JP2008021658A - Anisotropic conductive film and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide anisotropic conductive film which has elasticity in the film thickness direction, in which conduction in the film thickness direction with a low compressive load is possible, furthermore in which elasticity recovery is possible, and which is suitable for frequent uses. <P>SOLUTION: This anisotropic conductive film is characterized in that an electrically insulating porous film formed of a synthetic resin is used as a base film; conductive parts formed of a conductive metal adhering to the resin part of a porous structure on wall surfaces of through holes penetrating from a first surface to a second surface and formed by a process of forming the through holes in the film thickness direction of the porous film, and capable of giving conductivity only in the film thickness direction are respectively arranged independently in a plurality of parts of the base film; and the respective conductive parts are formed of the conductive metal adhering to the resin part of the porous structure on the wall surfaces of the respective through holes with the porous structure of the porous film held thereto. Its manufacturing method is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an anisotropic conductive film and a method for manufacturing the same, and more particularly to an anisotropic conductive film that can be suitably used for a burn-in test of a semiconductor device and a method for manufacturing the same.

  A burn-in test is performed as one of screening methods for removing an initial failure of a semiconductor device. In the burn-in test, accelerated stress higher than the operating conditions of the semiconductor device is applied to accelerate failure occurrence and remove defective products in a short time. For example, a large number of packaged semiconductor devices are arranged on a burn-in board, and a power source voltage and an input signal that are accelerated and stressed are applied from outside in a high-temperature bath for a certain time. Thereafter, the semiconductor device is taken out and a determination test is performed on a non-defective product and a defective product. In the determination test, an increase in leakage current due to a semiconductor device defect, a defective product due to a multilayer wiring defect, a contact defect, and the like are determined. The burn-in test is also performed on a semiconductor wafer.

  For example, when performing a burn-in test on a semiconductor wafer, the test is performed via an electrode pad made of aluminum or the like on the surface of the semiconductor wafer. At that time, in order to compensate for the contact failure due to the variation in the electrode height between the electrode pad of the semiconductor wafer and the head electrode of the measuring apparatus, a contact sheet having conductivity only in the film thickness direction is usually provided between these electrodes. Test with pinch. This contact sheet has an anisotropic conductive film due to the property of showing conductivity only in the film thickness direction in a conductive portion (also referred to as “conductive path” or “electrode portion”) arranged according to a pattern corresponding to the surface electrode. (Also called “anisotropic conductive sheet”).

  Conventionally, in the field of electronics, for the purpose of connecting a packaged integrated circuit to a printed wiring board, etc., as shown in FIG. 6, a flat porous flexible material 63 is used as a non-conductive insulating part, and at least An anisotropic conductive member 61 having a conductive portion 62 filled with a conductive metal in a cross section defined in one vertical direction (Z-axis direction) and fixed by filling with an adhesive such as an epoxy resin is provided. It is known (for example, refer to Patent Document 1). However, when this anisotropic conductive member 61 is used as an anisotropic conductive film for burn-in test, the conduction part 62 is buckled by the pressure at the time of inspection and does not recover elastically, so it must be disposable for each inspection. Absent. Therefore, the inspection is too expensive. Therefore, this anisotropic conductive member 61 is not suitable for an anisotropic conductive film for burn-in test that requires frequent use.

  Further, as shown in FIG. 7, a plurality of through holes are provided in the film thickness direction of the sealing insulating sheet 74 formed of a thermosetting resin such as an epoxy resin material, and the elastomer is formed in these through holes. A semiconductor element mounting sheet 71 having a structure in which a conductive path 72 is formed by filling a conductive path forming material in which conductive particles 73 are dispersed has been proposed (see, for example, Patent Document 2). As the conductive particles, for example, metal or alloy particles, or capsule-type conductive particles having a structure in which polymer particles are plated with a conductive metal are used.

  When the semiconductor element mounting sheet 71 is pressed in the film thickness direction, the elastomer of the conductive path 72 is compressed and the conductive particles 73 are connected, so that electrical conduction is obtained only in the film thickness direction of the conductive path. However, when this semiconductor element mounting sheet 71 is used as an anisotropic conductive film for a burn-in test, a high compressive load is required to obtain conduction in the film thickness direction, and the elasticity decreases due to deterioration of the elastomer. Can not be used frequently. Therefore, the semiconductor element mounting sheet having such a structure is not suitable as an anisotropic conductive film for a burn-in test such as a semiconductor wafer.

  On the other hand, anisotropic conductive films used as burn-in test interposers for semiconductor wafers, etc. connect the surface electrode of the semiconductor wafer to the head electrode of the measuring device, or connect the wiring from the semiconductor wafer to the semiconductor package. In addition to connecting with terminals, there is also a demand for stress relaxation. Therefore, the anisotropic conductive film is elastic in the film thickness direction, can conduct in the film thickness direction with a low compressive load, and can be elastically recovered, making it suitable for frequent use. It is required to be. In addition, with high-density mounting and the like, it is required to refine the pattern such as the size and pitch of each conductive portion of the anisotropic conductive film used for inspection. However, in the prior art, it has not been possible to develop an anisotropic conductive film that can sufficiently meet these requirements.

JP 10-503320 A (page 1-3, FIG. 4) Japanese Patent Laid-Open No. 10-12673 (page 1-2, FIG. 1)

  An object of the present invention is an anisotropic conductive film mainly used for inspection of semiconductor wafers, etc., which has elasticity in the film thickness direction, can conduct in the film thickness direction with a low compressive load, and is elastic. An object of the present invention is to provide an anisotropic conductive film which can be recovered and is suitable for frequent use. Another object of the present invention is to provide an anisotropic conductive film that can refine the size, pitch, and the like of each conductive portion.

  In the process of earnestly researching to achieve the above object, the present inventors have developed an anisotropic conductive film because an electrically insulating porous film formed from a synthetic resin has an appropriate elasticity and can be elastically restored. We paid attention to the fact that it is suitable as the base film of the conductive film. However, in the method in which a conductive metal is filled in a porous structure at a specific part of the porous membrane to form a conductive portion made of a conductive metal lump, the conductive metal lump does not buckle at the time of compressive load and does not recover elastically. Therefore, it cannot be used repeatedly.

  Therefore, as a result of further research, when a conductive part was formed by attaching a conductive metal to a resin part having a porous structure in a state penetrating in the film thickness direction at a plurality of locations in the porous film, It was found that the porous structure can be maintained. Of course, in the conductive part, since the conductive metal is attached to the resin part of the porous structure, the porous structure originally possessed by the porous film cannot be completely retained, but to some extent The porous structure can be maintained within a range. That is, in the anisotropic conductive film of the present invention, the conductive part is porous.

