JP2008210908A - Method for mounting electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for mounting an electronic component easy to display the anisotropic conductive performance of an anisotropic conductive film by using the anisotropic conductive film having a two-layer structure. <P>SOLUTION: When the electronic component is mounted by using the anisotropic conductive film with a first adhesive layer having a large number of conductive particles and a second adhesive layer laminated on one surface of the first adhesive layer, a heating is conducted from the first adhesive-layer side when at least the anisotropic conductive film is contact-bonded temporarily. It is preferable that the heating is conducted from the first adhesive-layer side when the electronic component is contact-bonded mainly after a temporary contact-bonding. It is preferable that a large number of the conductive particles are held to the first adhesive layer under the state mutually separating and regularly arraying the conductive particles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electronic component mounting method.

  In recent years, a method using an anisotropic conductive film is known as a method for mounting an electronic component such as an IC chip or TAB on a wiring board.

  In the above mounting method, in general, an anisotropic conductive film is temporarily pressure-bonded onto a wiring board placed on a base with a pressure-bonding head, and then the electronic component is finally pressure-bonded with the pressure-bonding head, thereby mounting the electronic component. Often done. At this time, heating at the time of pressure bonding is usually performed through a pressure bonding head.

  As the anisotropic conductive film, for example, a material in which a large number of conductive particles are dispersed in an adhesive resin formed in a film shape is widely used.

  For example, Patent Document 1 by the present applicant proposes an anisotropic conductive film having a three-layer structure in which an adhesive layer is coated on both sides of a porous film in which pores are filled with conductive particles.

  In addition to the above, the applicant has developed an anisotropic conductive film having a two-layer structure in which an adhesive layer having no conductive particles is laminated on one side of an adhesive layer having a large number of conductive particles. Patent applications have already been filed.

International Publication No. WO2005 / 096442 Pamphlet

  However, it has been found that in the conventional mounting method, it may be difficult to sufficiently exhibit the anisotropic conductive performance of the anisotropic conductive film having a two-layer structure. This is thought to be due to the following reasons.

  That is, from the viewpoint of improving the stability of anisotropic conductive performance, it is preferable that the conductive particles hardly flow before and after pressure bonding. In order to realize this, in the anisotropic conductive film having a two-layer structure, a material having a high melt viscosity is used as an adhesive layer material containing conductive particles.

  However, in the case of such a design, when the conventional mounting method is performed with the adhesive layer side having conductive particles as the wiring board side, the anisotropic conductive film can be sufficiently adhered to the wiring board during temporary pressure bonding. It becomes difficult. One possible cause is that the heat applied by the crimping head is absorbed by the base.

  In order to prevent this, if the heating temperature by the crimping head is excessively high, the adhesive layer on the side that does not have conductive particles will flow and this will fill the gaps between the bumps of the IC chip during the final crimping. It becomes difficult to secure a necessary amount of the adhesive layer. Therefore, this may cause a decrease in adhesion with the IC chip.

  As described above, in the conventional mounting method, it is difficult to sufficiently exhibit the anisotropic conductive performance of the two-layered anisotropic conductive film due to a decrease in adhesion.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a mounting method for an electronic component that uses an anisotropic conductive film having a two-layer structure and easily exhibits its anisotropic conductive performance.

  In order to solve the above problems, an electronic component mounting method according to the present invention includes a first adhesive layer having a large number of conductive particles, and a second adhesive layer laminated on one surface of the first adhesive layer. The method uses an anisotropic conductive film having heat treatment, and the gist is that heating is performed from the first adhesive layer side at least during temporary pressure bonding of the anisotropic conductive film.

  Here, in the mounting method, it is preferable that heating is performed from the first adhesive layer side at the time of the final pressure bonding of the electronic component performed after the temporary pressure bonding.

  Moreover, the base material which has mold release property is laminated | stacked on the said 2nd contact bonding layer surface, and it is good to peel the said base material after the said temporary crimping | compression-bonding.

  The plurality of conductive particles may be held by the first adhesive layer in a state of being regularly spaced from each other.

  Moreover, it is preferable that the plurality of conductive particles exist in substantially the same plane.

  In addition to the above, the plurality of conductive particles may be dispersed in the first adhesive layer.

  Further, the first adhesive layer preferably has a higher melt viscosity at the heating temperature at the time of provisional pressure bonding than the second adhesive layer.

  In the electronic component mounting method according to the present invention, an anisotropic conductive film having a first adhesive layer having a large number of conductive particles and a second adhesive layer laminated on one side of the first adhesive layer is provided. In mounting an electronic component by using, heating is performed from the first adhesive layer side during temporary pressure bonding of the anisotropic conductive film.

  Therefore, even when the melt viscosity of the first adhesive layer is set high to such an extent that the conductive particles hardly flow before and after the crimping, the gap between the anisotropic conductive film and the wiring board during the temporary crimping is set. The adhesion of is increased.

