Resin composition for flux, electronic component, method for manufacturing electronic component, mounting structure, and method for manufacturing mounting structure

Abstract

To provide a resin composition for a flux which has a high reinforcement effect due to a cured product that is a flux residue while functioning as a flux.SOLUTION: A resin composition for a flux contains 60 wt.% or more and 80 wt.% or less of an epoxy resin. The resin composition for the flux contains 0.01 wt.% or more and 2 wt.% or less of an imidazole compound. The resin composition for the flux contains 1 wt.% or more and 5 wt.% or less of a thixotropic agent. The resin composition for the flux contains 4 wt.% or more and 20 wt.% or less of an activator. The resin composition for the flux contains 7 wt.% or more and 30 wt.% or less of a phenolic compound. The epoxy resin contains 15 wt.% or more and 40 wt.% or less of at least one selected from the group consisting of a naphthalene type epoxy resin, a biphenyl aralkyl type epoxy resin, a trisphenol methane type epoxy resin, a biphenyl type epoxy resin, and a dicyclopentadiene type epoxy resin. The phenolic compound is liquid, and contains phenol novolac.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure generally relates to a resin composition for flux, an electronic component, a method for manufacturing an electronic component, a mounting structure, and a method for manufacturing the mounting structure. More specifically, the present disclosure relates to a resin composition for flux, an electronic component including a cured product of the resin composition for flux and a method for manufacturing the electronic component, and a mounting structure including a cured product of the resin composition for flux and a method for manufacturing the electronic component. [Background technology]

[0002] Flux used in soldering has the effect of chemically removing metal oxides present on the solder alloy and the metal surface of the objects to be soldered, and enabling the movement of metal elements at the interface between the two. Therefore, by using flux for soldering, an intermetallic compound can be formed between the solder alloy and the metal surface of the objects to be soldered, resulting in a strong bond. Flux generally used in soldering contains components that do not decompose or evaporate during reflow, so these remain around the solder as flux residue after soldering.

[0003] In recent years, as automobiles have become more sophisticated, the number of electronic devices installed in the automobiles has increased and the locations where they are installed have become more diverse. In this situation, the environments to which the electronic devices are exposed are becoming increasingly harsh, and depending on the location where they are installed, they are exposed to heat cycles of -40℃ to 85℃ during use.

[0004] On the other hand, in-vehicle devices are becoming smaller and more functional, and the soldered parts are becoming smaller. As a result, the soldered joints themselves are becoming smaller, making it more difficult to ensure the reliability of the soldered parts against heat cycles.

[0005] To address this issue, the soldered areas are reinforced by covering them with underfill material or resin molding material to ensure reliability. However, this requires cleaning off the flux residue before reinforcing the soldered areas, which can be time-consuming and costly.

[0006] In order to eliminate the need for cleaning, a method has been proposed in which a thermosetting resin is mixed into the flux and the flux residue is used as a reinforcing material.

[0007] Patent Document 1 discloses a flux that contains a bisphenol A type epoxy resin as a thermosetting resin, which hardens after soldering, thereby enabling the reinforcement of solder joints and eliminating the need for cleaning.

[0008] Patent Document 2 discloses a flux composition containing 20 wt % or more and 50 wt % or less of epoxy resin, 15 wt % or more and 45 wt % or less of diallyl bisphenol A, and 1 wt % or more and 30 wt % or less of organic acid. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2015 / 146473 [Patent Document 2] JP 2020-25973 A Summary of the Invention [Problem to be solved by the invention]

[0010] In the above-mentioned flux composition, it is desired that a reinforcing material having a high reinforcing effect can be obtained.

[0011] An object of the present disclosure is to provide a resin composition for flux that functions as a flux while having a high reinforcing effect due to the cured product, which is a flux residue.

[0012] Another object of the present disclosure is to provide an electronic component, a manufacturing method for an electronic component, a mounting structure, and a manufacturing method for a mounting structure, each of which uses the above-mentioned resin composition for flux. [Means for solving the problem]

[0013] The flux resin composition according to one embodiment of the present disclosure contains an epoxy resin in the range of 60% by weight to 80% by weight. The imidazole compound is contained in the range of 0.01% by weight to 2% by weight. The thixotropic agent is contained in the range of 1% by weight to 5% by weight. The activator is contained in the range of 4% by weight to 20% by weight. The phenol compound is contained in the range of 7% by weight to 30% by weight. The epoxy resin contains at least one selected from the group consisting of naphthalene type epoxy resin, biphenyl aralkyl type epoxy resin, trisphenol methane type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin in the range of 15% by weight to 40% by weight. The phenol compound is liquid and contains phenol novolac.

