CN114068788A

CN114068788A - Method for repairing electronic component mounting substrate, repairing material, cured product, and wiring substrate

Info

Publication number: CN114068788A
Application number: CN202110871748.9A
Authority: CN
Inventors: 刘文琪
Original assignee: Taiyo Ink Mfg Co Ltd
Current assignee: Taiyo Holdings Co Ltd
Priority date: 2020-07-31
Filing date: 2021-07-30
Publication date: 2022-02-18
Also published as: TW202226935A; JP2022027735A; KR20220015995A

Abstract

The invention provides a repairing method of an electronic component mounting substrate, which can obtain high connection reliability while easily performing rework operation. A method for repairing an electronic component mounting substrate, which is a method for repairing an electronic component mounting substrate in which an electronic component is mounted so as to be electrically connected to an electrode on a wiring substrate via a cured product of a conductive paste composition, the method comprising: heating an electronic component mounting region including at least an electronic component which is not normally mounted, removing the electronic component which is not normally mounted from a wiring substrate, irradiating the region from which the electronic component has been removed with a laser beam, removing all or at least a part of a cured product of the conductive paste composition from the wiring substrate, and remounting the electronic component on the region from which the cured product has been removed.

Description

Method for repairing electronic component mounting substrate, repairing material, cured product, and wiring substrate

Technical Field

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

Background

An electro-optical device such as a liquid crystal display device is used as a display portion of various electronic devices such as a computer and a mobile phone, and particularly, a liquid crystal display device is widely used as a display portion of various electronic devices because it is light and thin and consumes less power. In many of these liquid crystal display devices, a display device having a so-called backlight on the back side of an electro-optical member such as a liquid crystal panel is used.

In recent years, LED array substrates have been used as backlights for electro-optical devices and the like. The LED array substrate is a substrate in which a plurality of LED chips are mounted in a matrix on a wiring substrate, and each LED chip is electrically connected to the wiring substrate by solder or the like. Recently, in order to miniaturize or improve efficiency of a backlight, smaller LED chips are used in an LED array substrate, and the LED chips are integrated and mounted on a wiring substrate. Accordingly, in addition to conventional electrical connection by solder, conductive paste or conductive film called anisotropic conductive material has come to be used for mounting LED chips. The anisotropic conductive material is a material in which conductive particles are dispersed in an insulating curable resin adhesive, and by thermocompression bonding electrode portions of electronic components (here, a wiring board and an LED chip), the electronic components can be electrically connected to each other through the conductive particles only in a pressing direction, and the electronic components can be fixed by curing the curable resin adhesive while maintaining insulation between adjacent electrodes (for example, patent document 1 and the like).

The advantage of using anisotropic conductive material instead of solder is: a plurality of LED chips can be mounted on a wiring board simultaneously and in a short time. On the contrary, the anisotropic conductive material has a problem of inferior reworkability compared with solder connection. That is, in the case of solder connection, the target component can be easily removed from the wiring board by heating and reworking the target component and remounting the target component, but in the connection using the anisotropic conductive material as described above, since the electronic components are strongly adhered to each other by the resin adhesive and cannot be easily removed, even when the electronic components are removed, the cured resin adhesive remains on the wiring board, and therefore, it is necessary to remove the resin adhesive or the like using a dedicated solvent or the like.

To address these problems, patent document 2 describes the following technique: a new anisotropic conductive film is attached in a state where the cured anisotropic conductive material remains on the wiring substrate, and the electronic component can be laminated without using a repair agent.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 8-003529;

patent document 2: japanese patent application laid-open No. 2010-272545.

Disclosure of Invention

Problems to be solved by the invention

However, in the method proposed in patent document 2, it is necessary to design a cured product of the anisotropic conductive film to have an elastic modulus of 10MPa or less at 150 ℃. Further, since pressure is required when the electronic component is mounted again, damage to the wiring substrate cannot be avoided when a flexible wiring substrate (FPC) or the like is used as the wiring substrate.

In addition, in recent years, the LED chips have been miniaturized, and for example, an LED array substrate in which LED chips having an outer size of about several tens of micrometers are mounted on a wiring substrate at an adjacent interval of 1mm or less has been put into practical use, and it has become more difficult to remove the LED chips from the wiring substrate for repair. In addition, since the portion from which the defective LED chip is removed is narrow, the work of removing the cured resin adhesive remaining on the wiring substrate side is also very difficult. Although it is also conceivable to use a powerful removal solvent, in this case, there is a possibility that damage may be caused to the electronic components and the like around the mounting.

The present invention has been made in view of the above problems, and an object of the present invention is to provide: a method for repairing an electronic component mounting board, which can easily perform a rework operation and can obtain high connection reliability. Another object of the present invention is to provide: a repair material used in such a repair method, a cured product of the repair material, and a wiring board provided with the cured product of the repair material.

Means for solving the problems

In view of the above problems, the present inventors have obtained the following findings: a resin component remaining in the repair of a conventional electronic component mounting substrate is removed by laser irradiation before the electronic component is remounted, whereby the rework operation is facilitated and the connection reliability of the remounted electronic component can be improved. The present invention has been completed based on such findings. Namely, the gist of the present invention is as follows.

[1] A method for repairing an electronic component mounting substrate, which is a method for repairing an electronic component mounting substrate in which an electronic component is mounted so as to be electrically connected to an electrode on a wiring substrate via a cured product of a conductive paste composition, the method comprising:

heating an electronic component mounting region containing at least an electronic component which is not normally mounted, removing the electronic component which is not normally mounted from the wiring substrate,

irradiating the region from which the electronic component has been removed with a laser beam to remove all or at least a part of a cured product of the conductive paste composition from the wiring substrate,

and mounting an electronic component on the region where the cured product is removed.

[2] [1] the method, wherein a repair material containing a curable resin is applied to a region from which the cured product has been removed or an electronic component to be remounted, and the electronic component is remounted.

[3] The method according to [1] or [2], wherein the conductive paste composition contains a curable resin and conductive particles, and a light absorption wavelength of at least one of a cured product of the curable resin and the conductive particles is 300nm to 10600 nm.