  Moreover, since the 2nd contact bonding layer is not heated too much at the time of temporary crimping | compression-bonding, the flow of a 2nd contact bonding layer can be suppressed. Therefore, it is easy to secure the amount of the second adhesive layer necessary for the main pressure bonding of the electronic component, and the adhesion between the anisotropic conductive film and the electronic component at the time of the main pressure bonding is increased.

  Therefore, according to the mounting method of the electronic component, the anisotropic conductive performance of the anisotropic conductive film having a two-layer structure can be sufficiently exhibited.

  Here, when heating is performed from the first adhesive layer side during the final press-bonding of the electronic component performed after the temporary press-bonding, it becomes easy to ensure sufficient adhesion, contributing to the improvement of connection reliability. It becomes easy to do.

  In addition, since the adhesion between the anisotropic conductive film and the wiring board at the time of temporary pressure bonding is excellent, a base material having releasability is laminated on the surface of the second adhesive layer. When peeling a material, it is easy to peel only the said base material.

  In addition, when a large number of conductive particles are held in the first adhesive layer in a state of being regularly spaced from each other, the connection reliability is improved in combination with the effect of the mounting method. be able to.

  On the other hand, when a large number of conductive particles are dispersed in the first adhesive layer, the connection reliability can be improved, although not as described above.

  In addition, when the melt viscosity of the first adhesive layer is higher than the melt viscosity of the second adhesive layer at the heating temperature at the time of temporary pressure bonding, the effect of the mounting method is easily obtained.

  Hereinafter, an electronic component mounting method according to the present embodiment (hereinafter also referred to as “the present mounting method”) will be described in detail.

  This mounting method is a method of mounting an electronic component using an anisotropic conductive film. Specifically, the present manufacturing method is suitably applied, for example, when an electronic component such as an IC chip or TAB is mounted on a wiring board on which a circuit pattern is formed via an anisotropic conductive film. be able to.

  In this mounting method, an anisotropic conductive film having a two-layer structure is used. The anisotropic conductive film includes a first adhesive layer having a large number of conductive particles, and a second adhesive layer laminated on one surface of the first adhesive layer. At the time of mounting, the second adhesive layer side is disposed on the electronic component side.

  Specific examples of the adhesive layer material constituting the first adhesive layer and the second adhesive layer include various thermosetting resins, thermoplastic resins, and rubbers.

  More specifically, as both adhesive layer materials, for example, epoxy resins, melamine resins, phenol resins, diallyl phthalate resins, bismaleimide triazine resins, unsaturated polyester resins, polyurethane resins, phenoxy resins Thermosetting resins such as resins, polyamide resins, polyimide resins, cyanate resins, polyamide resins, polyester resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyvinyl acetal resins, Examples include thermoplastic resins such as polyethylene resins, polypropylene resins, and polyvinyl resins, rubbers and elastomers containing one or more functional groups such as hydroxyl groups, carboxyl groups, vinyl groups, amino groups, and epoxy groups. Can Kill. These may be contained alone or in combination of two or more.

  Both adhesive layer materials may be the same or different. Preferably, the adhesive layer materials are different from the viewpoint of easy adjustment of the melt viscosity, elastic modulus and the like of both adhesive layers.

  Moreover, it is preferable that the melt viscosity of 1st contact bonding layer material is larger than the melt viscosity of 2nd contact bonding layer material in the heating temperature at the time of temporary crimping | compression-bonding. This is because there is an advantage that it is difficult to flow through the first adhesive layer due to heat at the time of temporary pressure bonding, or it is possible to easily improve the trapping property of the conductive particles by preventing the flow of the first adhesive layer.

  In addition, the said melt viscosity is a viscosity in the state before hardening for what hardens | cures material.

  In addition, the melt viscosity is obtained by preparing a sample (diameter 20 mm, thickness 400 μm) using the adhesive layer material, stress control rheometer (for example, “AR500” manufactured by T.A. Instruments Japan Co., Ltd.) Can be obtained by measuring the melt viscosity at each temperature under the measurement conditions of a temperature rising rate of 5 ° C./min, a frequency of 1 Hz, and a strain of 0.1%.

  The thickness of the first adhesive layer can be determined in consideration of the particle size, strength, manufacturability, and the like of the conductive particles used.

  As will be described later, when the conductive particles of the first adhesive layer are regularly arranged, specifically, for example, the upper limit of the thickness of the first adhesive layer is preferably the conductive layer. 3/2 or less of the particle size of the conductive particles, more preferably 1 or less of the particle size of the conductive particles, and even more preferably 2/3 or less of the particle size of the conductive particles. .

