JPS6155809A - Conductive adhesive film wind - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a roll of anisotropically conductive adhesive film.

[Conventional technology]

As electronic components such as liquid crystals, EL (electroluminescence), and semiconductor integrated circuits become smaller, thinner, and more precise, connecting materials for high-density circuits that connect these electronic components or between electronic components and circuit systems are becoming more and more important. There is a strong demand for this, and molded products having anisotropic conductivity are attracting attention for this purpose.

Anisotropic conductivity generally refers to at least one direction being conductive and one direction being insulating among the three rotational axes of XYz, for example, a conductive layer and an insulating layer such as silicone rubber. There are known so-called zebra-type anisotropic conductive rubbers that have an alternating structure, and those that penetrate metal fibers in the thickness direction of an insulating layer to obtain quadrielectricity locally, but these do not have adhesive properties. In addition, since the molded product is mechanically cut into thin pieces, it is difficult to obtain large-sized products.

On the other hand, there have been attempts to form anisotropically conductive adhesives into sheet shapes, which have the following characteristics, for example.

(1) Connection of a large number of circuits can be completed simultaneously with a single connection operation by simple means of heating, pressurizing, or heating and pressurizing.

(2) Because it is in sheet form, the thickness is uniform and there is little variation in conductivity (high connection reliability).

(5) Since it is solvent-free, there is no environmental pollution caused by solvents, etc., which is seen with general adhesives during connection work.

However, since such adhesive sheets are relatively thick and the adhesive component is hard, it is difficult to form them into rolls, so they are supplied in the form of small pieces punched into predetermined shapes, making it difficult to automate circuit connections. It was there.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and provides a rolled body of anisotropically conductive adhesive film that enables automation of circuit connections and has excellent connection reliability. That is.

[Means for solving problems]

That is, in the present invention, on a removable base material, an average particle size of 001 to
A long tape formed by forming a flexible adhesive layer with a thickness of 100 μm or less, which is made by non-uniformly dispersing 50 μm″′C metal toughener by α1 to 10% by volume, is wound multiple times on a winding core. The present invention relates to an anisotropic 4 adhesive film roll.

The present invention will be described below with reference to drawings showing examples. FIG. 1 shows a cross section of an anisotropic electrosensitive adhesive film 1 according to the present invention, which basically consists of a removable base material 4 and a conductive film. It consists of an adhesive layer 2 formed by non-uniformly dispersing metal particles 3.

The adhesive component used in the present invention is not particularly limited as long as it has flexibility and insulation, but examples include ethylene-vinyl acetate copolymer, modified ethylene-vinyl acetate copolymer, polyethylene, ethylene-propylene ULF. polyisobutylene, atactic polypropylene, polyvinyl butyral, acrylonitrile-butadiene copolymer , styrene-butadiene block copolymer, styrene-isoprene block copolymer, polybutadiene, ethylene cellulose, polyester, polyamide, polycrethane, natural rubber, silyene rubber, polychloroprene, polyvinyl ether, etc. can be used alone or in combination. More than one species is used in combination.

In addition to the above-mentioned various polymers, adhesive components may also include tackifiers such as alkylphenols, plasticizers such as dioctyl phthalate, crosslinkers such as polyisocyanate, fillers, dispersants, anti-aging agents, etc. Two or more types are used in combination.

The metal particles used to impart conductivity have an average particle size of 0.01 to 50 μm. If the particle size is 0.01 μm or less, the surface area of the particles is large and contact between the particles occurs more than necessary, making it impossible to obtain insulating properties in the plane direction.

Further, if the average particle diameter is 50 μm or more, the probability that particles will exist between adjacent circuits increases when the circuits are fine, and insulation in the plane direction cannot be obtained.

Here, the average grain good day is calculated using the following formula.

D:J:nd/Σn n indicates the number of particles having a particle size of d. Methods for observing these particle sizes include commonly used electron microscopes, optical microscopes, Coulter counters, light scattering methods, and the like.