  Therefore, the anisotropic conductive film of the present invention has not only the base film but also the conductive part has elasticity and elastic recovery, and can be used frequently. In addition, the anisotropic conductive film of the present invention can conduct in the film thickness direction with a low compressive load. Furthermore, the anisotropic conductive film of the present invention can refine the conduction part, the pitch between the conduction parts, and the like. The present invention has been completed based on these findings.

  According to the present invention, an electrically insulating porous film formed from a synthetic resin is used as a base film, and the thickness direction of the porous film penetrates from the first surface to the second surface at a plurality of locations of the base film. The conductive portions attached to the resin portion of the porous structure on the wall surface of the through hole formed by the step of forming the through hole in the conductive portion, and the conductive portions that can impart conductivity only in the film thickness direction, respectively Provided independently, and each conducting part is formed of a conductive metal attached to the resin part of the porous structure on the wall surface of each through-hole while maintaining the porous structure of the porous film. An anisotropic conductive film is provided.

  Further, according to the present invention, from the first surface, a step of forming through holes in the film thickness direction of the porous film in a plurality of locations of the base film made of an electrically insulating porous film formed of a synthetic resin. A through-hole penetrating the second surface is formed, and then a conductive metal is attached to the porous resin portion on the wall surface of the through-hole so as to hold the porous structure, and is conductive only in the film thickness direction. Provided is a method for producing an anisotropic conductive film, characterized in that conductive portions capable of imparting are provided independently.

  Furthermore, the manufacturing method of the anisotropic electrically conductive film shown by following 1-3 is provided as an embodiment.

1. (1) A polytetrafluoroethylene film (B) and (C) are fused as mask layers on both sides of a base film made of a porous polytetrafluoroethylene film (A) to form a laminate having a three-layer structure. Process,
(2) By irradiating synchrotron radiation or laser light having a wavelength of 250 nm or less from the surface of one mask layer through a light shielding sheet having a plurality of independent light transmission portions in a predetermined pattern, Forming a patterned through-hole in the laminate,
(3) A step of attaching catalyst particles that promote a chemical reduction reaction to the entire surface of the laminate including the wall surface of the through-hole,
Porous polytetrafluoroethylene by each step of (4) peeling the mask layers on both sides, and (5) attaching the conductive metal to the resin part of the porous structure on the wall surface of the through hole by electroless plating Conductive metal is attached to the resin part of the porous structure on the wall surface of the through-hole penetrating from the first surface to the second surface at a plurality of locations on the base film made of a film, thereby imparting conductivity only in the film thickness direction. A method for producing an anisotropic conductive film, characterized in that each of the conductive portions that can be provided is provided independently.

2. (I) A three-layer laminate is formed by fusing the polytetrafluoroethylene films (B) and (C) as mask layers on both sides of a base film made of a porous polytetrafluoroethylene film (A). Process,
(II) Using a ultrasonic head having at least one rod at the tip, press the tip of the rod against the surface of the laminate and apply ultrasonic energy to form a patterned through-hole in the laminate The process of
(III) a step of attaching catalyst particles that promote a chemical reduction reaction to the entire surface of the laminate including the wall surface of the through-hole,
Porous polytetrafluoroethylene by each step of (IV) peeling the mask layer on both sides, and (V) attaching the conductive metal to the resin part of the porous structure on the wall surface of the through hole by electroless plating Conductive metal is attached to the resin part of the porous structure on the wall surface of the through-hole penetrating from the first surface to the second surface at a plurality of locations on the base film made of a film, thereby imparting conductivity only in the film thickness direction. A method for producing an anisotropic conductive film, characterized in that each of the conductive portions that can be provided is provided independently.

3. (I) A porous polytetrafluoroethylene film (B) and (C) are fused as mask layers on both sides of a base film made of a porous polytetrafluoroethylene film (A) to form a laminate having a three-layer structure. Forming step,
(Ii) impregnating the liquid into the porous body of the laminate and freezing the liquid;
(Iii) Using an ultrasonic head having at least one rod at the tip, the tip of the rod is pressed against the surface of the laminate and ultrasonic energy is applied to form a patterned through-hole in the laminate. The process of
(Iv) A step of raising the temperature of the laminated body to return the frozen body in the porous body to a liquid and removing it,
(V) a step of attaching catalyst particles that promote a chemical reduction reaction to the entire surface of the laminate including the wall surface of the through hole;
Porous polytetrafluoroethylene by each step of (vi) peeling the mask layers on both sides, and (vii) attaching a conductive metal to the resin part of the porous structure on the wall surface of the through hole by electroless plating Conductive metal is attached to the resin part of the porous structure on the wall surface of the through-hole penetrating from the first surface to the second surface at a plurality of locations on the base film made of the film, thereby providing conductivity only in the film thickness direction. The anisotropic conductive film manufacturing method characterized by providing the conductive part which can be each independently provided.

  According to the present invention, an anisotropic conductive film that is elastic in the film thickness direction, can conduct in the film thickness direction with a low compressive load, and can be elastically recovered and is suitable for frequent use. Is provided. In addition, according to the present invention, an anisotropic conductive film is provided in which the size and pitch of each conductive portion can be refined. The anisotropic conductive film of the present invention is an anisotropic conductive film for inspection mainly for semiconductor wafers, etc., which provides electrical conduction in the film thickness direction with a low compressive load. The thickness returns and can be used repeatedly for inspection.

1. Porous membrane (base membrane) ;
An anisotropic conductive film for burn-in test such as a semiconductor wafer is preferably excellent in heat resistance of the base film. The anisotropic conductive film needs to be electrically insulating in the lateral direction (a direction perpendicular to the film thickness direction). Therefore, the synthetic resin forming the porous film needs to be electrically insulating.

  Synthetic resin materials for forming a porous film used as a base film include polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer. (PFA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride copolymer, ethylene / tetrafluoroethylene copolymer (ETFE resin), etc .; polyimide (PI), polyamideimide (PAI), polyamide ( Engineering such as PA), modified polyphenylene ether (mPPE), polyphenylene sulfide (PPS), polyetheretherketone (PEEK), polysulfone (PSU), polyethersulfone (PES), liquid crystal polymer (LCP) Plastic; and the like. Among these, PTFE is preferable from the viewpoints of heat resistance, workability, mechanical properties, dielectric properties, and the like.

