JPH05152021A - Anisotropic conduction connector - Google Patents

Abstract

PURPOSE:To provide an anisotropic conduction connector, capable of becoming surely anisotropically conductive, high in electrical connection reliability, and also adequately cushiony. CONSTITUTION:Fine through hole 2 is made in a tilting direction so as to pass through the front face and the back face of a insulating film 1, such as a polyimide film, and metallic material 3 is filled in the through hole. It is desirable to form bump-like metallic protrusions 4 on both end portions of the through hole 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to anisotropic conductive connectors.

[0002]

2. Description of the Related Art In recent years, electronic devices have become more multifunctional and smaller and lighter. In the semiconductor field, wiring circuit patterns have been highly integrated and fine patterns with a large number of pins and a narrow pitch have been adopted. In order to cope with such fine patterning of a circuit, a method of interposing an anisotropic conductive connector in a connection between a plurality of conductor patterns formed on a substrate and a conductor pattern or IC or LSI connected to the conductor patterns has been attempted. There is.

For example, Japanese Unexamined Patent Publication No. 55-161306 discloses a sheet in which holes in selected regions of an insulating porous sheet are plated with metal to provide anisotropic conductivity. However, since such a sheet does not have a metal protrusion on the surface, it is necessary to form bump electrodes (bumps) on the connection pads on the IC side when connecting an IC or the like, which complicates the connection process.

Therefore, in order to solve this problem, fine holes provided in the thickness direction of the insulating film are filled with a metal substance to make it anisotropically conductive, and the metal substance is projected in a bump shape from the film surface to facilitate connection. The above-mentioned connector is proposed in JP-A-62-43008, JP-A-63-40218, and JP-A-63-94504.

[0005]

However, since such an anisotropically conductive connector generally has a structure as shown in FIG. 4, the adhesion between the filled metal substance and the insulating film is not sufficient, and the metal There is a risk that the substance may drop off and the fine pores that should originally have conductivity may not exhibit conductivity, resulting in a lack of reliability in electrical connection. Furthermore, since a metal substance is generally not flexible, when the metal substance is filled in the thickness direction of the insulating film as shown in FIG. When stress is applied, the stress cannot be relaxed sufficiently, and the connection part may come off and a connection failure may occur.

[0006]

Therefore, the inventors of the present invention have solved the above-mentioned problems of the conventional anisotropic conductive connector, and are capable of reliably providing anisotropic conductivity, high connection reliability, and appropriate cushioning property. The inventors of the present invention have made extensive studies to provide the anisotropic conductive connector, and completed the present invention.

That is, the present invention is an anisotropic conductive connector having fine through-holes electrically connected to the front and back surfaces of an insulating film, wherein the fine through-holes are filled with a metal substance, and the through-holes are also provided. Is provided in an oblique direction over the front and back surfaces of the insulating film.

The present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an example of the anisotropic conductive connector of the present invention.

In FIG. 1, the insulating film 1 is provided with fine through-holes 2 in an oblique direction over the front and back surfaces.
The conductive paths filled with the metal substance 3 reach the front and back surfaces. In this through hole 2, adjacent through holes do not communicate with each other, but are independent. In the anisotropic conductive connector of the present invention, by forming bump-shaped metal protrusions 4 at both ends of the through hole 2 as shown in the drawing, the connection operation becomes easy when used as a connector, which is preferable. is there. Further, by forming the so-called rivet shape in which the bottom area of the bump-shaped metal projection 4 is preferably 1.1 times or more larger than the through-hole area of the surface of the insulating film 1, the filled metal substance 3 is dropped. Since it has sufficient mechanical strength against stress in the thickness direction of the insulating film 1, the electrical connection reliability is improved, which is preferable. The height of the bump-shaped metal protrusion 4 is usually 5 μm or more,
It is preferably set in the range of 5 to 100 μm.

The diameter (hole diameter) of the fine through holes 2 is usually 5 to 100 μm, preferably 10 to 50 μm, and the pitch is 5 to 200 μm, preferably 10 to 100 μm in order to cope with the fine pitch.

The insulating film 1 used in the present invention is not limited in its material as long as it is a film having electric insulation properties, and may be a polyester resin, an epoxy resin, a urethane resin, a polystyrene resin, a polyethylene resin,
Any thermosetting resin or thermoplastic resin such as polyamide resin, polyimide resin, ABS resin, polycarbonate resin, or silicone resin can be selected according to the purpose. For example, when flexibility is required, it is preferable to use an elastic body such as silicone rubber, urethane rubber, or fluororubber, and when heat resistance is required, heat resistance such as polyimide, polyether sulfone, polyphenylene sulfide, etc. It is preferable to use a resin. Further, the thickness of the insulating film 1 can be arbitrarily selected, but from the viewpoint of film thickness accuracy (variation) and hole diameter accuracy of the through holes to be formed, it is usually
The thickness is 5 to 200 μm, preferably 10 to 100 μm.

Examples of the metal substance 3 which fills the fine through holes provided in the insulating film 1 and serves as a conduction path and the bump-shaped metal protrusion 4 are gold, silver, and the like.
Various metals such as copper, tin, lead, nickel, cobalt and indium, or various alloys containing these are used. As a method of forming the conductive path, a method such as sputtering, various vapor depositions, various platings can be adopted. In the case of using the plating method, it is possible to grow the metal protrusion 4 in a bump shape by prolonging the plating time.

