KR100735211B1 - Anisotropic conductive film with conductive ball of highly reliable electric connection - Google Patents

Abstract

An anisotropic conductive film having a conductive particle of highly reliable electric connection is provided to obtain safety in a connection process by adjusting property of the conductive particle included in the anisotropic conductive film. An anisotropic conductive film having a conductive particle of highly reliable electric connection includes an insulating adhesive(120), and the conductive particle having a shell(111), and a center unit(112). The insulating adhesive(120) has a storage elastic ratio of 10^4 to 10^6 Pa at 100 degrees centigrade. The conductive particle which is diffused in the insulating adhesive(120) has an elastic stress of 900 to 4600 MPa in case of deformation of 20%. The shell(111) of a sphere shape has a hollow. The center unit(112) has metal powder which is filled in the inside of the shell(111). The conductive particle is one selected from a group of gold, silver, iron, copper, nickel, and a mixture thereof.

Description

Anisotropic conductive film with conductive ball of highly reliable electric connection}

The following drawings attached to this specification are illustrative of preferred embodiments of the present invention, and together with the detailed description of the invention to serve to further understand the technical spirit of the present invention, the present invention is a matter described in such drawings It should not be construed as limited to.

1 is a cross-sectional view showing a state where a conventional anisotropic conductive film is interposed between a connected member having circuit electrodes facing each other.

2 is a cross-sectional view showing a connection example of a circuit structure electrically connected by a normal anisotropic conductive film.

3 is a cross-sectional view showing a structure electrically connected by an anisotropic conductive film according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100. Anisotropic conductive film 110. Conductive particles 120. Insulating adhesive

200, 300 ..Connected member 310 .. Electrode

The present invention relates to an anisotropic conductive film (ACF) used for electrical connection of a fine circuit board. In more detail, it is related with the anisotropic conductive film provided with the conductive particle which can improve the electrical connection reliability by adjusting the physical property of the conductive particle of an anisotropic conductive film.

In general, an anisotropic conductive film is a connection material used when the material of a member to be connected is special or the pitch of signal wiring is minute, so that the member and the member cannot be attached by soldering.

The anisotropic conductive film is typically used as a connection material for packaging LCD panels, printed circuit boards (PCBs), driver IC circuits, and the like in LCD modules.

For example, a plurality of driver ICs are mounted in the LCD module to drive thin film transistors (TFTs). The driver IC is largely mounted on the LCD panel through a chip on glass (COG) mounting method, which is a method of mounting the LCD panel in a gate area and a data area without a separate structure, and a tape carrier package (TCP) equipped with a driver IC. It is divided into TAB (Tape Automated Bonding) mounting method, which indirectly mounts the driver IC in the gate area and the data area of the.

However, since the electrodes on the driver IC element side and the electrodes on the LCD panel side are formed at minute pitch intervals, it is difficult to use a means such as soldering even if any mounting method is adopted. For this reason, an anisotropic conductive film is mainly used in the step of electrically connecting the electrode on the driver IC side and the electrode on the panel side.

Referring to FIG. 1, a conventional anisotropic conductive film 30 is obtained by dispersing conductive particles 50 in an insulating adhesive 40, and is interposed between the members 10 and 20 to be heated at a predetermined temperature and pressure. Squeezed. Then, as shown in FIG. 2, the conductive particles 50 are interposed between the opposing electrodes 11 and 21 to electrically interconnect the electrodes 11 and 21, and have insulating properties between neighboring electrodes. Keep it. In other words, insulation is maintained on the x-y plane and conductivity is maintained on the z-axis.

At this time, in order to ensure high connection reliability of the anisotropic conductive film, the conductive particles 50 are deformed into a suitable shape between the electrodes 11 and 21 of the member to be connected to provide a sufficient contact area between the conductive particles and the electrodes 11 and 21. (See Fig. 2 (a)).

As shown in FIG. 2B, if the conductive particles 50 'are connected between the electrodes 11 and 21 but are not sufficiently pressurized and deformed, the conductive particles 50' and the electrodes 11 and 21 are not. There is a problem that the electrical contact resistance is large because the contact area between the small. In addition, as shown in FIG. 2C, when the strength itself of the conductive particles 50 ″ is too small, the conductive particles 50 ″ are deformed but not completely in contact with the electrodes 11 and 12. There is a problem that the insulating adhesive 40 is cured to cause a gap between the conductive particles and the electrode.

In order to solve such a problem and to secure high connection reliability between electrodes, Korean Patent No. 2000-0048223 provides a predetermined protrusion on the surface of the conductive particle so that the protrusion of the conductive particle breaks through the oxide film of the connection electrode when pressed. A reliable connection was made between the electrodes.

However, the conventional method is not only cumbersome to form the surface of the conductive particles, but also has limitations in securing connection reliability between electrodes effectively and practically.

SUMMARY OF THE INVENTION The present invention has been made under the technical background as described above, and an object thereof is to provide an anisotropic conductive film in which the conductive particles are sufficiently pressurized and deformed between the electrodes of the member to be connected and can be reliably connected by controlling the properties of the conductive particles.

