TW202226935A - Repairing method of electronic component installing substrate, repairing material, cured prodcut and wiring substrate - Google Patents

Abstract

The present invention provides a repairing method for easily reprocessing so as to obtain the electronic component installing substrate with excellent connection reliability. A repairing method for an electronic component installing substrate, using installation method of energizing the electrodes and the electronic components through curing material of conductive paste composition, includes the following steps: heating an electronic component installing area including at least one incorrectly installed electronic component in order to remove the incorrectly installed electronic component from the wiring board; using laser light to irradiate the electronic component installing area where the incorrectly installing electronic component was removed, removing all or at least part of the solidifying material of the conductive paste composition from the wiring substrate; and reinstalling the electronic component to the electronic component installing area where the cured material has been removed.

Description

Repair method, repair material, cured product, and wiring substrate of electronic component mounting substrate

The present invention relates to a repairing method of an electronic component mounting substrate, a repairing material used therefor, a cured product of the repairing material, and a wiring substrate provided with the cured product.

Optoelectronic devices such as liquid crystal display devices are used as display parts of computers, mobile phones, and other various electronic devices, and the like. In particular, liquid crystal display devices are widely used as display parts of various electronic devices because of their light weight, thinness, and low power consumption. In many of these liquid crystal display devices, a so-called backlight provided on the back side of a photovoltaic element such as a liquid crystal panel is used.

In recent years, LED array substrates have been increasingly used as backlights for optoelectronic devices and the like. The LED array substrate is formed by mounting a plurality of LED chips in a matrix on a wiring substrate, and electrically connecting each LED chip and the wiring substrate by solder or the like. Recently, in order to reduce the size and efficiency of backlights, smaller LED chips are gradually used in LED array substrates, and each LED chip is integrated and mounted on a wiring substrate. Along with this, in the mounting of the LED chip, a conductive paste or a conductive film called an anisotropic conductive material has been used instead of the conventional electrical connection by solder. The anisotropic conductive material is a material obtained by dispersing conductive particles in an insulating curable resin binder. It is used by thermocompression bonding of the electrode parts of electronic components (here, the wiring board and the LED chip). Only The electronic components are electrically connected via conductive particles in the pressing direction, and the insulating properties are maintained between adjacent electrodes, and the electronic components are fixed by curing of the curable resin adhesive (for example, Patent Document 1, etc.).

The advantage of using an anisotropic conductive material instead of solder is that a large number of LED chips can be mounted on the wiring substrate simultaneously and in a short time. On the other hand, compared with soldering, anisotropic conductive materials have problems such as poor reworkability. That is, in the case of solder connection, the target element can be easily removed from the wiring board by heating the reworked target element and remounted, but if the connection is made with the anisotropic conductive material as described above, the electronic components are connected by each other. The resin adhesive is firmly attached, so it cannot be easily removed. Even if the electronic components can be removed, the cured resin adhesive will remain on the wiring board. Therefore, the resin adhesive must be removed with a special solvent, etc. remove etc.

In order to cope with these problems, Patent Document 2 describes a technique in which a new anisotropic conductive film is attached in a state where the cured anisotropic conductive material is left on a wiring board, so that a repairing agent is not used. In this state, the electronic components can be re-crimped. [Prior Art Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 8-003529 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-272545

[The problem to be solved by the invention]

However, in the method proposed in Patent Document 2, since the cured product of the anisotropic conductive film needs to be designed to have an elastic modulus of 10 MPa or less at 150°C, it is difficult to obtain connection reliability (heat resistance) between electronic components. Moreover, since it is necessary to pressurize when remounting an electronic component, when using FPC (flexible wiring board) etc. as a wiring board, it is unavoidable to damage the wiring board.

In addition, in recent years, LED chips have been miniaturized. For example, LED array substrates in which LED chips with an external dimension of about tens of microns are mounted on a wiring substrate with an adjacent interval of 1 mm or less have also been put into practical use. It becomes more difficult to remove the LED chip from the wiring board for repair. Moreover, since the space for removing the defective LED chip is narrow, the work of removing the cured resin adhesive remaining on the wiring board side is also very difficult. Although strong removal of the solvent is considered, in this case, it may cause damage to the surrounding electronic components.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a method of repairing an electronic component mounting board that can easily perform rework and can obtain excellent connection reliability. Another object of the present invention is to provide a repair material used in the repair method, a cured product of the repair material, and a wiring board provided with the cured product of the repair material. [Means of Solving Problems]

In view of the above-mentioned problems, the inventors of the present application have come to the following findings: before remounting the electronic components, the resin components remaining in the conventional repairing of the electronic component mounting board are removed by laser irradiation, thereby facilitating the reprocessing operation, and It can improve the connection reliability of re-installed electronic components. The present invention has been completed based on the above findings. That is, the object of the present invention is as follows.

[1] A method of repairing an electronic component mounting substrate, wherein the electronic component mounting substrate is mounted in such a way that electrodes on a wiring substrate and electronic components are energized through a cured product of a conductive paste composition, and the method is characterized by having the following steps: heating an electronic component mounting area, which has at least electronic components not normally installed, to remove the electronic components not normally installed from the wiring substrate; irradiating laser light to the region from which the electronic component has been removed to remove all or at least a part of the cured product of the conductive paste composition from the wiring substrate; and Reinstall the electronic components in the area where the cured product has been removed. [2] The method according to [1], wherein a repairing material containing a curable resin is applied to an area from which the cured product has been removed or an electronic component to be remounted, and the electronic component is then mounted. [3] The method according to [1] or [2], wherein the conductive paste composition contains conductive particles, and the light absorption wavelength of the conductive particles is 300 nm to 10600 nm. [4] The method according to [3], wherein the electronic component mounting region is heated at a temperature higher than the glass transition temperature of the cured product and at or above the melting point of the conductive particles. [5] The method according to any one of [2] to [4], wherein the conductive paste composition and the repair material contain a flux; the amount of the flux contained in the repair material is relative to The amount of the flux contained in the conductive paste composition is 2 to 10 times. [6] The method according to [5], wherein the repair material contains the flux in a proportion of 1 to 10% by mass relative to the solid content of the repair material. [7] A repair material, which is used for mounting electronic components after removing electronic components that are not normally mounted on an electronic component mounting substrate, the electronic component mounting substrate is cured by a conductive paste composition to make electrodes on a wiring substrate Installed in an energized manner with electronic components; this repair material is characterized by: Contains at least curable resin and flux, The flux is 1 to 20 mass % based on the solid content of the repair material. [8] The repair material according to [7], further comprising conductive particles. [9] A cured product of the repair material according to [7] or [8]. [10] A wiring board comprising the cured product according to [9]. [Effect of invention]

According to the present invention, the cured product of the conductive paste composition remaining on the wiring board can be removed by irradiating a laser beam to the region of the electronic component mounting substrate from which the electronic component has been removed, so that reprocessing can be performed simply and easily with a repair material. operation, and can also improve the connection reliability of re-installed electronic components. It is especially effective in repairing miniaturized LED chips.