  Examples of a method for producing a porous film made of a synthetic resin include a pore making method, a phase separation method, a solvent extraction method, a stretching method, and a laser irradiation method. By forming a porous film using a synthetic resin, elasticity can be given in the film thickness direction, and the dielectric constant can be further lowered.

  The porous film used as the base film of the anisotropic conductive film preferably has a porosity of about 20 to 80%. The porous membrane preferably has an average pore diameter of 10 μm or less or a bubble point of 2 kPa or more, and more preferably has an average pore diameter of 1 μm or less or a bubble point of 10 kPa or more from the viewpoint of fine pitching of the conducting part. . The film thickness of the porous membrane can be appropriately selected according to the purpose of use and the location of use, but is usually 3 mm or less, preferably 1 mm or less. In particular, in an anisotropic conductive film for burn-in test, the thickness of the porous film is preferably 5 to 500 μm, more preferably 10 to 200 μm, and particularly preferably about 15 to 100 μm in many cases.

  Among porous membranes, a porous polytetrafluoroethylene membrane (hereinafter abbreviated as “porous PTFE membrane”) obtained by stretching is excellent in heat resistance, processability, mechanical properties, dielectric properties, etc. Since it is easy to obtain a porous film having a uniform pore size distribution, it is the most excellent material as a base film of an anisotropic conductive film.

  The porous PTFE membrane used in the present invention can be produced, for example, by the method described in Japanese Patent Publication No. 42-13560. First, a liquid lubricant is mixed with the unsintered powder of PTFE, and extruded into a tube shape or a plate shape by ram extrusion. When a thin sheet is desired, the plate is rolled with a rolling roll. After the extrusion rolling process, the liquid lubricant is removed from the extruded product or the rolled product as necessary. When the extruded product or the rolled product thus obtained is stretched at least in a uniaxial direction, unsintered porous PTFE is obtained in the form of a film. An unsintered porous PTFE membrane is highly porous when heated and stretched to a temperature of 327 ° C. or higher, which is the melting point of PTFE, while being fixed so that shrinkage does not occur. A PTFE membrane is obtained. When the porous PTFE membrane is in a tube shape, a flat membrane can be obtained by opening the tube.

  The porous PTFE membrane obtained by the stretching method has a fine fibrous structure composed of very thin fibers (fibrils) formed by PTFE and nodes (nodes) connected to each other by the fibers. In the porous PTFE membrane, this fine fibrous structure forms a porous structure.

2. Formation of conduction part (electrode part) :
In the present invention, a conductive metal is attached to a resin portion having a porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations on the base film made of a synthetic resin and made of an electrically insulating porous film. Thus, the conductive portions capable of imparting conductivity in the film thickness direction are provided independently.

  In order to form conductive portions at a plurality of locations on the base film, first, it is necessary to specify the position where the conductive metal is attached. As a method for specifying the position where the conductive metal is attached, for example, a method in which a porous film is impregnated with a liquid resist, exposed in a pattern and developed, and the resist removal portion is set as the conductive metal attachment position. There is. In this invention, the method of forming a fine through-hole in the film thickness direction of the specific position of a porous film, and making the wall surface of this through-hole into the adhesion position of an electroconductive metal can be employ | adopted suitably. The method of the present invention for forming a large number of through-holes in a porous film is suitable for the case of depositing a conductive metal at a fine pitch as compared with the former method using a photolithography technique. Further, the method of forming a large number of through holes in the porous film is suitable for forming a conductive portion having a fine diameter of, for example, 30 μm or less, and further 25 μm or less.

  In the present invention, a conductive portion is formed by adhering a conductive metal to a resin portion having a porous structure in a state of penetrating from the first surface to the second surface at a plurality of locations on a base film made of a porous membrane. In the method using the photolithography technique, conductive metal particles are deposited on the resist removal portion by an electroless plating method or the like, and the conductive metal is continuously attached to the porous resin portion. In this case, the conductive metal is continuously attached to the resin portion having the porous structure so as to penetrate from the first surface to the second surface of the resist removal portion. In the method unique to the present invention for forming the through-hole, the conductive metal particles are adhered to the porous resin portion exposed on the wall surface of the through-hole by a method such as electroless plating.

  The resin part having a porous structure means a skeleton part forming the porous structure of the porous film. The shape of the resin part having a porous structure differs depending on the type of porous film and the method of forming the porous film. For example, in the case of a porous PTFE membrane formed by a stretching method, the porous structure is formed of a large number of fibrils each made of PTFE and a large number of nodes connected to each other by the fibrils. These are fibrils and nodes.

  A conductive metal is attached to the porous resin portion to form a conducting portion. Under the present circumstances, the porous structure in a conduction | electrical_connection part can be hold | maintained by controlling the adhesion amount of a conductive metal moderately. In the anisotropic conductive film of the present invention, since the conductive metal adheres along the surface of the porous resin part, the conductive metal layer is integrated with the porous structure to form a porous structure. As a result, it can be said that the conducting portion is porous.

  When an electroless plating method or the like is employed, the conductive metal particles adhere to the resin portion having a porous structure. In the anisotropic conductive film of the present invention, a state in which conductive metal particles are adhered is obtained while maintaining the porous structure (porosity) constituting the porous film to some extent. The thickness of the porous resin part (for example, the thickness of the fibril) is preferably 50 μm or less. The particle diameter of the conductive metal particles is preferably about 0.001 to 5 μm. The adhesion amount of the conductive metal particles is preferably about 0.01 to 4.0 g / ml in order to maintain porosity and elasticity. Although it depends on the porosity of the porous film that is the base film, if the amount of conductive metal particles attached is too large, the elasticity of the anisotropic conductive film becomes too large, and the normal use compression load causes anisotropy. The elastic recovery performance of the conductive film is significantly reduced. If the adhesion amount of the conductive metal particles is too small, it is difficult to obtain conduction in the film thickness direction even when a compressive load is applied.

