JPH07105741A - Anisotropic conductive sheet and its manufacture - Google Patents

Abstract

PURPOSE:To increase the connecting reliability and tb secure a specific position accuracy so as to obtain a sheet which can examine a circuit substrate by forming conductive members of an anisotropic conductive sheet to projections corresponding to an electrode to be examined, and forming an insulating sheet having openings corresponding the projections to the anisotropic conductive sheet integrally. CONSTITUTION:Conductive members 10 are projected in the openings 2 of an insulating sheet 1, and the ends of the projecting conductive members 10 are formed to be at the level almost same as the surface of the insulating sheet 1. In the conductive members 10, conductive particles 5 are filled closely in high polymer substances 4 having the insulating property and the elasticity, and they have normally a pressurizing conductibility which reduces the resistance value by a pressurization. By such a constitution, a necessary electric connection can be carried out surely, even though the electrode to be examined in a circuit substrate has a minute pitch and a complicated pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to achieve electrical connection between a circuit board to be inspected and an electrical inspection device in order to inspect the electrical performance of the printed circuit board or the like as an inspection object. The present invention relates to an anisotropic conductive sheet used in, and a method for manufacturing the anisotropic conductive sheet.

[0002]

2. Description of the Related Art Generally, a circuit board such as a printed circuit board tends to have an increased number of electrodes and a higher density, and the wiring tends to be complicated accordingly. For this reason, a multilayer substrate including an inner layer circuit board and an outer layer circuit board has been widely used. Further, from the viewpoint of increasing productivity, in manufacturing, a plurality of identical circuit boards are formed on a single base material to proceed with the manufacturing, which is multifaceted. In order to achieve such electrical connection between the lead electrodes of the inner layer circuit board and other circuit terminals to be connected thereto, conventionally, an anisotropic conductive sheet is interposed on each lead electrode area. Is being carried out. This anisotropic conductive sheet is one that exhibits conductivity only in the thickness direction, or one that has a large number of pressed conductive parts that exhibit conductivity only in the thickness direction when pressed, and The structure is, for example, Japanese Patent Publication Sho 56-
48951, JP-A-51-93393, JP-A-53-147772, JP-A-54-1468.
No. 73 publication and the like. However, each of the above anisotropically conductive sheets has a pressurizing conductive portion at an arbitrary point on the sheet.

[0003]

However, an anisotropic conductive sheet having a pressure conductive conductive portion at an arbitrary point on a conventional sheet is used for a circuit board such as an inner layer circuit board where a wiring portion is exposed. It did not always exhibit sufficient performance for inspection. Furthermore, with respect to the tendency of increasing the wiring density of the inner layer circuit board in recent years and increasing the size accompanying the multifaceting during manufacturing, it becomes more and more difficult to inspect using a conventional anisotropic conductive sheet. Is coming. The present invention solves the above problems, and its purpose is to:
The electrodes to be inspected such as the lead electrodes on the circuit board to be inspected have a fine electrode pitch and have a fine and high-density complex pattern, and the fine wiring connected to these lead electrodes is exposed. In this case, the required electrical connection can be reliably achieved for the circuit board, and therefore the connection reliability is high, and the circuit board can be sufficiently inspected while ensuring the required positional accuracy. It is to provide an anisotropic conductive sheet that can be formed.

[0004]

The anisotropic conductive sheet of the present invention is an electrical tester for electrically inspecting a circuit board to be inspected and the electrical inspection apparatus with the anisotropic conductive sheet interposed. In the mechanical inspection device, the anisotropic conductive sheet has a plurality of conductive portions extending in the thickness direction of the sheet, and is formed on the surface of the sheet at a protruding portion corresponding to the electrode to be inspected of the circuit board to be inspected, thereby providing anisotropic conductivity. On at least one surface side of the conductive sheet, an insulating sheet having an opening corresponding to the electrode to be inspected of the circuit board to be inspected is arranged integrally with the anisotropic conductive sheet, so that a plurality of sheets extending in the thickness direction of the sheet are provided. The conductive part of at least one surface side of the sheet is arranged so as to be insulated from each other by the insulating part, and the conductive particles are densely filled in the polymer material having insulating property and elasticity. Features .

