KR19980059066A - Anisotropic conductive film containing organic sulfur compound coupling agent - Google Patents

Abstract

The present invention relates to an anisotropic conductive film used for electrical connection of fine circuit boards, in particular, connection of liquid crystal displays (LCDs) and flexible circuit boards (EPCs), micro bonding of semiconductor ICs and IC mounting circuit boards, and tabs (TAB). The organic sulfur compound-based coupling agent of the formula CnH2n + 1-SH (n = 2-20), which is not sensitive to, prevents the weakening of the adhesive strength due to water absorption and has excellent affinity with not only the adhesive but also the metal particles. The present invention relates to an anisotropic conductive film that can maintain a constant connection thickness when connecting a plurality of fine circuits, and also has excellent weather resistance and connection reliability.

Description

Anisotropic conductive film containing organic sulfur compound coupling agent

[Industrial use]

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to anisotropic conductive films, and more particularly to electrical connections of fine circuit boards, in particular to liquid crystal displays (LCDs) and flexible circuit boards (EPCs), to microjunctions and tabs of semiconductor ICs and IC mounting circuit boards. It relates to an anisotropic conductive film containing a coupling agent used for (TAB) and the like.

[Private Technology]

Conventionally, anisotropic conductive films have been used in order to easily connect a liquid crystal display substrate and its driving integrated circuit to a liquid crystal display. That is, in the anisotropic conductive film shown in Fig. 2, a film obtained by dispersing conductive particles 5 having a diameter of about 5-10 μm in a thermosetting resin or a thermoplastic resin 4, which is a film-like insulating adhesive resin, is used as a glass substrate 6 of a liquid crystal display. ) And the electrodes 8 and 9 of the driving circuit 7. In this state, the anisotropic conductive film is heated at a predetermined temperature, and then pressurized onto the glass substrate 6 and the driving circuit 7 of the liquid crystal display, and the insulating substrate resin 6 and the glass substrate 6 and the driving circuit 7 of the liquid crystal display are pressed. Is filled in the space between the electrodes, and an electrically conductive passage between the electrode 8 and the tab electrode 9 of the liquid crystal display substrate is provided in the conductive particles 5.

1 shows a cross section of the anisotropic conductive film in more detail.

However, in this type of liquid crystal display, fine circuits are required in accordance with the trend of light weight, miniaturization, and thinness of electronic devices, so the pitch between electrical circuits increases, the number of circuit pins increases, and the spacing between circuit pins also increases. Narrows. As such, when the spacing between the circuit pins is narrowed, problems arise such that an electric short occurs when the conductive particles are not uniformly dispersed.

In order to solve the above problems, conventionally, an inorganic metal coupling agent such as silicon or titanium is used as the coupling agent in the adhesive to achieve uniform dispersion of the conductive particles. However, such a conventional method has a problem that the coupling agent has a very sensitive property to moisture, such as weakening of adhesive strength, weakening of connection reliability, and deterioration of weather resistance due to water absorption.

The present invention has been made to solve the above problems, and an object of the present invention is to prevent weakening of adhesive strength due to moisture absorption by using a coupling agent that is not sensitive to moisture, and has excellent affinity with metal particles as well as adhesives. It is possible to maintain a constant connection thickness when connecting a plurality of microcircuits, and to provide an anisotropic conductive film having excellent weather resistance and connection reliability.

1 is a cross-sectional view of the anisotropic conductive film

2 is a cross-sectional view of a liquid crystal display connection use state of the anisotropic conductive film.

DESCRIPTION OF SYMBOLS 1 Adhesive film 2 Polymer particle 3 Metal plating layer

DESCRIPTION OF SYMBOLS 4: adhesive resin 5: electroconductive particle 6: glass substrate of a liquid crystal display

7 driving circuit 8 electrode of liquid crystal display substrate 9 tab electrode

[Means for solving the problem]

In order to achieve the above object, the present invention is a conductive layer formed on a release film and the release film, the conductive layer is formed by coating a conductive layer composition comprising an insulating adhesive resin, conductive particles, a coupling agent, the coupling agent Provided is an anisotropic conductive film which is an organic sulfur compound based on a chemical formula represented by C _n H _{2n + 1} -SH, wherein n is an integer of 2 to 20.

In the present invention described above, it is preferable to include 1 to 20 parts by weight of the organic sulfur compound coupling agent described above with respect to 100 parts by weight of the adhesive resin.