  A method of attaching a conductive metal to the resin portion having a porous structure on the wall surface of the through hole will be described with reference to the drawings. FIG. 1 is a perspective view of a porous membrane having through holes formed therein. The porous film (base film) 1 is formed with a plurality of through holes 4 penetrating from the first surface 2 to the second surface 3. These through holes are generally formed in the porous film in a predetermined pattern. FIG. 2 is a cross-sectional view taken along the line AA ′ in FIG. 1 and shows a state in which conductive metal particles adhere to the porous resin portion on the wall surface of the through hole to form a conductive portion. ing. In FIG. 2, a porous film 6 is a base film, and through holes 4 are provided at a plurality of predetermined locations, and conductive metal particles adhere to the resin portion of the porous structure on the wall surface of the through holes. Thus, the conductive portion 5 is formed. Since this conducting part is formed by adhering to the surface of the resin part having a porous structure, it has a characteristic as a porous material, and by applying pressure (compression load) in the film thickness direction, the film thickness Conductivity is imparted only in the direction. When the pressure is removed, the entire anisotropic conductive film including the conducting portion is elastically recovered, so that the anisotropic conductive film of the present invention can be used repeatedly.

  FIG. 3 is an enlarged cross-sectional view of one conducting portion of FIG. 2, wherein a represents the diameter of the through hole, and b represents the diameter of the conducting portion (electrode) formed by adhering conductive metal particles ( Represents the outer diameter). Since the conductive metal particles adhere to the wall surface of the through hole in a state of slightly penetrating into the porous structure, the diameter b of the conducting portion is larger than the diameter a of the through hole.

  In the anisotropic conductive film of the present invention, the resistance value of the conducting part is large when no compressive load is applied, and the resistance value of the conducting part may be 0.5Ω or less when a predetermined compressive load is applied. desirable. The resistance value of the conduction part is measured using the conduction confirmation device shown in FIG. 5, and details thereof will be described in the embodiment.

  As shown in FIG. 1, it is difficult to attach a conductive metal only to the wall surface of a through-hole by electroless plating or the like only by providing a through-hole at a plurality of locations in the porous film. For example, when a porous PTFE film is used as the porous film, conductive metal particles are deposited not only on the wall surface of the through-hole but also on the entire resin portion of the porous structure due to electroless plating. Therefore, the present invention proposes a method of attaching a conductive metal only to the wall surface of the through hole using, for example, a mask layer. Specifically, since the conductive metal is deposited only on the wall surface of the through hole, mask layers are formed on both surfaces of the base film so that catalyst particles that promote the chemical reduction reaction in electroless plating do not adhere to the surface of the base film. Form.

  For example, when a porous PTFE film obtained by a stretching method is used as the base film, the material used as the mask layer has good adhesion to the base film, and through holes can be formed simultaneously with the base film. A PTFE film made of the same material as the base film is preferable because it can be easily peeled off from the base film after the role is finished. In addition, the mask layer is a porous PTFE film because the etching rate for forming the through-hole can be increased and the separation from the base film can be further facilitated after completing the role as the mask layer. Is more preferable. The porous PTFE film of the mask layer preferably has a porosity of about 20 to 80% from the viewpoint of easy peeling, and the film thickness is preferably 3 mm or less, more preferably 1 mm or less. , 100 μm or less is particularly preferable. Moreover, it is preferable that the average hole diameter is 10 micrometers or less (or a bubble point is 2 kPa or more) from a water resistant viewpoint as a mask layer.

  When the porous PTFE membrane (A) obtained by the stretching method is used as a base membrane, and the PTFE membrane of the same material, preferably the porous PTFE membranes (B) and (C) are used as a mask layer, FIG. Will be described with reference to FIG. As shown in FIG. 4, the porous PTFE membranes (B) 44 and (C) 45 are fused as mask layers on both sides of the base membrane composed of the porous PTFE membrane (A) 43 to form a laminate having a three-layer structure. Form. More specifically, these porous PTFE membranes are superposed on three layers as shown in FIG. 4, and both surfaces thereof are sandwiched between two stainless steel plates 41 and 42. Each stainless steel plate has a parallel surface. By heating each stainless steel plate at a temperature of 320 to 380 ° C. for 30 minutes or more, three layers of porous PTFE membranes are fused to each other. In order to increase the mechanical strength of the porous PTFE membrane, it is preferable to rapidly cool it with cooling water after the heat treatment. In this manner, a laminate having a three-layer structure is formed.

  Examples of the method for forming the through hole in the film thickness direction at a specific position of the porous film include a chemical etching method, a thermal decomposition method, an ablation method using laser light or soft X-ray irradiation, and an ultrasonic method. When a porous PTFE film obtained by a stretching method is used as the base film, a method of irradiating synchrotron radiation or laser light having a wavelength of 250 nm or less, and an ultrasonic method are preferable.

  The method for producing an anisotropic conductive film using a porous PTFE film as a base film and including a step of forming a through hole by irradiation with synchrotron radiation or laser light having a wavelength of 250 nm or less is preferably (1 ) Forming a three-layer laminate by fusing the polytetrafluoroethylene films (B) and (C) as mask layers on both sides of the base film made of the porous polytetrafluoroethylene film (A); (2) By irradiating synchrotron radiation or laser light having a wavelength of 250 nm or less from the surface of one mask layer through a light shielding sheet having a plurality of independent light transmission portions in a predetermined pattern, A step of forming a patterned through-hole in the laminate, (3) a step of attaching catalyst particles for promoting a chemical reduction reaction to the entire surface of the laminate including the wall surface of the through-hole, and (4) a mask layer on both sides A step of peeling, and (5) a production method comprising a step of adhering a conductive metal to the resin portion of the porous structure in the wall surface of the through-hole by electroless plating.

  As the light shielding sheet, for example, a tungsten sheet is preferable. A plurality of patterned openings are formed in the tungsten sheet, and the openings are referred to as light transmitting portions (hereinafter, simply referred to as “openings”). A portion where light is transmitted through and irradiated from a plurality of openings of the light shielding sheet is etched to form a through hole.

  The pattern of the opening part of the light shielding sheet can be any shape such as a circle, a star, an octagon, a hexagon, a quadrangle, and a triangle. The hole diameter of the opening may be one side or a diameter of 0.1 μm or more and larger than the average hole diameter of the porous PTFE membrane to be used. Since the hole diameter of the through-hole determines the size of the conductive part (electrode) of the anisotropic conductive film to be manufactured, it may be appropriately formed according to the size of the conductive part to be manufactured. For example, when used as an interposer for burn-in test of a semiconductor wafer, 5 to 100 μm is preferable, and 5 to 30 μm is more preferable. As for the pitch between conduction | electrical_connection parts (electrodes), 5-100 micrometers is preferable.

