JP2000149677A - Manufacturing device of anisotropic conductive adhesive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the secondary coagulation of conductive particles by providing a means for spraying a certain flow rate of the conductive particles and a means for monodispersing them on the surface of an insulating adhesive formed on a separator traveling at a constant speed. SOLUTION: A film 1 formed by applying an insulating adhesive to the surface of a separator in advance is installed from a reel-out roll 2 to a reel-in roll 3. A consistent quantity of conductive particles 8 are continuously fed from a particle feeder 7 to a vacuum hole of a vacuum ejector 9, and the conductive particles 8 are fluidized and monodispersed by compressed air. The conductive particles 8 are charged to the same level when moving rapidly in an air tube 10, are sprayed from a spray nozzle 11 horizontally with respect to the film 1 in a spray box 12. An electric field in a direction vertical to the film 1 is generated by an upper electrode 13 and a lower electrode 14 located on the upper and lower wall surfaces of the spray box 12, and hence, the conductive particles 8 atomized along that direction are separated from the atomizing air and are sprayed on the surface of the insulating adhesive layer traveling at a constant speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an apparatus for producing an anisotropic conductive adhesive film.

[0002]

2. Description of the Related Art An anisotropic conductive adhesive film is used for making a circuit connection between substrates and an electric connection between a substrate circuit and a semiconductor chip. For example, an electric connection is made between a liquid crystal substrate and a driving substrate by a flat cable. It is used to connect to each other. This anisotropic conductive adhesive film is composed of an insulating adhesive and conductive particles, and the conductive particles are particles or metal particles obtained by substantially covering the surface of a polymer core with a thin metal layer, or The particles are a mixture of both. The method for producing this anisotropic conductive adhesive film is usually such that an adhesive resin varnish in which an insulating resin such as an epoxy resin and a coupling agent, a curing agent, a curing accelerator and conductive particles are mixed and dispersed is placed on a carrier film (separator). It is manufactured by coating and drying. Furthermore, a varnish containing no conductive particles is applied to the surface to form a multilayer structure.

[0003]

However, in recent years,
With the development of electronic devices, the density of wiring and the function of circuits have been increased, and as a result, connection circuits have also been required to have higher definition.
What is about 00 μm is now required to be 50 μm or less. Along with this, it is required that the connection using the anisotropic conductive adhesive film can also support a high-density connection circuit.

However, according to the conventional method, conductive particles having a small diameter are added and dispersed in the adhesive varnish, so that the adhesive varnish is mixed and dispersed before it is applied to the separator. Therefore, there is a problem that the conductive particles are likely to settle, or secondary aggregation of the conductive particles is likely to occur, and the possibility of short-circuiting between adjacent electrodes is increased.

[0005] Furthermore, as the distance between the connection electrodes becomes smaller, the size and the amount of the conductive foreign matter that can be tolerated are also problematic. It is preferable to perform filtration immediately before applying the adhesive varnish. If the viscosity of the varnish is reduced, the adhesiveness is reduced, so that the viscosity cannot be reduced. Therefore, filtration is difficult unless a considerable pressure is applied, and there is also a problem that the conductive particles to be added are limited.

The present inventors first dispose the conductive particles uniformly on the surface layer of the insulating adhesive so that the secondary particles of the conductive particles can be maintained while maintaining the conventional connection characteristics with a small amount of added particles. A method for producing an anisotropic conductive adhesive film which is free from aggregation and excellent in suppressing the mixing of conductive foreign substances has been proposed. This production method is a method for producing an anisotropic conductive adhesive film, in which conductive particles are dispersed and embedded on the surface of an insulating adhesive formed on a peelable film substrate. By the way, this method has been completed in principle, but has an economic problem.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and means for uniformly arranging conductive particles on a surface layer of an insulating adhesive maintains the conventional connection characteristics with a small amount of added particles. It is an object of the present invention to provide an apparatus for manufacturing an anisotropic conductive adhesive film which is excellent in suppressing secondary aggregation and also excellent in suppressing mixing of conductive foreign matter.

