JPH038213A - Manufacture of anisotropic conductive film - Google Patents

Abstract

PURPOSE:To improve connection reliability by adsorbing conductive particles to only a charged portion of a sensitive drum and transferring conductive particles on the sensitive drum to the surface of resin film. CONSTITUTION:Patterned light 2 is irradiated to the surface of a sensitive drum 1 to form a charged portion 3. Next, conductive particles 4 are arranged under the sensitive drum and the conductive particles 4 are adsorbed to only the charged portion 3 on the drum 1 by turning the drum 1. Then, tacky resin film 5 is passed under the rotating sensitive drum 1 to transfer the conductive particles 4 to the surface of the film 5. It is thus possible to get anisotropic conductive film which does not short between adjacent electrodes and improve connection reliability.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing an anisotropic conductive film.

[Conventional technology]

Conventional anisotropic conductive films are made by mixing conductive particles into a viscous resin, then stirring the resin mixed with the conductive particles to disperse the conductive particles, increasing the viscosity of the resin, and forming a film. It was processed and manufactured.

[Problem to be solved by the invention]

FIG. 6 shows a cross-sectional view of a mounting section using a conventional anisotropic conductive film.

In the conventional method, it is only possible to mix conductive particles over the entire surface of the film, and when a pair of electrodes are electrically connected through an anisotropic conductive film, as shown in FIG.
If the conductive particles 4 between the insulators 20 are located at four parts, there is a problem in that the conductive particles 4 between the insulators become an obstacle, making it difficult to connect between the electrodes 19. Moreover, by applying pressure horns even further than the state shown in FIG. 6, it is possible to obtain electrical connection between the electrodes via the conductive particles 4, but due to the destruction of the insulators and conductive particles due to excessive pressure, This has the problem that the reliability of the connection decreases.

Furthermore, even in connection between electrodes where the electrode 19 is not located in a concave shape with respect to the insulator 20, when the connection electrode pitch is narrowed due to a plurality of conductive particles agglomerated during the production of the anisotropic conductive film, the distance between adjacent electrodes is reduced. This has the problem of causing a short circuit.

Therefore, the present invention has been made to solve the above problems, and its purpose is to provide a method for manufacturing an anisotropic conductive film with high connection reliability.

[Means to solve the problem]

The anisotropic conductive film of the present invention includes (a) a step of charging a part or the entire surface of a photosensitive drum with light; (b) a step of adsorbing conductive particles only on the charged photosensitive drum; (C) The method is characterized by comprising a step of transferring conductive particles on a photosensitive drum onto a resin film.

〔Example〕

Example 1 Ag with a pad arrangement of 300 tt m pitch as follows:
An example in which an anisotropic conductive film according to the present invention is used for connection between a pad IC and a substrate having a nickel electrode formed on glass will be described in detail, including the manufacturing process.

FIGS. 1(a) to 1(d) show the manufacturing process of an anisotropic conductive film. First, a patterned light 2 is irradiated onto the photosensitive drum 1, and a charged portion 3 is formed only on the irradiated photosensitive drum 1 (FIG. 1(a)). was illuminated at a pitch of 300 μm in accordance with the arrangement of the AΩ pads.

Next, by placing the conductive particles 4 under the photosensitive drum 1 and rotating the drum, the conductive particles 4 are attracted only to the charged portions of the drum (FIG. 1b). In this example, as the conductive particles 4, nickel-plated resin balls having a diameter of 10 μm were used.

Next, the conductive particles 4 on the photosensitive drum 1 were transferred onto the resin film 5 by passing a resin film 5 having some tackiness under the rotating photosensitive drum 1 (FIG. 1C).

In this example, a thermoplastic resin having a thickness of 10 μm was used as the resin film 5. Further, the gap between the resin film 5 and the photosensitive drum 1 was set to 5 μm so that half of the conductive particles were buried in the resin film.

Using the anisotropic conductive film produced through the above steps, conductive particles could be arranged in correspondence with the positions of the aluminum pads. (FIG. 1(d)) FIG. 2 shows Example 1, in which a substrate with a nickel electrode 7 formed on galamuro and an IC 9 having an aluminum pad 8 are connected by thermocompression bonding via an anisotropic conductive film. FIG.