  In order to form a through-hole in the film thickness direction at a specific position of the porous film by the ultrasonic method, as shown in FIG. 10, an ultrasonic head 101 having at least one rod 102 attached to the tip is used. The tip of the rod 102 is pressed against the surface of the porous membrane 103 to apply ultrasonic energy. In the step of forming the through hole, the porous film 103 is placed on the plate-like body 104 formed of a hard material such as silicon, ceramics, or glass. Instead of using a plate-like body, rods may be opposed to each other above and below the porous membrane.

  The rod is preferably a rod-like body formed of an inorganic material such as metal, ceramics, or glass. The diameter of the rod is not particularly limited, but is usually selected from the range of 0.05 to 0.5 mm from the viewpoint of the strength of the rod, workability, the desired hole diameter of the through hole, and the like. The cross-sectional shape of the rod is generally circular, but other shapes such as a star, octagon, hexagon, quadrangle, and triangle may be used. Instead of attaching only one rod 102 to the tip of the ultrasonic head 101, a large number of rods may be attached to form a large number of openings in the porous film by batch processing.

  The pressing pressure of the rod 102 is usually in the range of 1 gf to 1 kgf, preferably 1 to 100 gf per rod. The frequency of the ultrasonic waves is usually in the range of 5 to 500 kHz, preferably 10 to 50 kHz. The output of the ultrasonic wave is usually in the range of 1 to 100 W, preferably 5 to 50 W per rod.

  When the ultrasonic head is operated by pressing the rod 102 against the surface of the porous membrane 103, the ultrasonic energy is applied only to the vicinity of the porous membrane where the tip of the rod is pressed, and the ultrasonic vibration energy causes local localization. When the temperature rises, the resin component in the portion is decomposed by melting, evaporation, etc., and a through hole is formed in the porous film.

  In general, it is difficult for a porous PTFE membrane to form through holes by machining. For example, when a through hole is formed in a porous PTFE film by a normal punching method, burrs are generated, and it is difficult to form a through hole having a clean and accurate shape. On the other hand, when processed by the ultrasonic method described above, a through hole having a desired shape can be easily and inexpensively formed in the porous PTFE membrane.

  The cross-sectional shape of the through hole is arbitrary such as a circle, a star, an octagon, a hexagon, a quadrangle, and a triangle. The diameter of the through-hole can be usually 5 to 100 μm, preferably about 5 to 30 μm in the field of application where a small hole diameter is suitable, while it is usually 100 to 1000 μm, preferably in a field where a relatively large hole diameter is suitable. Can be about 300 to 800 μm.

  The method for producing an anisotropic conductive film including a step of using a porous PTFE film as a base film and forming a through-hole in a film thickness direction at a specific position of the porous film by an ultrasonic method is preferably ( I) A step of forming a three-layer laminate by fusing the polytetrafluoroethylene films (B) and (C) as mask layers on both sides of a base film made of a porous polytetrafluoroethylene film (A) (II) Using an ultrasonic head having at least one rod at the tip, and applying ultrasonic energy by pressing the tip of the rod against the surface of the laminate, a patterned through-hole is formed in the laminate. A step of forming, (III) a step of attaching catalyst particles that promote a chemical reduction reaction to the entire surface of the laminate including the wall surface of the through-hole, (IV) a step of removing the mask layers on both sides, and (V) electroless Porous structure tree on the wall of the through hole by plating It is a manufacturing method including the step of depositing a conductive metal part.

  As another preferable manufacturing method of the anisotropic conductive film including the step of using a porous PTFE film as a base film and forming a through hole in the film thickness direction at a specific position of the porous film by an ultrasonic method, For example, (i) porous polytetrafluoroethylene films (B) and (C) are fused as mask layers on both sides of a base film made of a porous polytetrafluoroethylene film (A) to form a three-layer laminate Forming a body, (ii) impregnating a liquid into the porous body of the laminate and freezing the liquid, (iii) using an ultrasonic head having at least one rod at the tip, A step of forming a pattern-like through-hole in the laminated body by applying ultrasonic energy by pressing the tip of the rod against the surface of the laminated body; (iv) heating the laminated body and removing the frozen body in the porous body The process of returning to the liquid and removing it, (V) including the wall surface of the through hole A step of attaching catalyst particles for promoting a chemical reduction reaction to the entire surface of the layered body, (vi) a step of removing the mask layer on both sides, and (vii) a resin portion having a porous structure on the wall surface of the through hole by electroless plating The manufacturing method including the process of making a conductive metal adhere to is mentioned.

  In the case of using a three-layer laminate, the through hole forming method shown in FIG. 10 uses an ultrasonic head 101 in which at least one rod 102 is attached to the tip, and the tip of the rod 102 is laminated ( Usually, ultrasonic energy is applied by pressing against the surface of a three-layer porous PTFE membrane) 103.

  In the production method including the step of immersing a liquid in the porous body of the laminate and freezing the liquid, water or alcohol (for example, methanol, for example) is contained in the porous body of the laminate composed of a porous PTFE membrane having a three-layer structure. A liquid such as an organic solvent such as a lower alcohol such as ethanol or isopropanol) is soaked and cooled to freeze the liquid. While the soaked liquid is in a frozen state, an ultrasonic head having at least one rod at the tip is used to press the tip of the rod against the surface of the laminate to apply ultrasonic energy. And the pattern-like through-hole can be formed beautifully. When water is used as the liquid, when the cooling temperature is zero degrees or lower, preferably -10 ° C. or lower and frozen, workability is improved. In the case of an organic solvent such as alcohol, workability is improved by cooling to −50 ° C. or lower, preferably to a liquid nitrogen temperature. The organic solvent is preferably a liquid at room temperature. The organic solvent such as alcohol may be a mixture of two or more kinds, or may contain water.

  Examples of a method for making an electrically insulating porous film conductive include sputtering, ion plating, and electroless plating. In order to deposit and attach a conductive metal to a resin portion having a porous structure. Is preferably an electroless plating method. In the electroless plating method, it is usually necessary to apply a catalyst for promoting a chemical reduction reaction to a portion where plating is desired to be deposited. In order to perform plating only on the resin portion having a porous structure at a specific location of the porous membrane, a method of applying a catalyst only to the location is effective.