The anisotropic conductive film according to the present invention for achieving the above object is an anisotropic conductive film in which conductive particles are dispersed based on an insulating adhesive, the insulating adhesive has a storage modulus of 10 ⁴ to 10 ⁶ Pa at 100 ℃, The conductive particles dispersed in the insulating adhesive is characterized in that the elastic stress is 900 to 4600MPa at 20% deformation.

Preferably, the conductive particles have an elastic stress of 1200 to 2000 MPa at 20% strain.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention, and do not represent all of the technical idea of the present invention, it is possible to replace them at the time of the present application It should be understood that there may be various equivalents and variations in the range.

3 is a cross-sectional view schematically showing the configuration of a circuit connection structure having an anisotropic conductive film and a connected member thermally compressed using the anisotropic conductive film according to a preferred embodiment of the present invention. For example, the lower connected member 200 is a glass substrate coated with a silver (Ag) layer having a thickness of 6000 Å, and the upper connected member 300 is a flexible circuit board having a pitch of 60 μm between electrodes.

Referring to FIG. 3, the anisotropic conductive film 100 according to the present invention includes an insulating adhesive 120 and conductive particles 110.

The insulating adhesive 120 is made of an adhesive electrically insulating material to firmly fix and fix the members 200 and 300 to be connected. In addition, the insulating adhesive 120 maintains insulation on the x-y plane of the anisotropic conductive film 100. That is, the insulating adhesive 120 separates adjacent conductive particles 110 so that conduction occurs due to mutual contact between adjacent conductive particles 110 on the xy plane in the connected members 200 and 300 having fine wiring. prevent.

The insulating adhesive 120 is composed of a curing agent and a hardening material added thereto using a thermosetting resin or a thermoplastic resin as a base resin.

The insulating adhesive 120 has a storage modulus of about 10 ⁴ to 10 at 100 ° C., which is the best fluidity when the fluidity is measured by using a dynamic mechanical thermal analyzer (DMTA). ⁶ Pa.

The conductive particles 110 electrically connect the lower connected member 200 and the electrode 310 formed on the upper connected member 300.

The conductive particles 110 include a spherical shell 111 having a hollow and a central portion 112 made of a metal powder filled in the shell 111.

The shell 111 may be made of an insulating polymer resin such as polyester, polystyrene, polyvinyl alcohol, nylon, or a mixture thereof, or may be made of metal such as gold. If the components of the shell 111 have insulation, the conductive particles 110 adjacent to each other on the x-y plane can be effectively prevented from conducting. At this time, the shell 111 is melted by heat to expose the metal powder of the central portion 112 when the thermocompression bonding for the connection of the member to be connected. On the other hand, when the component of the coating layer 111 has electroconductivity, it is efficient to electrically connect between electrodes.

The central portion 112 serves to electrically connect the lower connected member 200 and the electrode 310 of the upper connected member 300 to be electrically connected. The central portion 112 is made of a metal powder filled in the shell 111, and preferably, the metal powder is particles having a diameter of several nm to several μm. As the metal powder, gold, silver, iron, copper, nickel or any one or more metals selected from these may be employed.

On the other hand, when the anisotropic conductive film 100 is interposed between the members 200 and 300 to be thermally compressed, the conductive particles 110 in the anisotropic conductive film 100 are connected to the lower connected member 200 and the upper to-be-connected. The form is deformed by the pressure by the electrode 310 of the member. In this case, the shape of the deformed conductive particles 110 is changed according to the strength of the conductive particles 110. Here, the strength of the conductive particles 110 is closely related to the material of the components constituting the central portion 112.

Accordingly, the strength of the conductive particles 110 is adjusted by changing the material of the components constituting the central portion 112 of the conductive particles 110. The strength of the conductive particles 110 is 20% of the spherical conductive particles 110. In the deformation, it is preferable that the elastic stress of the conductive particles 110 is 900 to 4600 MPa. More preferably, at 20% strain, the elastic stress of the conductive particles 110 is 1200 to 2000 MPa.

The conductive particles 110 preferably have a diameter of 1 to 15 μm in order to sufficiently connect the connected member having a fine electrode pitch. However, the present invention is not limited thereto and may be variously modified according to the characteristics of the connected member.

Hereinafter, the present invention will be described in more detail by explaining more specific experimental examples of the present invention. However, the present invention is not limited to the following experimental examples, and various forms of embodiments may be implemented within the scope of the appended claims.

In the present experimental example, in producing an anisotropic conductive film, an insulating adhesive was used as the base resin, and conductive particles having different strengths were dispersed in the insulating adhesive.

Experimental Example 1

30 to 70 parts by weight of a thermoplastic resin mixed with polyester, phenoxy resin, polyvinyl butyl al resin, rubber such as NBR, SBR, polystyrene, polyamide resin, etc. A thermosetting resin and a curing initiator were mixed to prepare an insulating adhesive having a total of 100 parts by weight. At this time, the insulating adhesive had a storage elastic stress of about 10 ⁴ to 10 ⁶ Pa at 100 ° C.

