TWI464814B - Anisotropic conductive film - Google Patents

Description

Anisotropic conductive film (1) Field of invention

The present invention relates to an anisotropic conductive film. More particularly, the present invention relates to an anisotropic conductive film including a color composite inorganic pigment (CICP) which makes it easy to confirm the existence of the anisotropic conductive film after pre-compacting the film to a circuit component such as a PCB Without degrading the electrical and thermal properties of the film.

Background of the invention

The anisotropic conductive film refers to a film-like adhesive in which conductive particles such as metal particles or metal-coated plastic particles are dispersed. Anisotropic conductive films are widely used in various fields, including circuit connections in the field of flat panel displays and component assembly in semiconductor devices. When the anisotropic conductive film is inserted between the circuits to be connected and then hot pressed under suitable temperature, pressure and time conditions, the circuit terminals are electrically connected by the conductive particles, and the insulating adhesive resin is filled adjacent circuit terminals. The gap between them is such that the conductive particles are independent of each other, thereby achieving insulation between the circuit terminals.

The high transparency of the anisotropic conductive film is due to the presence of the conductive particles dispersed in the binder portion including the thermoplastic resin, so that it is difficult to determine the existence of the film even after the film member is pre-compressed. This also increases the manufacturing cost in terms of failure of the pressing device.

On the other hand, an anisotropic conductive film is usually colored by adding a coloring agent such as a pigment. This coloring helps to confirm the presence of the film after pre-compression, but degrades the basic electrical properties of the film, including bond strength, connection resistance, and insulation resistance.

Therefore, there is a need to develop an anisotropic conductive film which maintains its electrical properties even after pre-pressing circuit elements and can easily determine its presence or absence.

Summary of invention

An aspect of the invention provides an anisotropic conductive film. In one embodiment, the anisotropic conductive film comprises (A) a binder portion, (B) a cured portion, (C) a radical initiator, (D) a conductive particle, and (E) a color composite inorganic pigment. (CICP).

In one embodiment, the CICP may be a composite oxide or hydroxide of two or more metals selected from the group consisting of nickel, copper, chromium, magnesium, zinc, aluminum, manganese, titanium, iron, and ruthenium. Preparation.

In one embodiment, based on 100 parts by weight of the binder portion (A), the cured portion (B), the radical initiator (C), and the conductive particles (D), The amount of CICP may be from 0.1 to 10 parts by weight.

In one embodiment, the brightness of the anisotropic conductive film may be at least 20% lower than the brightness of the circuit terminals after pre-compacting the film to the circuit terminals.

Simple illustration

The above and other aspects, features, and advantages of the present invention will become apparent from the Detailed Description of the Description

1 is an optical microscope image taken after pre-compacting the anisotropic conductive film prepared in Example 1 on the circuit terminal of the PCB, and FIG. 2 is a test comparing the brightness of the anisotropic conductive film with the brightness of the circuit terminal. result;

Fig. 3 is an optical microscope image taken after pre-compacting the anisotropic conductive film prepared in Comparative Example 1 on the circuit terminal of the PCB, and Fig. 4 shows a test comparing the brightness of the anisotropic conductive film with the brightness of the circuit terminal. result;

Figure 5 is an optical microscope image of the circuit terminals of the PCB, and Figure 6 shows the brightness of the circuit terminals using the Image J program;

Fig. 7 is an optical microscope image taken after attaching a film to a circuit terminal of a PCB according to an exemplary embodiment of the present invention, and Fig. 8 is a view showing a circuit terminal brightness using an Image J program.

Detailed description of the preferred embodiment

Aspects of the present invention provide an anisotropic conductive film including a binder portion, a solidified portion, a radical initiator, conductive particles, and a color composite inorganic pigment (CICP).

Adhesive part

The binder portion serves as a matrix for the anisotropic conductive film and exhibits high adhesion under pressure. Therefore, when the anisotropic conductive film is thermally pressed against the circuit, the adhesive portion provides a good connection to the circuit terminals due to its high adhesive strength and good adhesion.