According to the anisotropic conductive sheet of the present invention, an insulating sheet having openings corresponding to the inspection electrodes of the circuit board to be inspected is integrally arranged on at least one surface side thereof, and each of the conductive sheets is electrically conductive. Since the surface of the part is formed so as to project into the opening of the insulating sheet, the non-inspection electrodes such as lead electrodes on the circuit board to be inspected have a fine electrode pitch and are fine and high-density complicated. Even if the fine wiring connected to these lead electrodes is exposed, it is possible to surely achieve the required electrical connection for the circuit board, and therefore the connection reliability is improved. The circuit board can be sufficiently inspected while ensuring a high position accuracy.

In addition, on at least one surface side of the anisotropic conductive sheet of the present invention, an insulating sheet having an opening corresponding to the electrode to be inspected of the circuit board to be inspected is integrally arranged, and each conductive portion is formed. Since the surface is formed in a shape protruding into the opening of the insulating sheet, the molding material layer is arranged between a pair of the insulating sheets, and a parallel magnetic field is applied to the molding material layer by the thickness of the layer. When the layer is fluidized and cured while moving the conductive particles by the magnetic force in the direction, the insulating sheet and the anisotropic conductive sheet can be joined together under pressure to manufacture.

Therefore, the plurality of conductive portions extending in the thickness direction of the anisotropic conductive sheet are mutually provided on at least one surface side of the sheet by the insulating sheet having the opening corresponding to the electrode to be inspected of the circuit board to be inspected. The conductive parts are arranged in a protruding shape corresponding to the electrodes to be inspected of the circuit board to be inspected on at least one surface, and are electrically conductive in the insulating and elastic polymer substance. An anisotropic conductive sheet in which particles are densely packed can be easily manufactured with high accuracy.

[0008]

The present invention will be described in detail below with reference to the drawings. 9 and 10 show a specific example of the configuration of the anisotropic conductive sheet of the present invention, in which a plurality of conductive portions 10 extending in the thickness direction of the sheet are mutually insulated by the insulating portion 1. In this state, the conductive portions 10 are arranged corresponding to the electrodes to be inspected of the circuit board to be inspected, and each conductive portion 10 projects into the opening 2 of the insulating sheet 1 on one surface of the sheet, and the end portion of the projected conductive portion is formed. Are formed in a shape such that they are at substantially the same level as the surface of the insulating sheet.

Each conductive portion 10 is formed by densely filling conductive particles 5 in a polymeric substance 4 which is insulative and elastic, and usually has a pressure conductive property in which the resistance value is reduced by pressurization. . The filling rate of the conductive particles 5 in the conductive portion 10 is 3 vol% or more and 30 vol% or less, preferably 5 vol% or more 20
Volume% or less. Note that when the filling rate of the conductive particles 5 is low, the resistance value does not decrease even if the pressure is increased in the anisotropic conductive sheet, and thus reliable electrical connection becomes difficult. The thickness D of the conductive portion 10 is preferably 0.1 to 5 mm, particularly 0.3 to 3 mm. If the thickness D of the conductive portion 10 is within this range, effective conductivity can be reliably obtained even with a small pressure.

The thickness d of the insulating sheet 1 is practically 0.01 to 0.8 mm, particularly preferably 0.02.
It is 0.2 mm. If the thickness d of the insulating sheet 1 is within this range, it is possible to suppress the displacement of the conductive portion of the anisotropic conductive sheet due to the molding strain generated during the molding of the anisotropic conductive sheet within a range that can sufficiently withstand the circuit board inspection, Moreover, effective conductivity can be reliably obtained even with a small pressure. Insulation sheet 1
The height h of the conductive portion protruding into the opening is preferably the same as the thickness d of the insulating sheet, but it may be increased or decreased to some extent as long as it does not interfere with the inspection of the circuit board.

As the conductive particles forming the conductive portion 10,
For example, particles of magnetic metals such as nickel, iron, and cobalt, or particles of alloys thereof, or those particles plated with gold, silver, palladium, rhodium, or the like, nonmagnetic metal particles, glass beads, or the like. Examples thereof include inorganic particles or polymer particles plated with a conductive magnetic material such as nickel or cobalt. From the viewpoint of reducing the manufacturing cost, particles of nickel, iron, or an alloy thereof are particularly preferable, and gold-plated particles can be preferably used in terms of electrical characteristics such as low contact resistance.