For ICs with aluminum pads, passivation film 1
Although the pad part is concave compared to 0, by using the anisotropic conductive film according to this example in which the conductive particles 4 are arranged only in the part corresponding to the pad, a highly reliable connection can be achieved. I was able to obtain

Example 2 FIG. 3 shows a second embodiment of the invention.

IC9 with gold bumps 11 arranged at a pitch of 80 μm
and a copper electrode 12 patterned to correspond to the gold bump.
It was connected to a ceramic substrate 13 having a.

By using the anisotropic conductive film according to this example, conductive particles between the gold bumps could be eliminated, and connections at a pitch of 80 μm could be made without shorting between the bumps.

The method for producing the anisotropic conductive film was the same as in Example 1, except that the light irradiation method to the photosensitive drum was changed to a liquid crystal shutter method instead of a laser beam method.

Example 3 FIG. 4 shows a third embodiment of the present invention.

A substrate with transparent electrodes 14 patterned on a glass 6 at a pitch of 150 μm and a pattern width of 75 μm, and a flexible tape with copper electrodes patterned on a polyimide tape 15 with a pitch of 150 μm and a pattern width of 75 μm,
Connections were made by thermocompression bonding using an anisotropic conductive film in which 25 μm square regions of conductive particles were patterned over the entire surface at a pitch of 50 μm.

In the above method, since the inter-electrode gap is sufficiently large at 75 μm for the region width of the conductive particles of 25 μm, fine connections at a pitch of 150 μm are possible without aligning the anisotropic conductive film.

In this example, an LED array was used to irradiate the photosensitive drum with light, and nickel particles with a diameter of 10 μm were used as the conductive particles. Furthermore, since a thermosetting resin was used as the resin film, the reliability of the connection part was improved.

Example 4 Embodiment 4 of the present invention is shown in FIG.

A mask made at twice the scale of the aluminum pad pitch of the IC is scaled down to 1/2, and a photosensitive drum is charged. Copper particles of 20 μmφ are adsorbed onto the drum and deposited on a 40 μm thick paraffin film. The particles were transferred. The anisotropic conductive film produced in this manner was placed between an IC with an aluminum pad specification and a glass epoxy substrate 16 having a copper electrode 12 at a portion corresponding to the pad position, with the conductive particle position matching the electrode position. .

Next, the glass epoxy substrate and the IC were pressed together using springs 17, and the whole was heated to the melting temperature of paraffin, and the paraffin was melted to expose only the conductive particles, thereby establishing a connection between the aluminum pad and the copper electrode.

With this method, an aluminum pad IC with electrodes on four parts
I was able to make the connection.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to easily connect between electrodes located in recessed portions, there is no formation of a mass of conductive particles in the anisotropic conductive film, and it is possible to implement a fine connection pitch. It is possible to manufacture an anisotropic conductive film.

Furthermore, since it is no longer necessary to arrange conductive particles in areas where conduction is not required, the amount of conductive particles used can be reduced.

Furthermore, since the method uses a method of charging the photosensitive drum, mass production is excellent, and if the charging method of the photosensitive drum is electronic, such as with a liquid crystal shutter, LED array, or laser beam, it is extremely easy to change the pattern of the conductive particle arrangement. It has the advantage that it can be done quickly.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) are diagrams showing the method for manufacturing an anisotropic conductive film of the present invention. FIG. 2 is a diagram showing Embodiment 1 of the present invention. FIG. 3 is a diagram showing a second embodiment of the present invention. FIG. 4 is a diagram showing a third embodiment of the present invention. FIG. 5 is a diagram showing a fourth embodiment of the present invention. FIG. 6 is a cross-sectional view of a mounting section using a conventional anisotropic conductive film.・・Photosensitive drum・・Light・・Charging part・・Conductive particles・・Resin film・・・Glass・・Nickel electrode・・Aluminum pad φ・IC・・Passivation film 11 ・ 12 ・ ] 3 ・ 14 ・ 15 ・ 16 ・17 ・ 18 ・ 19 ・ 20 ・ Gold bump copper electrode ceramic substrate transparent electrode polyimide tape glass epoxy substrate spring paraffin electrode insulator or higher

Claims (1)

[Claims] (a) A step of charging a part or the entire surface of the photosensitive drum with light; (b) A step of adsorbing conductive particles only on the charged photosensitive drum; (c) A step of adsorbing conductive particles on the photosensitive drum. 1. A method for producing an anisotropic conductive film, comprising the step of transferring conductive particles onto a resin film.