[0014] An electronic component according to one aspect of the present disclosure includes an electronic component body, a conductor, a solder bump, and a reinforcing portion. The conductor is formed on a surface of the electronic component body. The bump is disposed on the conductor. The bump is electrically connected to the conductor. The reinforcing portion is a cured product of the flux resin composition. The reinforcing portion reinforces a joint between the conductor and the bump.

[0015] A method for producing an electronic component according to an embodiment of the present disclosure includes applying the flux resin composition to a joint between the conductor and the bump, and then curing the flux resin composition.

[0016] A mounting structure according to one embodiment of the present disclosure includes a circuit board, an electronic component, a solder bump, and a reinforcing portion. The circuit board includes a first conductor. The electronic component includes a second conductor. The bump is disposed between the first conductor and the second conductor. The bump electrically connects the first conductor and the second conductor. The reinforcing portion is a cured product of the flux resin composition. The reinforcing portion reinforces at least one of a joint between the first conductor and the bump and a joint between the second conductor and the bump.

[0017] A method for manufacturing a mounting structure according to one aspect of the present disclosure is a method for manufacturing the mounting structure, comprising the steps of: applying the flux resin composition to at least one of a joint between the first conductor and the bump and a joint between the second conductor and the bump, and then curing the flux resin composition. Effect of the Invention

[0018] According to the present disclosure, there is an advantage in that a resin composition for flux can be obtained that functions as a flux while having a high reinforcing effect due to the cured product, which is the flux residue. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a graph showing an example of a reflow profile when a resin composition for flux according to an embodiment of the present disclosure and solder are heated. [Diagram 2] FIG. 2 is a schematic cross-sectional view illustrating an example of an electronic component according to an embodiment of the present disclosure. [Diagram 3] 3A to 3C are schematic cross-sectional views showing an example of a method for manufacturing the electronic component. [Figure 4] 4A to 4C are schematic cross-sectional views showing an example of a mounting structure according to an embodiment of the present disclosure. [Diagram 5] 5A to 5C are schematic cross-sectional views showing an example of a method for manufacturing the above mounting structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] 1. Overview The flux resin composition (X) of this embodiment contains an epoxy resin (A), an imidazole compound (B), a thixotropic agent (C), an activator (D), and a phenol compound. The flux resin composition (X) contains an epoxy resin (A) in the range of 60% by weight to 80% by weight. The flux resin composition (X) contains an imidazole compound (B) in the range of 0.01% by weight to 2% by weight. The flux resin composition (X) contains a thixotropic agent (C) in the range of 1% by weight to 5% by weight. The flux resin composition (X) contains an activator (D) in the range of 4% by weight to 20% by weight. The flux resin composition (X) contains a phenol compound (E) in the range of 7% by weight to 30% by weight.

[0021] The epoxy resin (A) contains at least one selected from the group consisting of naphthalene type epoxy resins, biphenyl aralkyl type epoxy resins, trisphenolmethane type epoxy resins, biphenyl type epoxy resins, and dicyclopentadiene type epoxy resins in an amount within the range of 15% by weight to 40% by weight.

[0022] The phenol compound (E) is liquid and contains phenol novolak.

[0023] Since the flux resin composition (X) of this embodiment contains liquid phenol novolac, the coverage rate of the cured product (reinforcing part) is improved, and the reinforcing effect of the cured product, which is the flux residue, is high. That is, compared with a flux resin composition not containing liquid phenol novolac, the flux resin composition (X) of this embodiment has a higher height of the cured product, a larger area attached to the bump, and an improved coverage rate of the bump (coverage rate). Therefore, the bump is easily reinforced by the cured product. In addition, the flux resin composition (X) of this embodiment has a high glass transition temperature of the cured product, high reliability of the reinforcing part, and good storage stability, so that productivity is also good.

[0024] The flux residue refers to a cured product that remains after the flux resin composition (X) has acted as a flux.