The particle size of the conductive particles is from 10 to 400 from the viewpoint of ensuring sufficient electrical contact between the conductive particles in the conductive portion 10 and maintaining sufficient contact stability of the conductive portion 10.
μm is preferable, and 20 to 100 μm is particularly preferable.

As the insulating and elastic polymer substance forming the conductive portion 10, a polymer substance having a crosslinked structure is preferable, and an uncrosslinked polymer which can be used to obtain the polymer substance having such a crosslinked structure. Materials include silicone rubber, polybutadiene, natural rubber, polyisoprene, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, ethylene-propylene copolymer rubber, urethane rubber, polyester rubber, chloroprene rubber, epichlorohydrin. Examples thereof include rubber.

As the insulating sheet 1, the above-mentioned insulating and elastic polymer substance, or a thermoplastic resin such as polyethylene terephthalate resin, vinyl chloride resin, polystyrene resin, polyacrylonitrile resin, polyethylene resin, acrylic resin, Such as polybutadiene resin,
A thermosetting resin such as a polyimide resin or an epoxy resin is used.

Next, a method for manufacturing the anisotropic conductive sheet of the present invention will be described. Specifically, as shown in FIG. 1, a circular opening having a diameter substantially the same as the width of the electrode to be inspected is formed in a portion of the insulating sheet 1 corresponding to the electrode to be inspected on the circuit board to be inspected, which is an NC controlled drill hole. Two pieces formed by using a dawning device or a laser processing device using an excimer laser light as a light source are prepared.

Next, as shown in FIG. 3, an adhesive sheet 3 having a smooth surface and a uniform thickness covers the openings and the periphery of these insulating sheets, and the two insulating sheets are separated by a guide pin or the like. A layer of a molding material made of a mixture of conductive particles having magnetic properties and a polymer material is formed as shown in FIG. 4 in a state where the corresponding openings are aligned so as to face each other.

Next, as shown in FIG. 5, while the molding material is made to flow under pressure to the mixture sheet consisting of two insulating sheets and a layer of the molding material to change its outer shape, a parallel magnetic field is applied to the sheet. 8A, the conductive particles are cured while being oriented in the thickness direction of the sheet by the magnetic force in the thickness direction to produce 20A as shown in FIG. 8 in which the two insulating sheets and the molding material layer are integrated. Cross-linking is generally used as a means for curing after changing the outer shape of the mixture sheet. Next, as shown in FIG. 9, the adhesive sheet 3 of 11 is removed, and an anisotropic conductive sheet is manufactured. Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0018]

[Example] Thickness 0.05 mm, length 300 mm, width 400
2 sheets of polyethylene terephthalate sheet 1 having a diameter of 2 mm are piled up, and a hole having a diameter of 0.2 mm is formed at a position corresponding to the electrode to be inspected on the circuit board to be inspected by an NC control drilling device, and 3 at four corners of the sheet. Four guide holes 6 having a diameter of 0.0 mm were opened (see FIGS. 1 and 2). Next, the opening of the polyethylene terephthalate sheet 1 excluding the guide hole 6 and its periphery were covered with a polyimide adhesive sheet having a thickness of 0.05 mm (see FIG. 3). next,
The surface of one of the two polyethylene terephthalate sheets was roughened with # 600 sandpaper, and a thermosetting silicone rubber was thinly applied to the surface.

Next, a molding material is prepared by mixing room temperature curable silicone rubber with conductive magnetic particles of nickel plated with gold having an average particle diameter of 40 μm at a ratio of 12% by volume. The anisotropic conductive sheet material layer 20 is formed between the polyethylene terephthalates and is placed in the cavity of the mold. This mold is composed of an upper mold 21 and a lower mold 22 which respectively form an electromagnet, and the upper mold 21 and the lower mold 22 each have a ferromagnetic portion M having a pattern corresponding to an electrode to be inspected of a circuit board to be inspected. There are provided a magnetic pole plate 23 and a magnetic pole plate 24 having a flat lower surface, which is composed of the other non-magnetic material portion N. The ferromagnetic pin portions M of the magnetic pole plate 23 and the magnetic pole plate 24 were aligned with the guide pins so that the openings of the insulating sheet of the anisotropic conductive sheet material layer were overlapped (see FIG. 5). In this state, the electromagnets of the upper die 21 and the lower die 22 are operated, thereby applying a pressing force and a parallel magnetic field in the thickness direction of the anisotropic conductive sheet material layer, and in this state, 8 ° C at 8 ° C.
After left for curing for one hour, the polyimide adhesive tape and one of the pair of polyethylene terephthalate sheets were removed to produce an anisotropic conductive sheet in which one polyethylene terephthalate sheet and the molding material were integrated.

