JPH03108210A - Manufacture of anisotropic conductive resin film mold - Google Patents

Abstract

PURPOSE:To obtain an anisotropic conductive resin film mold excellent in resolution and connection reliability by forming into a film a resin compound of binder resin in which conductive particles are dispersed and mixed, and by rolling the film. CONSTITUTION:When a resin compound mixed with conductive particles 1 whose surfaces are coated with an electric insulating layer 3 flows and spreads into a film, the particles 1 cohere individually or mutually into dispersed resin matrices 2, which become uneven in thickness because of the cohered particles after drying. After rolling the matrices 2, insulator layers 3 on the protrudent parts of the particle 1 is removed from the film surface, the particles 1 are disposed in the film surface directions evenly in thickness.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is an anisotropically conductive resin film molding that has conductivity only in the thickness direction through conductive particles exposed on the front and back sides of a resin film molded product. Concerning methods of manufacturing things.

[Prior Art] As electronic components become smaller and thinner, the circuits used in these components become denser and more precise. Since it is difficult to connect these microcircuits with conventional solder or rubber connectors, anisotropically conductive adhesives and film-like materials (hereinafter referred to as connection members) have recently come into widespread use. Ta.

In this method, a connecting member layer made of an adhesive or film material containing a predetermined amount of conductive material is provided between opposing circuits, and by applying pressure or heating pressure means, the electrical connection between the upper and lower circuits is established. It provides insulation between adjacent circuits at the same time as connection.

Prior art documents regarding anisotropically conductive resin film moldings that exhibit conductivity only in the thickness direction include, for example, as disclosed in JP-A-51-21192, conductive particles are formed with a non-conductive base. A structure in which the mixture held in a state where they do not touch each other is formed into a sheet with a thickness approximately equal to the size of the conductive particles, and has conductivity only in the thickness direction of the sheet through the conductive particles. be.

The general method for forming these resin film moldings is to cast conductive particles uniformly dispersed in a liquid resin to a constant thickness using a bar coater, etc., and then dry or harden it to a desired thickness. This is to obtain a molded product.

[Problems to be Solved by the Invention] However, in the above method, the coating thickness when casting the resin in which conductive particles are dispersed must be thicker than the thickness of the film molded product. In particular, when a solution resin is used, the coating thickness may be several times the film thickness, and agglomeration of the conductive particles in the film molding occurs during the drying process.

In addition, in order to increase the number of conductive points per unit area of the film and achieve high resolution, it is necessary to increase the amount of conductive particles in the film. This agglomeration of conductive particles causes a problem in that the decomposition performance deteriorates.

The present invention has been made in view of this situation, and aims to provide a novel method for producing an anisotropically conductive resin film molded product that has excellent decomposition performance and connection reliability.

[Means to solve the problem]

That is, in the present invention, a resin composition formed by dispersing and mixing conductive particles is formed into a film, and then this is rolled using a press or roll to arrange the conductive particles in the plane direction, and the thickness of the film is adjusted. The present invention is characterized in that it is a molded resin film having conductivity only in one direction.

The type of conductive particles used in the present invention is not particularly limited, and metal particles, glass, ceramic, or plastic particles with a plating layer formed on their surfaces can be used alone or in combination.

In addition, to improve the connection reliability of finer circuits,
When increasing the amount of conductive particles mixed, it is also possible to use one whose conductive surface is coated with an electrically insulating layer that can be removed by heat or solvent in order to ensure insulating properties in the plane direction. be.

Furthermore, if conductive particles are used with plastic particles as cores that can be deformed by heat or pressure, the thickness of the resin film molded product after rolling can be made smaller than the particle size of the plastic particles, allowing the particles to be exposed on the surface of the film. Since the area of the conductive portion can be increased, connection reliability is increased.

The particle size of the conductive particles is selected depending on the fineness of the circuit to be connected, but the particle size of each particle needs to be as uniform as possible.

Next, resins used as binders for conductive particles include various synthetic resins and elastomers that are soluble in solvents,
Thermoplastic resins such as polyethylene, vinyl acetate, polypropylene, polyethylene tylsulfone with high heat resistance,
Resins such as polyetherimide and polyimide can also be used. The thickness of the resin film molded product is not particularly limited, but as it becomes thicker, the particle size of the conductive particles used increases and the resolution decreases, making it unsuitable for connecting fine circuits. In addition, if it becomes thinner, it is not easy to handle and manufacturing becomes difficult due to wrinkles, etc.
．． 0.005 m - 0.1 mm is appropriate.