The method for repairing an electronic component mounting substrate of the present invention includes the following steps: (i) heating an electronic component mounting area having at least electronic components not normally mounted, so as to remove the electronic components not normally mounted from the wiring substrate (ii) the step of irradiating laser light to the region from which the electronic component has been removed to remove all or at least a part of the cured product of the conductive paste composition from the wiring substrate; and (iii) the region where the cured product has been removed Steps for re-installing electronic components.

The electronic component mounting board used in the repairing method of this invention means the wiring board mounted so that the electrode on the wiring board and an electronic component may be electrically connected through the hardened|cured material of a conductive paste composition. However, an electronic component mounting board mounted in such a way that the electrodes on the wiring board and electronic components are energized by an electrical connection method such as solder is not actively excluded. Of course, the repairing method of the present invention can also be used for the component mounting substrate.

Mounting electronic components on a wiring board, as described above, generally involves applying a conductive paste composition such as an anisotropic conductive adhesive to the wiring board, arranging each electronic component on the electrode position on the wiring board, and then using The composition is cured by heating, and the electronic component is attached to the wiring board, and at the same time, the conductive particles of the wiring board and the electronic component are electrically connected through the conductive particles in the composition. During heating, pressure can also be applied from the electronic component side as required. The conductive paste composition itself is insulating, but the conductive particles contained in the conductive paste composition are melted by heating, and are interposed between the electrodes on the wiring board side and the electrodes on the electronic component side to form conductive paths. As a result, electrical connection between the components can be performed. On the other hand, even in the region not sandwiched between the electrodes after heating, the conductive particles are kept in a dispersed state, so that the insulating properties can be maintained. Thereby, a so-called anisotropic conductive connection structure is formed. Of course, the electronic component mounting board may be manufactured by a method other than the above, and is not limited to the manufacture by the above method.

The electronic component mounting substrate applicable to the repairing method of the present invention is not particularly limited as long as it is an electronic component mounting substrate produced by using the above-mentioned conductive paste composition, and the manufacturing method is not particularly limited. The paste composition mounts the electronic components on the wiring board and manufactures them by heating the electronic components on the wiring board after placing the electronic components on the wiring board.

Moreover, as an electronic component mounting board|substrate to which the repairing method of this invention is applicable, for example, the chip board (COB) etc. which arrange|position electronic components, such as a bare chip or an LED chip, directly on a wiring board and are connected are mentioned. Hereinafter, the repairing method of the electronic component mounting substrate of the present invention will be described in detail.

<Removal steps for electronic components not installed properly> First, among the electronic components mounted on the wiring board, electronic components that are not normally mounted (hereinafter referred to as "defects") are identified. In the present invention, the defects are not only those that fail to function normally due to defects of the electronic components when conducting an energization inspection on the electronic component mounting board, but also those that the electronic components themselves function normally but have poor connection with the electrodes of the wiring board. The place where the connection with the electrode of the electronic component and the wiring board is normal, but the dislocation of the electronic component is not good. Moreover, as a wiring board, not only a rigid printed wiring board but a flexible printed wiring board may be sufficient as it.

Defects can be determined visually, and can also be performed using a general-purpose inspection machine or the like. For example, when the electronic component mounting substrate is an LED array substrate, defects can be identified by performing a lighting inspection to identify LED chips that are not lit, have problems such as emission color and brightness.

Next, the electronic component mounting region including at least the defect identified in the above-described manner is heated to remove the electronic component that is not normally mounted from the wiring board. The electronic component mounting area here may only be a determined electronic component that is not normally installed, and may also be a surrounding area including the electronic component. For example, when only one electronic component is defective, it may be the place where the electronic component is mounted, or the surrounding area including the electronic component that is located around the electronic component and functions normally.

As the heating area, it is only necessary to include the identified electronic components, and when there is only one defect, the identified electronic components can be removed by heating only the defect. Moreover, when there are many defects in an electronic component mounting board, each defect may be heated, and the whole wiring board may be heated, and the determined electronic component may be removed.

The heating temperature is not particularly limited as long as it is a temperature at which the electronic components mounted on the wiring board can be removed, but it is preferably a temperature higher than the glass transition temperature of the cured product of the conductive paste composition, and is preferably conductive The temperature of the melting point and above of the molten solidified product of the particles (that is, the conductive particles contained in the conductive paste composition). Although it also depends on the curable resin and conductive particles contained in the conductive paste composition to be used, it is preferably heated at 100 to 240°C, more preferably at 120 to 220°C, and particularly preferably at 140 to 200°C . Moreover, the heating time is 1 to 60 seconds, preferably 1 to 30 seconds, and more preferably 1 to 15 seconds.

Heating can be performed from the surface on the side where the electronic components are mounted on the wiring board, or from the surface on the opposite side, but from the viewpoint of minimizing thermal damage to the electronic components, it is preferable to heat the wiring board from the surface on the side where the electronic components are mounted. The side on which the electronic components are mounted is the opposite side to be heated. Further, the heating method is not particularly limited, and various methods can be used. For example, when only a localized heating defect is required, a heating method such as a spot heater or a hot oven can be applied, and the entire wiring board can be heated. In this case, a planar heating method such as a hot plate can be applied.

The cured product of the conductive paste composition that fixes (bonds) the wiring board and the electronic component is softened by heating, and the molten cured product of the conductive particles in the cured product is remelted, so that unnecessary stress can be applied without applying unnecessary stress. The electronic component mounting substrate removes electronic components. As a method of removing electronic components, it can be performed manually using tweezers or the like, and a removal device provided with a dedicated holding tool can also be used.