In addition, the insulating adhesive resin is one selected from the group consisting of styrene-butadiene resin, styrene resin, modified epoxy resin, urethane resin, phenol resin, amide resin, acrylate resin, polyimide resin, polyether imide resin Conductive particles are composed of a core and a metal plating layer, while the core is a homopolymer or a copolymer of polystyrene, polymethacrylate, polymethylmethacrylate, polyvinylacetate, or a degree of curing thereof of 20 to 100%. It is selected from the group consisting of hardened and the metal plating layer is a high hardness, high melting point metal selected from the group consisting of gold, silver, iron, copper, nickel, cadmium, bismuth, indium, aluminum, palladium, platinum, chromium It is preferable to carry out plating process by selecting from the group which consisted of.

Hereinafter, the present invention will be described in more detail.

The anisotropic conductive film according to the present invention is composed of organic sulfur compounds containing conductive particles composed of a metal plating layer which is excellent in electrical conductivity and has a high melting point and a much higher hardness than polymer particles. After the dispersion is uniformly dispersed using a coupling agent, a crude liquid formed by dispersing a predetermined amount in the adhesive film 1 is coated on a release film and dried to form a film having a thickness of 10 to 100 μm or less.

In the present invention, the coupling agent uses an organic sulfur compound represented by the formula C _n H _{2n + 1} -SH (n = 2 to 20), and when a compound having n less than 2 is used, the compound has a high volatility as a coupling agent. When the compound is difficult to continuously exhibit the effect and n is more than 20, it is difficult to prepare the compound itself, and when using it as a coupling agent, there is a concern that the physical properties of the anisotropic conductive film are lowered.

Preferably, the organic sulfur compound coupling agent is included in an amount of 1 to 20 parts by weight based on 100 parts by weight of the adhesive resin, but when used in an amount less than 1 part by weight, the effect as a coupling agent is extremely insignificant. There exists a possibility of bringing about the fall of the physical property of an electroconductive film.

The conductive particles 2 are composed of a polymer particle core and a metal plating layer having a uniform particle size distribution having a particle size variation within ± 0.1 μm at each particle diameter, and the conductive particles are 3 to 100 parts by weight of the insulating adhesive resin component. It is used by dispersing 10 parts by weight. The core of the conductive particles is selected from the group consisting of homopolymers and copolymers such as polystyrene, polymethacrylate, polymethyl methacrylate, polyvinylacetate, and more preferably 20 to 100%. It is good to use after curing. The metal plating layer may be selected from the group consisting of metals having high hardness and high melting point such as gold, silver, iron, copper, nickel, cadmium, bismuth, indium, aluminum, palladium, platinum, and chromium.

On the other hand, 5-10 volume parts are suitable for the compounding quantity of the whole electroconductive particle with respect to 100 volume parts of thermosetting resins or thermoplastic resins which are insulating adhesive resins. If it is less than 5 volume parts, it is difficult to obtain a stable conductive path, and if it exceeds 10 volume parts, it will be difficult to obtain insulation reliability between the connection circuits.

The metal plating layer of electroconductive particle is a material which shows the strain rate within 4% at 120-250 degreeC of thermocompression bonding conditions, and 3.0-5.0 Kg / cm <2> pressure in connection between circuits by an anisotropic conductive film, Especially said gold, silver, Iron, copper, nickel, cadmium, bismuth, indium, aluminum, palladium, platinum, chromium, and the like are included and may be used in combination.

Adhesive film 1 used in the present invention is a thermoplastic, thermosetting and photo-curable resin exhibiting insulating properties, for example, styrene-butadiene resin, styrene resin, ethylene-vinyl resin, acrylonitrile butadiene rubber, silicone resin, acrylic resin , Epoxy resins, modified epoxy resins, urethane resins, phenolic resins, amide resins, acrylate resins, polyimide resins, polyetherimide resins, and those selected from the group used. You may use it together. Moreover, if necessary, a tackifier, an anti-ageing crab, a coupling agent, etc. which are represented by rosin, a turbine resin, a gumarodine resin, etc. can also be used.

EXAMPLE

Hereinafter, preferred examples and comparative examples of the present invention are described. However, the following examples are only one preferred embodiment of the present invention and the present invention is not limited to the following examples.

Example 1

45 parts by weight of bisphenol-A epoxy resin (YD-128, Kukdo Chemical), 45 parts by weight of phenoxy resin (YP50, Kukdo Chemical), 1 part by weight of organic sulfur compound coupling agent of formula C ₂ H ₅ -SH toluene / methylethylketone It reflux-dissolved in (3/1 = V / V) to prepare an adhesive. After cooling the solution to room temperature, 4 parts by weight of a curing agent (2 MZ, Kukdo Chemical), a core was polystyrene resin, and the metal plating layer was mixed with 4 parts by weight of conductive particles with respect to the resin solids to disperse the conductive particles. . An anisotropic conductive film was manufactured by such a crude liquid.