[0008]

That is, the present invention comprises means for spraying conductive particles at a constant flow rate on the surface of an insulating adhesive formed on a separator running at a constant speed and means for monodispersing. The present invention relates to an apparatus for producing an anisotropic conductive adhesive film. In addition, the means for monodispersion charges the conductive particles by passing them between the opposing electrodes that generate the electric field, and the conductive particles uniformly dispersed on the surface of the insulating adhesive formed on the separator have an insulating property. It is preferable to provide a means for embedding in the adhesive layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The means for spraying conductive particles at a constant flow rate on the surface of an insulating adhesive on a separator according to the present invention includes a method of spraying air on dry conductive particles and spraying the same. A method of supplying and spraying conductive particles,
There are spray spraying method, screen printing method, etc., and among them, the method of spraying by supplying conductive particles in a high-speed air flow,
It is preferable in terms of dispersion of the conductive particles, and it is more preferable that the conductive particles have the same charge because the degree of dispersion can be further improved. At this time, when the conductive particles are sprayed horizontally to the spray nozzle using an air tube, the conductive particles are charged to the same charge by contact charging, and the sprayed conductive particles are separated from the spray air. By doing so, it can be dropped and spread evenly.

[0010] When the charged conductive particles are sprayed, electrodes are provided above and below the spraying box to generate an electric field, and the conductive particles travel in the direction of the electric field. Becomes possible. In the case where connection is performed at a precise location such as a conductor width / conductor interval of 0.05 mm / 0.02 mm, the size of the conductive particles is set to 3 to 10 μm and the insulating bonding is performed. 5000 on the surface of the agent
It is preferable that the spraying is performed so as to be in a range of ２０20,000 / mm ² .
The size of the container, the air pressure, the nozzle material, the positional relationship between the nozzle and the insulating adhesive, etc., and the spraying state per unit area are experimentally determined in advance, and the conditions are such that the distribution is near the center of the distribution of the optimum spraying conditions. Do with.

Further, as a means for embedding the dispersed conductive particles in the insulating adhesive layer, a plastic film having a releasable surface is superimposed on the surface of the insulating adhesive on which the conductive particles have been dispersed, and pressed or pressed. It can be realized by applying pressure by laminating or the like. Further, when embedding the conductive particles, it is preferable to heat the insulating adhesive, the heating temperature is such that the insulating adhesive is not completely cured, the substrate and the substrate to be performed later Heating is preferably performed to the extent that tackiness and plastic deformation required at the time of connection are left, and it can be experimentally determined in advance depending on the type of insulating adhesive along with other conditions such as time and pressure. A single layer or multiple layers of another adhesive layer may be laminated to the insulating adhesive in which the conductive particles have been dispersed, and the particle layer may be arranged at a specific position in the thickness direction. It is preferable to make a difference in the melt viscosity of the adhesive layer.For example, when the insulating adhesive in which the conductive particles are dispersed is an epoxy resin, the insulating adhesive layer to be superimposed on the surface is melted with the same epoxy resin. If the viscosity is increased, the conductive particles are not pushed until the insulating adhesive is superimposed when the conductive particles are pushed into the dispersed insulating adhesive, and the position of the conductive particles in the thickness direction can be controlled, which is preferable. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments. FIG. 1 shows an overall view of an apparatus for producing an anisotropic conductive adhesive film of the present invention. The film 1 in which the insulating adhesive is applied on the separator in advance is set from the unwinding roll 2 to the winding roll 3. Protective film 4 for protecting the surface of the insulating adhesive on which the conductive particles are dispersed.
From the unwinding roll 5 to the winding roll 6. The particle feeder 7 is filled with the conductive particles 8 and a certain amount of particles is continuously supplied to the vacuum ejector 9.

The particle feeder 7 is inserted into the vacuum port of the vacuum ejector 9.
The particles supplied from are dropped, and the conductive particles are fluidized with compressed air to perform a monodispersion operation. The fluidized conductive particles are charged to the same charge when moving in the air tube 10 at a high speed, and are sprayed horizontally from the spray nozzle 11 onto the film in the spray box 12. The conductive particles sprayed from the spray nozzle 11 generate an electric field in the direction perpendicular to the film in the spray box 12 by the upper electrode 13 and the lower electrode 14 installed on the upper and lower wall surfaces of the spray box 12, and in that direction. Along the way, the sprayed conductive particles separate from the spray air and are sprayed on the surface of the insulating adhesive layer running at a constant speed. The conductive particles not separated from the spray air are sucked into the cyclone 16 from the exhaust port 15 and collected. The insulating adhesive on which the conductive particles are dispersed is applied to the upper laminating roll 17,
The conductive particles are embedded in the insulating adhesive by the lower laminating roll 18 via the peelable protective film. With respect to the film that has passed through the laminating roll, the protective film is wound up by the winding roll 6, and the film in which the separator / conductive particles are embedded in the surface of the insulating adhesive layer is wound up by the winding roll 3.