<Removal step of cured product> When a certain electronic component is removed from the electronic component mounting board in the above-described manner, the cured product of the conductive paste composition for bonding the wiring board and the electronic component will remain on the surface of the electronic component mounting board after removal. These residues may cause poor connections or misplacement of electronic components when new electronic components are installed. In the present invention, the cured product of the conductive paste composition is irradiated with laser light, the energy irradiated with the laser light is converted into heat, and the resin component constituting the remaining cured product is removed by the heat. That is, as described above, laser light is irradiated to an area after removing a certain electronic component from the electronic component mounting board, and the cured product of the conductive paste composition remaining on the wiring board is removed. From the viewpoint of the connection stability of the electronic components after remounting, it can be said that it is preferable to remove all the cured products remaining on the wiring board. For example, if the cured product contains a resin component and a component derived from conductive particles (those obtained by melting and solidifying the conductive particles), the resin component can be removed by laser irradiation, but the component derived from the conductive particles is hardly removed. In the present invention, from the viewpoint of effectively removing the cured product remaining on the substrate, the cured product is preferably a cured product of a conductive paste composition comprising a curable resin and conductive particles capable of absorbing at least a part of the wavelength band of laser light .

The laser light to be irradiated is not particularly limited as long as the conductive particles contained in the cured product of the conductive paste composition can absorb the irradiated light and convert it into heat in a wavelength range (300 nm to 10600 nm), and various wavelengths and types can be used. The laser light can be continuous wave laser or pulse wave laser. As the continuous wave laser, for example, yttrium vanadate (YVO ₄ ) laser, fiber laser, excimer laser, green laser, carbon dioxide laser, ultraviolet laser, and yttrium aluminum garnet (YAG) laser can be used , semiconductor laser, glass laser, ruby laser, helium-neon (He-Ne) laser, nitrogen laser, chelate laser, pigment laser, etc. Moreover, as a pulse wave laser, a nanosecond pulse laser, a millisecond pulse laser, etc. can be used, for example.

The output of the laser light is not particularly limited as long as the resin component in the cured product can be removed, but if the output is high, overheating may occur and the substrate may be damaged. Therefore, it is preferable to repeatedly perform laser light irradiation with an average output of about 0.2 to 1.0 W. The number of repetitions is not particularly limited, but is preferably about 5 to 50 times from the viewpoint of both avoiding damage to the substrate and practicality. In addition, the laser light irradiation may be repeatedly performed using a continuous wave laser, or a pulse wave laser may be used. The beam diameter of the laser light is, for example, about 5 μm to 200 μm.

In the repair method of the present invention, in the cured product (cured product of the conductive paste composition) remaining on the wiring board when the mounted electronic components are removed, the main resin component is decomposed and removed by irradiating laser light. According to the irradiation of laser light, even in a narrow area, all or at least a part of the cured product can be removed reliably, and the thermal influence on the surrounding can be reduced, so it is not easy to cause adverse effects on other normal electronic components installed due to heat. . Therefore, it can be said that it is suitable for repairing electronic component mounting substrates such as a chip board (COB) in which electronic components such as bare chips and LED chips are directly mounted and connected to the substrate. In particular, it is suitable for use when removing and remounting electronic components whose outer dimensions are 0.3 mm or less, more preferably 0.2 mm or less, from the wiring board. In addition, the external dimensions of electronic components refer to the length of the longest side among the three sides of the vertical, horizontal and height. Moreover, it is also suitable for the repair of the board|substrate which mounts such a small electronic component at a high density. For example, it is particularly suitable for repairing electronic component mounting substrates in which the interval between adjacent electronic components is 5 mm or less, preferably 4 mm or less.

Here, the conductive paste composition suitably used for the electronic component mounting board|substrate to which the repairing method of this invention is applied is demonstrated. The conductive paste composition generally contains curable resin and conductive particles, and may contain other components as long as the above-mentioned anisotropic conductive adhesive function is not impaired.

The curable resin contained in the conductive paste composition functions as a binder for the conductive fine particles, and also has a function of curing to fix the wiring board and the electronic components. The curable resin is preferably a curable resin that can be cured by heat, for example, epoxy resins, phenol resins, melamine resins, unsaturated polyester resins, maleimide resins, polyurethane resins, Silicone resin, cyanate resin, acrylic resin, etc. Among them, epoxy resin or acrylic resin is preferably used, and epoxy resin is particularly preferred.

The epoxy resin is not limited as long as it has two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, brominated bisphenol A type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin can be mentioned. Epoxy resin, cresol novolak epoxy resin, bisphenol A novolac epoxy resin, biphenyl epoxy resin, naphthol epoxy resin, naphthalene epoxy resin, dicyclopentadiene ring Oxygen resin, triphenylmethane-type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, phosphorus-containing epoxy resin, onion-type epoxy resin, norbornene-type epoxy resin, adamantane-type epoxy resin Oxygen resin, phenolic epoxy resin, aminophenol type epoxy resin, aminocresol type epoxy resin, alkylphenol type epoxy resin, etc. The said epoxy resin can be used individually by 1 type or in combination of 2 or more types.

Among the above epoxy resins, a liquid state is preferable to a solid state from the viewpoint of making the composition into a paste form. Specifically, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, and a bisphenol E type epoxy resin are preferable. As commercial products of these resins, for example, ZX-1059 (mixture of bisphenol A type/bisphenol F type epoxy resin) manufactured by NIPPON STEEL Chemical & Material Co., Ltd., and jER manufactured by Mitsubishi Chemical Co., Ltd. -828, the same company's jER-834, the same company's jER-1001 (bisphenol A type epoxy resin), the same company's jER-807, the same company's jER-4004P (bisphenol F type epoxy resin), AIR R710 (bisphenol E type epoxy resin) manufactured by WATER INC. etc.

The acrylic resin is not particularly limited as long as it has a (meth)acrylic group, and examples thereof include trimethylolpropane trimethacrylate, epoxy acrylate having a trimethylpropane skeleton, and the like. Trifunctional methacrylate monomers, etc. Among them, monofunctional (meth)acrylates, bifunctional (meth)acrylates, polyfunctional (meth)acrylates of trifunctional or more, epoxy (meth)acrylates, Urethane (meth)acrylate, polyester (meth)acrylate with more than bifunctional.