The binder portion may be contained in an amount of 20 to 58% by weight based on the total solid content of the binder portion, the solidified portion, the radical initiator, and the conductive particles. When it is in this range, the solubility of the anisotropic conductive film in a solvent is not lowered, and the connection reliability of the anisotropic conductive film is not deteriorated. Preferably, the binder portion is present in an amount of from 20 to 50% by weight.

The binder portion may be selected from an acrylonitrile butadiene (NBR) copolymer, an epoxy resin, a phenoxy resin, an olefin resin, a carboxyl terminated acrylonitrile butadiene copolymer, and an ethylene-vinyl acetate copolymer. , polyvinyl butyral resin, polyvinyl acetal resin, polyester resin, phenolic resin, polymerizable acrylic resin, polyimine resin, polyamide resin, polyurethane resin, poly At least one of the group consisting of an ester resin, a polyester urethane resin, a styrene-butene-styrene resin, a modified epoxy resin, and a mixture thereof.

Curing part

The cured portion may include at least one compound selected from the group consisting of a (meth) acrylate monomer, a propylene oxide-epoxy resin, and a urethane acrylate.

The content of the solidified portion may be 40 to 65 wt% based on the total solid content of the binder portion, the solidified portion, the radical initiator, and the conductive particles. Within this range, good adhesion and high connection reliability can be exhibited, and a dense structure is obtained after curing, thereby ensuring good long-term connection reliability without deteriorating the bonding strength. Preferably, the content of the cured portion is from 45 to 60% by weight.

The (meth) acrylate monomer is used as a reactive diluent in the anisotropic conductive film composition. The (meth) acrylate monomer may be selected from the group consisting of 1,6-hexanediol mono(meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. , 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 1,4-butanediol (meth) acrylate, 2-hydroxyethyl (Meth) propylene decyl phosphate, 4-hydroxycyclohexyl (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolethane di (meth) acrylate, tris Methyl propane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, pentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, glycerin Di(meth)acrylate, hydrogenated furyl (meth) acrylate, isodecyl (meth) acrylate, 2-(2-ethoxyethoxy)ethyl (meth) acrylate, (A) Octadecyl acrylate, dodecyl (meth)acrylate, 2-phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, tridecyl (meth) acrylate Ethoxylated nonylphenol (meth) acrylate, Diol (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,3- Butanediol di(meth)acrylate, tripropylene glycol di(meth)acrylate, ethoxylated bisphenol-A di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate , t-phenoxy glycol (meth) acrylate (phenoxy- t -glycol (meth) acrylate ), 2- methyl-Bing Xixi yloxymethyl phosphate, 2-oxyethyl phosphoryl Bing Xixi Ester, dimethylol tricyclodecane di(meth) acrylate, trimethylolpropane benzoate acrylate, (meth)acrylic acid phosphoxy ethyl At least one of the group consisting of and a mixture thereof, but is not limited thereto.

The propylene oxide-epoxy resin is not limited as long as it has two or more epoxy groups in one molecule and at least one propylene oxide moiety in the molecular chain.

Examples of propylene oxide-epoxy resins suitable for the cured portion include: bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol A type epoxy acrylate resin, and bisphenol F type epoxy resin. Aromatic epoxy compounds such as polyglycidyl ether epoxy resins and polyglycidyl epoxy resins; alicyclic epoxy compounds; phenolic epoxy resins such as cresol novolak type epoxy resins and phenol novolacs Epoxy resin; glycidylamine type epoxy compound; glycidyl ester type epoxy compound; biphenyl diglycidyl ether epoxy compound.

The urethane acrylate includes a urethane bond and a double bond at both ends. The polymerization method for preparing the urethane acrylate is not particularly limited.