[4] [3] the method, wherein the electronic component mounting region is heated at a temperature higher than the glass transition point of the cured product and not lower than 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 flux contained in the repair material is 2 to 10 times the amount of flux contained in the conductive paste composition on a mass basis.

[6] [5] the method according to [5], wherein the repair material contains the flux in a proportion of 0.5 to 20 mass% relative to the solid content of the repair material.

[7] A repair material used when an electronic component is remounted from an electronic component mounting substrate on which an electronic component is mounted so as to be electrically connected to an electrode on a wiring substrate via a cured product of a conductive paste composition, the repair material being used when the electronic component is remounted, the repair material being characterized in that:

at least comprises a curable resin and a soldering flux,

the flux is contained in a proportion of 0.5 to 20 mass% with respect to the solid component amount of the repair material.

[8] The repair material according to [7], which further comprises 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 ].

Effects of the invention

According to the present invention, since the cured product of the conductive paste composition remaining on the wiring board is removed by irradiating the region where the electronic component is removed from the electronic component mounting board with a laser beam, the rework operation can be easily and easily performed using the repair material, and the connection reliability of the remounted electronic component can be improved. The method is particularly effective in repairing miniaturized LED chips.

Detailed Description

The method for repairing an electronic component mounting substrate of the present invention includes: a step (i) of heating an electronic component mounting region including at least an electronic component which is not normally mounted, and removing the electronic component which is not normally mounted from a wiring substrate; a step (ii) of irradiating the region from which the electronic component has been removed with a laser beam to remove all or at least a part of a cured product of the conductive paste composition from the wiring substrate; and (iii) mounting an electronic component on the region where the cured product is removed.

The electronic component mounting substrate used in the repairing method of the present invention is a wiring substrate on which an electronic component is mounted so that an electrode on the wiring substrate and the electronic component are electrically connected via a cured product of the conductive paste composition. However, the repairing method of the present invention is not positively excluded from electronic component mounting substrates in which electronic components are mounted by electrical connection means such as solder so that electrodes on a wiring substrate are electrically connected to the electronic components, and can be applied to any electronic component mounting substrate in which electronic components are fixed (bonded) to a wiring substrate via a resin.

In general, mounting electronic components on a wiring board is performed by applying a conductive paste composition such as an anisotropic conductive adhesive or the like to the wiring board as described above, disposing each electronic component at an electrode position on the wiring board, and then curing the composition by heating to bond the electronic component to the wiring board and electrically connect the electrode of the wiring board and the electronic component via conductive particles in the composition. In heating, pressurization can be performed from the electronic component side as needed. Although the conductive paste composition itself is insulating, the conductive particles contained in the conductive paste composition are melted by heating and sandwiched between the electrode on the wiring substrate side and the electrode on the electronic component side, thereby forming a conductive path. As a result, electrical connection between the members can be performed. On the other hand, the region not sandwiched between the electrodes after heating is still in a state in which the conductive particles are dispersed, and therefore, the insulating property is maintained. This results in a so-called anisotropic conductive connection structure. Of course, the electronic component mounting substrate can be manufactured by a method other than the above-described method, and is not to be construed as being limited to the substrate manufactured by the above-described method.

The electronic component mounting substrate to which the repairing method of the present invention is applied is not particularly limited as long as it is an electronic component mounting substrate produced using the conductive paste composition described above, and for example, it can be produced by applying the conductive paste composition onto a wiring substrate, disposing an electronic component on the wiring substrate via the conductive paste composition, and then heating the wiring substrate to mount the electronic component on the wiring substrate.

Further, as an electronic component mounting substrate to which the repairing method of the present invention can be applied, there are mentioned: a Chip On Board (COB) or the like for directly mounting electronic elements such as a bare Chip and an LED Chip On a wiring substrate and connecting them. The method for repairing an electronic component mounting board according to the present invention will be described in detail below.

< removal Process of electronic component not normally mounted >

First, among the electronic components mounted on the wiring board, an electronic component which is not normally mounted (hereinafter, also referred to as a "defective portion") is specified. In the present invention, the defective portion includes not only a portion which does not normally function due to a defect of the electronic component when the electrical inspection is performed on the electronic component mounting substrate, but also a portion in which a connection failure occurs with an electrode of the wiring substrate although the electronic component itself normally functions, or a portion in which a position of the electronic component is not well arranged such as a positional displacement although the connection between the electronic component and the electrode of the wiring substrate is normal. The wiring board may be not only a rigid printed wiring board but also a flexible printed wiring board.

The defective portion may be identified visually or by using a general-purpose inspection machine. For example, in the case where the electronic component mounting substrate is an LED array substrate, the defective portion can be identified by performing lighting inspection, and an LED chip having a defect in terms of non-lighting, emission color, luminance, or the like is identified.

Then, the electronic component mounting region including at least the defective portion determined as described above is heated, and the electronic component which is not normally mounted is removed from the wiring substrate. The electronic component mounting region may be only the specified electronic component which is not normally mounted, or may be a peripheral region including the electronic component. For example, when there is only one defective electronic component 1, the defective electronic component may be only a portion where the electronic component is mounted, or may be a peripheral region including a normally functioning electronic component located around the electronic component.

The heating region may include the specified electronic component, and when the defective portion is only 1 portion, the specified electronic component can be removed by heating only the defective portion. In addition, when there are a plurality of defective portions in the electronic component mounting substrate, each of the defective portions may be heated, or the entire wiring substrate may be heated to remove a specific electronic component.

The heating temperature is not particularly limited as long as it is a temperature at which the electronic component mounted on the wiring substrate can be removed, and is preferably a temperature higher than the glass transition point of the cured product of the conductive paste composition, and is preferably a temperature equal to or higher than the melting point of the molten cured product of the conductive particles (that is, the conductive particles contained in the conductive paste composition). The heating is preferably performed at 100 to 240 ℃, more preferably at 120 to 220 ℃, and particularly preferably at 140 to 200 ℃, although it depends on the curable resin and the conductive particles contained in the conductive paste composition used. The heating time is 1 to 60 seconds, preferably 1 to 30 seconds, and more preferably 1 to 15 seconds.