Examples of monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and (meth)acrylate. Butyl acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, tertiary butyl (meth)acrylate, butoxyethyl (meth)acrylate, amyl (meth)acrylate Esters, Hexyl (Meth)acrylate, 2-Ethylhexyl (Meth)acrylate, Heptyl (Meth)acrylate, Octylheptyl (Meth)acrylate, Nonyl (Meth)acrylate, (Meth) Decyl acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, ( Cetyl (meth)acrylate, octadecyl (meth)acrylate, behenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, ( Aliphatic (meth)acrylates such as 3-chloro-2-hydroxypropyl meth)acrylate, 2-hydroxybutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclopentyl (meth)acrylate Hexyl ester, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, isobornyl (meth)acrylate, 3-methyl-3-oxetane (meth)acrylate Alicyclic (meth)acrylates such as methyl ester, 1-adamantyl (meth)acrylate, phenyl (meth)acrylate, nonylphenyl (meth)acrylate, p-cumyl (meth)acrylate Phenyl (meth)acrylate, o-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate, 2-naphthyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxy (meth)acrylate -3-Phenoxypropyl, 2-hydroxy-3-(o-phenylphenoxy)propyl (meth)acrylate, 2-hydroxy-3-(1-naphthoxy)propyl (meth)acrylate Esters, aromatic (meth)acrylates such as 2-hydroxy-3-(2-naphthyloxy)propyl (meth)acrylate, 2-tetrahydrofurfuryl (meth)acrylate, N-(methyl) Heterocyclic (meth)acrylates such as acryloxyethylhexahydrophthalimide and 2-(meth)acryloyloxyethyl-N-carbazole.

As the bifunctional (meth)acrylate, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol Glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate , tetrapropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 2-methyl-1,3-propanediol di(methyl)acrylate ) acrylate, 1,4-butanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 3-methyl-1,5-pentanediol di(meth)acrylate , 1,6-hexanediol di(meth)acrylate, 2-butyl-2-ethyl-1,3-propanediol di(meth)acrylate, 1,9-nonanediol di(methyl)acrylate ) acrylates, aliphatic (meth)acrylates such as 1,10-decanediol di(meth)acrylate, glycerol di(meth)acrylate, tricyclodecane dimethanol (meth)acrylate, Lipids such as cyclohexanedimethanol (meth)acrylate, tricyclodecanedimethanol (meth)acrylate, hydrogenated bisphenol A di(meth)acrylate, hydrogenated bisphenol F di(meth)acrylate, etc. Cyclic (meth)acrylate, bisphenol A di(meth)acrylate, bisphenol F di(meth)acrylate, bisphenol AF di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate Aromatic (meth)acrylates such as base) acrylates and phenylephrine di(meth)acrylates, and heterocyclic (meth)acrylates such as isocyanuric acid di(meth)acrylates.

Tri- or higher polyfunctional (meth)acrylates include, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and di-trimethylolpropane tetra(meth)acrylate. ) acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethoxylated glycerol tri(meth)acrylate and other aliphatic (meth)acrylates Heterocyclic (meth)acrylates such as acrylates and isocyanuric tri(meth)acrylates.

Other curable resins may be contained in the conductive paste composition. For example, a polyfunctional epoxy resin may be contained in addition to the above-mentioned epoxy resin. Examples of the polyfunctional epoxy resin include EP-3300E manufactured by ADEKA Corporation, which is a hydroxybenzophenone-type liquid epoxy resin, and an aminophenol-type liquid epoxy resin (p-aminophenol-type liquid epoxy resin). Oxygen resin) jER-630 made by Mitsubishi Chemical Co., Ltd., ELM-100 made by Sumitomo Chemical Co., Ltd., etc., glycidylamine type epoxy resins made by Mitsubishi Chemical Co., Ltd. jER-604, NIPPON STEEL Chemical & Material Co. ., EPOTOHTOYH-434 manufactured by Ltd., SUMI-EPOXY ELM-120 manufactured by Sumitomo Chemical Co., Ltd., DEN-431 manufactured by Dow Chemical Co., Ltd. as a phenol novolak epoxy resin, and the like. These polyfunctional epoxy resins can be used individually by 1 type or in combination of 2 or more types.

The conductive paste composition may contain a curing agent for curing the above-mentioned curable resin. As the curing agent, conventional curing agents generally used for curing thermosetting resins can be used, such as amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and polymers containing these functional groups, and can also be customized as required Use these various ingredients. Amines include dicyandiamide, diamine diphenylmethane and the like. Imidazoles include alkyl-substituted imidazoles, benzimidazoles, and the like. In addition, the imidazole compound may be an imidazole latent curing agent such as an imidazole adduct. The polyfunctional phenols include hydroquinone, resorcinol, bisphenol A and its halides, further novolaks, resole resins, etc., which are condensates with aldehydes. Acid anhydrides include phthalic anhydride, hexahydrophthalic anhydride, Methyl Nadic Anhydride, benzophenone tetracarboxylic acid and the like. Examples of the isocyanates include tolyl diisocyanate, isophorone diisocyanate, and the like, and those obtained by masking the isocyanate with phenols or the like may also be used. These curing agents may be used alone or in combination of two or more.

The curing speed of the resin can be controlled by adjusting the type or compounding amount of the curing agent or curing accelerator, but from the viewpoint of anisotropic conductivity, the reaction temperature (curing temperature) of the resin is preferably higher than the following: The melting point of the conductive particles is more preferably higher than 5°C. By making the reaction temperature (curing temperature) of the resin higher than the melting point of the conductive particles, the dispersed conductive particles in the composition can be autoagglutinated before the resin is cured.

Regarding the selection of curable resin and curing agent or curing accelerator, a combination such as coloring of the cured resin may be used. As described below, the conductive particles preferably have the function of absorbing the laser light and converting it into thermal energy, but even if the conductive particles do not absorb the laser light, the cured resin only needs to be able to absorb the laser light and convert it into thermal energy. That is, the cured resin can absorb at least a part of the wavelength band of the laser light wavelength band. The removability of the resin component in the cured product can be improved by converting the resin component into thermal energy by absorbing the laser light.

The conductive particles can be used as long as they are conductive materials without particular limitations, but preferably those that can absorb at least a part of the wavelength band of the laser light can be used, for example, gold, silver, nickel, copper, lead, and The following low melting point solder particles and the like. The conductive particles may also be composite particles in which non-conductive particles such as glass, ceramics, and plastics are coated with a metal layer as a core, or composite particles including the non-conductive particles and metal particles. If the conductive particles are the above-mentioned composite particles or hot-melt metal particles, the conductive particles can be melted and deformed by heating, so the contact area with the electrodes during connection increases, and particularly high reliability can be obtained. In addition, as the conductive particles, silver-coated copper particles and metal particles having a shape in which a large number of fine metal particles are connected in a chain shape can also be used.