The conditions for drying or curing the liquid resin in which conductive particles are dispersed after coating may be such that it can be rolled using a press or roll. It can also be carried out by drying the solvent, etc., to the extent that it can be rolled, or by completely drying it and then heating it to a temperature that can be rolled. If it is a thermosetting resin, it may be rolled in a semi-hard core state after drying the solvent and the like.

The amount of the conductive particles mixed varies depending on the type of the conductive particles, the thickness of the resin film, etc., but is approximately 20 to 80% by volume.

The resin composition containing the conductive particles described above is formed into a film by a casting method or the like, and then rolled to a thickness approximately equal to that of the desired resin film molded product using a hot press, rolls, or the like.

When conductive particles whose surfaces are covered with an electrically insulating film are used, a method for exposing the conductive part of the conductive particles on the surface of a resin film molded article is as follows: There are a method of wet etching the insulating layer previously formed on the surface using a soluble solvent, a dry etching method such as plasma etching or sputter etching, and a method of mechanically removing it by polishing or the like.

If the insulating layer is coated with a thermoplastic resin, no special treatment is required since the insulating layer is melted by rolling while heating and the surface of the conductive particles is exposed on the surface of the resin film.

When the anisotropically conductive resin film molded product of the present invention is used as a connection material for circuits, the molded product of the present invention is inserted between the circuits to be connected, and then both circuits are held under pressure. Alternatively, the objective can be achieved by a method such as injecting a liquid adhesive into the gap between the circuits under pressure and then hardening and fixing the adhesive. Furthermore, the resin film molded product of the present invention can be applied not only to the above-mentioned circuit connection material, but also to switch members, multilayer circuit members, circuit continuity test members, and the like.

[Effect]

The effect of the present invention will be explained with reference to the drawings, taking as an example the case where conductive particles whose surfaces are covered with an insulating layer 3 are used. This figure shows a state in which a resin composition containing conductive particles 1 is cast, and the conductive particles 1 are dispersed in a resin matrix 2 either alone or in aggregates with each other. FIG. 1(b) shows a cross section of the dried resin film, showing that the thickness is uneven due to the agglomerated particles. Figure 1(c) shows a state in which the insulating layer on the surface of the conductive particles exposed on the film surface has been removed after further rolling.The conductive particles are arranged in the plane direction of the film and have a thickness. Since this becomes uniform, it is possible to obtain an anisotropically conductive resin film molded product with excellent high resolution and connection chain properties, which are the objectives of the present invention.

〔Example〕

The details of the present invention will be described below based on examples, but the present invention is not limited thereto.

Example 1 Conductive particles with nickel-gold plating on the surface of cross-linked polystyrene particles with a particle size of around 30 tna (heat resistant temperature 300°C) were mixed into a toluene solution of ethylene vinyl acetate copolymer and thoroughly stirred. Thereafter, it was cast onto a polyethylene terephthalate film as a separator to obtain a film having a thickness of 90 nm after drying. The drying conditions at this time were 120°C and 3 minutes.

This film was sandwiched between two polyethylene terephthalate films of a separator, and further sandwiched between two stainless steel end plates with smooth surfaces, and a 20 ps stainless steel spacer was used for 30 seconds at 150"C and 20 kgf/al. It was pressed and rolled to obtain an anisotropically conductive film with a thickness of about 22 mm.

In addition, a similar sample was inserted between two stainless steel rolls with a gap of 2 On at 170°C and rolled to a thickness of about 2
An anisotropically conductive film of No. 5- was obtained. Example 2 Soluble nylon (melting temperature: about 110°C) was applied to the surface of conductive particles made of nickel-gold plating on the surface of cross-linked polystyrene particles (heat resistant temperature: 300°C) with a particle size of around 30 Jrm.
) was used to obtain an anisotropic O conductive film in the same manner as in Example 1. The soluble nylon used at this time was insoluble in toluene, and coating was performed using a 3% methanol solution.

Example 3 Ni particles with a particle size of around 35 mm were mixed into a toluene solution of ethylene vinyl acetate copolymer, thoroughly stirred, and then cast onto a polyethylene terephthalate film as a separator to determine the thickness after drying. A film having a diameter of 80 to 100 nm was obtained. The drying conditions at this time were 120°C for 3 minutes.

This film was sandwiched between two stainless steel end plates with smooth surfaces coated with a release agent, and
Press and roll for 30 seconds under CD conditions to a thickness of approximately 38 cm.
- An anisotropic conductive film was obtained.

