trade name IRGACURE651 manufactured by Ciba Specialty Chemicals] 2.0 g, epoxy resin [trade name Epicoat Y manufactured by Japan Epoxy Resin Co., Ltd.]
L-983U] 10 g, latent curing agent [Available from Asahi Kasei Epoxy Co., Ltd. under the trade name Novacure HX-3941HP] 30
g, 2 g of a silane coupling agent (trade name: KBM403 manufactured by Shin-Etsu Chemical Co., Ltd.), and a phenoxy resin that is fine particles of insulating resin [trade name: PKHC, Tg manufactured by Inchem Corporation]
= 95 ° C] by a chemical pulverization method, and the average particle size is 5μ.
The conductive fine particles [Micropearl AU-205 manufactured by Sekisui Fine Chemical Co., Ltd.]
Was mixed in 5 parts by volume to prepare an anisotropic conductive adhesive.

Next, the anisotropic conductive adhesive is applied to a thickness of 50
A film-type anisotropic conductive adhesive having an adhesive thickness of 18 μm was obtained by applying the coating film to a μm release-treated PET film using a coating device and irradiating it with 2.0 J / cm ² ultraviolet light under a high-pressure mercury lamp. Was. After obtaining the anisotropic conductive adhesive in this manner, the line width is 75 μm and the pitch is 150 μm using the anisotropic conductive adhesive.
m, an FPC having 300 copper circuits having a thickness of 18 μm;
I with a thin layer of indium oxide (hereinafter ITO)
TO glass (thickness: 1.1 mm, surface resistance: 30 Ω / □) was heated and pressed by a thermocompression device and connected over a width of 2 mm to produce a circuit connection body. As the thermocompression bonding apparatus, a constant heat type was used. In addition, the heating and pressing work
The test was performed at 180 ° C. and 4 MPa for 20 seconds.

At the time of manufacturing a circuit connection body, an adhesive surface of a film-shaped anisotropic conductive adhesive is pasted on ITO glass in advance,
Temporary connection was performed by heating and pressurizing under conditions of 70 ° C., 0.5 MPa, and 5 seconds, and then the release-treated PET film was peeled off, and another FPC as an adherend was connected.

Example 2 Basically the same as in Example 1, except that the photopolymerizable epoxy acrylate resin was changed to a urethane acrylate oligomer (AH-600 manufactured by Kyoeisha Chemical Co., Ltd.). Example 3 Basically the same as Example 1, except that the insulating resin fine particles were made of a polyester resin [product name UE manufactured by Unitika Ltd.
3230, Tg = 3 ° C.]. This polyester resin was pulverized by a chemical pulverization method to have an average particle diameter of 8 μm. Example 4 Basically the same as Example 1, except that the insulating resin fine particles were changed to polyimide silicone resin (trade name: X-22-8951, manufactured by Shin-Etsu Chemical Co., Ltd., Tg = 60 ° C.).
This polyimide silicone resin was pulverized by a chemical pulverization method to have an average particle diameter of 4 μm.

Example 5 Basically the same as in Example 1, but instead of a liquid epoxy resin, a solid epoxy resin [Epicoat 1010 manufactured by Japan Epoxy Resin Co., Ltd.] was jet-milled to an average particle diameter of 7 μm. The crushed one was used. In addition, a phenoxy resin [trade name YP manufactured by Toto Kasei Co., Ltd.]
−70, Tg = 70 ° C.] by a chemical grinding method to obtain an average particle diameter of 5 μm. Example 6 Basically the same as Example 1, except that the conductive fine particles were changed to nickel powder having an average particle diameter of 8 μm. Example 7 Basically the same as Example 1, except that the latent curing agent was PN-
23 [trade name of Ajinomoto Fine Techno Co., Ltd.].

Example 8 Commercially available silica for filler was added to the anisotropic conductive adhesive, and this anisotropic conductive adhesive was applied to a line width of 40 μm and a pitch of 70 μm.
μm, a thickness of 20 μm by screen printing on a chip-on-film substrate (COF substrate) having a copper circuit of 9 μm thickness
It was applied and formed to a thickness of μm, and formed into a film with an ultraviolet curing device. After the anisotropic conductive adhesive was formed in this manner, the test IC chip having the gold-plated bumps having a height of 20 μm was heated and pressurized by a COF crimping apparatus to make a conductive connection. Heat and press work is 18
The test was performed at 0 ° C., 3 MPa, and 20 seconds. Irradiation with ultraviolet rays was performed under the conditions of a high-pressure mercury lamp of 2.0 J / cm ² .

Example 9 Using the anisotropic conductive adhesive obtained in Example 1, a line width of 7
5 μm, 150 μm pitch, 18 μm thick copper circuit
FPC having a thickness of 100 and an ITO glass (thickness: 1.1 mm, surface resistance: 30 Ω / □) provided with a thin layer of ITO are heated and pressed by a thermocompression bonding apparatus combined with ultraviolet irradiation.
Ultraviolet rays were simultaneously irradiated from the glass side and connected over a width of 2 mm to prepare a circuit connection body. As a thermocompression bonding apparatus combined with ultraviolet irradiation, a constant heat type heating method was used, and ultraviolet irradiation was performed using a high-pressure mercury lamp.
The heating and pressurizing operation was performed under the conditions of 180 ° C., 3 MPa, and 20 seconds. Further, the irradiation amount of the ultraviolet light applied to the anisotropic conductive adhesive was set to 2.0 J / cm ² . At the time of the above operation, ultraviolet rays were irradiated for 17 seconds after 3 seconds had elapsed only after heating and pressurization, and the two processes were simultaneously completed 20 seconds after heating and pressurization.