The urethane acrylate may have a weight average molecular weight of from 1,000 to 50,000 g/mol. Within this range, the film can be satisfactorily formed and highly compatible.

The above cured portion may further include an acetal compound and/or a carbodiimide compound.

Free radical initiator

The radical initiator may be a photopolymerization initiator, a heat curing agent, or a combination thereof. A heat curing agent is preferred.

The content of the radical initiator may be from 0.1 to 5 wt% based on the total solid content of the binder portion, the solidified portion, the radical initiator, and the conductive particles. Within this range, the long-term reliability of the wiring resistance can be maintained continuously. Preferably, the free radical initiator is present in an amount of from 0.5 to 3% by weight.

Examples of the thermosetting agent suitable for use in the anisotropic conductive film described above include, but are not limited to, peroxide initiators such as laurel peroxide, benzammonium peroxide, and cumene hydroperoxide. A mixture of two or more initiators may be used depending on the curing conditions. In this case, the ratio of the initiator is not limited.

Conductive particles

Conductive particles are used as a filler to impart electrical conductivity to the anisotropic conductive film.

The conductive particles may be included in an amount of from 1 to 20% by weight based on the total solid content of the binder portion, the solidified portion, the radical initiator, and the conductive particles. Within this range, the wiring resistance of the film after the reliability test is continuously maintained. Preferably, the conductive particles are contained in an amount of from 3 to 10% by weight.

Examples of the conductive particles suitable for use in the anisotropic conductive film include: metal particles such as nickel (Ni), gold (Au), silver (Ag), copper (Cu), and solder metal particles; carbon particles; metal coated Resin particles such as polyethylene coated with gold (Au), silver (Ag), nickel (Ni), copper (Cu) and solder metal, polypropylene, polyester, polystyrene, polyvinyl alcohol and their modification Particles of the resin; and conductive particles coated with insulating particles.

There is no particular limitation on the size of the conductive particles. For example, preferred conductive particles in terms of adhesive strength and connection reliability have a diameter of 1 to 20 μm.

Color composite inorganic pigment (CICP)

CICP refers to an inorganic colorant prepared by sintering a composite oxide or hydroxide of two or more metals at a temperature of 1000 ° C or higher. This high temperature sintering allows the CICP to have a very stable crystalline structure such as spinel or rutile.

In order to confirm the existence of the above film after the pre-pressing, a coloring agent such as a pigment is usually added to the anisotropic conductive film. However, anisotropic conductive films should not include the arbitrary use of any colorants because they require improved recognizability while maintaining their inherent electrical and thermal properties. For example, carbon black, which is known as a black coloring agent, considerably improves the recognizability of an anisotropic conductive film, but it deteriorates physical properties of the film such as wiring resistance, insulation resistance, and bonding strength.

In contrast, the use of CICP in an anisotropic conductive film is effective in achieving improved film recognizability while maintaining film wiring resistance, insulation resistance, and bonding strength.

The CICP can be prepared from a composite oxide or hydroxide of two or more metals selected from the group consisting of nickel, copper, chromium, magnesium, zinc, aluminum, manganese, titanium, iron, and ruthenium. The color of the CICP may be black, yellow, blue, green or brown depending on the color of the composite metal oxide or hydroxide used.

The CICP may be contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the binder portion, the curing portion, the radical initiator, and the conductive particles. A CICP dosage of less than 0.1 parts by weight results in little improvement in the recognizability of the film after pre-compression. At the same time, a CICP dosage of more than 10 parts by weight may result in excessive hardening or poor adhesion of the film and may result in an increase in wiring resistance after the reliability test. Preferably, the CICP is contained in an amount of from 1 to 5 parts by weight.

CICP is currently available on the market. Examples of commercially available products of CICP include, but are not limited to, Black 30C965, Black 20C980, Black 20C920, Black 444, Black 10C909, Black 411, Violet 11, Blue 385, Blue 211, Green 187B, Green 410, Green 223, Green 260 Yellow 10C112, Yellow 10C242, Yellow 10C272 and Brown 20C819.