Then, conductive particles were mixed with the insulating adhesive to prepare an anisotropic conductive film. As the conductive particles, AUEL 003A manufactured by Sekisui Co., Ltd. was used, and AUEL 003A has a property of having an elastic stress of about 1640 MPa at 20% deformation in the insulating adhesive.

Experimental Example 2

Thermosetting resins of monomers and oligomers having one and a plurality of acrylic groups in 30 to 70 parts by weight of thermoplastic resin mixed with polyester, phenoxy resin, polyvinyl butylal resin, rubber such as NBR, SBR, polystyrene, polyamide resin, etc. And a curing initiator were mixed to prepare an insulating adhesive having a total of 100 parts by weight. At this time, the insulating adhesive had a storage elastic stress of about 10 ⁴ to 10 ⁶ Pa at 100 ° C.

Then, conductive particles were mixed with the insulating adhesive to prepare an anisotropic conductive film. AUE 003A manufactured by Sekisui Co., Ltd. was used as the conductive particles, and AUE 003A has a characteristic of having an elastic stress of about 4650 MPa when 20% deformation in the insulating adhesive.

Experimental Example 3

30 to 70 parts by weight of a thermoplastic resin mixed with polyester, phenoxy resin, polyvinyl butyl al resin, rubber such as NBR, SBR, polystyrene, polyamide resin, etc. A thermosetting resin and a curing initiator were mixed to prepare an insulating adhesive having a total of 100 parts by weight. At this time, the insulating adhesive had a storage elastic stress of about 10 ⁴ to 10 ⁶ Pa at 100 ° C.

Then, conductive particles were mixed with the insulating adhesive to prepare an anisotropic conductive film. AUEF 003A manufactured by Sekisui Co., Ltd. was used as the conductive particles, and AUEF 003A has a property of having an elastic stress of about 850 MPa at 20% deformation in the insulating adhesive.

After interposing the anisotropic conductive films prepared as described above between the members to be connected, a predetermined pressure (3 MPa, 5 MPa, 7 MPa) is applied to crimp the connected members, and the contact resistance between the electrodes of the crimped connected members is pressed. Measured. At this time, the contact resistance was measured by measuring the contact resistance between electrodes, and when the average value of the contact resistance measured under a given pressure was 1 Ω or less, or the deviation between the measured contact resistance and the average value was 30% or less, it was judged as a pass.

Table 1 below shows the contact resistance value between the electrodes according to the adhesive pressure and the evaluation of the connection state according to the bonding pressure when connecting the member to be connected using the anisotropic conductive film prepared according to the experimental example.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Type of conductive particles AUEL 003A AUEL003A AUEF 003A Adhesion Pressure (MPa) 3 5 7 3 5 7 3 5 7 Contact resistance between electrodes (Ω) 0.56 0.43 0.35 2.7 0.92 0.52 2.3 1.7 0.68 Connection status evaluation pass fail fail

Referring to Table 1, in Experimental Example 1 in which the strength of the conductive particles was 1640 MPa, the contact resistance between the electrodes of the connected member was 0.35 to 0.56 Ω, and the average value of the contact resistance was 0.45 Ω. Accordingly, the maximum deviation between the average value of the contact resistance and the measured contact resistance was 0.11, which was within 30%.

On the other hand, in Experimental Example 2 in which the strength of the conductive particles was 4650 MPa, the contact resistance between the electrodes of the connected member was 0.52 to 2.7 Ω, and the average value of the contact resistance was 1.38 Ω. Accordingly, the maximum deviation between the average value of the contact resistance and the measured contact resistance was 1.32, which exceeded 30%. In addition, in Experimental Example 3 in which the strength of the conductive particles was 850 MPa, the contact resistance between the electrodes of the connected member was 0.68 to 2.3 Ω, and the average value of the contact resistance was 1.56. Accordingly, the maximum deviation between the average value of the contact resistance and the measured contact resistance exceeded 30% at 0.88. That is, when the strength of the conductive particles is too large as in Experimental Example 2 or too small as in Experimental Example 3, the contact resistance was significantly increased as the adhesion pressure was lowered.

Therefore, it is preferable that the intensity | strength of the electroconductive particle which can improve the electrical connection reliability of a to-be-connected member is 900-4600 Mpa.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

According to the present invention, by controlling the physical properties of the conductive particles included in the anisotropic conductive film, deformation of the conductive particles may sufficiently occur by thermal compression when the member to be connected is connected. Therefore, the to-be-connected member thermally crimped using the anisotropic conductive film can ensure stability in a connection process, and can manufacture a reliable product.

Claims (3)

In an anisotropic conductive film in which conductive particles are dispersed based on an insulating adhesive agent, The insulating adhesive has a storage modulus of 10 ⁴ to 10 ⁶ Pa at 100 ° C., and the conductive particles dispersed in the insulating adhesive have an elastic stress of 900 to 4600 MPa at 20% deformation. . The method of claim 1, The conductive particles have a spherical shell having a hollow and a central portion made of a metal powder filled in the shell. The method according to claim 1 or 2, The conductive particles are any one selected from the group consisting of gold, silver, iron, copper, nickel and mixtures thereof.

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