[0025] 2.Details The flux resin composition (X) of this embodiment, the electronic component 100 (see FIG. 2), the manufacturing method of the electronic component 100 (see FIGS. 3A to 3C), the mounting structure 1 (see FIGS. 4A to 4C), and the manufacturing method of the mounting structure 1 (see FIGS. 5A to 5C) will be described in detail below.

[0026] 2-1. Resin composition for flux (X) As described above, the resin composition for flux (X) of this embodiment contains the epoxy resin (A), the imidazole compound (B), the thixotropic agent (C), the activator (D), and the phenol compound (E). The epoxy resin (A), the imidazole compound (B), the thixotropic agent (C), the activator (D), and the phenol compound (E) will be described in detail below.

[0027] (1) Epoxy resin (A) The epoxy resin (A) is a compound having an epoxy group, and has the property of being cured by heating. Therefore, the epoxy resin (A) can impart thermosetting properties to the flux resin composition (X). The epoxy resin (A) preferably has two or more epoxy groups in one molecule, and in this case, it is easier to cure than an epoxy resin having only one epoxy group in one molecule.

[0028] The epoxy resin (A) is preferably liquid at room temperature. When the epoxy resin (A) is liquid at room temperature, it is possible to easily mix the epoxy resin (A) with other components in the resin composition for flux (X). Here, being liquid at room temperature means having fluidity under atmospheric pressure and at an ambient temperature of 5°C or higher and 28°C or lower (particularly around 20°C). Therefore, the epoxy resin (A) may be composed of only components that are liquid at room temperature, or may be composed of components that are liquid at room temperature and components that are not liquid at room temperature, or the epoxy resin (A) may be liquid at room temperature due to a reactive diluent, solvent, etc.

[0029] The epoxy resin (A) includes two types of epoxy resins: an epoxy resin (A1) and an epoxy resin (A2) other than the epoxy resin (A1).

[0030] The epoxy resin (A1) is more rigid than the epoxy resin (A2) and contains at least one selected from the group consisting of naphthalene type epoxy resins, biphenyl aralkyl type epoxy resins, trisphenolmethane type epoxy resins, biphenyl type epoxy resins, and dicyclopentadiene type epoxy resins. In this case, the glass transition temperature (Tg) of the cured resin composition for flux (X) is easily improved.

[0031] Naphthalene type epoxy resin, biphenyl aralkyl type epoxy resin, trisphenol methane type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin have two or more cyclic structures in one molecule, and therefore tend to have a higher glass transition temperature (Tg) of the cured product than epoxy resins that do not have two or more cyclic skeletons in one molecule. This is thought to be because the presence of a cyclic skeleton restricts the movement of the molecular chain. Specifically, naphthalene type epoxy resin, biphenyl aralkyl type epoxy resin, trisphenol methane type epoxy resin, biphenyl type epoxy resin, and dicyclopentadiene type epoxy resin tend to have a glass transition temperature of 85°C or higher in the cured product.

[0032] The naphthalene type epoxy resin is an epoxy resin containing one or more naphthalene skeletons in one molecule. The naphthalene skeleton has rigidity and hydrophobicity, and can increase the glass transition temperature of the cured product of the flux resin composition (X).

[0033] The biphenylaralkyl type epoxy resin is an epoxy resin containing one or more aralkyl skeletons having a biphenyl group in one molecule, and since the aralkyl skeleton has a rigid biphenyl group, the glass transition temperature of the cured product of the resin composition for flux (X) can be increased.

[0034] The trisphenolmethane type epoxy resin is an epoxy resin having three epoxy groups with phenylmethane skeletons in one molecule, and has a high functional group (epoxy group) density, so that the glass transition temperature of the cured product of the flux resin composition (X) can be increased.

[0035] The dicyclopentadiene type epoxy resin is an epoxy resin having one or more dicyclopentadiene skeletons in one molecule, and the rigid dicyclopentadiene skeleton can increase the glass transition temperature of the cured product of the flux resin composition (X).

[0036] The epoxy resin (A1) preferably has an epoxy group equivalent in the range of 100 or more and 500 or less.