The reason why metal particles are used as the conductive particles is that they have good heat dissipation properties in the connecting circuit portion. If heat dissipation in the connection is poor, the connection will generate heat due to Joule heat due to the current flowing through the circuit, and in extreme cases, the connection will separate.

Examples of these metal particles include Fe, Ni, and Cr.

Co, All, Sb, Mo, Cu, Ag,
There are Pt, Au, etc., and these materials may be used alone, as an alloy, or as an oxide, and it is also possible to use two or more of these materials in combination. Furthermore, among the metal particles, those having the metal layer provided on the surface of glass or synthetic resin can also be used.

The content of these conductive metal particles is preferably 0.1 to 10% by volume 41! Show your gender.

If it is less than 0.1 volume %, it is difficult to obtain tetraelectricity in the thickness direction in connection of fine circuits, and if it is more than 10 volume %, insulation between adjacent circuits cannot be obtained.

For these reasons, the content is more preferably 0.5 to 5% in order to obtain reliable anisotropic conductivity.

It is preferable that the particles have a spherical shape because this facilitates contact between the particles or between the particles and the circuit surface during circuit connection.

These conductive metal particles are non-uniformly dispersed within the insulating adhesive. That is, they are densely packed in the thickness direction and provide conductivity after circuit connection, and are randomly distributed in one surface direction, so that they do not have conductivity in any direction in the surface direction when circuit connection is made. ``The thickness of the adhesive layer is preferably 100 μm or less in order to obtain transparency and flexibility. The adhesive layer is JIS K-6
714, the total light transmittance is maintained at 40% or more.

When the adhesive layer is transparent, quality control during manufacturing is easy to perform, and alignment during circuit connection can be performed by looking through the adhesive layer, resulting in very good workability.

In addition, the adhesive layer is thin and highly flexible, making it easy to roll up into rolls. Furthermore, it has high followability even when stress is applied to the circuit connection during connection work (although the circuit connection still remains It is also possible to bend the material, giving a greater degree of freedom when designing equipment.

As a removable base material, the peeling force with the adhesive layer is 2 to 200 g.
/191!1In (based on JIS C-2107).

If the peeling force is less than 2 g/19III11, it will be easy to peel off during the connection operation (and if it is more than 200 g/19 mm, it will be difficult to peel off and the connection workability will be poor).

In order to obtain the above-mentioned appropriate peeling force, it is necessary to
SK-6768) can be used as a guide,
The standard for selection is approximately 5 dy/cm or more smaller than the wetting index of the adhesive.

In order to obtain such a peeling force, the surface of the base material may be treated with a release agent such as silicone or polyvinyl carbamate, but in this case, it is necessary to use a material that does not transfer or migrate to the adhesive layer as much as possible. Or it may lead to a decrease in reliability (.

Furthermore, a fibrous base material is not preferred because foreign matter tends to adhere to the adhesive layer.

Things that meet the above conditions vary depending on the combination with the adhesive, but polyethylene, polypropylene, polyethylene terephthalate, cellulose triacetate, hexafluorinated polypropylene, 42) ethylene, tetrafluorinated ethylene-ethylene copolymer, polyethylene Various plastic films such as vinylidene chloride, polyamide, and polyimide can be used.

Furthermore, the releasable base material may be either transparent or opaque. When the adhesive layer is transparent, it gives the product an aesthetic appearance together with the transparency of the adhesive layer, and quality control during manufacturing is easier.

On the other hand, when the releasable base material is opaque, it is possible to prevent forgetting to peel off the releasable base material after temporary connection. The releasable base material may sandwich the adhesive layer and be arranged in the form of a sandwich.The method for producing a rolled body using the above constituent materials includes a polymer as an adhesive component and other additives used as necessary. After dissolving the adhesive composition in a solvent to make it liquid, conductive metal particles are mixed by normal stirring, etc., and applied onto a base material such as a separator, and the volume in the thickness direction is reduced by volatilization of the bath agent during drying. Methods include arranging and densifying metal particles in the thickness direction by shrinkage, molding a lubricant or conductive adhesive composition under a magnetic field, and arranging magnetic conductive metal particles in the thickness direction. By this method, it is possible to obtain an adhesive in which conductive particles are arranged anisotropically, and by winding this material into a roll, a rolled body can be obtained.Basically, the particles form an arrangement structure in the thickness direction of the film. The manufacturing method is not particularly limited as long as it is distributed randomly in the direction of the cutting surface.