The heating may be performed from the surface of the wiring substrate on the side where the electronic component is mounted, or may be performed from the surface on the opposite side. The heating device is not particularly limited, and various methods can be employed, and for example, when heating only a defective portion locally, a heating device such as a spot heater or a heat drier can be applied, and when heating the entire wiring board, a planar heating device such as a hot plate can be applied.

By heating, a cured product of the conductive paste composition that fixes (bonds) the wiring board and the electronic component is softened, and a melted cured product of the conductive particles in the cured product is remelted, so that the electronic component can be removed from the electronic component mounting board without applying unnecessary stress. As a method of removing the electronic component, a method using a pincette or the like may be manually performed, or a removing device provided with a dedicated gripping tool may be used.

< procedure for removing cured product >

When the electronic component is removed from the electronic component mounting substrate in this manner, a cured product of the conductive paste composition for bonding the wiring substrate and the electronic component remains on the surface of the electronic component mounting substrate after the removal. When a new electronic component is mounted again, such residue may cause a connection failure or cause a positional deviation of mounting of the electronic component. In the present invention, a cured product of the conductive paste composition is irradiated with a laser beam, the energy of the laser beam irradiation is converted into heat, and the resin component constituting the remaining cured product is removed by the heat. That is, the region where the specified electronic component is removed from the electronic component mounting substrate is irradiated with the laser light in the above-described manner, and the cured product of the conductive paste composition remaining on the wiring substrate is removed. From the viewpoint of connection stability of the electronic component after remounting, although it is preferable to remove all of the cured product remaining on the wiring substrate, it is not necessary to remove all of the cured product, and at least a part of the cured product may be removed. For example, the cured product contains a resin component and a component derived from the conductive particles (a component obtained by melting and curing the conductive particles), but the resin component can be removed by laser irradiation, and the component derived from the conductive particles can hardly be removed. In the present invention, the cured product is preferably a cured product of a conductive paste composition containing a curable resin and conductive particles that can absorb at least a part of the wavelength band of the laser light, from the viewpoint of efficiently removing the cured product remaining on the substrate.

The laser light to be irradiated is not particularly limited as long as it is in a wavelength range (300nm to 10600nm) in which the conductive particles contained in the cured product of the conductive paste composition can absorb the irradiated light and convert it into heat, and various wavelengths or types of laser light may be used, and may be a continuous wave laser or a pulse wave laser. As the continuous wave laser, for example, there can be used: YVO₄Laser, fiber laser, excimer laser, green laser, carbon dioxide gas laser, ultraviolet laser, YAG laser, semiconductor laser, glass laser, ruby laser, He-Ne laser, nitrogen laserOptical, chelate, pigment, etc. Further, as the pulse wave laser, for example, there can be used: nanosecond pulsed lasers, millisecond pulsed lasers, and the like.

The output of the laser is not particularly limited as long as it is sufficient to remove the resin component in the cured product, and if the output is high, excessive heat may be generated to damage the substrate. Therefore, it is preferable to repeat the laser irradiation at an average output power of about 0.2 to 1.0W. The number of repetitions is not particularly limited, but is preferably about 5 to 50 times from the viewpoint of both damage to the substrate and practicality. Further, the laser irradiation may be repeated using a continuous wave laser, or a pulse wave laser may be used. The beam diameter of the laser is, for example, 5μm～200μAnd m is about.

In the repairing method of the present invention, the resin component is mainly decomposed and removed by laser irradiation from the cured product (cured product of the conductive paste composition) remaining on the wiring board when the mounted electronic component is removed. According to the laser irradiation, all or at least a part of the cured product can be accurately removed even in a narrow area, and the influence of heat on the surroundings can be reduced, so that the adverse influence of heat on other normal electronic components to be mounted is not easily exerted. Therefore, it is considered that the method is suitable for repairing an electronic component mounting substrate such as a Chip On Board (COB) in which an electronic component such as a bare chip or an LED chip is directly mounted on a substrate and connected. In particular, such an electronic component having an external dimension of 0.3mm or less, more preferably 0.2mm or less is removed from the wiring substrate and is preferably used when the electronic component is remounted. The external dimension of the electronic component means the length of the longest side among the three sides of the vertical, horizontal, and height. Further, it is also suitable for repairing a substrate on which such small electronic components are mounted at high density. For example, it is particularly suitable for repairing such an electronic component mounting substrate that the interval between adjacent electronic components is 5mm or less, preferably 4mm or less.

Here, a conductive paste composition suitable for an electronic component mounting substrate to which the repairing method of the present invention is applied will be described. The conductive paste composition usually contains a curable resin and conductive particles, but may contain other components as long as the anisotropic conductive adhesive function described above is not impaired.

The curable resin contained in the conductive paste composition functions as a binder for the conductive fine particles and also cures to have a function of fixing the wiring board and the electronic component. The curable resin is preferably a curable resin that is cured by heat, and examples thereof include: among these, epoxy resins or acrylic resins can be preferably used, and epoxy resins are particularly preferred.

The epoxy resin may be used without limitation as long as it has 2 or more epoxy groups in 1 molecule. Examples thereof include: 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, cresol novolac-type epoxy resin, bisphenol a novolac-type epoxy resin, biphenyl-type epoxy resin, naphthol-type epoxy resin, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, triphenylmethane-type epoxy resin, alicyclic epoxy resin, aliphatic chain epoxy resin, phosphorus-containing epoxy resin, anthracene-type epoxy resin, norbornene-type epoxy resin, adamantane-type epoxy resin, fluorene-type epoxy resin, aminophenol-type epoxy resin, aminomethylphenol-type epoxy resin, alkylphenol-type epoxy resin, and the like. The epoxy resin can be used alone 1 or a combination of 2 or more.

In the above epoxy resin, from the viewpoint of rendering the composition in a paste form, it is more preferably in a liquid state than in a solid state. Specifically, bisphenol a type epoxy resins, bisphenol F type epoxy resins, and bisphenol E type epoxy resins are preferable. Commercially available products thereof include: ZX-1059 (a mixture of bisphenol A and bisphenol F epoxy resins) manufactured by Nissan Chemical Co., Ltd, or jER-828, jER-834, jER-1001 (bisphenol A epoxy resin), jER-807, jER-4004P (bisphenol F epoxy resin), R710 (bisphenol E epoxy resin) manufactured by Air Water Co., Ltd.