  For example, in the case where only the wall surface (hole wall) of a porous PTFE film in which fine through-holes of an arbitrary shape are formed in the film thickness direction is imparted with electroless copper plating, three layers in which a mask layer is formed A through-hole is formed in the laminated body in a fused state, and this laminated body is immersed in the palladium-tin colloid catalyst application liquid with sufficient stirring. When the mask layers (B) and (C) on both surfaces are peeled after being immersed in the catalyst application liquid, a porous PTFE membrane (A) in which catalyst colloidal particles are attached only to the wall surfaces of the through holes can be obtained. By immersing the porous PTFE membrane (A) in the plating solution, copper can be deposited only on the wall surface of the through hole, whereby a cylindrical conductive portion (electrode) is formed. In addition to copper, nickel, silver, gold, nickel alloy, and the like can form the conductive portion by the same method, but it is preferable to use copper particularly when high conductivity is required. As a method for forming a through-hole in a three-layer laminate, a method of irradiating synchrotron radiation or laser light of 250 mm or less, and an ultrasonic method are preferable.

  Plating particles (crystal grains) initially precipitate so as to get entangled with fine fibers (fibrils) exposed on the wall surface of the porous PTFE membrane, so the conductive metal adhesion state is controlled by controlling the plating time. can do. If the electroless plating time is too short, it is difficult to obtain conductivity in the film thickness direction. If the electroless plating time is too long, the conductive metal is not porous and becomes a metal lump, and it becomes difficult to recover elastically under normal use compression load. By setting it to an appropriate plating amount, a porous conductive metal layer is formed, and it is possible to give conductivity in the film thickness direction as well as elasticity.

  The cylindrical conductive part (electrode) produced as described above is preferably used with an antioxidant or coated with a noble metal or a noble metal alloy in order to improve oxidation prevention and electrical contact. As the noble metal, palladium, rhodium, and gold are preferable from the viewpoint of low electric resistance. The thickness of the coating layer of noble metal or the like is preferably 0.005 to 0.5 μm, and more preferably 0.01 to 0.1 μm. If the thickness of the coating layer is too thin, the effect of improving electrical contact is small, and if the thickness is too thick, the coating layer tends to peel off, which is not preferable. For example, when the conductive part is coated with gold, a method of performing displacement gold plating after coating the conductive metal layer with nickel of about 8 nm is effective.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited only to these examples. The physical properties are measured as follows.

(1) Bubble point (BP):
The bubble point of the porous PTFE membrane by the stretching method was measured according to ASTM-F-316-76 using isopropyl alcohol.

(2) Porosity:
The porosity of the porous PTFE membrane by the stretching method was measured according to ASTM D-792.

(3) Conduction start load:
The conduction start load of the anisotropic conductive film was measured using the conduction confirmation apparatus shown in FIG. 5, the anisotropic conductive film 51 is placed on a gold-plated copper plate (referred to as “Au plate”) 52, and the whole is placed on a weighing scale 56. A copper pillar 53 having an outer diameter of 3 mmφ is used as a probe, and a load is applied. The resistance value of the anisotropic conductive film is measured by the 4-needle method. A pressing load pressure was calculated from a load having a resistance value of 0.5Ω or less, and was defined as a conduction start load pressure. In FIG. 5, 54 indicates a constant current power source, and 55 indicates a voltmeter.

(4) Number of continuity tests:
An anisotropic conductive film was cut into 5 mm squares to prepare samples. TMA / SS120C manufactured by Seiko Instruments Inc. was used, and 3 mmφ quartz was used as an indentation probe at room temperature and in a nitrogen gas atmosphere, and the elastic recovery performance was verified by a penetration method. Weighting and unloading were repeated 10 times with a load at which the film thickness distortion was 38% so that each anisotropic conductive film was conducted, and then a reconducting test was performed with a change in film thickness and a conduction start load.

[Example 1]
Stainless steel of 3mm thickness, 150mm length and 100mm width by superposing three porous PTFE membranes by stretching method with an area of 10cm square, porosity of 60%, average pore diameter of 0.1μm (BP = 150kPa) and film thickness of 30μm The sample was sandwiched between two plates and heat-treated at 350 ° C. for 30 minutes together with the load of the stainless plate. After heating, it was quenched with water from the top of the stainless steel plate to obtain a laminate of porous PTFE membranes fused in three layers.

  Next, a tungsten sheet having an aperture ratio of 9%, an aperture diameter of 15 μmφ, and a pitch of 80 μm is arranged on one side of the laminated body, and irradiated with synchrotron radiation, and in the film thickness direction, the hole diameter is 15 μmφ and the pitch of 80 μm. Evenly arranged through holes were formed.

  The laminate with 15 μmφ through-holes made hydrophilic by immersing in ethanol for 1 minute, and then immersed in Melplate PC-321 made by Meltex for 4 minutes at a temperature of 60 ° C. diluted to 100 ml / L. Degreasing treatment was performed. Further, after immersing the laminate in 10% sulfuric acid for 1 minute, as a pre-dip, immersed in 0.8% hydrochloric acid for 2 minutes in a solution of Meltex Co., Ltd. Enplate PC-236 dissolved at a rate of 180 g / L. did.

  Further, the laminate was prepared by adding 150% of Enplate PC-236 manufactured by Meltex Co., Ltd. in an aqueous solution prepared by dissolving 3% of Enplate Activator 444 manufactured by Meltex Co., Ltd., 1% of Enplate Activator Additive, and 3% of hydrochloric acid. The catalyst particles were adhered to the surface of the laminate and the wall surface of the through hole by immersing in a solution dissolved with the inclusion of L for 5 minutes. Next, the laminate was immersed in a 5% solution of Enplate PA-360 manufactured by Meltex Co., Ltd. for 5 minutes to activate the palladium catalyst nucleus. Thereafter, the first layer and the third skin mask layer were peeled off to obtain a porous PTFE membrane (base membrane) in which catalytic palladium particles adhered only to the wall surface of the through hole.

  Meltex Co., Ltd. Melplate Cu-3000A, Melplate Cu-3000B, Melplate Cu-3000C, Melplate Cu-3000D are each 5%, and Melplate Cu-3000 Stabilizer is 0.1%. The base film was immersed for 20 minutes in the electrolytic copper plating solution with sufficient air stirring, and only the wall surface of the 15 μmφ through hole was made conductive with copper particles (electrode outer diameter = 25 μm). Furthermore, it was immersed in Entex Cu-56 manufactured by Meltex Co., Ltd., which was bathed at 5 ml / L, for 30 seconds and subjected to rust prevention treatment to obtain an anisotropic conductive film having a porous PTFE film as a base film.

  In the plating process, after immersion in each liquid other than between the pre-dip process and the catalyst application process of electroless steel plating, the plate was washed with distilled water for about 30 seconds to 1 minute. The temperature of each solution was all normal temperature (20-30 degreeC) except the degreasing process.