In the present invention, if the cured product of the conductive paste composition contains conductive particles, the conductive particles in the cured product are irradiated with laser light during the removal step of the cured product, so that the conductive particles in the cured product absorb the laser light and are converted into light energy, so that the localized Heat the cured product. As a result, it is considered that the resin component mainly constituting the cured product is thermally decomposed, and all or at least a part of the cured product is removed.

The conductive particles are preferably thermally fusible conductive particles, particularly preferably those that are melted by heating at 170° C. or lower, among them, low-melting solder particles are more preferred, and Sn-Pb-based and Sn-Bi-based are more preferred Low melting point solder particles. In addition, the low melting point solder particles mean solder particles having a melting point of 200°C or lower, preferably 170°C or lower, and more preferably 150°C or lower. In particular, the melting point of the conductive particles may be higher or lower than the glass transition temperature of the cured product of the above-mentioned curable resin, from the viewpoint of easy removal of electronic components in the above-mentioned step of removing defective electronic components.

In addition, the low melting point solder particles are preferably lead-free solder particles, and the lead-free solder particles mean a lead content rate of 0.10 mass % or less as defined in JIS Z 3282:2017 (Solder-Chemical Composition and Shape). solder particles.

As the lead-free solder particles, low-melting solder particles composed of at least one metal selected from the group consisting of tin, bismuth, indium, copper, silver, and antimony are preferably used. In particular, it is preferable to use an alloy of tin (Sn) and bismuth (Bi) from the viewpoint of the balance of cost, handleability, and bonding strength.

The content ratio of Bi in such low melting point solder particles can be appropriately selected within the range of 15 to 65 mass %, preferably 35 to 65 mass %, and more preferably 55 to 60 mass %.

By making the content ratio of Bi to 15 mass % or more, the alloy starts to melt at about 160°C. If the content ratio of Bi is further increased, the melting onset temperature will gradually decrease, the melting onset temperature of 20 mass % or more becomes 139°C, and 58 mass % becomes a eutectic composition. Therefore, by setting the content ratio of Bi in the range of 15 to 65 mass %, the effect of lowering the melting point can be sufficiently obtained, and as a result, sufficient conduction can be obtained even at low temperature.

The conductive particles are preferably spherical. Here, spherical conductive particles refer to those containing 90% or more of spherical powder at a magnification at which the shape of the conductive particles can be confirmed, and the ratio of the major axis to the minor axis is 1 to 1.5. In addition, the average particle diameter of the conductive particles is preferably 1 to 100 μm, more preferably 3 to 80 μm, and even more preferably 5 to 60 μm. In addition, in this specification, the average particle diameter means the median diameter (D50) measured using a laser diffraction particle size distribution analyzer.

In addition, the specific surface area of the conductive particles is preferably 300 cm ² /g to 2000 cm ² /g, more preferably 500 cm ² /g to 1500 cm ² /g. By using the conductive particles with the specific surface area in the above-mentioned range, the stability of the conductive connection between the electrodes of the wiring board and the electronic components is improved. In addition, the specific surface area of the conductive particles means the value measured by the BET method. Specifically, an inert gas with a known molecular size (such as nitrogen) can be adsorbed on the surface of the measurement sample, and the amount of adsorption is related to the non-reactive gas. The occupied area of the active gas was used to obtain the specific surface area.

The blending amount of the conductive particles is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, and particularly preferably 40 to 50% by mass relative to the solid content in the conductive paste composition. By making the compounding quantity of an electrically conductive particle into 20 mass % or more, adhesiveness between a wiring board and an electronic component can be ensured, and sufficient conduction|electrical_connection can be ensured. Moreover, by making the compounding quantity of an electroconductive particle into 70 mass % or less, it is possible to secure the electrical conductivity and secure sufficient adhesiveness.

In addition to the curable resin and the conductive fine particles, the conductive paste composition may contain other components. In order to improve the stability of the conductive connection, the conductive paste composition may also contain flux. As the flux, conventional fluxes used in the conductive paste composition can be used, such as zinc chloride, a mixture of zinc chloride and inorganic halide, a mixture of zinc chloride and inorganic acid, molten salt, phosphoric acid, Derivatives of phosphoric acid, organic halides, hydrazine, organic acids, rosin, etc. These fluxes can be used alone or in combination of two or more.

Among the above-mentioned fluxes, organic acids are preferably used. As a preferable organic acid, other than monocarboxylic acid, polycarboxylic acid, such as a dicarboxylic acid, a tricarboxylic acid, and a tetracarboxylic acid, is mentioned, for example. Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, capric acid, lauric acid, tetradecanoic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, and hexadecanoic acid. Fatty acid, tuberculous stearic acid, eicosic acid, behenic acid, behenic acid, glycolic acid, etc. Examples of the dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, and tartaric acid. , Diglycolic acid, etc. As tricarboxylic acid, benzene-1,2,5-tricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,3-propanetricarboxylic acid etc. are mentioned, for example. Moreover, as a tetracarboxylic acid, benzophenone tetracarboxylic acid, 1, 2, 3, 4- butane tetracarboxylic acid etc. are mentioned, for example. Among these carboxylic acids, dicarboxylic acid is preferred, glutaric acid and adipic acid are more preferred, and adipic acid is particularly preferred.

The content of the flux in the conductive paste composition is preferably 0.5 to 15 mass %, more preferably 0.5 to 10 mass % with respect to the solid content in the composition. Conductivity can be further improved by using a conductive paste composition having a flux content within the above range.

Moreover, in order to adjust the activity degree of a flux, a basic organic compound may be contained. As a basic organic compound, aniline hydrochloride, hydrazine hydrochloride, etc. are mentioned, for example.

Furthermore, in order to improve the physical strength of the cured product, etc., a filler may be blended into the conductive paste composition as required. As the filler, known inorganic or organic fillers can be used, but barium sulfate, spherical silica, hydrotalcite, and talc are particularly preferably used. In addition, metal oxides for obtaining flame retardancy and metal hydroxides such as aluminum hydroxide can be used as extender pigment fillers. Among these fillers, those having a wavelength band capable of absorbing at least a part of the wavelength band of laser light can be preferably used, for example, titanium oxide and the like. By including these fillers, the cured product can easily convert the absorbed laser light into thermal energy, thereby improving the removability of the resin component in the cured product.