The acrylic resin is not particularly limited as long as it is a resin having a (meth) acrylic group, and examples thereof include: and 3-functional methacrylate monomers such as trimethylolpropane trimethacrylate and epoxyacrylate having a trimethylpropane skeleton. Among these, monofunctional (meth) acrylates, 2-functional (meth) acrylates, 3-or more-functional (meth) acrylates, epoxy (meth) acrylates, urethane (meth) acrylates, and 2-or more-functional polyester (meth) acrylates can be preferably used.

Examples of monofunctional (meth) acrylates include: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, butoxyethyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl heptyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, stearyl (meth) acrylate, dodecyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl acrylate, decyl (meth) acrylate, butyl acrylate, decyl (meth) acrylate, decyl acrylate, butyl, Aliphatic (meth) acrylates such as behenyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-chloro-2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate; alicyclic (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, dicyclopentyl (meth) acrylate, dicyclopentenyl (meth) acrylate, isobornyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, and 1-adamantyl (meth) acrylate; aromatic (meth) acrylates such as phenyl (meth) acrylate, nonylphenyl (meth) acrylate, p-cumylphenyl (meth) acrylate, o-biphenyl (meth) acrylate, 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3- (o-phenylphenoxy) propyl (meth) acrylate, 2-hydroxy-3- (1-naphthyloxy) propyl (meth) acrylate, and 2-hydroxy-3- (2-naphthyloxy) propyl (meth) acrylate; heterocyclic (meth) acrylates such as 2-tetrahydrofurfuryl (meth) acrylate, N- (meth) acryloyloxyethylhexahydrophthalimide, and 2- (meth) acryloyloxyethyl-N-carbazole.

Examples of the 2-functional (meth) acrylate include: ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene 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-butylene glycol di (meth) acrylate, 2-methyl-1, 3-propylene glycol di (meth) acrylate, 1, 4-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 3-methyl-1, 5-pentanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, propylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, propylene glycol acrylate, Aliphatic (meth) acrylates such as 2-butyl-2-ethyl-1, 3-propanediol di (meth) acrylate, 1, 9-nonanediol di (meth) acrylate, 1, 10-decanediol di (meth) acrylate, glycerol di (meth) acrylate, tricyclodecanedimethanol (meth) acrylate; alicyclic (meth) acrylates such as cyclohexanedimethanol (meth) acrylate, tricyclodecanedimethanol (meth) acrylate, hydrogenated bisphenol a di (meth) acrylate, and hydrogenated bisphenol F di (meth) acrylate; aromatic (meth) acrylates such as bisphenol a di (meth) acrylate, bisphenol F di (meth) acrylate, bisphenol AF di (meth) acrylate, ethoxylated bisphenol a di (meth) acrylate, and fluorene type di (meth) acrylate; heterocyclic (meth) acrylates such as isocyanuric acid di (meth) acrylate.

Examples of the 3-or more-functional polyfunctional (meth) acrylate include: aliphatic (meth) acrylates such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and ethoxylated glycerol tri (meth) acrylate; heterocyclic (meth) acrylates such as isocyanuric acid tri (meth) acrylate.

The conductive paste composition may contain another curable resin. For example, a polyfunctional epoxy resin may be contained in addition to the above-described epoxy resin. As the polyfunctional epoxy resin, there can be mentioned: EP-3300E manufactured by ADEKA as a hydroxybenzophenone type liquid Epoxy resin, jER-630 manufactured by Mitsubishi Chemical corporation as an aminophenol type liquid Epoxy resin (p-aminophenol type liquid Epoxy resin), ELM-100 manufactured by Sumitomo Chemical corporation, etc., jER-604 manufactured by Mitsubishi Chemical corporation as a glycidylamine type Epoxy resin, Epoto YH-434 manufactured by Nintenna Chemical and Material, Sumi-Epoxy ELM-120 manufactured by Sumitomo Chemical industry, etc., DEN-431 manufactured by Dow Chemical corporation as a phenol novolac type Epoxy resin, etc. These polyfunctional epoxy resins may be used alone in 1 kind or in combination of 2 or more kinds.

The conductive paste composition may contain a curing agent for curing the curable resin. As the curing agent, known curing agents generally used for curing thermosetting resins can be used, and examples thereof include amines, imidazoles, polyfunctional phenols, acid anhydrides, isocyanates, and polymers containing functional groups thereof, and a plurality of these can be used as necessary. Examples of the amines include dicyandiamide and diaminodiphenylmethane. The imidazoles include alkyl-substituted imidazoles and benzimidazoles. The imidazole compound may be an imidazole latent curing agent such as an imidazole adduct. Examples of the polyfunctional phenols include hydroquinone, resorcinol, bisphenol a and halides thereof, and novolaks and resols which are condensates thereof with aldehydes. Examples of the acid anhydride include phthalic anhydride, hexahydrophthalic anhydride, methylnadic anhydride, and benzophenone tetracarboxylic acid. Examples of the isocyanate include tolylene diisocyanate and isophorone diisocyanate, and the isocyanate may be masked with phenols or the like. These curing agents can be used alone in 1 or a combination of 2 or more.

The curing rate of the resin can be controlled by adjusting the kind or blending amount of the curing agent or the curing accelerator, but from the viewpoint of anisotropic conductivity, the reaction temperature (curing temperature) of the resin is preferably higher than the melting point of the conductive particles described later, and more preferably higher than 5 ℃. By making the reaction temperature (curing temperature) of the resin higher than the melting point of the conductive particles, the conductive particles dispersed in the composition can be made to aggregate themselves before the resin is cured.

The curable resin and the curing agent or the curing accelerator may be selected from such combinations that the cured resin is colored. As described later, the conductive particles preferably have a function of absorbing laser light and converting it into thermal energy, but even in the case where the conductive particles do not absorb laser light, as long as the cured resin is a resin that can absorb laser light and convert it into thermal energy. That is, the cured resin may have a wavelength band that can absorb at least a part of the wavelength band of the laser light. The resin component absorbs the laser beam and converts the laser beam into heat energy, thereby improving the removability of the resin component in the cured product.