[0037] Examples of the epoxy resin (A1) include HP-4302D (semi-solid, manufactured by DIC Corporation) as a naphthalene type epoxy resin represented by formula (1), HP-4700 (softening point 85° C.-95° C., manufactured by DIC Corporation) and HP-4710 (softening point 85° C.-105° C., manufactured by DIC Corporation) as a naphthalene type epoxy resin represented by formula (2), and HP-4710 (softening point 85° C.-105° C., manufactured by DIC Corporation) as a naphthalene type epoxy resin represented by formula (3). Examples of the naphthalene-type epoxy resin represented by formula (4) include EXA-4750 (softening point 80°C, manufactured by DIC Corporation); HP-4770 (softening point 67°C-77°C, manufactured by DIC Corporation) as the naphthalene-type epoxy resin represented by formula (4); and HP-6000 (softening point 65°C-85°C, manufactured by DIC Corporation) and HP-6000L (softening point 59°C, manufactured by DIC Corporation) as the mixture of the naphthalene-type epoxy resin represented by formula (5) and formula (6).

[0038] Examples of the trisphenolmethane type epoxy resin represented by formula (7) include HP-7241 (softening point 66°C, manufactured by DIC Corporation), examples of the trisphenolmethane type epoxy resin represented by formula (8) include HP-7250 (semi-solid, manufactured by DIC Corporation), and examples of the trisphenolmethane type epoxy resin represented by formula (9) include EPPN-501H (softening point 51°C-57°C, manufactured by Nippon Kayaku Co., Ltd.), EPPN-501HY (softening point 57°C-63°C, manufactured by Nippon Kayaku Co., Ltd.), and EPPN-502H (softening point 60°C-72°C, manufactured by Nippon Kayaku Co., Ltd.).

[0039] Examples of the biphenyl aralkyl type epoxy resin represented by the formula (10) include NC-3000 (softening point 53°C-63°C, manufactured by Nippon Kayaku Co., Ltd.), NC-3000L (softening point 45°C-60°C, manufactured by Nippon Kayaku Co., Ltd.), NC-3000-H (softening point 65°C-75°C, manufactured by Nippon Kayaku Co., Ltd.), and NC-3100 (softening point 90°C-103°C, manufactured by Nippon Kayaku Co., Ltd.).

[0040] Examples of the biphenyl type epoxy resin represented by the formula (11) include YH4000 (softening point 105° C., manufactured by Mitsubishi Chemical Corporation) and YX4000H (softening point 105° C., manufactured by Mitsubishi Chemical Corporation).

[0041] Examples of the dicyclopentadiene type epoxy resin represented by the formula (12) include HP-7200 (softening point 56°C-66°C, manufactured by DIC Corporation), HP-7200L (softening point 50°C-60°C, manufactured by DIC Corporation), HP-7200H (softening point 78°C-88°C, manufactured by DIC Corporation), HP-7200HH (softening point 88°C-98°C, manufactured by DIC Corporation), HP-7200HHH (softening point 100°C-110°C, manufactured by DIC Corporation), and XD-1000 (softening point 68°C-78°C, manufactured by Nippon Kayaku Co., Ltd.).

[0042] [ka]

[0043] [ka]

[0044] [ka]

[0045] [ka]

[0046] The epoxy resin (A2) has a lower rigidity than the epoxy resin (A1), and may contain, for example, one or more components selected from the group consisting of glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, olefin oxide type (alicyclic) epoxy resins, bisphenol type epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins, hydrogenated bisphenol type epoxy resins such as hydrogenated bisphenol A type epoxy resins and hydrogenated bisphenol F type epoxy resins, alicyclic epoxy resins, phenol novolac type epoxy resins, cresol novolac type epoxy resins, aliphatic epoxy resins, and triglycidyl isocyanurate.

[0047] It is particularly preferable that the epoxy resin (A2) contains any one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, and hydrogenated bisphenol F type epoxy resin. In this case, the viscosity of the resin composition for flux (X) can be easily reduced, and the physical properties of the cured product of the resin composition for flux (X) can be easily improved.