FIG. 2 is a sectional view of a spray box according to the present invention. The wall material of the spray box is upper wall 19 and lower wall 20 is S
The US steel plate, the right wall 21 and the left wall 22 are made of PVC. The lower wall surface 20 is grounded, and a high voltage is applied to the upper wall surface 19 by a DC high-voltage power supply 23 to generate a downward electric field in the spray box 12 from above. still,
The direction of the electric field can be freely changed by changing the polarity of the electrode, and the electric field strength can be set to an arbitrary value by the output of the high-voltage power supply. In the embodiment, the upper electrode is +10 kV.
And the lower electrode was grounded. Using this apparatus, an anisotropic conductive adhesive film was produced as follows. Novacure HP-3942HP, a liquid epoxy resin containing a phenoxy resin PKHA (manufactured by Union Carbide Co., Ltd., trade name: 40 parts by weight) and a microcapsule-type latent hardener, a high-molecular epoxy resin (manufactured by Asahi Kasei Corporation) Name: 100 parts by weight) and a weight ratio of 30/7
At 0, ethyl acetate was diluted to 30% by weight to obtain an adhesive varnish. The adhesive varnish was cast and dried on a 50 μm biaxially stretched polyethylene terephthalate resin film-separated separator 24 having been subjected to release treatment, and dried to form an insulating adhesive layer 28 having an average thickness of 23 μm.
5 was obtained. Plastic particles having an Ni / Au plating film having an average diameter of 5 μm and an average thickness of 0.25 μm
g, fluidized through an air ejector in a container having a volume of 0.1 liter and a pressure of 0.5 MPa from a spray nozzle.
Was sprayed on the film 25 at an average rate of 6000 pieces / mm ² to obtain a film 26. This film 25
Was moved at a speed of 2 m / min, and the spray nozzle was fixed at a height of 20 cm from the film 25 and sprayed in the horizontal direction.

On the film 26, the release-treated surface of the biaxially stretched PET resin film 24 subjected to the release treatment and the conductive particle scattering surface are placed face to face, and the temperature is 50 ° C., the pressure is 0.3.
An anisotropic conductive adhesive film 27 in which the dispersed conductive particles were pressed into the surface layer of the film 26 and fixed by being passed between a rubber and a metal roll under the conditions of MPa and a speed of 2 m / min. This anisotropic conductive adhesive film 27 was adhered to an ITO glass substrate by heating and pressing at 100 ° C. and 2 kg / cm ² for 5 seconds, and the separator film was peeled off.
A bare chip having a gold bump of × 90 μm was aligned, and heated and pressed at 200 ° C. and 30 kg / cm ² for 20 seconds to make a circuit connection. Anisotropic conductive adhesive film 27
Observation was performed with a 00-power optical microscope, and the number a of conductive particles per unit area and the secondary aggregation state were measured. In addition, the number b of conductive particles on the bare chip bumps after circuit connection was measured, and the connection resistance between electrodes facing each other and the connection resistance between adjacent electrodes were also measured.

COMPARATIVE EXAMPLE 1 Using the same adhesive varnish as in the example, 1
A conductive particle-free insulating adhesive layer 14 having a thickness of 5 μm was formed. Also, the same conductive particles (addition amount: 9.5% by volume) as those used in the examples were dispersed in the adhesive varnish to contain conductive particles having a thickness of 8 μm and an average of 8000 particles / mm ^2. The insulating adhesive layer 29 was prepared. A two-layer anisotropic conductive adhesive film 31 in which the insulating adhesive layer 30 and the insulating adhesive layer 29 were bonded to each other was obtained. Using the two-layer anisotropic conductive adhesive film 31, the same connection and measurement as in the example were performed.