  On the other hand, the lower limit of the thickness of the first adhesive layer is preferably 1/10 or more times the particle size of the conductive particles, more preferably 1/5 or more times the particle size of the conductive particles, More preferably, it is 1/3 times or more the particle diameter of the conductive particles.

  When the thickness of the first adhesive layer is within the above range, when the conductor (such as an IC chip bump) included in the electronic component crushes the conductive particles, the first adhesive layer is unlikely to hinder it. . Therefore, the conductive particles are easily captured during mounting, and the conduction performance in the film thickness direction is easily improved.

  Further, the thickness of the second adhesive layer can be determined in consideration of the height of the conductor of the electronic component such as the bump of the IC chip, the filling property with the adhesive layer material after pressure bonding, and the like.

  The upper limit of the thickness of the second adhesive layer is preferably not more than 3 times the height of the conductor of the electronic component to be mounted, more preferably not more than 2 times, and even more preferably not more than 1.75 times. And good.

  The lower limit of the thickness of the adhesive layer is preferably 1 or more times the conductor height of the electronic component to be mounted, more preferably 1.2 times or more, and even more preferably 1.3 times or more. good.

  In the anisotropic conductive film applied to this mounting method, the first adhesive layer has a large number of conductive particles.

  As in the anisotropic conductive film 10 illustrated in FIG. 1, a large number of conductive particles 12 may be held by the first adhesive layer 14 in a state of being regularly spaced from each other. Further, as in the anisotropic conductive film 20 illustrated in FIG. 2, a large number of conductive particles 24 may be randomly dispersed in the first adhesive layer 22. In any of the anisotropic conductive films 10 and 20, the second adhesive layer 16 does not have conductive particles.

  As the anisotropic conductive film used in this mounting method, the anisotropic conductive film illustrated in FIG. 1 is preferable from the viewpoint that the connection reliability can be improved in combination with the effect of this mounting method. Hereinafter, the anisotropic conductive film illustrated in FIG. 1 will be mainly described.

  Specific examples of the regular array include, for example, an array such as a lattice, a staggered pattern, and a honeycomb, and an inclination of these arrays. Preferably, a staggered arrangement, an inclined staggered arrangement, or the like is used.

  In addition, a large number of conductive particles are preferably present in substantially the same plane (a plane substantially parallel to the first adhesive layer surface). In this case, a plurality of conductive particles are not stacked in the thickness direction. Therefore, the contact resistance between the conductive particles is not involved in the conduction in the thickness direction, and the conduction performance is easily improved. In addition, the conductive particles stacked at the time of crimping are ejected from between the conductor of the electronic component and the wiring pattern of the wiring board, and there is no fear of deteriorating the insulation in the film surface direction.

  In addition, the upper limit of the particle size of the conductive particles may be smaller than the narrowest of the intervals between the plurality of conductors of the electronic component or the wiring board from the viewpoint of improving the insulation reliability in the film surface direction. preferable. More preferably, it should be 1/2 or less of the narrowest.

  The upper limit of the particle size of the conductive particles is preferably 10 μm or less, more preferably 7 μm or less, and even more preferably 5 μm or less.

  On the other hand, the lower limit of the particle size of the conductive particles is preferably 1 μm or more, more preferably, from the viewpoint that the conductive particles are less likely to aggregate during the production of the anisotropic conductive film and the handleability is good. It is 2 μm or more, and more preferably 3 μm or more.

  In addition, the particle diameter of the said electroconductive particle is an average particle diameter measured with the particle size distribution measuring apparatus (The Seishin company make, "PITA-1").

  In addition, the upper limit of the interval between the conductive particles may be smaller than the narrowest width among the plurality of conductors of the electronic component or the wiring board from the viewpoint of improving the conduction reliability in the film thickness direction. preferable. More preferably, it should be 1/2 or less of the narrowest.

  The upper limit of the interval between the conductive particles is preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less.

  On the other hand, the lower limit of the interval between the conductive particles is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more, from the viewpoint of improving the insulation reliability in the film surface direction. .

  Specific examples of the conductive particles shown in FIGS. 1 and 2 include, for example, a substantially spherical shape (including a substantially elliptical cross section), a substantially columnar shape, a spindle shape, and a needle shape. it can. Preferably, the form of the conductive particles is preferably substantially spherical from the viewpoints of easy regular arrangement, excellent insulation reliability in the film surface direction, and easy compression.

  The conductive particles only need to have conductivity that allows the film thickness direction to be electrically connected after the main pressure bonding.

  Specific examples of the conductive particles include, for example, particles that are filled with a conductive substance from the surface to the center thereof, and the surface of the polymer particles that are coated with one or more conductive layers. The particle | grains etc. which can be illustrated can be illustrated.

  The latter particles are preferably used. This is because the particles are easily elastically deformed by the pressurization, so that the contact area with the conductor is increased after the main pressure bonding, and the conductivity in the film thickness direction is easily secured.