The conductive particles are not particularly limited as long as they are a material having conductivity, and particles that can absorb at least a part of the wavelength band of the laser light can be preferably used, and examples thereof include: gold, silver, nickel, copper, lead, low melting point solder particles described below, and the like. The conductive particles may be composite particles in which non-conductive particles such as glass, ceramics, plastics, or the like as cores are coated with a metal layer, or composite particles having the non-conductive particles and the metal particles. When the conductive particles are the composite particles or the thermally fusible metal particles, the conductive particles are melted and deformed by heating, and therefore the contact area with the electrode at the time of connection is increased, and particularly high reliability can be obtained. As the conductive particles, silver-coated copper particles or metal particles having a shape in which a plurality of fine metal particles are connected in a chain form may be used.

In the present invention, when the conductive particles are contained in the cured product of the conductive paste composition, the conductive particles in the cured product absorb the laser light by the laser irradiation in the removal step of the cured product, and the optical energy is converted into heat, whereby the cured product is locally heated. As a result, it is considered that the resin component mainly constituting the cured product is thermally decomposed, and the entire or at least a part of the cured product is removed.

The conductive particles are preferably heat-fusible conductive particles, and particularly preferably those melted by heating at 170 ℃ or lower, among them, low-melting solder particles are more preferable, and Sn-Pb-based or Sn-Bi-based low-melting solder particles are more preferable. The low melting point solder particles are solder particles having a melting point of 200 ℃ or less, preferably 170 ℃ or less, and more preferably 150 ℃ or less. 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 curable resin, from the viewpoint of ease of removal of the electronic component in the step of removing the defective electronic component.

As the low melting point solder particles, solder particles containing no lead are preferable, and the solder particles containing no lead are JIS Z3282: 2017 (solder-chemical composition and shape), and has a lead content of 0.10 mass% or less.

As the solder particles not containing lead, low melting point solder particles composed of 1 or more metals selected from tin, bismuth, indium, copper, silver, and antimony are suitably used. In particular, an alloy of tin (Sn) and bismuth (Bi) is preferably used from the viewpoint of balance among cost, workability, and bonding strength.

The content of Bi in the low-melting-point-welding-tin particles is appropriately selected within a range of 15 to 65 mass%, preferably 35 to 65 mass%, and more preferably 55 to 60 mass%.

When the content of Bi is 15 mass% or more, the alloy starts to melt at about 160 ℃. When the content of Bi is further increased, the melting start temperature decreases, and at 20 mass% or more, the melting start temperature is 139 ℃, and at 58 mass%, the eutectic composition is formed. Therefore, by setting the content of Bi within the range of 15 to 65 mass%, the effect of lowering the melting point can be sufficiently obtained, and as a result, sufficient electrical connection can be obtained even at low temperatures.

The conductive particles are preferably spherical. The spherical conductive particles are particles containing 90% or more of a powder having a ratio of the major axis to the minor axis of 1 to 1.5, at a magnification at which the shape of the conductive particles can be confirmed. In addition, the average particle diameter of the conductive particles is preferably 1 to 100μm, more preferably 3 to 80μm, more preferably 5 to 60μAnd m is selected. In the present specification, the average particle diameter refers to a median diameter (D50) measured by a laser diffraction particle size distribution meter.

In addition, the specific surface area of the conductive particles is preferably 300cm²/g～2000cm²G, more preferably 500cm²/g～1500cm²(ii) in terms of/g. By using the conductive particles having a specific surface area within the above range, the stability of the conductive connection between the electrode of the wiring substrate and the electronic component is improved. The specific surface area of the conductive particles is a value measured by the BET method, and specifically, the specific surface area can be determined from the amount of adsorption and the occupied area of the inert gas by adsorbing the inert gas (for example, nitrogen gas) having a known size of one molecule on the surface of the measurement sample.

The amount of the conductive particles to be added is preferably 20 to 70 mass%, more preferably 30 to 60 mass%, and particularly preferably 40 to 50 mass% with respect to the amount of the solid component in the conductive paste composition. By setting the blending amount of the conductive particles to 20 mass% or more, sufficient conductive connection can be ensured while ensuring adhesion between the wiring substrate and the electronic component. Further, by setting the blending amount of the conductive particles to 70 mass% or less, sufficient adhesion can be secured while securing conductive connectivity.

The conductive paste composition may contain other components in addition to the curable resin and the conductive fine particles. In the conductive paste composition, a flux may be included to improve the stability of the conductive connection. As the flux, known fluxes used in the conductive paste composition can be used, and examples thereof include: zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, derivatives of phosphoric acid, organic halides, hydrazine, organic acids, rosin, and the like. These fluxes may be used alone in 1 kind or in combination of 2 or more kinds.

Among the above-mentioned fluxes, organic acids can also be suitably used. Preferred organic acids include, in addition to monocarboxylic acids: polycarboxylic acids such as dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids, and the like. As monocarboxylic acids, there may be mentioned: formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecanoic acid, palmitic acid, heptadecanoic acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, glycolic acid, and the like. As dicarboxylic acids, there may be mentioned: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, tartaric acid, diglycolic acid, and the like. As the tricarboxylic acid, there may be mentioned: benzene-1, 2, 5-tricarboxylic acid, 1,2, 4-benzenetricarboxylic acid, 1,2, 3-propanetricarboxylic acid, etc. Further, as the tetracarboxylic acid, there can be mentioned: benzophenone tetracarboxylic acid, 1,2,3, 4-butane tetracarboxylic acid, and the like. Among these carboxylic acids, dicarboxylic acids are 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% by mass, more preferably 0.5 to 10% by mass, relative to the amount of solid components in the composition. By forming the conductive paste composition with the flux content in the above range, the conductive connectivity can be further improved.

In addition, an alkaline organic compound may be included to adjust the activity of the flux. Examples of the basic organic compound include: aniline hydrochloride and hydrazine hydrochloride, and the like.