In addition, a similar sample was inserted between two stainless steel rolls with a gap of 30° at 170°C and rolled to a thickness of approximately 37°C.
- An anisotropic conductive film was obtained.

Example 4 An anisotropic conductive film was prepared in the same manner as in Example 3 using Ni particles with a particle size of around 351,111 coated with soluble nylon (melting temperature: 110°C) in the same manner as in Example 2. I got it.

Example 5 Ni particles with a particle size of around 35 mm were mixed with a polyamic acid fest using dimethylformamide as a solvent, thoroughly stirred, and then cast onto a glass plate at 100°C until the solvent in the varnish was 30% by weight. %. This was peeled off from the glass plate and made into a film with a thickness of approximately 11,001 tons, which was sandwiched between two stainless steel mirror plates with smooth surfaces.
Pressing was performed for 30 seconds at 00° C. and 20 kgf/cd to obtain a film with a thickness of about 5 On.

Further, a similar sample was inserted between two stainless steel rolls with a gap of 55 nm at 100° C. and rolled to obtain a film with a thickness of about 6 On.

Thereafter, these samples were heat-treated at 400° C. to imidize them to obtain molded polyimide films containing 30% by volume of conductive particles. After rough polishing both sides of these films with sandpaper (#1000 to #2000),
Final polishing is done with 0.3n puff polishing agent, and the thickness is approx.
An anisotropically conductive polyimide film was obtained, and it was confirmed with an optical microscope and an electron microscope that conductive particles were exposed on the surface of the film.

Example 6 Ni particles with a particle size of around 357I11 were heat-treated at 700°C for 1 hour, and the same method as in Example 1 was carried out using conductive particles having an approximately 3-electrically insulating Ni0 layer on the surface. An anisotropically conductive polyimide film was obtained.

Comparative Examples 1 to 4 Examples 1 to 4, except that rolling with a press or roll was not performed, the front and back surfaces of the dried film were polished to expose the conductive particles, and other manufacturing processes and materials were the same. were designated as Comparative Examples 1 to 4 corresponding to each Example. After drying, the film was roughly polished with #1000 to #2000 sandpaper, and finished with a 0.3-sized puff abrasive.

The conduction resistance of these films was measured by the method shown in FIG. In FIG. 2, 4 is a resin film molded product, and 5 is a copper plate having a thickness of 2 m, the surface of which is vapor-deposited with gold. 6 is a gold-plated probe (probe A) whose tip has a diameter of φ100-. Lightly press this probe 6 against the resin film molded product 4 to measure the conduction resistance in the film thickness direction (3Ω or less is considered conductive). was measured. In addition, a probe (probe B) having the shape shown in 7 in FIG. 3 was used, and the resistance in the film surface direction was measured to obtain a measure of insulation resolution. The probe 7 shown in FIG. 3 has a structure in which copper foil electrodes 9 are formed on the surface of a polyimide film 8, and the spacing between the copper foil electrodes and the width of the copper foil electrodes are about 100n, and the length is 10+ia. The measurement was carried out by placing the resin film molded product 4 on the insulating plate 10, pressing the probe 7 from above, and measuring the insulation resistance (10''Ω or more was considered insulation).

In both the measurement methods shown in FIG. 2 and FIG. 3, 100 measurement points were used for each sample, and Table 1 shows the results of conductivity and insulation rate.

Margin below table 1

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the state of the resin film molded product of the present invention during the manufacturing process, Figure 2 is a conceptual diagram of a method for measuring resistance in the thickness direction, and Figure 3 is a method for measuring resistance in the plane direction. It is a conceptual diagram. Explanation of symbols 1 Conductive particles 2 Resin binder 3 Insulating coating 4 Resin film molded product 5 Copper plate
6 Probe (A) 710-B (B) 8 Insulating film 9 Electrode 10 Insulating plate

Claims (1)

[Claims] 1. A resin composition prepared by dispersing and mixing conductive particles in a binder resin is formed into a film, and then rolled to arrange the conductive particles in the plane direction, and to form a resin composition in the thickness direction of the film. A method for producing an anisotropically conductive resin film molded article, characterized in that conductivity is imparted only to. 2. An anisotropic conductive resin according to claim 1, characterized in that the conductive particles are arranged in the plane direction by rolling the resin composition containing the conductive particles, and the surface layer on the surface of the film is removed. A method for producing a film molded product. 3. The method for producing an anisotropically conductive resin film molded article according to claim 2, wherein the surface of the conductive particles is coated in advance with an electrical insulator.