The CICP may be selected from the group consisting of the products shown in Table 1, but is not limited thereto.

After the film is pre-compressed to the circuit terminals, the brightness of the anisotropic conductive film may be at least 20% lower than the brightness of the circuit terminals. Due to the low brightness of the anisotropic conductive film after pre-compression, it can be discerned. Preferably, the brightness of the anisotropic conductive film is at least 25% lower than the brightness of the circuit terminals.

Brightness can be determined by suitable methods known in the art. For example, brightness can be determined by observing an anisotropic conductive film and circuit terminals under an optical microscope and analyzing the bar graph of the image contrast using an Image J program equipped with a reflection mode at a maximum light intensity of 20× magnification. Multiple lenses without the media screening program to get the image.

The circuit terminal is not particularly limited as long as the above anisotropic conductive film can be pre-compressed. Examples of such circuit terminals include PCB, ITO, IZO, COF, and FPC. The pre-pressing method is not particularly limited. For example, the pre-pressing can be carried out at a pressure of 0.5 to 3 MPa and a temperature of 40 to 100 ° C for 0.5 to 10 seconds.

The anisotropic conductive film can be fabricated using a film composition including a binder portion, a curing portion, a radical initiator, conductive particles, and CICP. The anisotropic conductive film described above can be prepared by any suitable method known in the art.

No special device or equipment is required to manufacture the anisotropic conductive film. For example, the anisotropic conductive film can be produced by dissolving the film composition in a suitable organic solvent (for example, toluene), stirring the solution at a rate that does not cause the conductive particles to be pulverized, and applying the solution on the release film. It is applied to a suitable thickness (for example, 10 to 50 μm), and the solution is dried for a period of time sufficient to evaporate the organic solvent.

The anisotropic conductive film may further include one or more additives to provide other physical properties as long as the basic physical properties of the anisotropic conductive film are not impaired. Examples of such additives include polymerization inhibitors, antioxidants, and heat stabilizers. The amount of the additive may be from 0.03 to 0.3 parts by weight based on 100 parts by weight of the anisotropic conductive film composition.

Hereinafter, the composition and function of the present invention will be explained in more detail with reference to the following examples. The examples are provided for illustrative purposes only and are not to be construed as limiting the invention in any way.

The disclosures not included in the text are easily recognized and understood by those skilled in the art, and thus the explanation thereof is omitted.

The components used in Examples 1 to 7 and Comparative Examples 1 to 3 are as follows:

1. Adhesive part

Acrylonitrile Butadiene Rubber (NBR) (N34, NIPPON ZEON)

2. Curing part

Bisphenol A type epoxy resin (Bis-A-E) (E4275, JAPAN Epoxy Resins Co., Ltd.)

Bisphenol A type epoxy acrylate resin (Bis-A-EA) (3002A, KYOEISHA)

Phosphorus (meth) acrylate (MAM) (Phosmer-M, Uni-chemical)

3. Free radical initiator

Peroyl-L, Nippon Oils and Fats

Benzoyl peroxide (PEROX-B95, Hosung Chemex, Co., Ltd. (Korea))

4. Conductive particles

Nickel particles with an average particle diameter (D50) of 5 μm (N525, Novamet)

5.CICP

Copper-chromium oxide (Black 30C965, Shepherd)

Metal-meal oxides (black 444 (Cu, Fe, Mn), black 20C920 (Cu, Cr, Mn), blue 30C527 (Co, Cr, Al), brown 20C819 (Fe, Al, Ti), Shepherd)

Example 1: Preparation of an anisotropic conductive film

30 g solution (25 vol%) of acrylonitrile butadiene rubber (weight average molecular weight = 30,000,000 g/mol) in toluene/methyl ethyl ketone 2:1 (v/v), 15 g of bisphenol A type epoxy resin , 33 g of bisphenol A epoxy acrylate resin, 5 g of (di)phosphoryl (meth) acrylate, 1 g of lauricium laurate, 1 g of benzoyl peroxide, 8 g of nickel particles having an average particle diameter (D50) of 5 μm 1 g of copper-chromium oxide (Black 30C965, Shepherd) was blended to prepare an anisotropic conductive film composition. This composition was coated on a polyethylene terephthalate film which is a release film, and dried to obtain an anisotropic conductive film having a coating thickness of 35 μm.