Comparative Example 2 The generation of an electric field was eliminated by applying no voltage to the electrode, and the same material and method as in the example were used.
In a, the film speed that can be sprayed on the film at an average rate of 6000 pieces / mm ² was measured.

Table 1 shows the measurement results of the example and the comparative example.

[Table 1]

Table 2 shows the results of Example and Comparative Example 2.

[Table 2]

In this embodiment, first, the secondary aggregated particle diameter of the conductive particles is reduced. Second, the arrangement of the conductive particles is concentrated in a layer very close to the surface layer of the anisotropic conductive adhesive film to improve the flow of particles during circuit connection, increase the particle trapping rate, and add conductive particles to the adhesive. The number can be reduced. As a result, the number of conductive particles existing in the inter-circuit space is significantly reduced, and the short-circuit potential between the circuits can be reduced. In addition, speed can be improved by generating an electric field. Further, as described above, fine filtration can be performed immediately before the application of the insulating adhesive, and a great effect has been recognized in reducing foreign substances in the anisotropic conductive adhesive film.

[0021]

As described above, according to the present invention, the conductive particles can be uniformly arranged on the surface layer of the insulating adhesive, the amount of added particles is small, the suppression of secondary aggregation is excellent, and the conductive foreign matter is excellent. It is possible to provide an apparatus capable of economically realizing the production of an anisotropic conductive adhesive film which is also excellent in suppressing the mixing of water.

[Brief description of the drawings]

FIG. 1 is an overall view of an apparatus for producing an anisotropic conductive adhesive film according to the present invention.

FIG. 2 is a sectional view of a spray box according to the present invention.

FIGS. 3A, 3B, and 3C are cross-sectional views of an anisotropic conductive adhesive film in which conductive particles are arranged on the surface of an insulating adhesive layer formed according to the present invention.

FIG. 4 is a cross-sectional view showing a two-layer anisotropic conductive adhesive film prepared by a conventional method in a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Film 2 Unwind roll 3 Take-up roll 4 Peeling protection film 5 Unwind roll 6 Take-up roll 7 Particle feeder 8 Conductive particles 9 Vacuum ejector 10 Air tube 11 Spray nozzle 12 Spray box 13 Upper electrode 14 Lower electrode 15 Exhaust port 16 Cyclone 17 Upper laminating roll 18 Lower laminating roll 19 Upper wall surface 20 Lower wall surface 21 Right side surface 22 Left side surface 23 DC high-voltage power supply 24 Separator 25 Film 26 Film 27 Anisotropic conductive adhesive film 28 Insulating adhesive layer 29 Conductivity Insulating adhesive layer containing particles 30 Insulating adhesive layer without conductive particles 31 Two-layer anisotropic conductive adhesive film

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01R 11/01 H01R 11/01 J // B32B 7/12 B32B 7/12 C09J 9/02 C09J 9/02 F-term (for reference) 4F071 AA01 AA43 AE15 AG12 AH12 BC01 4F100 AK01 AK53 AK53H AR00A AR00B BA02 CA02 CB00A DE01B EH71 EH76 EJ17 EJ19 EJ91 EK00 GB41 JG01B JG04A JL11A 4J01 DB01 GA03 KA02 KA03 KA16 KA32 LA09 NA20 QB04 5G323 AA01

Claims (4)

[Claims] 1. An anisotropic conductive material comprising: means for dispersing conductive particles at a constant flow rate; and means for monodispersing conductive particles on the surface of an insulating adhesive formed on a separator running at a constant speed. Production equipment for adhesive film. 2. The apparatus for producing an anisotropic conductive adhesive film according to claim 1, wherein the means for monodispersing the conductive particles charges the conductive particles by passing them between opposed electrodes that generate an electric field. 3. The anisotropic conductive adhesive film according to claim 2, further comprising means for embedding conductive particles dispersed on the surface of the insulating adhesive formed on the separator in a surface layer of the insulating adhesive. manufacturing device. 4. An insulating film formed on a peelable protective film or a separator for protecting the surface of the insulating adhesive on which the conductive particles are dispersed when the conductive particles are embedded in the surface layer of the insulating adhesive. 4. The apparatus for producing an anisotropic conductive adhesive film according to claim 3, further comprising means for bonding an adhesive.