The thickness of the adhesive layer needs to be 100 μm or less.

That is, if the thickness is 100 μm or more, the electrical resistance level increases, the reliability of circuit connection tends to decrease (and the flexibility and transparency deteriorate), which is not preferable.

FIG. 2 is a schematic diagram showing the roll body, and it is preferable that the core 5 is made of plastic because foreign matter does not stick to the adhesive layer when cutting into a narrow tape.

Continuously wound rolls usually have a product length of 2 m or less, but in the case of this wide roll, they can be used, for example, as a through-hole substitute for multilayer circuit wiring boards; It is useful because it can be supplied continuously.

On the other hand, it is also possible to make a wide rolled material into a narrow tape shape by a conventional method, such as cutting the wide rolled material into narrow strips during winding with a slit blade, or cutting the wide rolled material into pieces using a rotary blade. (Figure 3).

If it is in the form of a narrow tape, it can automate the connection process because it can continuously supply a constant width of tape as a connection material when the connection area is extremely narrow, such as when connecting a liquid crystal display element to a circuit system. It has the advantage of being possible.

When made into a tape, the width can be set arbitrarily, but it is usually 1 to 10.
Supplied as ordered.

The rolled body of the present invention can be used for connecting display elements such as liquid crystals, EL, solar cells, and circuit systems, and for electronic components such as ICs! Applications include connections between 4@ and circuit board systems, membrane switches, and multilayer printed wiring boards.

The present invention will be explained in more detail below using examples.

Conductive metal particles are % by volume of insulating adhesive after drying
It was displayed in In addition, the characteristics of the obtained rolled body were evaluated by connecting 7 lexiple circuit boards (hereinafter abbreviated as FPC) with line width α1, pitch Q, 2 mm0, which are made of copper foil and synthetic resin layers at 5 mRO during connection. evaluated.

Example-1 A thermoplastic polyester with a molecular weight of about 20.000 was dissolved in methyl ethyl ketone to obtain a solution with a solid content of 55% (A
Liquid) n On the other hand, nickel particles with a particle size of 0.03 μm were ultrasonically dispersed in methanol containing a surfactant to a concentration of 50%. Here, the surfactant is 10% nonionic polyoxyethylene sorbitan monostearate in methanol.
Contained.

As a result of the above, nickel powder with a particle size of 03 μm can now exist as a single particle without agglomeration (B).
.

Solutions A and B were blended so that the nickel content was 5% by volume cL, and mixed and dispersed in a ball mill for 5 hours. This mixed solution is applied to a stretched polypropylene film (m
It was coated on a surface of 50 μm (with a friction index of 30 dyn/cco) so that the thickness after drying was 10 μm, and it was heated at 100°C-5
After drying for several minutes to remove the solvent, the product was wound around a plastic awn to obtain a roll. This roll body had an effective width of 1 m, and the winding length was arbitrarily set, but it was wound as 100 m.

This rolled body was re-wound and slit to a slit width of 5 mm'' lfl width to obtain a large number of tape-shaped rolled bodies.

Using this tape-shaped roll, place it on one side of one FPC, heat and pressurize at 100°C-5kg/an'-5 seconds to make a temporary connection, then peel off the polypropylene filler, and then After placing the FPC on the peeled surface and aligning it so that the circuits match, the FP is further heated and pressurized at 150°C for 5 kg/--10 seconds.
The Cs were connected facing each other.

The properties of this product are shown in Table 1. After temporary attachment, the base material can be easily peeled off from the adhesive surface, and the connected FPC can be heated at 60°C.
No major deterioration was observed even after treatment for 1,000 hours in a −90% RH tank.