Example 2

Except that in Example 1 3 parts by weight of an organic sulfur compound coupling agent of the formula C ₄ H ₉ -SH was carried out substantially the same as in Example 1.

Example 3

Except that in Example 1 5 parts by weight of an organic sulfur compound coupling agent of the formula C ₆ H ₁₃ -SH was carried out substantially the same as in Example 1.

Example 4

Except that in Example 1 7 parts by weight of the organic sulfur compound coupling agent of the formula C ₈ H ₁₇ -SH was carried out substantially the same as in Example 1.

Example 5

Except that in Example 1 9 parts by weight of an organic sulfur compound coupling agent of the formula C ₁₀ H ₂₁ -SH was carried out substantially the same as in Example 1.

Example 6

Except for using 11 parts by weight of the organic sulfur compound coupling agent of the formula C ₁₃ H ₂₇ -SH in Example 1 was carried out substantially the same as in Example 1.

Example 7

Except that in Example 1 15 parts by weight of an organic sulfur compound coupling agent of the formula C ₁₇ H ₃₅ -SH was carried out substantially the same as in Example 1.

Example 8

Except that in Example 1 20 parts by weight of the organic sulfur compound coupling agent of the formula C ₂₀ H ₄₁ -SH was carried out substantially the same as in Example 1.

Comparative Example 1

Except that in Example 1 1 part by weight of the silane coupling agent as a coupling agent was carried out substantially the same as in Example 1.

Comparative Example 2

Except that in Example 1 1 part by weight of the titanium-based coupling agent as a coupling agent was carried out substantially the same as in Example 1.

In order to compare the physical properties of the anisotropic conductive films prepared according to the above Examples and Comparative Examples, using the anisotropic conductive films prepared according to the above Examples and Comparative Examples, line width 0.1mm, pitch 0.2mm, thick film 35㎛, terminal Flexible circuit boards (FPCs) with several 160 copper circuits and transparent conductive circuit glass substrates (ITO circuits) were connected by thermocompression bonding. The connection resistance value was measured by the four-terminal method (Four Probe Method) after the initial connection, after leaving the high temperature and high humidity, and the adhesive strength was obtained through the peel test.

The results of the following Examples and Comparative Examples are summarized in Table 1.

In Table 1, the larger the value, the better the adhesive strength. The smaller the difference between the maximum value and the minimum value is, the better the control effect of the connection thickness is. The smaller the value, the better the reliability of the connection resistance value between the connection terminals.

As shown in Table 1, in Examples 1 to 6, the adhesive force, the control of the connection thickness, and the reliability of the connection resistance between the connection terminals showed excellent effects. The reliability of the connection resistance between the terminals was excellent. In Comparative Examples 1 and 2, the variation in connection thickness was more severe than in Examples 1 to 8, the control effect of the connection thickness was decreased, the connection resistance value after the high temperature and high humidity test was increased, and the reliability of the connection resistance value was lowered.

As described above, when the anisotropic conductive film is prepared by using an organic sulfur compound having excellent affinity with organic matter and inorganic metal as a coupling agent without being sensitive to moisture to uniformly disperse the conductive particles according to the method of the present invention, Not only does the dispersion rate increase, but also the dispersion is excellent, preventing the weakening of adhesive strength due to water absorption, while maintaining a constant connection thickness when connecting a plurality of microcircuits, and the variation in the connection resistance value between the connection circuits is extremely small. And the effect of improving the connection reliability can be seen.

Claims (4)

The conductive layer is formed on a release film and the release film, the conductive layer is formed by coating a conductive layer composition comprising an insulating adhesive resin, conductive particles, a coupling agent, the coupling agent is a chemical formula C _n H _{2n + 1-} An anisotropic conductive film containing a conductive layer which is an organic sulfur compound of SH (n = 2-20, an integer). The anisotropic conductive film of claim 1, wherein the content of the coupling agent is 1 to 20 parts by weight based on 100 parts by weight of the insulating adhesive resin. The method of claim 1, wherein the insulating adhesive resin in the group consisting of styrene-butadiene resin, styrene resin, modified epoxy resin, urethane resin, phenol resin, amide resin, acrylate resin, polyimide resin, polyether imide resin Anisotropic conductive film using 1 or more types selected. The method of claim 1, wherein the conductive particles are selected from the group consisting of polystyrene, polymethacrylate, polymethylmethacrylate, homopolymers or copolymers of polyvinylacetate, or those cured at 20 to 100%. An anisotropic conductive film made of a metal core plated with a core made of gold, silver, iron, copper, nickel, cadmium, bismuth, indium, aluminum, palladium, platinum, and chromium.