Instead of the pole plate 23 and the pole plate 24,
As shown in FIG. 6, a ferromagnetic material portion M having a pattern corresponding to the electrodes to be inspected of the circuit board to be inspected and a non-magnetic material portion N other than the pattern are formed.
It is also possible to use the magnetic plates 25 and 26 in which the ferromagnetic material portion M projects from the non-magnetic material portion N on the upper surface of 2. In these cases as well, a stronger parallel magnetic field acts on the anisotropic conductive sheet material layer 20 in the conductive portion arranged corresponding to the electrode to be inspected of the circuit board to be inspected.

Instead of the magnetic pole plate 23 and the magnetic pole plate 24, as shown in FIG. 7, ferromagnetic plates 27 and 28 having a smooth surface and a uniform thickness can be used. In these cases, a uniform parallel magnetic field is applied at any point on the anisotropic conductive sheet material layer 20. In these cases, the electric resistance value of the conductive portion of the formed anisotropic conductive sheet arranged corresponding to the electrode to be inspected of the circuit board to be inspected is determined by the magnetic pole plate 23 and the magnetic pole plate 24 or the magnetic pole plate 25 and the magnetic pole plate 26. It shows a slightly higher value than the case of molding using.

Using the anisotropic conductive sheet obtained in the example, an electrical test was conducted with the configuration shown in FIG. All the wiring parts of the circuit board to be inspected were exposed, and the minimum pitch of the wiring and the electrodes to be inspected was as small as 0.5 mm. However, with sufficient performance, the circuit board to be inspected for electrical continuity and short circuit can be inspected. I was able to do it.

[0023]

According to the anisotropic conductive sheet of the present invention, a plurality of conductive portions extending in the thickness direction of the sheet are provided on at least one surface side of the sheet with a protruding portion corresponding to the electrode to be inspected of the circuit board to be inspected. An insulating sheet having an opening corresponding to the electrode to be inspected of the circuit board to be inspected is arranged integrally with the anisotropic conductive sheet on at least one surface side of the anisotropic conductive sheet, and the surface of each conductive portion is Since it is formed in a shape protruding into the opening of the insulating sheet, the electrodes to be inspected such as the lead electrodes in the circuit board to be inspected have a fine electrode pitch, and a fine and high-density complicated pattern Even if the fine wiring connected to these lead electrodes is exposed, it is possible to reliably achieve the required electrical connection for the circuit board, and therefore the connection reliability is high. , Yet it can be inspected of the circuit board sufficiently while ensuring the required positional accuracy.

Further, an insulating sheet having an opening corresponding to the electrode to be inspected of the circuit board to be inspected is integrally arranged on at least one surface side of the anisotropically conductive sheet of the present invention, and each electrically conductive section is formed. Since the surface is formed in a shape protruding into the opening of the insulating sheet, the molding material layer is arranged between the pair of insulating sheets, and a parallel magnetic field is applied to the molding material layer in the thickness direction of the layer. The insulating sheet and the anisotropic conductive sheet can be joined to each other when the layer is fluidized and cured under pressure while moving the conductive particles by the magnetic force.

Therefore, a plurality of conductive portions extending in the thickness direction of the anisotropic conductive sheet are arranged in a state of being insulated from each other by the insulating portion, and each conductive portion is on the front and back surfaces of the circuit board to be inspected. It is possible to easily and highly accurately manufacture an anisotropic conductive sheet which is arranged corresponding to an electrode and in which conductive particles are densely filled in a polymeric substance having an insulating property and elasticity.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a state where an opening corresponding to an electrode to be inspected of a circuit board to be inspected is formed in two insulating sheets by an NC controlled drilling device in an example.