★ The resistance between adjacent circuits was 101 OΩ or more, indicating sufficient insulation both before and after treatment.

Example 2 An insulating adhesive solution was prepared consisting of 100 parts by weight of a styrene-butadiene block copolymer, 50 parts by weight of an aromatic tackifier with a softening point of 100°C, and 200 parts by weight of toluene. Nickel powder having a particle size of 20 μm was mixed in an amount of 10% by volume with respect to the dried adhesive.

This mixed solution was applied onto a hexafluoride polypropylene sheet <si abrasion index 35 dyn/C+n) 100 ttm in the same manner as in Example 1 so that the thickness after drying would be 50 μm. A rolled body was obtained.

Connection was evaluated in the same manner as in Example-1 except that this rolled body was used and the temporary connection temperature was 150°C.

In this case, the releasable base material had high heat resistance (temporary attachment at 150° C. was possible), and sufficient insulation between adjacent circuits was demonstrated with lQ of 100 or more.

Comparative Example The same procedure as in Example 2 was used except that the silicone-treated polyethylene terephthalate film of Comparative Example 1 was used as the releasable base material. The results are shown in Table 1. In this case, the adhesive strength was lower than in Example-2 (the resistance at the connection portion was also high).

In addition, in the comparative example, the adhesive layer and the releasable base material were transparent, making it easy to forget to remove the releasable base material after temporary connection, but in Example-2, the releasable base material was , it was white and there was no mistake of forgetting to remove it.

Table 1 In Table 1, (1) Peeling force of the base material after temporary connection was determined based on JISC-2107, 90 degree peeling, speed 300mm 1 minute, measurement was 2
It was carried out at 0°C. In order to achieve 90 degree peeling, the FPC after temporary attachment was fixed to a pedestal with double-sided adhesive tape and measured.

(2) The total light transmittance of the adhesive layer was measured using a digital turbidimeter DH-20D manufactured by Nippon Denshoku Industries in accordance with JISK-6714.

(3) Adhesive strength) tJIs Z-0257VC compliant 90 degree peeling method was used, and one FPC was reinforced from the back side with an aluminum plate of 1.011111ft.

Peeling speed is 50fflIII/min Measured at 20℃-65%
This was done at RH.

(4) The resistance was measured using a multimeter between the opposing "rJL" poles of the FPC including the connection part.

(5) Initial values were measured within one day after connection. The aging wave characteristics are measured values after the connected FPC was subjected to constant temperature and humidity at 60° C. and 90% RH for 1,000 hours.

4. Effects of the Invention As detailed above, the anisotropically conductive adhesive film roll of the present invention is in the form of a continuous roll and has excellent unwinding properties and transparency, making it possible to automate the connection process. It became.

Furthermore, by using a peelable base material that has not been subjected to peeling treatment and a core made of plastic, it is possible to prevent foreign matter from entering or adhering to the adhesive layer, thereby improving connection reliability.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; FIG. 1 is a cutaway view of the adhesive film, and FIGS. 2 and 3 are perspective views of the rolled body. Explanation of symbols 1. Adhesive film 2. #Adhesive layer 5 s'eL particles 4. Peelable base material 5, winding core

Claims (1)

[Claims] 1. A removable substrate with a thickness of 100 μm or less, which is made by dispersing 0.1 to 10% by volume of metal particles with an average particle size of 0.01 to 50 μm on a removable base material. An anisotropically conductive adhesive film roll made by multiple windings of a long tape formed with a flexible adhesive layer on a core. 2. Peel strength between peelable base material and adhesive layer (JIS C-
2107) is 2 g/19 mm to 200 g/19 mm, the anisotropically conductive adhesive film roll according to claim 1. 3. The conductive adhesive film roll according to claim 1 or 2, wherein the releasable base material is a plastic film without surface treatment and the winding core is a plastic winding core. 4. Adhesive layer has total light transmittance (JIS K-6714)
40% or more and has conductivity only in the translayer direction.