  The anisotropic conductive film having the porous PTFE film obtained as described above as a base film was cut into a 10 mm square, and the conduction start load was measured with the apparatus shown in FIG. The probe used a 3 mmφ copper column, and the resistance value was measured by the 4-needle method. The pressing load was calculated from the load having a low resistance value of 0.5Ω or less, and was determined as the conduction start load pressure. As a result, the conduction start load pressure was 6 kPa.

  In addition, the anisotropic conductive film was cut into 5 mm squares, and TMA / SS120C manufactured by Seiko Instruments Inc. was used. Quartz 3 mmφ was used as an indentation probe at room temperature and in a nitrogen gas atmosphere. Verified. A total of 10 weightings and unweightings were repeated, and film thickness displacement and film thickness direction continuity tests were performed each time. If the resistance value is 0.5Ω or less as in the above case, it is considered to be conductive. As a result, the conduction start load pressure was 6 kPa. Even after repeated weighting and unloading 10 times at a load pressure of 27.7 kPa at which the film thickness distortion is 38%, sufficient conduction is obtained, and the film thickness before the test is substantially reduced when unweighted. It was maintained and conduction was confirmed even at a conduction starting load pressure of 6 kPa.

[Example 2]
A porous body was formed by fusing three porous PTFE films under the same method and the same conditions as in Example 1. A through-hole of 10 μmφ was formed in this laminate, and then a pretreatment for plating was performed. After the mask layer is peeled off, the base film is immersed for 20 minutes in the electroless copper plating solution with sufficient air agitation, and the copper particles are attached only to the wall surface of the 10 μmφ through hole to make it conductive (electrode outer diameter = 17 μm). Further, the same antirust treatment as in Example 1 was performed to obtain an anisotropic conductive film having a porous PTFE film by a stretching method as a base film. When the same test as Example 1 was done using the obtained anisotropic conductive film, the conduction start load pressure was 6 kPa. Even after repeated weighting and unloading 10 times at a load pressure of 27.7 kPa at which the film thickness distortion is 38%, sufficient conduction is obtained, and the film thickness before the test is substantially reduced when unweighted. It was maintained and conduction was confirmed even at a conduction starting load pressure of 6 kPa.

[Comparative Example 1]
Three stainless steel PTFE membranes with an area of 10 cm square, porosity of 60%, average pore diameter of 0.1 μm (BP = 150 kPa), and a film thickness of 30 μm are laminated to have a thickness of 3 mm, a length of 150 mm, and a width of 100 mm. The sample was sandwiched between two sheets and heat-treated at 350 ° C. for 30 minutes together with the load on the stainless steel plate. After heating, it was quenched with water from the top of the stainless steel plate, and three sheets were fused to obtain a laminate.

  Next, a tungsten sheet having an aperture ratio of 9%, an aperture diameter of 25 μmφ, and a pitch of 60 μm, which is uniformly arranged, is overlapped on one side of the laminate, and irradiated with synchrotron radiation. The through-hole arrange | positioned in was formed.

  Degrease treatment by immersing the laminate with 25 μmφ holes in ethanol for 1 minute to make it hydrophilic and then immersing it in Melplate PC-321 manufactured by Meltex Co., Ltd. diluted to 100 ml / L for 4 minutes at a water temperature of 60 ° C. Went. Further, after immersing the laminate in 10% sulfuric acid for 1 minute, the laminate was immersed in 0.8% hydrochloric acid as a pre-dip for 2 minutes in a solution obtained by dissolving Meltex Co., Ltd. Enplate PC-236 at a rate of 180 g / L. .

  Next, a ratio of 150 g / L of Meltex Co., Ltd. Enplate PC-236 in an aqueous solution in which Meltex Co., Ltd. Enplate Activator 444 is dissolved by 3%, Enplate Activator Additive is 1%, and hydrochloric acid is dissolved by 3%. The laminate was immersed in the solution dissolved in 5 minutes to adhere the catalyst particles to the surface of the laminate and the wall surface of the through hole. Further, the laminate was immersed in a 5% solution of Enplate PA-360 manufactured by Meltex Co., Ltd. for 2 minutes to activate the palladium catalyst nucleus.

  Meltex Co., Ltd. Melplate Cu-3000A, Melplate Cu-3000B, Melplate Cu-3000C, Melplate Cu-3000D are each 5%, and Melplate Cu-3000 Stabilizer is 0.1%. The laminate was immersed for 5 minutes in the electrolytic copper plating solution with sufficient air stirring, and the surface and wall surfaces of the through holes were made conductive with copper particles.

Subsequently, as an electrolytic copper plating solution, Meltex Co., Ltd. copper cream CLX was used, and the through holes were filled with copper by electrolytic copper plating at a current density of 2 A / dm ^{2 for} 30 minutes. Excess plating on the mask surface is immersed in a 10% sulfuric acid solution until the surface of the mask layer is visually observed and etched, then the mask layer is peeled off so as to tear by hand, and an electrode having an outer diameter of 25 μmφ that conducts in the film thickness direction. An anisotropic conductive film having conductivity only in the film thickness direction and having a protruding electrode of 7 μm on the film surface was obtained.

  This anisotropic conductive film was immersed in Meltex Co., Ltd. Entec Cu-56, which was built at 5 ml / L, for 30 seconds to prevent rust, and a porous PTFE film formed by stretching was used as the base film. An anisotropic conductive film filled with a conductive metal was obtained.

  In the plating process, after immersion in each liquid other than between the pre-dip process and the catalyst application process of electroless copper plating, the plate was washed with distilled water for about 30 seconds to 1 minute. The temperature of each solution was all normal temperature (20-30 degreeC) except the degreasing process.

  In this way, as shown in FIG. 8, an anisotropic having a conductive portion (electrode) 82 with a porous PTFE film 83 as a base film, each through hole filled with a conductive metal, and having protrusions on both sides. The conductive film 81 was obtained. When the same test as Example 1 was done using this anisotropic conductive film, the conduction start load pressure was 3 kPa. After sufficient conduction and repeated loading and unloading 10 times at a load pressure of 37.0 kPa at which the film thickness distortion becomes 38%, the film thickness decreases by 6.1 μm, and the conduction start load pressure No conduction was obtained at 3 kPa.