In addition, in the case of blending a filler, in order to improve the dispersibility in the conductive paste composition, the filler may be surface-treated. Aggregation can be suppressed by using a surface-treated filler. The surface treatment method is not particularly limited, as long as a conventional method is used, but it is preferably a surface treatment agent with a curable reactive group, such as a coupling agent with a curable reactive group as an organic group, etc. surface treatment.

As the coupling agent, silane-based, titanate-based, aluminate-based, and aluminozirconate-based coupling agents can be used. Among them, a silane-based coupling agent is preferable. Examples of the silane-based coupling agent include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxy Silane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3- Glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3- Methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. may be used alone or in combination of two or more.

From the viewpoint of ease of preparation and coatability, an organic solvent may be blended in the conductive paste composition. As the organic solvent, ketones such as methyl ethyl ketone and cyclohexanone can be used; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; Methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, tripropylene glycol monomethyl ether and other glycol ethers; Ethyl acetate, butyl acetate, butyl lactate, celusol acetate, butyl cyluthol acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, Commonly used organic solvents such as esters such as dipropylene glycol monomethyl ether acetate and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, naphtha, and solvent naphtha. These organic solvents may be used alone or in combination of two or more.

<Reinstallation procedure of electronic components> As described above, the electronic component is remounted in the area where all or at least a part of the cured product is removed. For the re-installation of electronic components, the repair material can be applied to the area where the electronic components are arranged on the wiring substrate or the electronic components to be re-installed. After the electronic components are installed, the repair material is cured by heating, thereby fixing the wiring substrate and the electronic components ( Next), to re-install the electronic components. During heating, pressure can also be applied from the electronic component side as required. The following describes the repair materials used when remounting electronic components on the wiring board.

The repairing material used in the repairing method of the present invention must have the function of adhering the wiring board from which the cured product has been removed and the electronic component to be remounted. Therefore, the repair material contains curable resin. As curable resin, the same thing as the curable resin used for the said conductive paste composition can be used. In the repair method of the present invention, as described above, when the cured product remaining on the wiring board is removed by irradiating laser light, although the resin component constituting the cured product is thermally decomposed and removed from the wiring board, the conductive material contained in the cured product is removed from the wiring board. The molten solidified product of the particles is heated and remelted by irradiation with laser light, but usually does not decompose or evaporate, and remains in a state of adhering to the electrodes on the wiring board. Therefore, by heating to a temperature at which the remaining conductive particles are remelted, the electrodes of the wiring board and the electronic components can be electrically connected. Moreover, since the curable resin contained in the repair material is cured by heating and becomes a cured product, the electronic component can be fixed (bonded) to the wiring board.

The repair material contains flux in addition to curable resin. As the flux, the same ones as those used in the above-mentioned conductive paste composition can be used. In the present invention, as described above, when the resin component in the cured product remaining on the wiring board is removed by irradiating the laser light, the molten cured product of the conductive particles in the cured product converts the light energy of the laser light into heat Oxidation occurs. In particular, an oxide film may also form on the surface of the molten solidified product in contact with the air. Therefore, when the electronic component is mounted again, the conductive connection between the electrode of the wiring board and the electronic component may be defective due to the influence of the oxide film. In the present invention, the repair material contains the flux, whereby the influence of the oxide film can be suppressed and the electrical conductivity can be improved.

From the viewpoint of electrical continuity, the content of the flux contained in the repair material is preferably 2 to 10 times, more preferably 4 to 6 times, by mass relative to the content of the flux contained in the above-mentioned conductive paste composition. times. Moreover, it is preferable that content of a flux is 1-20 mass % with respect to the solid content of a repair material from a viewpoint of electrical continuity.

Even if the repair material does not contain conductive particles, as described above, the electrodes of the wiring board can be electrically connected to the electronic components to be remounted, but the repair material may also include conductive particles. As the conductive particles, the same ones as those used in the above-mentioned conductive paste composition can be used. When the repair material contains conductive particles, the blending amount thereof is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, and still more preferably 35 to 55% by mass relative to the solid content in the repair material.

In addition, the repair material may contain the same components as the conductive paste composition (for example, fillers, organic solvents, etc.), and the blending amount may be the same as the conductive paste composition.

The method of applying the repair material to the area where the electronic component is to be reinstalled (that is, the area where the cured product is removed by irradiating laser light), or the method of applying the repair material to the electronic component to be reinstalled is not particularly limited, From the viewpoint of being partially coatable, for example, a method of coating with a squeegee through a mesh or a metal mask, and a method of coating using a dispenser are exemplified. Among these coating methods, the method of coating using a dispenser is preferred from the viewpoint that the repair material can be easily and easily coated on a desired area. In electronic component mounting substrates such as a wafer board (COB) in which electronic components such as bare chips or LED chips are directly mounted on the substrate and connected, even a narrow area can be reliably coated with an appropriate coating amount and repaired Material. When applying the repair material using a dispenser, a syringe filled with the repair material can be attached to the dispenser, and the repair material can be applied to a desired area while adjusting the discharge volume. Repair material can also be applied to both the area where the electronic component is to be reinstalled and the electronic component to be reinstalled.

After the repairing material is applied to the area where the electronic component is installed or the electronic component is installed, the electronic component is arranged and heated in the reinstallation area where the repairing material has been applied. The repair material is cured by heating, and at the same time, the molten solidified product of the conductive particles remaining on the substrate electrode is remelted, thereby conducting the connection between the electrode of the wiring substrate and the electronic component, and fixing (then) the electronic component to the electronic component mounting substrate. Complete the repair. During heating, pressure can also be applied from the electronic component side as required.

The temperature during heating is not particularly limited as long as the repair material can be cured and the molten solidified product of the conductive particles remaining on the electrodes of the wiring board can be remelted, and it can be 100 to 240°C, preferably 120~200℃, more preferably 145~200℃. As long as the electrical conductivity is not impaired, the electronic components can also be crimped by applying pressure as required while heating. In the case of thermocompression bonding, the compression bonding is performed at 0.5 to 5.0 MPa, preferably 0.8 to 3.0 MPa, more preferably 1.0 to 2.0 MPa, and the heating time is 1 to 60 seconds, preferably 1 to 30 seconds. More preferably, it is 1 to 15 seconds. If this heating or crimping condition is used, the re-installed electronic components and the surrounding electronic components will not be damaged by heating or crimping, so the conductive connection can be ensured.