  More specifically, for example, as an example of the former particles, metal particles, carbon particles and the like are used, and as an example of the latter particles, one or two or more metal plating layers (electrolytic plating, Electrolytic plating etc.) and particles having a sputtered layer can be exemplified.

  Specific examples of metals that can be used in the conductive material and conductive layer include gold, silver, white metals (platinum, palladium, ruthenium, rhodium, osmium, iridium), nickel, copper, zinc, and iron. 2 such as lead, tin, aluminum, cobalt, indium, chromium, titanium, antimony, bismuth, germanium, cadmium, etc., tin-lead alloy, tin-copper alloy, tin-silver alloy, tin-lead-silver alloy, etc. Examples include alloys composed of more than one kind of metal. These may be contained alone or in combination of two or more.

  Specific examples of the polymer applicable to the polymer particles include polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polytetrafluoroethylene, polyisobutylene, polybutadiene, polyalkylene terephthalate, polysulfone, Polycarbonate, polyamide, phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, (meth) acrylic acid ester polymer, divinylbenzene polymer, divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid Examples thereof include divinylbenzene polymers such as ester copolymers. These may be contained alone or in combination of two or more. In addition, the said (meth) acrylic acid ester may be bridge | crosslinked as needed.

  Preferred are dimethybenzene-based polymers such as (meth) acrylic acid ester polymers, divinylbenzene polymers, divinylbenzene-styrene copolymers and divinylbenzene- (meth) acrylic acid ester copolymers.

Furthermore, particles in which one or two or more insulating layers made of an insulating oxide such as TiO ₂ or the above polymer are coated on the surface of the conductive particles may be used. However, it is necessary that the insulating layer has a thickness at which at least a portion in contact with the conductor is broken and becomes conductive after the main pressure bonding. In the case where such particles are used, the insulating layer is difficult to break in the portion not in contact with the conductor, so that it is easy to improve the insulation in the film surface direction.

  Note that the anisotropic conductive film shown in FIGS. 1 and 2 may include one or more of the above-described conductive particles.

  The anisotropic conductive film shown in FIG. 1 can be obtained, for example, as follows.

  That is, a large number of conductive particles held in a mold having regularly arranged holes are transferred to a flat membrane surface formed from the first adhesive layer material.

  Next, the transferred conductive particles are embedded and held in a flat film, and are separated from each other to form a first adhesive layer holding a large number of regularly arranged conductive particles.

  Next, a second adhesive layer is formed on any one surface of the first adhesive layer. At this time, as a method for forming the second adhesive layer, specifically, for example, a coating solution prepared by adjusting the second adhesive layer material so as to have an appropriate solid content and viscosity is applied to a known coating material such as a coater. The first adhesive layer surface is prepared by coating the surface of the first adhesive layer using a construction means, and drying the film as necessary. Examples of the method of attaching to the substrate can be given.

  The first adhesive layer can also be formed by filling conductive particles in the pores of a porous membrane having a number of regularly arranged pores.

  In this case, the porous film can be formed by pressing a mold having regularly arranged convex portions against the surface of the flat film formed from the first adhesive layer material. In addition, a support obtained by casting a solution containing a hydrophobic and volatile organic solvent, a first adhesive layer material soluble in the organic solvent, and a surfactant is placed in a high-humidity atmosphere. It may be a porous film in which pores are formed using water droplets condensed on the solution surface as a template.

  As a method for holding the conductive particles in the hole, specifically, for example, (1) after spraying the conductive particles themselves or a dispersion thereof on the hole forming surface, a brush, a brush, a blade, etc. A method of scrubbing with a scraping means and putting conductive particles in the hole, (2) After spraying the conductive particles themselves or a dispersion thereof on the hole forming surface, magnetic force or vibration is applied from the outside, and the hole is made conductive. A method of putting particles, (3) a method of immersing the mold in the dispersion, (4) placing a plate-like member spaced apart from the hole forming surface by a certain distance, and placing the dispersion in the gap formed Examples thereof include a method of introducing and slidingly moving the mold / porous membrane and / or the plate-like member, and a combination thereof.

  Since the conductive particles are physically pushed into the pores, the method (1) is preferably used from the viewpoint of easily holding the conductive particles more reliably and relatively short time required for holding. Is good. More preferably, from the viewpoint of being able to carry out by a dry method, it is preferable to use powdered conductive particles themselves in the method (1). More preferably, in the method (1), the conductive particles are attracted to the hole forming surface by a magnetic force from the side opposite to the hole forming surface from the viewpoint that the conductive particles are easily introduced into the hole. It is good to wear by means.

  Here, in this mounting method, heating is performed from the first adhesive layer side at least when the anisotropic conductive film is temporarily pressed.