The fine through holes 2 provided in the insulating film 1 may be formed by a mechanical processing method such as punching, a dry etching method using laser, plasma or the like. In the case of the etching method, a mask having a desired hole shape, for example, a circle, a square, or a rhombus is brought into close contact with the insulating film 1, and an indirect etching method in which treatment is performed from above the mask; Alternatively, there are a dry etching method in which a laser beam is imaged on a film through a mask, and a direct etching method in which fine holes are patterned in advance using a photosensitive resist and then wet etching is performed. Particularly, in the case of a dry etching method using ablation with an ultraviolet laser such as an excimer laser, it is preferable because the irradiation angle can be set with respect to the insulating film and the formation angle of the fine through holes can be arbitrarily controlled and set. It is a thing.

FIG. 2 is a sectional view showing another example of the anisotropic conductive connector of the present invention, in which the through hole 2 is an insulating film 1.
The metal substance 3 is filled in the through hole by being bent and formed in an oblique direction. As a method for obtaining such a connector, first, a laser beam having a predetermined pulse number is obliquely irradiated from one surface of the insulating film to perform half etching to form a non-through hole, and then the other surface side is formed as described above. Laser light is obliquely irradiated to penetrate the bottom of the unpenetrated hole. After that, it can be obtained by filling with a metal substance.

In the anisotropic conductive connector of the present invention, the insulating film 1 is filled with the metal substance 3 as a conducting path in an oblique direction to make it anisotropically conductive, so that the metal substance is detached as compared with the conventional one. In addition, when connecting to the external electrodes 5 and 6 as shown in FIG. 3, since the metal substance 3 is obliquely filled, a cushioning effect is produced and connection failure is less likely to occur. In order to fully exert the above-mentioned cushioning effect, the formation angle (α in FIG. 1) of the through hole 2 is set to a range of 10 degrees or more, preferably 20 degrees or less.

Examples of the method for obtaining the anisotropic conductive connector of the present invention include a method comprising the following steps.

A laminated film of an insulating film and a conductive layer (a three-layer film with an adhesive interposed or a two-layer film directly laminated).
Layer film) is provided with a fine through hole in an oblique direction by using a laser beam only on the insulating film, or a conductive layer is laminated on an insulating film provided with a fine through hole (however, the fine through hole penetrates the conductive layer. Stack or remove after lamination) to form a resist layer on the surface of the conductive layer and insulate the surface, and then etch the through hole to form a rivet-shaped groove (recess) in the conductive layer portion in contact with the through hole. ) Is formed,

A step of performing electrolytic plating or electroless plating on the fine through-holes and filling a metal substance to form bump-shaped metal protrusions;

The step of removing the conductive layer and the resist layer laminated on the insulating film by a chemical etching solution or electrolytic corrosion.

The bump-shaped metal protrusions may be formed after the step in the above step.

In the present invention, the metal protrusion 4 is formed in a bump shape.
Is preferably formed as a fine crystal metal crystal. If electrolytic plating is performed at a high current density,
Since dendritic crystals are formed, it may not be bump-shaped. In addition, a smooth and uniform protrusion can be obtained by adjusting the deposition rate of metal crystals, the type of plating solution, and the temperature of the plating bath.

[0022]

EXAMPLES Examples of the present invention will be shown below and will be described more specifically.

A polyimide precursor solution was coated on a copper foil so that the thickness after drying was 25 μm, and heat imidized to prepare a two-layer film of a copper foil and a polyimide film.

Then, the surface of the polyimide film is irradiated with KrF excimer laser light having an oscillation wavelength of 248 nm from an oblique direction (45 degrees) through a mask to perform dry etching, and the polyimide film layer is 60 μmφ in pitch, 200 μm in depth. Micropores having a size of 25 μm were formed in an area of 8 cm ² .

Next, a resist was coated on the surface of the copper foil, cured to insulate it, and immersed in a chemical polishing solution at 50 ° C. for 2 minutes.

After washing this with water, the copper foil portion was connected to an electrode and immersed in a gold cyanide plating bath at 60 ° C., a gold plating layer was grown and filled in the through holes, and gold crystals were formed from the surface of the insulating film. When there is a slight protrusion (protrusion height: 10 μm)
The plating process was interrupted.

Finally, the coated resist layer is peeled off and 2
An anisotropic conductive connector of the present invention was obtained by dissolving and removing the copper foil of the layer film with cupric chloride.

[0028]

EFFECT OF THE INVENTION Since the anisotropic conductive connector of the present invention has the above-mentioned structure, the metallic substance filled as the conducting path does not fall off from the insulating film, and originally,
This is a connector with a highly reliable electrical connection because the fine conductive paths that must have conductivity exhibit sufficient conductivity. Since the metallic substance is filled in the diagonal direction, the connector itself has a cushioning property, the stress can be sufficiently relaxed even when an external stress is applied, and there is no fear that the connecting portion will come off.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an anisotropic conductive connector of the present invention.

FIG. 2 is a cross-sectional view showing another example of the anisotropic conductive connector of the present invention.

FIG. 3 is a cross-sectional view showing a state in which electrodes on an external substrate are connected to each other using the anisotropic conductive connector of the present invention.

FIG. 4 is a cross-sectional view of a conventional anisotropic conductive connector.

[Explanation of symbols]

 1 Insulating Film 2 Micro Through Hole 3 Metallic Material 4 Bump-shaped Metal Projection

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Toshiki Naito 1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (3)

[Claims] 1. An anisotropic conductive connector having fine through holes independently conducted on the front and back surfaces of an insulating film,
An anisotropic conductive connector, characterized in that the fine through holes are filled with a metal substance, and the through holes are formed diagonally over the front and back surfaces of the insulating film. 2. The anisotropic conductive connector according to claim 1, wherein bump-shaped metal projections for connection are formed on at least one end of both ends of the through hole. 3. The anisotropic conductive connector according to claim 2, wherein a bottom area of the bump-shaped metal protrusion is larger than a through-hole area of the surface of the insulating film.