In addition, a filler may be added to the conductive paste composition as needed in order to improve the physical strength of the cured product. As fillers, known inorganic or organic fillers can be used, in particular barium sulfate, spherical silica, hydrotalcite and talc are preferably used. In addition, metal hydroxides such as metal oxides and aluminum hydroxide may be used as extender pigment fillers for flame retardancy. Among these fillers, a filler having a wavelength band that can absorb at least a part of the wavelength band of the laser light can be preferably used, and examples thereof include: titanium oxide, and the like. By containing such a filler, the cured product easily absorbs the laser light and converts it into thermal energy, and the removability of the resin component in the cured product is improved.

In addition, in the case of blending a filler, the filler may be a filler subjected to surface treatment in order to improve its dispersibility in the conductive paste composition. By using the filler subjected to the surface treatment, aggregation can be suppressed. The surface treatment method is not particularly limited as long as a known conventional method is employed, and it is preferable to treat the surface of the inorganic filler with a surface treatment agent having a curable reactive group, for example, a coupling agent having an organic group as a curable reactive group.

As coupling agents, use may be made of: silane-based, titanate-based, aluminate-based, and zircoaluminate-based coupling agents. Among them, silane coupling agents are preferable. Examples of such silane coupling agents include: vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminomethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and the like, and these coupling agents may be used alone in 1 kind or in combination of 2 or more.

The conductive paste composition may be blended with an organic solvent from the viewpoint of ease of preparation and coatability. As organic solvents, use may be made of: ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; known and conventional organic solvents such as petroleum solvents including petroleum ether, petroleum naphtha, solvent naphtha, etc., and these organic solvents may be used alone in 1 kind or in combination of 2 or more kinds.

< Process for remounting electronic component >

In this manner, the electronic component is mounted on the region from which all or at least a part of the cured product has been removed. In the remounting of the electronic component, a repair material is applied to a region on the wiring substrate where the electronic component is to be arranged or the electronic component to be remounted to arrange the electronic component, and then the repair material is cured by heating to fix (bond) the wiring substrate and the electronic component, thereby remounting the electronic component. The pressing may be performed from the electronic component side as necessary at the time of heating. The following describes a repair material used when an electronic component is mounted on a wiring board.

The repair material used in the repair method of the present invention is required to have a function of bonding the wiring substrate from which the cured product has been removed and the electronic component to be mounted again. Therefore, the repair material contains a curable resin. As the curable resin, the same resin as the curable resin used in the above-described conductive paste composition can be used. In the repairing method of the present invention, as described above, when the cured product remaining on the wiring substrate is removed by laser irradiation, the resin component constituting the cured product is thermally decomposed and removed from the wiring substrate, but the molten cured product of the conductive particles contained in the cured product is heated by laser irradiation and remelted, but usually does not decompose or evaporate, but remains in a state of adhering to the electrode on the wiring substrate. Therefore, the electrodes of the wiring substrate and the electronic component can be electrically connected by heating to such a temperature that the remaining conductive particles are remelted. Further, since the curable resin contained in the repair material is cured by heating to become a cured product, the electronic component can be fixed (bonded) to the wiring substrate.

The repair material contains a flux in addition to the curable resin. As the flux, the same flux as that used in the above-described 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 substrate is removed by laser irradiation, the molten cured product of the conductive particles in the cured product is oxidized when the light energy of the laser is converted into heat. In particular, an oxide film may be formed on the surface of the molten and solidified material which is in contact with air. Therefore, when the electronic component is mounted again, a failure may occur in the electrical connection between the electrode of the wiring substrate and the electronic component due to the influence of the oxide film. In the present invention, by including the flux in the repair material, the influence of the oxide film can be suppressed, and the conductive connectivity can be improved.

From the viewpoint of electrical connectivity, the content of the flux contained in the repair material is preferably 2 to 10 times, and more preferably 4 to 6 times, by mass, relative to the amount of the flux contained in the conductive paste composition. In addition, from the viewpoint of electrical connectivity, the content of the flux is preferably 0.5 to 20 mass%, more preferably 1 to 10 mass%, relative to the solid content of the repair material.

Even if the repair material does not contain conductive particles, the conductive connection between the electrode of the wiring board and the electronic component to be mounted again can be performed by the above operation. As the conductive particles, the same conductive particles as those used in the above-described conductive paste composition can be used. When the conductive particles are contained in the repair material, the amount of the conductive particles to be mixed is preferably 20 to 70 mass%, more preferably 30 to 60 mass%, and still more preferably 35 to 55 mass% with respect to the amount of the solid component in the repair material.

The repair material may contain the same components (e.g., filler, organic solvent, etc.) as those of the conductive paste composition, and the amount of the components may be set to be the same as that of the conductive paste composition.

The method of applying the repair material to the region where the electronic component is remounted (i.e., the region where the cured product is removed by laser irradiation) or the method of applying the repair material to the electronic component to be remounted is not particularly limited, and from the viewpoint of enabling local application, there may be mentioned: a method of coating via a screen or a metal mask using a doctor blade, or a method of coating using a dispenser. Among these coating methods, a method of coating using a dispenser is also preferable in terms of easily and easily coating the repair material on a desired region. In an electronic component mounting substrate such as a Chip On Board (COB) for directly mounting electronic components such as bare chips and LED chips on a substrate and connecting them, a repair material can be applied in an appropriate amount of application even in a narrow area. In the case of applying the repair material using the dispenser, a syringe filled with the repair material may be attached to the dispenser, and the repair material may be applied to a desired region while adjusting the discharge amount. The repair material may be applied to both the area where the electronic component is remounted and the electronic component desired to be remounted.

After a repair material is applied to a region where an electronic component is remounted or an electronic component, the electronic component is arranged and heated in the remounted region where the repair material is applied. The repair material is cured by heating, and the melted and cured conductive particles remaining on the substrate electrodes are remelted to electrically connect the electrodes of the wiring substrate and the electronic component, whereby the electronic component is fixed (bonded) to the electronic component mounting substrate, and the repair is completed. The electronic component can be pressurized as necessary during heating.