[Comparative Example 2]
At room temperature, nickel particles (manufactured by Nippon Atomizing Co., Ltd., average particle size 10 μm) are added to silicone rubber (manufactured by Shin-Etsu Polymer Co., Ltd., addition type RTV rubber KE1206) to which a predetermined amount of a crosslinking agent has been added. Blended and mixed. This compound was cast on a glass plate with a doctor knife having a gap of 25 μm and then cured in a thermostatic bath at 80 ° C. for 1 hour to obtain an anisotropic conductive film in which metal particles having a thickness of about 22 μm were dispersed in a silicone elastomer. .

  Thus, as shown in FIG. 9, an anisotropic conductive film 91 having a structure in which conductive particles 93 are dispersed in a base film 92 made of silicone rubber was obtained. When the same test as Example 1 was done using this anisotropic conductive film, the conduction start load pressure was 25 kPa. After repeated loading and unloading 10 times at a load pressure of 28.0 kPa at which the film thickness distortion becomes 38%, sufficient film conduction is obtained, the film thickness decreases by 0.7 μm, and the conduction start load pressure No conduction was obtained at 25 kPa.

(Footnote) The film thickness of Comparative Example 1 includes the protrusion height of the conductive portion.

  The anisotropic conductive film of the present invention is elastic in the film thickness direction, can conduct in the film thickness direction with a low compressive load, and can be elastically recovered, making it suitable for frequent use. It is a isotropic conductive film. In addition, the anisotropic conductive film of the present invention is an anisotropic conductive film capable of refining the size and pitch of each conductive portion.

  For this reason, the anisotropic conductive film of the present invention is used for a contact sheet for a burn-in test as one of screening methods for removing an initial failure of a semiconductor device.

FIG. 1 is a perspective view of a porous membrane having through holes formed therein. FIG. 2 is a cross-sectional view showing a state in which conductive metal particles are attached to a resin portion having a porous structure on the wall surface of each through hole to form a conductive portion in the anisotropic conductive film of the present invention. FIG. 3 is an explanatory diagram showing the relationship between the diameter a of the through hole and the outer diameter b of the conducting portion (electrode). FIG. 4 is a cross-sectional view showing a manufacturing process of a laminate having a base film as a central layer. FIG. 5 is a schematic cross-sectional view of an anisotropic conductive film conduction confirmation device. FIG. 6 is a cross-sectional view showing an example of a conventional anisotropic conductive film. FIG. 7 is a cross-sectional view showing another example of a conventional anisotropic conductive film. 3 is a cross-sectional view of an anisotropic conductive sheet produced in Comparative Example 1. FIG. 6 is a cross-sectional view of an anisotropic conductive sheet produced in Comparative Example 2. FIG. It is explanatory drawing which shows the method of forming a through-hole in a porous membrane by the ultrasonic method.

Explanation of symbols

1: porous membrane (base membrane), 2: first surface, 3: second surface,
4: through-hole, 5: conductive part to which conductive metal is attached, 6: porous film,
41, 42: SUS plate, 43: base film, 44, 45: mask layer,
51: anisotropic conductive film, 52: Au plate, 53: copper pillar,
54: Constant current power supply, 55: Voltmeter, 56: Weigh scale,
61: anisotropic conductive film, 62: lump of conductive metal (conductive portion), 63: porous film,
71: anisotropic conductive film, 72: conductive path forming part,
73: Capsule-type conductive particles, 74: Insulating part made of thermosetting resin,
81: anisotropic conductive film, 82: lump of conductive metal (conductive portion), 83: porous film,
91: anisotropic conductive film, 92: silicone rubber, 93: conductive particles,
101: Ultrasonic head, 102: Rod, 103: Porous film, 104: Plate-like body.

Claims (14)

  Using an electrically insulating porous film formed of a synthetic resin as a base film, through holes are formed in a plurality of locations of the base film from the first surface to the second surface in the film thickness direction of the porous film. A conductive portion formed by a conductive metal attached to the resin portion of the porous structure at the wall surface of the through hole formed by the process, and each of the conductive portions capable of imparting conductivity only in the film thickness direction are provided independently, In addition, each of the conductive portions is formed of a conductive metal attached to the resin portion of the porous structure on the wall surface of each through-hole while maintaining the porous structure of the porous membrane. Conductive film.   The anisotropic conductive film according to claim 1, wherein each conducting portion is formed of conductive metal particles attached to a porous resin portion on the wall surface of each through hole.   The anisotropic conductive film according to claim 2, wherein the conductive metal particles are electroless plated particles of conductive metal.   The anisotropic conductive film according to any one of claims 1 to 3, wherein the porous film is a porous polytetrafluoroethylene film.   5. The anisotropic conductive material according to claim 4, wherein the resin portion of the porous structure is a fibril and a node of the porous structure formed from fibrils made of polytetrafluoroethylene and nodes connected to each other by the fibrils. film.   The anisotropic conductive film according to claim 1, wherein by applying pressure in the film thickness direction, conductivity is imparted only in the film thickness direction in each conduction portion.   Through-holes penetrating from the first surface to the second surface by forming the through-holes in the film thickness direction of the porous film at a plurality of locations of the base film made of a synthetic resin and made of an electrically insulating porous film Next, a conductive metal can be attached to the porous resin portion on the wall surface of the through hole so as to hold the porous structure, and conductivity can be imparted only in the film thickness direction. A method for producing an anisotropic conductive film, wherein the portions are provided independently.   The manufacturing method according to claim 7, wherein a plurality of portions of the base film are irradiated with synchrotron radiation light or laser light having a wavelength of 250 nm or less to form through holes penetrating from the first surface to the second surface.   The manufacturing method according to claim 7, wherein through holes penetrating from the first surface to the second surface are formed at a plurality of locations of the base film by ultrasonic processing.   The manufacturing method of any one of Claims 7 thru | or 9 which provides a conduction | electrical_connection part by making the particle | grains of a conductive metal adhere to the resin part of the porous structure in the wall surface of each through-hole.   The manufacturing method of any one of Claims 7 thru | or 10 which adheres a conductive metal to the resin part of the porous structure in the wall surface of each through-hole by electroless plating.   The manufacturing method according to claim 11, wherein after the catalyst particles that promote the chemical reduction reaction are attached to the resin portion having a porous structure on the wall surface of each through-hole, the conductive metal is attached by electroless plating based on the chemical reduction reaction.   The manufacturing method according to claim 7, wherein the porous film is a porous polytetrafluoroethylene film.   The conductive metal particles having a particle diameter of 0.001 to 5 μm are adhered at a deposition amount of 0.001 to 4.0 g / ml when the conductive metal is adhered to the porous resin portion. 2. The production method according to item 1.

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