FIG. 2 is an explanatory cross-sectional view showing a state where openings corresponding to electrodes to be inspected of a circuit board to be inspected are formed in two insulating sheets by an NC controlled drilling device in an example.

FIG. 3 is an explanatory cross-sectional view showing a state in which an adhesive sheet is attached to two insulating sheets having openings formed therein in an example.

FIG. 4 is a view showing a state in which a layer of a forming material made of a mixture of conductive particles having magnetism and a polymer material is arranged between two insulating sheets to which an adhesive sheet is stuck in Example. FIG.

FIG. 5: A layer of a molding material composed of a mixture of conductive particles having magnetic properties and a polymer material in Examples is added to a layer arranged between two insulating sheets to which an adhesive sheet is attached. It is an explanatory sectional view showing a state where a pressure and a parallel magnetic field are applied.

FIG. 6 shows a layer of a molding material made of a mixture of conductive particles having a magnetic property and a polymer material in Example, which is added between two insulating sheets to which an adhesive sheet is attached. It is an explanatory sectional view showing a state where a pressure and a parallel magnetic field are applied.

FIG. 7 shows a layer of a molding material composed of a mixture of conductive particles having magnetic properties and a polymer material in Example, added to a layer disposed between two insulating sheets to which an adhesive sheet is attached. It is an explanatory sectional view showing a state where a pressure and a parallel magnetic field are applied.

FIG. 8 is an explanatory cross-sectional view showing an anisotropic conductive sheet material molded product after integrally molding an insulating sheet and an anisotropic conductive sheet in an example.

FIG. 9 is an explanatory cross-sectional view showing an anisotropic conductive sheet completed by removing the polyimide pressure-sensitive adhesive sheet and one polyester sheet from 20A of FIG. 8 in Example.

FIG. 10 is an explanatory diagram showing a completed anisotropically conductive sheet obtained by removing the polyimide pressure-sensitive adhesive sheet and one polyester sheet from FIG. 6 in Example.

FIG. 11 is an explanatory cross-sectional view showing the configuration of an apparatus that performs an electrical inspection using the anisotropic conductive sheet manufactured in the example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Insulating sheet 2 Opening part 3 Adhesive sheet 4 Insulating and elastic polymer substance 5 Conductive particles 6 Guide hole 7 Spacer 10 Anisotropic conductive sheet conductive part end part 11 Anisotropic conductive sheet 20 Anisotropic conductivity Material layer for sheet 20A Integrated material layer for anisotropically conductive sheet 21 Upper mold 22 Lower mold 23 Magnetic pole plate 24 Magnetic pole plate 25 Magnetic pole plate 26 Magnetic pole plate 27 Magnetic pole plate 28 Magnetic pole plate M Ferromagnetic material portion N Non-magnetic material portion 61 Inspection head 62 PCR sheet (having a plurality of conductive parts in the thickness direction,
Anisotropic conductive sheet with flat surface) 63 Off-grid adapter 64 Printed circuit board 64A Inspected part 65 Inspected electrode

Claims (2)

[Claims] 1. An electrical inspection apparatus for electrically inspecting a circuit board to be inspected and an electrical inspection apparatus by interposing an anisotropic conductive sheet, wherein the anisotropic conductive sheet is a sheet. A plurality of conductive portions extending in the thickness direction form protrusions corresponding to the electrodes to be inspected of the circuit board to be inspected on the surface of the sheet, and at least one surface side of the anisotropic conductive sheet is An insulating sheet having an opening corresponding to the electrode to be inspected is integrally arranged with the anisotropic conductive sheet, and conductive particles are densely filled in a polymer substance having an insulating property and elasticity. Anisotropic conductive sheet. 2. The method for manufacturing an anisotropically conductive sheet according to claim 1, wherein a pair of insulating sheets having openings corresponding to electrodes to be inspected of a circuit board to be inspected is used, and a pair of insulating sheets is used. The molding material layer is disposed between the layers, and a parallel magnetic field is applied to the molding material layer in the thickness direction of the layer to move the conductive particles by the magnetic force, while flowing the layer under pressure to change its outer shape. At the time of curing, at least one of the pair of insulating sheets and the anisotropic conductive sheet are joined together to manufacture the anisotropic conductive sheet according to claim 1. Production method.