The temperature during heating is not particularly limited as long as the repair material is solidified and the melted and solidified material of the conductive particles remaining on the electrode of the wiring substrate is remelted, and the temperature is 100 to 240 ℃, preferably 120 to 200 ℃, and more preferably 145 to 200 ℃. Within the range of not damaging the conductive connectivity, the electronic components can be pressed by heating and pressing according to the needs. When the heating and pressing are performed, the pressing is performed at 0.5 to 5.0MPa, preferably 0.8 to 3.0MPa, more preferably 1.0 to 2.0MPa, and the heating time is 1 to 60 seconds, preferably 1 to 30 seconds, more preferably 1 to 15 seconds. Under such heating or pressing conditions, the remounted electronic component or the electronic components around the remounted electronic component are not damaged by heating or pressing, and conductive connection can be secured.

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

Further, the present invention provides a wiring board comprising the cured product. The types of wiring boards provided with cured products of the repair materials include: a printed wiring board, a substrate having a wiring layer on a glass substrate or a ceramic substrate, or the like. The wiring board may be single-sided, double-sided, or multi-layered.

According to the present invention, the following embodiments are included.

[1] A method for repairing an electronic component mounting substrate, which is a method for repairing an electronic component mounting substrate in which an electronic component is mounted so that an electrode on a wiring substrate is electrically connected to the electronic component via a cured product of a conductive paste composition containing a curable resin and conductive particles capable of absorbing at least a part of a wavelength band of a laser beam, the method comprising:

determining the bad part of the electronic element which is not normally installed,

heating an electronic component mounting region including at least the defective portion, removing the specified electronic component from the wiring substrate,

irradiating the region from which the electronic component has been removed with a laser beam to remove all or at least a part of a cured product of the conductive paste composition,

applying a repair material containing a curable resin to the region from which the cured product has been removed or to the electronic component to be remounted, disposing the electronic component on the electrode of the wiring substrate from which the electronic component has been removed, and curing the repair material to remount the electronic component.

[2] [1] the method according to any one of the preceding claims, wherein the conductive paste composition contains the conductive particles in a proportion of 20 to 70 mass% relative to the amount of solid components in the conductive paste composition.

[3] The method according to [1] or [2], wherein the light absorption wavelength of the conductive particles is 300nm to 10600 nm.

[4] The method according to any one of [1] to [3], wherein the electronic component mounting region is heated at a temperature higher than a glass transition point of the cured product and at a temperature equal to or higher than a melting point of the conductive particles.

[5] [1]～[4]The method according to any one of the above, wherein the specific surface area of the conductive particles is 300cm²/g～2000cm²/g。

[6] The method according to any one of [1] to [5], wherein the conductive paste composition and the repair material contain a flux,

[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 mass% with respect to a 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 according to any one of [1] to [9], wherein the electronic component has an external dimension of 1mm or less.

[11] The method according to any one of [1] to [10], wherein a spacing between adjacent electronic components of the electronic component mounting substrate is 5mm or less.

[12] A repair material used for remounting an electronic component from an electronic component mounting substrate mounted with an electrode on a wiring substrate and the electronic component electrically connected via a cured product of a conductive paste composition,

the patching material at least comprises a curable resin and a soldering flux,

the flux is contained in a proportion of 1 to 20 mass% with respect to the solid component amount of the repair material.

[13] [12] the repair material further comprising conductive particles.

Examples

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples. In the following description, "part" and "%" are based on mass unless otherwise specified.

[ example 1]

< preparation of electronic component mounting substrate >

First, each component shown below was mixed at a predetermined ratio and kneaded using a three-roll mill to prepare an anisotropic conductive paste composition.

Seed and seed epoxy resin 55 parts by mass

(jER-828, liquid at room temperature, manufactured by Mitsubishi Chemical Co., Ltd.)

Seed and seed curing agent (DICY, dicyandiamide) 3 parts by mass

Seed and seed scaling powder (adipic acid) 1 part by mass

Seed Low-melting Point solder particle 41 parts by mass

(42Sn-58Bi spherical particles, a melting point of 139 ℃ and a specific surface area of 541cm²(g) (value measured by BET method), manufactured by Kimura Metal industries Co., Ltd.)

Then, a rigid substrate (base material: FR-4, electrode width: 120)μm, electrode length: 200um, wide spacing: 0.6mm, electrode count 150, Flash Au treatment), a doctor blade was used to remove the impurities through a metal mask (mask thickness: 100μm, opening: 200μm×100μm) coating the obtained anisotropic conductive paste composition to a thickness of 80μm。

Then, the anisotropic conductive paste group is coatedEach LED chip (125) is arranged at each electrode position of the rigid substrate in the state of compoundμm×75μm) were stacked, and heating was performed at 180 ℃ for 10 minutes from the LED chip side, thereby producing a substrate on which 150 LED chips were mounted.

< repair of electronic component mounting substrate >

First, the LED-mounted substrate obtained as described above was subjected to an on-state lighting inspection using a signal generator (DC signal source 7011, manufactured by japan electric products), and it was confirmed that all of the 150 LEDs were turned on. From these 10 LEDs were arbitrarily selected, and the 10 LEDs were virtually determined as defective portions. When 10 LEDs are selected, adjacent LEDs are not selected.

Then, the substrate was heated at 170 ℃ for 1 minute from the back surface side of the substrate on which the LED identified as the defective portion was mounted using a hot plate having a heating surface partially masked with a heat insulating material, and after removing the LED identified as the defective portion from the substrate, the substrate was cooled to room temperature. When each portion from which the LED was removed was visually observed, it was confirmed that the cured product of the anisotropic conductive paste composition remained on the electrode on the surface of the substrate in all 10 portions.

Then, a fiber laser (wavelength: 1064nm, beam diameter: 40) was usedμm) the portion where the LED was removed was irradiated with a laser beam at an output of 0.4W for 1 second. This operation was repeated 15 times. When the laser-irradiated portion was visually observed, it was confirmed that solder remained on the electrode surface of the substrate in all 10 portions, but no resin solid remained.