  Usually, as shown in FIGS. 3 and 4, the mounting apparatus is a crimping head that crimps an electronic component 38 having a base 34 on which a wiring board 32 on which a wiring pattern 30 is formed and a conductor 36 such as a bump is mounted. 40.

  In order to perform temporary pressure bonding using such a mounting apparatus, as shown in FIG. 3, the anisotropic conductive film 10 is disposed on the wiring substrate 32 placed on the base 34 (first adhesion). Then, the anisotropic conductive film 10 is pressed by the pressure bonding head 40. In addition, it is preferable that a base material 42 having a releasability is laminated on the surface of the second adhesive layer 16 from the viewpoint of preventing contamination of the pressure-bonding head 40 during temporary pressure bonding.

  In this case, as a method of heating the first adhesive layer side, for example, a method of heating the base with a heater or the like provided on the base can be exemplified.

  Conventionally, the heat required for temporary crimping has been supplied from the crimping head. On the other hand, in this mounting method, heat necessary for temporary pressure bonding is supplied from a base or the like, and the first adhesive layer side is heated to improve the adhesion between the anisotropic conductive film and the wiring board. Can do. In addition, the second adhesive layer is difficult to flow, and the adhesion between the anisotropic conductive film and the electronic component can be improved during the main press bonding.

  It is preferable that the crimping head is not heated during the temporary crimping. This is because the heat transferred from the first adhesive layer to the second adhesive layer is easily absorbed by the pressure-bonding head, so that the second adhesive layer is difficult to flow and is advantageous during the main pressure bonding. In particular, the effect is increased when the melt viscosity of the second adhesive layer is smaller than the melt viscosity of the first adhesive layer.

  However, as long as the effects of the present invention are not impaired, the pressure-bonding head may be heated during the temporary pressure bonding. The heat may be naturally attached or heated. In this case, the temperature on the second adhesive layer side is lower than the temperature on the first adhesive layer side.

  The heating temperature on the first adhesive layer side at the time of the temporary pressure bonding varies depending on the first adhesive layer material and the like. Basically, the first adhesive layer material may be at a temperature at which adhesion with the wiring substrate is exhibited. Preferably, the temperature is in the vicinity of the lowest temperature at which the adhesion is exhibited. This is because if the heating temperature on the first adhesive layer side is excessively increased, the second adhesive layer tends to flow during temporary pressure bonding.

  In the mounting method, the heating temperature is preferably in the range of 80 ° C. to 120 ° C., more preferably in the range of 100 ° C. to 110 ° C.

  Moreover, the applied pressure at the time of temporary pressure bonding is not particularly limited, and may be a pressure applied at the time of normal temporary pressure bonding.

  Usually, the applied pressure at the time of temporary pressure bonding is in the range of about 0.1 to 1.0 MPa.

  In the present mounting method, the final pressure bonding is performed after the temporary pressure bonding.

  In the main compression bonding, for example, as shown in FIG. 4, an electronic component 38 such as an IC chip is disposed on the surface of the second adhesive layer 16 of the anisotropic conductive film 10 temporarily bonded onto the wiring substrate 32. Thereafter, the electronic component 38 is pressurized by the crimping head 40.

  In addition, when the base material 42 having releasability is laminated on the surface of the second adhesive layer 16, it may be peeled off after the provisional pressure bonding and before entering the main pressure bonding. At this time, in this mounting method, since the adhesiveness between the anisotropic conductive film and the wiring board at the time of temporary pressure bonding is excellent, only the base material can be peeled off.

  The heat necessary for the main pressure bonding may be supplied from the first adhesive layer side or from the second adhesive layer side. Moreover, you may supply from both sides.

  In this case, as a method of heating the first adhesive layer side, for example, a method of heating the base with a heater or the like provided on the base can be exemplified. As a method of heating the second adhesive layer side, for example, a method of heating with a heater or the like provided in the crimping head can be exemplified.

  From the viewpoint of easily securing sufficient adhesion after the main pressure bonding and contributing to improvement of connection reliability, it is preferable to heat at least from the first adhesive layer side. In this case, the temperature on the second adhesive layer side is lower than the temperature on the first adhesive layer side.

  The heating temperature on the first adhesive layer side during the main press-bonding varies depending on the first adhesive layer material and the like.

  The heating temperature at the time of the main pressure bonding is not particularly limited, and may be a temperature used at the time of normal main pressure bonding.

  The heating temperature at the time of the main press-bonding is preferably 160 to 210 ° C, more preferably 160 to 180 ° C.

  Further, the pressure applied during the main pressure bonding is not particularly limited, and may be a pressure used during normal main pressure bonding.

  Usually, the applied pressure at the time of main press-bonding is in the range of about 50 to 150 MPa.

  Hereinafter, the present invention will be described in detail using examples.

1. Preparation of Anisotropic Conductive Film First, an anisotropic conductive film to be applied to this mounting method was prepared by the following procedure.