According to the present invention, a cured product of the above repair material is also provided. In the cured product of the repair material, the production conditions such as the temperature during heating are as described above.

Moreover, according to this invention, the wiring board provided with the said hardened|cured material is also provided. As a kind of wiring board provided with the hardened|cured material of a repair material, the board|substrate etc. which have a wiring layer on a printed wiring board, a glass substrate, a ceramic substrate, etc. are mentioned, for example. The wiring board may be single-sided or double-sided, and may be multilayered.

According to the present invention, the following embodiments are included. [1] A method of repairing an electronic component mounting substrate, wherein the electronic component mounting substrate is mounted in such a way that electrodes on a wiring substrate and electronic components are energized through a cured product of a conductive paste composition, the conductive paste composition comprising a curable resin and Conductive particles capable of absorbing at least a part of the wavelength band of laser light, the method is characterized by having the following steps: determining the defect that the electronic component is not normally mounted; Removing the determined electronic component from the wiring board; irradiating the region from which the electronic component has been removed with laser light to remove all or at least a part of the cured product of the conductive paste composition; applying a repair material containing curable resin to the removed On the area of the cured product or the electronic component to be remounted, the electronic component is placed on the electrode of the wiring board from which the electronic component has been removed, and the repair material is cured to remount the electronic component. [2] The method according to [1], wherein the conductive paste composition contains the conductive particles in a ratio of 20 to 70 mass % with respect to the solid content in the conductive paste composition. [3] The method according to [1] or [2], wherein the light absorption wavelength of the conductive particles is 300 nm to 10600 nm. [4] The method according to any one of [1] to [3], wherein the electronic component mounting region is performed at a temperature higher than the glass transition temperature of the cured product and at or above the melting point of the conductive particles heating. [5] The method according to any one of [1] to [4], wherein the conductive particles have a specific surface area of 300 cm ² /g to 2000 cm ² /g. [6] The method according to any one of [1] to [5], wherein the conductive paste composition and the repair material contain a flux; and, on a mass basis, the amount of the flux contained in the repair material is relative to The amount of the flux contained in the conductive paste composition is 2-10 times. [7] The method according to any one of [1] to [6], wherein the repair material contains the flux in a proportion of 1 to 10% by mass relative to the solid content of the repair material. [8] The method according to any one of [1] to [7], wherein the flux contains a carboxylic acid compound. [9] The method according to any one of [1] to [8], wherein the curable resin is an epoxy resin. [10] The method of any one of [1] to [9], wherein the electronic component has an outer dimension of 1 mm or less. [11] The method according to any one of [1] to [10], wherein the distance between the electronic component mounting substrate and the adjacent electronic components is 5 mm or less. [12] A repair material for use when mounting electronic components after removing electronic components that are not normally mounted on an electronic component mounting substrate, the electronic component mounting substrate is cured by a conductive paste composition to make electrodes on a wiring substrate It is installed in a way of electrifying electronic components; the repair material is characterized in that: it contains at least a curable resin and a flux; the flux is 1-20 mass % relative to the solid content of the repair material. [13] The repair material according to [12], further comprising conductive particles. [Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples. In addition, the following "parts" and "%" are the quality standards unless otherwise specified.

[Example 1] <Preparation of Electronic Component Mounting Board> First, each component shown below was mixed in a predetermined ratio, and kneaded with a three-roll mill to prepare an anisotropic conductive paste composition. ･55 parts by mass of epoxy resin (jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Corporation) ･3 parts by mass of curing agent (DICY, dicyandiamide) ･1 part by mass of flux (adipic acid)･ 41 parts by mass of low melting point solder particles (42Sn-58Bi spherical particles, melting point 139°C, specific surface area 541 cm ² /g (value measured by BET method), manufactured by Senju Metal Industry Co., Ltd.)

Next, the obtained anisotropic conductive paste composition was applied to a hard plate (substrate: substrate: FR-4, electrode width: 120μm, electrode length: 200um, spacing: 0.6mm, number of electrodes 150, flash gold (Flash Au) treatment). Next, the electrodes of each LED chip (125 μm×75 μm) were placed on the respective electrode positions of the hard board in the state where the anisotropic conductive paste composition had been applied, and the electrodes were placed so as to overlap, and the heating was performed at 180° C. from the LED chip side for 10 minutes. , making a substrate with 150 LED chips.

<Repair of electronic component mounting board> First, on the LED mounting board obtained in the above-described manner, a signal generator (a DC signal source (DC signal source) 7011, manufactured by Hioki Electric Co., Ltd.) was used to conduct a lighting check, and it was confirmed that all 150 LEDs were turned on. Among them, 10 LEDs are arbitrarily selected, and the 10 LEDs are assumed to be defective. Also, when selecting 10 LEDs, avoid selecting adjacent LEDs. Next, using a heating plate that partially shields the heating surface with a heat insulating material, from the back side of the substrate on which the LEDs identified as defectives are mounted, at 170°C for 1 minute, the LEDs identified as defectives are removed from the substrate, and then the LEDs identified as defectives are removed from the substrate. The substrate is cooled to room temperature. As a result of visual observation of each place where the LEDs were removed, it was confirmed that in all 10 places, the cured product of the anisotropic conductive paste composition remained on the electrodes on the surface of the substrate. Next, using a fiber laser (wavelength: 1064 nm, beam diameter: 40 μm), laser light was irradiated for 1 second at an output of 0.4 W to the portion where the LED had been removed. Repeat this operation 15 times. The place where the laser light was irradiated was visually observed, and it was confirmed that in all 10 places, although the solder remained on the electrode surface of the substrate, the resin solid content did not remain.

Using a dispensing apparatus, 300 mg of the anisotropic conductive paste composition was applied to the place where the LEDs had been removed (area at 1 place: about 120 μm×200 μm), and the same LEDs as those used for the LED mounting substrate were placed on the Where the repair material is applied, the positions of the electrodes of the substrate and the electrodes of the LEDs are adjusted to overlap. Next, the LED was remounted by heating at 180° C. from the LED wafer side for 10 minutes.

<Continuity test evaluation> For the board on which 10 more LEDs are installed, a signal generator (made by Nikki Electric Co., Ltd., DC signal source 7011) is used to check the continuity and lighting in the same way as above. As a result, 4 of the installed LEDs are lit, and 6 are not lit. lamp. In addition, a thermal humidity test (Thermal Humidity Test) at a temperature of 85° C. and a humidity of 85%RH for 1000 hours was performed on the remounted board, and then a continuity lighting inspection was performed in the same manner as above. As a result, 4 of the remounted LEDs turned on. , 6 are not lit.