Using a dispenser device at the location where the LED has been removed (area of 1 location: about 120)μm×200μm) 300mg of the anisotropic conductive paste composition was applied, and the same LED as that used for the LED-mounted substrate was disposed at the portion where the repair material was applied, and the positions of the electrode of the substrate and the electrode of the LED were adjusted so as to overlap each other.

Then, the LED chip was heated at 180 ℃ for 10 minutes from the LED chip side, and the LED was mounted again.

< evaluation of conduction test >

When the on-state lighting inspection was performed on the substrate on which 10 LEDs were further mounted by using a signal generator (DC signal source 7011, manufactured by japan electric products corporation) in the same manner as described above, 4 of the remounted LEDs were turned on, but 6 were not turned on.

After a TH Test (Thermal Humidity Test) was performed on the remounted substrate for 1000 hours at a temperature of 85 ℃ and a Humidity of 85% RH, 4 of the remounted LEDs were turned on but 6 were not turned on when conducting the conduction lighting Test in the same manner as described above.

[ example 2]

< preparation of repair Material 1 >

The following components were blended at a predetermined ratio and kneaded with a mixer to obtain repair materials 1 to 4.

Repair material 1

Seed and seed epoxy resin 54 parts by mass

Seed and seed curing agent (DICY, dicyandiamide) 3 parts by mass

3 parts by mass of seed dressing flux (adipic acid)

Seed and Low-melting Point solder particles 40 parts by mass

(42Sn-58Bi spherical particles, a melting point of 139 ℃ and a specific surface area of 541cm²(iv) g manufactured by King Metal industries Co., Ltd.)

LED remounting was performed and conduction test evaluation was performed in the same manner as in example 1, except that the repair material 1 was used instead of the anisotropic conductive paste composition used in LED remounting. As a result, 6 LEDs of the remounted LEDs were lit, but 4 were not lit. In the on lighting test after the TH test, 6 LEDs to be mounted again were turned on, but 4 were not turned on.

[ example 3]

< preparation of repair Material 2 >

Seed and seed epoxy resin 52 parts by mass

Seed and seed curing agent (DICY, dicyandiamide) 3 parts by mass

6 parts by mass of seeding and soldering flux (adipic acid)

Seed Low-melting Spot welding tin particles 39 parts by mass

(42Sn-58Bi spherical particles, a melting point of 139 ℃ and a specific surface area of 541cm²(iv)/g, manufactured by Kimura Metal industries Co., Ltd.).

LED remounting was performed and conduction test evaluation was performed in the same manner as in example 1, except that the repair material 2 was used instead of the anisotropic conductive paste composition used in LED remounting. As a result, it was confirmed that all of the remounted 10 LEDs were turned on. In the on-lighting inspection after the TH test, it was confirmed that all of the remounted 10 LEDs were turned on.

[ example 4]

< preparation of repair Material 3 >

Seed and seed epoxy resin 49 parts by mass

Seed and seed curing agent (DICY, dicyandiamide) 3 parts by mass

9 parts by mass of seeding and soldering flux (adipic acid)

Seed Low-melting Spot welding tin particles 39 parts by mass

LED remounting was performed and conduction test evaluation was performed in the same manner as in example 1, except that the repair material 1 was used instead of the anisotropic conductive paste composition used in LED remounting. As a result, it was confirmed that all of the remounted 10 LEDs were turned on. In the on lighting test after the TH test, 9 LEDs mounted again were turned on, but 1 LED was not turned on.

[ example 5]

< preparation of repair Material 4 >

Seed and seed epoxy resin 46 parts by mass

Seed and seed curing agent (DICY, dicyandiamide) 3 parts by mass

12 parts by mass of seeding and soldering flux (adipic acid)

Seed Low-melting Spot welding tin particles 39 parts by mass

LED remounting was performed and conduction test evaluation was performed in the same manner as in example 1, except that the repair material 1 was used instead of the anisotropic conductive paste composition used in LED remounting. As a result, it was confirmed that all of the remounted 10 LEDs were turned on. In the on lighting test after the TH test, 6 LEDs to be mounted again were turned on, but 4 were not turned on.

Comparative example 1

In the repair process of the electronic component mounting substrate, 10 more LEDs were mounted on the substrate in the same manner as in example 1, except that the laser irradiation was not performed.

Then, when the on-state lighting inspection was performed in the same manner as in example 1, all of the remounted 10 LEDs were not turned on. In the on-lighting inspection after the TH test, all of the re-mounted 10 LEDs were not turned on.

Comparative example 2

In the repair process of the electronic component mounting substrate, 10 more LEDs were mounted on the substrate in the same manner as in example 1, except that the organic solvent (methyl ethyl ketone) was used instead of the laser irradiation to remove the deposits remaining on the electrodes of the substrate at the positions where the LED chips were removed.

Claims

1. A method for repairing an electronic component mounting substrate, which is a method for repairing an electronic component mounting substrate in which an electronic component is mounted so as to be electrically connected to an electrode on a wiring substrate via a cured product of a conductive paste composition, the method comprising:

2. The method according to claim 1, wherein a repair material comprising a curable resin is applied to the region from which the cured product has been removed or the electronic component to be remounted, and the electronic component is remounted.

3. The method according to claim 1 or 2, wherein the conductive paste composition comprises a curable resin and conductive particles, and the light absorption wavelength of at least one of a cured product of the curable resin and the conductive particles is 300nm to 10600 nm.

4. The method according to claim 3, wherein the electronic component mounting region is heated at a temperature higher than a glass transition point of the cured product and not lower than a melting point of the conductive particles.

5. The method of claim 2, wherein,

the conductive paste composition and the repair material contain a flux,

6. The method according to claim 5, wherein the repair material contains the flux in a proportion of 0.5 to 20 mass% relative to the solid content of the repair material.

7. A repair material used when an electronic component is remounted from an electronic component mounting substrate on which an electronic component is mounted so as to be electrically connected to an electrode on a wiring substrate via a cured product of a conductive paste composition, the repair material being used when the electronic component is remounted, the repair material being characterized in that:

at least comprises a curable resin and a soldering flux,

8. The repair material according to claim 7, further comprising conductive particles.

9. A cured product of the repair material according to claim 7 or 8.

10. A wiring board comprising the cured product according to claim 9.