  That is, 23.39 parts by weight of an alcohol-soluble polyamide resin, 25.16 parts by weight of a phenoxy resin (manufactured by Toto Kasei Co., Ltd., “EFR-0010M30”), and an epoxy resin (manufactured by Toto Kasei Co., Ltd.) 4.9 parts by weight of “FX289EK75”), 2.67 parts by weight of epoxy resin (manufactured by Tohto Kasei Co., Ltd., “FX305EK70”), and melamine resin (manufactured by Sanwa Chemical Co., Ltd., “Nicarac MX-750”). ] 1.37 parts by weight, 0.38 parts by weight of a curing agent (“C11Z” manufactured by Shikoku Kasei Co., Ltd.) and 0.57 of a curing agent (“F-TMA” manufactured by Mitsubishi Gas Chemical Company, Inc.) 1 part by weight, 24.26 parts by weight of methanol, 48.05 parts by weight of toluene, and 69.2 parts by weight of methyl cellosolve were mixed to prepare a first adhesive layer forming solution.

  Next, using a comma coater, the first adhesive layer forming solution was applied to the release surface of a continuously supplied base material (polyethylene terephthalate, thickness 38 μm, “PET38X” manufactured by Lintec Corporation).

  Next, this coating layer was dried at 160 ° C. for 90 seconds to form a flat film (thickness 2 μm) made of a resin mainly composed of a polyamide-based resin and a phenoxy-based resin. Then, the release surface of the base material (polyethylene terephthalate, thickness 75 μm, manufactured by Lintec Co., Ltd., “PET75C”) was put on the surface of the flat film and wound up.

  As a result, a resin-made flat film composed mainly of a polyamide-based resin and a phenoxy-based resin sandwiched between base materials having releasability was prepared.

  Next, a Ni electroforming mold having a large number of recesses arranged in a staggered pattern (a substantially cylindrical shape with an opening diameter of 5 μm and a recess depth of 3.5 μm, pitch = a distance between the centers of adjacent openings) of 10 μm was prepared.

  Next, resin plating particles having an average particle diameter of 4 μm (Sekisui Chemical Co., Ltd., “Micropearl AU-204”), in which the surfaces of particles made of a divinylbenzene-based crosslinked resin were coated with a Ni plating layer and an Au plating layer in order. ) Was spread on the concave surface of the Ni electroforming mold.

  Next, with a permanent magnet installed on the opposite side of the concave surface (manufactured by Seiko Sangyo Co., Ltd., ferrite magnet, 1000 gauss), the resin plating particles are attracted to the mold, and the surface is scraped off with a brush to resin plating in the concave portion. Particles were introduced.

  Resin plating particles adhering to the mold surface where no recesses are formed or resin plating particles adhering to resin plating particles introduced into the recesses due to electrostatic force, etc. ("Bieful EP50" manufactured by Kimoto Co., Ltd.) was used for removal.

  Thus, a Ni electroforming mold was prepared in which resin plating particles were held one by one for each recess.

  Then, the surface of the flat film exposed by peeling off one of the substrates and the holding surface of the resin plating particles of the Ni electromold are overlapped, and this is heated at a temperature of 120 ° C., a pressing force of 0.1 MPa, and heating and pressing. The laminate was heat laminated under the condition of 60 seconds, cooled to room temperature, and then the mold was removed.

  As a result, a large number of resin plating particles held in the recesses of the Ni electroforming mold were transferred to the flat film surface. In addition, on the surface of the flat film after the transfer, a large number of resin plating particles were regularly arranged in a zigzag manner inclined at about 8 ° while being separated from each other.

  Next, a release surface of a base material (polyethylene terephthalate, thickness 38 μm, “PET38C” manufactured by Lintec Corporation) is overlaid on the surface of the flat film after the transfer, and this is heated at a temperature of 140 ° C. and a pressure of 0.1 MPa. Thermal lamination was performed under the condition of a pressing time of 60 seconds.

  As a result, the transferred resin plating particles were embedded in the flat film while maintaining the regular arrangement, and held on the film. The resin plating particles were held in the film in a state in which a part thereof slightly protruded from the transfer surface and a part thereof was not exposed on the surface opposite to the transfer surface.

  As described above, the first adhesive layer that holds a large number of resin plating particles regularly spaced apart from each other was formed. In addition, this 1st contact bonding layer is pinched | interposed between the base materials which have mold release property.

  Next, 90 parts by weight of dicyclopentadiene type epoxy resin (Dainippon Ink Co., Ltd., “Epiclon HP7200HH”) and nitrile rubber (NBR) (Nippon Zeon Co., Ltd., “Nipol 1072J”) 10 parts by weight Then, 187 parts by weight of a curing agent (manufactured by Asahi Kasei Chemicals Co., Ltd., “Novacure HXA3932HP”) was diluted with toluene so that the solid content was 42%, to prepare a second adhesive layer forming solution.