Example 10 The anisotropic conductive adhesive obtained in Example 1 was applied to a line width of 75 μm.
m, pitch 150μm, thickness 18μm copper circuit 300
Along with the screen printing on the terminal portion of the FPC having the present invention, an ultraviolet ray having an irradiation amount of 2.0 J / cm ² was irradiated with a high pressure mercury lamp to form a heat seal connector (FPC with an anisotropic conductive adhesive) having a thickness of 18 μm. Obtained. After the heat seal connector was obtained, it was heated and pressed by a thermocompression bonding apparatus on ITO glass (thickness: 1.1 mm, surface resistance: 30 Ω / □) provided with a thin layer of ITO to produce a circuit connection body. As a thermocompression bonding device,
A constant heat type was used, and ultraviolet light was irradiated from a high-pressure mercury lamp. The heating and pressing operation is 180
C., 4 MPa, 20 seconds.

Example 11 An anisotropic conductive adhesive was prepared from the compounded material of Example 1 by removing the initiator, and this anisotropic conductive adhesive was applied to a 50 μm-thick release-treated PET film by a coating apparatus. Apply, 300 ke
Giving an absorbed dose of 50 kGy with an accelerating voltage device up to V
A film-shaped anisotropic conductive adhesive having an adhesive thickness of 18 μm was obtained. After obtaining the anisotropic conductive adhesive in this way, the line width of 75 μm and the pitch of 1
FP having 300 copper circuits of 50 μm and 18 μm thickness
C and ITO glass with a thin layer of ITO (thickness 1.1
mm and a surface resistance of 30 Ω / □) were heated and pressed by a thermocompression bonding apparatus and connected over a width of 2 mm to produce a circuit connection body. As the thermocompression bonding apparatus, a constant heat type was used. The heating and pressurizing operation is 180 ° C, 4MP
a, 20 seconds.

Comparative Example 1 An anisotropic conductive adhesive was prepared from the material used in Example 1 except for the fine particles of the insulating resin, and a circuit connecting body was produced in the same manner as in Example 1.

The initial resistance value and the repairability of the connection bodies of the circuits in Examples 1 to 11 and Comparative Example 1 were evaluated, and the results are summarized in Table 1. For the initial resistance value,
After the connection of the circuit connection body, the resistance between adjacent circuits of the FPC including the connection portion was measured by a multimeter. As for the repairability, a cotton swab impregnated with acetone, a general-purpose solvent, was rubbed, and the ease of peeling was evaluated in three stages.

[0031]

[Table 1]

As is clear from Table 1, Examples 1 to 11
The initial resistance value and the repairability of the connection body of the circuit in were good. In contrast, the connection of the circuit obtained in Comparative Example 1 could not be repaired.

[0033]

As described above, according to the present invention, there is an effect that the separation from the electrode can be facilitated and the disposal of the electronic component or the electric / electronic device can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of an anisotropic conductive adhesive according to the present invention.

FIG. 2 is an explanatory sectional view showing an embodiment of an anisotropic conductive adhesive according to the present invention and a connection structure using the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Adhesive resin binder 2 Conductive fine particles 3 Insulating resin fine particles 4 Glass substrate (1st electric joint) 5 Substrate (2nd electric joint)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05K 1/14 H05K 1/14 A 3/36 3/36 A F term (Reference) 4J040 EC001 EC002 FA141 FA142 FA151 FA152 FA161 FA162 FA181 FA182 FA261 FA262 FA281 FA282 FA291 FA292 HB18 HC24 HD21 JB07 JB10 KA03 LA06 LA11 MA05 MA10 NA19 NA20 PA30 PA32 PA33 5E344 AA01 AA02 AA22 BB03 BB04 CD04 DD06 EE21 EE30 5G301 DA02 DA03 DA05 DA06 DA03 DA03 DA03 DA03 DA03 HB05 HC01

Claims (4)

[Claims] 1. An anisotropic conductive adhesive characterized in that conductive fine particles and insulating resin fine particles are dispersed in an adhesive resin binder. 2. The anisotropic conductive adhesive according to claim 1, wherein the insulating resin fine particles can be dissolved in a general-purpose solvent, and the glass transition point of the insulating resin fine particles is 160 ° C. or lower. 3. The anisotropic conductive adhesive according to claim 1, wherein a film is formed or cured at a wavelength of 0.01 to 400 nm. 4. A connection structure using an anisotropic conductive adhesive for connecting opposing first and second electric joints with an anisotropic conductive adhesive, wherein the anisotropic conductive adhesive is used. Item 1. The anisotropic conductive adhesive according to item 1, 2, or 3, wherein the anisotropic conductive adhesive is 0.01
A connection structure using an anisotropic conductive adhesive, characterized in that a film is formed at a wavelength of 400 nm and heated and pressurized to electrically connect the first and second electric joints.