Examples 2 to 7: Fabrication of an anisotropic conductive film

An anisotropic conductive film was produced in the same manner as in Example 1 except that the content and/or kind of each component was changed as shown in Table 2.

Comparative Examples 1 to 3: Fabrication of an anisotropic conductive film

An anisotropic conductive film was produced in the same manner as in Example 1 except that the content and/or kind of each component was changed as shown in Table 3.

Test Example 1: Evaluation of physical properties of anisotropic conductive film

The physical properties of the anisotropic conductive films produced in Examples 1 to 7 and Comparative Examples 1 to 3 were measured, and the results are shown in Tables 4 and 5.

<Method for measuring physical properties>

1. Wiring resistance and reliability: PCB (pitch=200 μm, terminal width=100 μm, interval between terminals=100 μm) and COF (terminal width=100 μm, interval between terminals=100 μm) were used. The release film was removed by pre-compacting each of the anisotropic conductive films prepared in Examples 1 to 7 and Comparative Examples 1 to 3 to the PCB circuit terminals at 1 MPa and 70 ° C for 1 second. Thereafter, the COF circuit terminals were arranged to be opposed to the PCB circuit terminals, and then finally pressed at 3 MPa and 180 ° C for 5 seconds. The wiring resistance of the sample was measured by a 2-point probe method. After 500 hours of storage at 85 ° C and RH 85%, the wiring resistance of the sample was measured.

2. Insulation resistance and reliability: A sample for insulation resistance measurement was prepared in the same manner as in the above 1.

The insulation resistance of each sample was measured for 60 seconds using a SM8215 type (TOADK) and a 2-point probe method while applying a DC voltage of 100 V to the sample. As in the measurement of the wiring resistance, the insulation resistance of the sample was measured after storage at 85 ° C and RH 85% for 500 hours.

3. Optical Density (OD): The OD value of the anisotropic conductive film was measured with a hydrometer (Model: 301X, X-Rite, USA).

4. Recognizability: The anisotropic conductive film was pre-compressed in the same manner as described above. The PCB terminals and anisotropic conductive films were observed under an optical microscope (BX51, Olympus) to determine whether the films were identifiable.

5. Brightness after pre-compression: After the anisotropic conductive film was pre-compressed in the same manner as above, the brightness of each film was evaluated as compared with the brightness of the PCB terminal by Image J. The brightness value is represented by a level of 0 (black) to 255 (white).

6. Adhesive strength: Samples were prepared in the same manner as in the measurement of the wiring resistance. The 90° adhesion strength of each sample was measured.

As can be seen from the results in Tables 4 and 5, the anisotropic conductive films prepared in Examples 1 to 7 respectively including the binder portion, the solidified portion, the radical initiator, and the conductive particles in the above range were Excellent characteristics in terms of wiring resistance, insulation resistance, wiring resistance reliability, insulation resistance reliability, and bonding strength while maintaining their electrical properties. In addition, these anisotropic conductive films have high OD values (i.e., high haze), suggesting improved recognizability.

Fig. 1 shows a state in which the anisotropic conductive film prepared in Example 1 is pre-compressed to the PCB circuit terminal, and Fig. 2 shows the brightness of the anisotropic conductive film in comparison with the brightness of the PCB circuit terminal. As shown in Fig. 2, the brightness of the film is at least 20% lower than the brightness of the PCB circuit terminals, making it possible to determine the presence of the film.