  Next, using a comma coater, the second adhesive layer forming solution was applied to the release surface of a continuously supplied base material (polyethylene terephthalate, thickness 38 μm, “PET38C” manufactured by Lintec Corporation). .

  Subsequently, this coating layer was dried at 110 ° C. for 90 seconds to form a second adhesive layer (thickness 20 μm). Then, the release surface of the base material (polyethylene terephthalate, thickness 38 μm, manufactured by Lintec Corporation, “PET38B”) was put on the surface of the second adhesive layer and wound up.

  As described above, the second adhesive layer sandwiched between the substrates having releasability was prepared.

  Next, the first adhesive layer surface (transfer surface side of the resin plating particles) exposed by peeling off the substrate on one side, and the second adhesive layer surface exposed by peeling off the substrate on one side, Were stacked and pasted together.

  As described above, the first adhesive layer that holds a large number of resin plating particles regularly spaced apart from each other, and the second adhesive layer laminated on one side of the first adhesive layer An anisotropic conductive film (thickness 22 μm) having a two-layer structure was prepared. The anisotropic conductive film is sandwiched between base materials having releasability. In the mounting described later, the anisotropic conductive film was cut into a size of 3 mm × 17 mm.

2. Preparation of Wiring Board and Electronic Component A wiring board having a circuit pattern (material ITO, pattern pitch 30 μm, pattern width 20 μm) formed on the surface of a 0.7 mm thick glass substrate was prepared.

  Also, an IC chip (bump area 20 μm × 100 μm, pitch 30 μm, bump height 15 μm) having Au bumps was prepared as an electronic component.

3. Mounting Method According to Example and Comparative Example (Example 1)
The wiring board was placed on a base heated to 110 ° C. Next, the anisotropic conductive film from which the substrate on the first adhesive layer (including resin plating particles) side has been peeled is placed on the circuit pattern of the wiring board, with the first adhesive layer side being the wiring board side. Arranged.

Note that the heating temperature was set to 110 ° C., which is a temperature in the vicinity of the lowest temperature at which the first adhesive layer of the prepared anisotropic conductive film can exhibit adhesion with glass, and at this temperature, This is because the prepared second adhesive layer of the anisotropic conductive film can flow. The melt viscosity of the first adhesive layer material at 110 ° C. is 2.0 × 10 ⁴ Pa · s, and the melt viscosity of the second adhesive layer material is 3.0 × 10 ² Pa · s. .

  Next, a pressure bonding head (temperature: 30 ° C.) is used to pressurize the anisotropic conductive film through the base material on the second adhesive layer (pressurizing pressure: 0.2 MPa, pressing time: 5 seconds). An anisotropic conductive film was temporarily pressure-bonded thereon. At this time, the pressure-bonding head is not heated.

  Next, the base material on the second adhesive layer was peeled off. At this time, the temporarily pressure-bonded anisotropic conductive film was not taken together with the base material and was sufficiently adhered to the wiring board.

  Next, the heating temperature of the base was set to 110 ° C. to 80 ° C., and the circuit pattern of the wiring board and the Au bumps of the IC chip were placed on the preliminarily pressure-bonded anisotropic conductive film so as to face each other.

  Next, the upper part of the IC chip was pressed (pressurizing pressure 80 MPa, pressurizing time 10 seconds) using a pressure-bonding head heated to 210 ° C., and then pressure-bonded.

  As described above, the IC chip was mounted on the wiring board.

(Comparative Example 1)
The mounting method according to Example 1 above, except that the base was not heated until the temporary crimping (base temperature was 30 ° C.) and the crimping head heated to 110 ° C. was used during the temporary crimping. Similarly, the IC chip was mounted on the wiring board.

  In this comparative example 1, after temporary bonding, when the base material on the second adhesive layer is peeled off, the anisotropic conductive film is also removed together with the base material, and the anisotropic conductive film is sufficient for the wiring board. Could not be adhered to. Therefore, the anisotropic conductive film was pressed down, the base material on the second adhesive layer was peeled off, and the main pressing operation was performed.

4). Evaluation 4.1 Flow Rate of Second Adhesive Layer After Temporary Pressure Bonding In the mounting methods according to the example and the comparative example, the second flowing out from the end of the base material on the second adhesive layer at the time of the temporary pressure bonding. The distance to the edge of the adhesive layer was measured with a microscope, and this was defined as the flow rate (μm) of the second adhesive layer.

4.2 Filling state of second adhesive layer after main press-bonding In the mounting method according to the example and the comparative example, after the main press-bonding, the filling state of the adhesive layer (IC chip / glass by a microscope from the glass substrate side) (Between substrates) was confirmed.