[Example 2] <Preparation of Restoration Material 1> Restoration materials 1 to 4 were obtained by mixing each component shown below in a predetermined ratio and kneading it with a mixer. Repair material 1 ･54 parts by mass of epoxy resin (jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Corporation) ･Curing agent (DICY, dicyandiamide) 3 parts by mass ･Flux (adipic acid) 3 Parts by mass・40 parts by mass of low melting point solder particles (42Sn-58Bi spherical particles, melting point 139°C, specific surface area 541cm ² /g, manufactured by Senju Metal Industry Co., Ltd.)

Reinstallation of the LED was carried out in the same manner as in Example 1, except that the anisotropic conductive paste composition used at the time of LED remounting was replaced with the repairing material 1, and the continuity test evaluation was performed. As a result, 6 of the re-installed LEDs are lit, and 4 are not lit. In addition, in the continuity lighting inspection after the heat-humidity test, 6 of the remounted LEDs were lit, and 4 were not lit.

[Example 3] <Preparation of Repair Material 2> ･52 parts by mass of epoxy resin (jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Corporation) ･3 parts by mass of curing agent (DICY, dicyandiamide) ･6 parts by mass of flux (adipic acid) ･39 parts by mass of low melting point solder particles (42Sn-58Bi spherical particles, melting point 139°C, specific surface area 541cm ² /g, manufactured by Senju Metal Industry Co., Ltd.)

Reinstallation of the LED was carried out in the same manner as in Example 1, except that the anisotropic conductive paste composition used at the time of LED remounting was used instead of the repairing material 2, and the continuity test evaluation was performed. As a result, it was confirmed that all 10 LEDs to be remounted were turned on. In addition, it was confirmed that all 10 LEDs that were remounted were turned on in the conduction lighting inspection after the heat and humidity test was carried out.

[Example 4] <Preparation of Repair Material 3> ･49 parts by mass of epoxy resin (jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Co., Ltd.) ･3 parts by mass of curing agent (DICY, dicyandiamide) ･Soldering flux (adipic acid) 9 parts by mass ･39 parts by mass of low melting point solder particles (42Sn-58Bi spherical particles, melting point 139°C, specific surface area 541cm ² /g, manufactured by Senju Metal Industry Co., Ltd.)

Reinstallation of the LED was carried out in the same manner as in Example 1, except that the anisotropic conductive paste composition used at the time of LED remounting was used instead of the repairing material 3, and the continuity test evaluation was performed. As a result, it was confirmed that all 10 LEDs to be remounted were turned on. In addition, in the continuity lighting inspection after the heat-humidity test, 9 of the LEDs that were remounted were lit, and 1 was not lit.

[Example 5] <Preparation of Repair Material 4> ･46 parts by mass of epoxy resin (jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Co., Ltd.) ･3 parts by mass of curing agent (DICY, dicyandiamide) ･12 parts by mass of flux (adipic acid) ･39 parts by mass of low melting point solder particles (42Sn-58Bi spherical particles, melting point 139°C, specific surface area 541cm ² /g, manufactured by Senju Metal Industry Co., Ltd.)

Reinstallation of the LED was carried out in the same manner as in Example 1, except that the anisotropic conductive paste composition used at the time of LED re-installation was used instead of the repairing material 4, and the continuity test evaluation was carried out. As a result, it was confirmed that all 10 LEDs to be remounted were turned on. In addition, in the continuity lighting inspection after the heat-humidity test, 6 of the remounted LEDs were lit, and 4 were not lit.

[Comparative Example 1] In the above-mentioned repairing step of the electronic component mounting board, 10 LEDs were remounted on the board in the same manner as in Example 1, except that the laser light was not irradiated. Next, as in Example 1, the conduction lighting inspection was carried out, and as a result, none of the 10 LEDs that were remounted were turned on. In addition, in the conduction lighting inspection after the heat and humidity test, none of the 10 LEDs that were remounted were turned on.

[Comparative Example 2] In the above-mentioned repairing step of the electronic component mounting substrate, an organic solvent (methyl ethyl ketone) is used instead of irradiating laser light to remove the attachments remaining on the substrate electrodes where the LED chip has been removed. 10 LEDs were remounted on the substrate in the same manner. Next, as in Example 1, the conduction lighting inspection was carried out, and as a result, all 10 LEDs that were remounted were not turned on. In addition, in the conduction lighting inspection after the heat-humidity test, all 10 LEDs that were remounted were not turned on.

none.

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Claims (10)

A method for repairing an electronic component mounting substrate, wherein the electronic component mounting substrate is mounted in such a way that electrodes on a wiring substrate and electronic components are energized through a cured product of a conductive paste composition, characterized in that the method has the following steps: heating an electronic component mounting area having at least electronic components not normally mounted to remove the electronic components not normally mounted from the wiring substrate; removing all or at least a part of the cured product of the conductive paste composition from the wiring substrate by irradiating laser light to the region from which the electronic component has been removed; Reinstall the electronic components in the area where the cured product has been removed. The method according to claim 1, wherein a repairing material containing a curable resin is applied to the area from which the cured product is removed or the electronic component to be remounted, and then the electronic component is mounted. The method according to claim 1 or 2, wherein the conductive paste composition contains conductive particles, and the light absorption wavelength of the conductive particles is 300 nm to 10600 nm. The method of claim 3, wherein the electronic component mounting region is heated at a temperature higher than the glass transition temperature of the cured product and at or above the melting point of the conductive particles. The method according to claim 2, wherein the conductive paste composition and the repair material contain flux; and, on a mass basis, the amount of the flux contained in the repair material is relative to the flux contained in the conductive paste composition The amount is 2 to 10 times. The method according to claim 5, wherein the repair material contains the flux in a proportion of 1-10% by mass relative to the solid content of the repair material. A repair material used for mounting electronic components after removing electronic components that are not normally installed on an electronic component mounting substrate, the electronic component mounting substrate is made of a cured product of a conductive paste composition to make electrodes on a wiring substrate and electronic components It is installed in an electrified manner; it is characterized in that the repair material: Contains at least curable resin and flux, The flux is 1 to 20 mass % with respect to the solid content of the repair material. The repair material according to claim 7, further comprising conductive particles. A cured product of the repair material according to claim 7 or 8. A wiring board comprising the cured product of claim 9.