In contrast, the CICP-free anisotropic conductive film prepared in Comparative Examples 1 to 3 exhibited low reliability in terms of wiring resistance and insulation resistance. In addition, the film is poorly identifiable.

Fig. 3 shows a state in which the anisotropic conductive film prepared in Comparative Example 1 is pre-compressed to the PCB circuit terminal, and Fig. 4 shows the luminance of the anisotropic conductive film in comparison with the luminance of the PCB circuit terminal. In Fig. 4, the brightness of the film is almost the same as the brightness of the PCB circuit terminals, making it difficult to determine the presence of the film.

The anisotropic conductive films of Comparative Examples 2 and 3 including carbon black instead of CICP, respectively, were satisfactory in recognizability, but the electrical properties were deteriorated.

Although the foregoing embodiments of the present invention have been described in conjunction with the drawings and the drawings, the present invention is not limited to these embodiments and may be embodied in various forms. It is to be understood by those skilled in the art that the present invention may be practiced without departing from the spirit and scope of the invention. Therefore, it should be understood that the embodiments are to be considered in all respects

1 is an optical microscope image taken after pre-compacting the anisotropic conductive film prepared in Example 1 on the circuit terminal of the PCB, and FIG. 2 is a test comparing the brightness of the anisotropic conductive film with the brightness of the circuit terminal. result;

Fig. 3 is an optical microscope image taken after pre-compacting the anisotropic conductive film prepared in Comparative Example 1 on the circuit terminal of the PCB, and Fig. 4 shows a test comparing the brightness of the anisotropic conductive film with the brightness of the circuit terminal. result;

Figure 5 is an optical microscope image of the circuit terminals of the PCB, and Figure 6 shows the brightness of the circuit terminals using the Image J program;

Fig. 7 is an optical microscope image taken after attaching a film to a circuit terminal of a PCB according to an exemplary embodiment of the present invention, and Fig. 8 is a view showing a circuit terminal brightness using an Image J program.

Claims (8)

An anisotropic conductive film comprising: (A) a binder portion, (B) a cured portion, (C) a radical initiator, (D) a conductive particle, and (E) a color composite inorganic pigment, wherein The color composite inorganic pigment is contained in an amount of 0.1 to 10 parts by weight based on parts by weight of the components (A), (B), (C) and (D). The anisotropic conductive film according to claim 1, wherein the content of the color composite inorganic pigment is based on 100 parts by weight of the components (A), (B), (C) and (D). 1 to 5 parts by weight. The anisotropic conductive film according to claim 1, wherein the color composite inorganic pigment is selected from the group consisting of nickel, copper, chromium, magnesium, zinc, aluminum, manganese, titanium, iron, and lanthanum. A composite oxide or hydroxide of two or more metals is prepared. The anisotropic conductive film according to claim 3, wherein the color composite inorganic pigment is prepared by sintering the composite metal oxide or hydroxide at a temperature of 1000 ° C or higher. The anisotropic conductive film according to claim 1, wherein the color composite inorganic pigment has a spinel or rutile crystal structure. The anisotropic conductive film according to claim 1, wherein the total solid content of the binder portion, the solidified portion, the radical initiator, and the conductive particles is The content of the binder portion, the curing portion, the radical initiator, and the conductive particles are 20 to 58 wt%, 40 to 65 wt%, 0.1 to 5 wt%, and 1 to 20 wt%, respectively. The anisotropic conductive film of claim 1, wherein the cured portion comprises a monomer selected from the group consisting of (meth) acrylate monomers and propylene oxide At least one compound of the group consisting of an alkane-epoxy resin and a urethane acrylate. The anisotropic conductive film according to claim 1, wherein the anisotropic conductive film has a luminance lower than a luminance of the circuit terminal by at least 20% after the film is pre-compressed to the circuit terminal.