4.3 Evaluation of anisotropic conductive performance (measurement of electrical resistance in the film thickness direction of anisotropic conductive film)
For each crimped body obtained by the above mounting method, the electrical resistance between the opposing circuit pattern and Au bump is measured by a four-terminal four-probe method using a resistivity meter ("Loresta GP" manufactured by Dia Instruments). did. In addition, the number of samples was N = 10 [pieces], respectively, an average value was calculated by arithmetic average, and this was set as the electric resistance in the film thickness direction.

(Measurement of electric resistance in the film surface direction of anisotropic conductive film)
About each crimping | compression-bonding body obtained by the said mounting method, the electrical resistance between adjacent circuit patterns was measured using tester T2 (the product made by AND, "AD5522"). The number of samples was N = 10 [pieces], and an average value was calculated by arithmetic average, and this was used as the electric resistance in the film surface direction.

5. Results Table 1 summarizes the evaluation results.

  A relative comparison of Table 1 shows the following. That is, in Comparative Example 1, when mounting an IC chip, heating is performed from the second adhesive layer side during temporary pressure bonding of an anisotropic conductive film having a two-layer structure.

  Therefore, the anisotropic conductive film and the wiring board cannot be sufficiently adhered. This is considered to be because heat is absorbed by the base and heat applied to the second adhesive layer is absorbed.

  In addition, the second adhesive layer was likely to flow due to the high heat generated by the pressure bonding head during temporary pressure bonding. Therefore, the second adhesive layer could not be sufficiently filled between the Au bumps of the IC chip after the main pressure bonding, and the adhesion between the anisotropic conductive film and the IC chip was lowered.

  Therefore, the anisotropic conductive performance of the anisotropic conductive film having a two-layer structure is hardly exhibited.

  On the other hand, in Example 1, when mounting the IC chip, heating is performed from the first adhesive layer side during temporary pressure bonding of the anisotropic conductive film having a two-layer structure.

  Therefore, even when the melt viscosity of the first adhesive layer is higher than the melt viscosity of the second adhesive layer, the anisotropic conductive film and the wiring board can be sufficiently adhered.

  Moreover, the flow of the 2nd contact bonding layer by temporary crimping was able to be suppressed. Therefore, after the main pressure bonding, the second adhesive layer can be sufficiently filled between the Au bumps of the IC chip, and the adhesion between the anisotropic conductive film and the IC chip can be improved.

  Therefore, the anisotropic conductive performance of the anisotropic conductive film having a two-layer structure can be sufficiently exhibited, and the connection reliability can be improved.

  Although one embodiment and one example of the present invention have been described above, the present invention is not limited to the above embodiment and example, and various modifications can be made without departing from the spirit of the present invention. is there.

  For example, in the above embodiment, the anisotropic conductive film having the first adhesive layer that holds a large number of resin plating particles regularly spaced apart from each other is used. The same effect can be obtained even when an anisotropic conductive film having a first adhesive layer in which fine conductive particles are dispersed is used.

It is an example of typical sectional drawing of the anisotropic conductive film suitably applicable to this mounting method. It is an example of the typical sectional view of the anisotropic conductive film applicable to this mounting method. It is the figure which showed the state at the time of temporary press-bonding typically. It is the figure which showed the state at the time of this press-bonding typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Anisotropic conductive film 12 Conductive particle 14 1st contact bonding layer 16 2nd contact bonding layer 20 Anisotropic conductive film 22 1st contact bonding layer 24 Conductive particle 30 Wiring pattern 32 Wiring board 34 Base 36 Conductor 38 Electronic component 40 Crimp head 42 Base material having releasability

Claims (7)

A method for mounting an electronic component using an anisotropic conductive film having a first adhesive layer having a large number of conductive particles and a second adhesive layer laminated on one side of the first adhesive layer. ,
A method of mounting an electronic component, wherein heating is performed from the first adhesive layer side at least when the anisotropic conductive film is temporarily crimped.   The method for mounting an electronic component according to claim 1, wherein heating is performed from the first adhesive layer side during the final pressure bonding of the electronic component performed after the temporary pressure bonding.   3. The electronic component according to claim 1, wherein a base material having releasability is laminated on the surface of the second adhesive layer, and the base material is peeled off after the temporary pressure bonding. 4. Implementation method.   4. The electronic component according to claim 1, wherein the plurality of conductive particles are held in the first adhesive layer in a state of being regularly spaced from each other. 5. How to implement   The electronic component mounting method according to claim 4, wherein the plurality of conductive particles exist in substantially the same plane.   4. The electronic component mounting method according to claim 1, wherein the plurality of conductive particles are dispersed in the first adhesive layer.   The electronic component mounting method according to claim 1, wherein the first adhesive layer has a higher melt viscosity at a heating temperature at the time of provisional pressure bonding than the second adhesive layer.

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