[0048] (2) Imidazole compounds (B) The imidazole compound (B) is a curing agent for the epoxy resin (A). The flux resin composition (X) needs to be cured after functioning as a flux during reflow. In this embodiment, since the melting point of the imidazole compound (B) is high, it is difficult for the imidazole compound (B) to function as a curing agent at temperatures between room temperature and the melting point of the solder bump, and curing of the epoxy resin is difficult to proceed. Therefore, during this period, the flux resin composition (X) acts as a flux. Then, when the temperature is further increased to a temperature equal to or higher than the melting point of the solder bump, the imidazole compound (B) begins to act as a curing agent after soldering is completed, so that ring-opening polymerization of the epoxy resin (A) and the imidazole compound (B) proceeds, and the flux resin composition (X) is cured. Then, the flux resin composition (X) after curing acts as the reinforcing part 4.

[0049] The imidazole compound (B) is preferably a solid having a melting point of 130° C. or higher. In this case, the imidazole compound (B) is difficult to melt at a temperature below 130° C. (e.g., 25° C.) and remains in a solid state, so that it is difficult to mix with the epoxy resin (A) compared with a case where the imidazole compound (B) is in a liquid state. This makes it possible to suppress the reaction between the epoxy resin (A) and the imidazole compound (B), and improves the storage stability of the flux resin composition (X).

[0050] Examples of the imidazole compound (B) include 2-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., product number: 2MZ-H, melting point 140-148° C.), 2-phenylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., product numbers: 2PZ, 2PZ-PW, melting point 137-147° C.), 2-phenyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd., product number: 2P4MZ, melting point 174-184° C.), 2,4-diamino-6-[2 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine (manufactured by Shikoku Kasei Co., Ltd., product numbers: 2MZ-A, 2MZA-PW, melting point: 248-268°C), 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine (manufactured by Shikoku Kasei Co., Ltd., product number: C11Z-A, melting point: 187-195°C), 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (manufactured by Shikoku Kasei Co., Ltd., product number: C11Z-A, melting point: 187-195°C), midazolyl-(1')]-ethyl-s-triazine (manufactured by Shikoku Kasei Co., Ltd., product number: 2E4MZ-A, melting point 215-225°C), 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct (manufactured by Shikoku Kasei Co., Ltd., product number: 2MA-OK, 2MAOK-PW, melting point 260°C), 2-phenylimidazole isocyanuric acid adduct (manufactured by Shikoku Kasei Co., Ltd., product number: 2MA-OK, 2MAOK-PW, melting point 260°C), One or more of the following compounds can be selected and used: 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Kasei Co., Ltd., product number: 2PZ-OK, melting point 140°C), 2-phenyl-4,5-dihydroxymethylimidazole (manufactured by Shikoku Kasei Co., Ltd., product number: 2PHZ-PW, melting point 230°C), and 2-phenyl-4-methyl-5-hydroxymethylimidazole (manufactured by Shikoku Kasei Co., Ltd., product number: 2P4MHZ-PW, melting point 191-195°C).

[0051] The form of the solid imidazole compound (B) is not particularly limited, but is preferably, for example, powder, granule, or particulate. In this case, it is easy to achieve both the reaction suppression of the flux resin composition (X) at room temperature and the rapid curing of the flux resin composition (X) during reflow. When the imidazole compound (B) is in the form of powder, etc., its average particle size is preferably 0.5 μm or more and 50 μm or less, but is not limited thereto. The average particle size can be, for example, the median diameter (D50) of the particle size distribution obtained using a laser diffraction / scattering method.

[0052] (3) Thixotropic agent (C) The thixotropic agent (C) is a compound that imparts thixotropy to the flux resin composition (X). Here, "thixotropy" refers to the property of a substance's viscosity decreasing when subjected to shear stress. Thixotropy is quantified by the thixotropic ratio, which can be obtained, for example, by measuring two viscosities at a constant temperature while changing the rotational speed of a rotational viscometer, and calculating the ratio of the two viscosities. The rotational speed of the rotational viscometer is, for example, 0.25 rpm and 2.5 rpm at 25°C.

[0053] The flux resin composition (X) preferably has a viscosity of 10 Pa·s or more and 250 Pa·s or less at 25° C. and 2.5 rpm, and a thixotropic ratio of 1.5 or more and 8 or less.

[0054] The thixotropic agent (C) can be, for example, one or more selected from the group consisting of 1,3:2,4-bis-O-benzylidene-D-glucitol (dibenzylidene sorbitol) (manufactured by New Japan Chemical Co., Ltd., product name: Gelall D), 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol (manufactured by New Japan Chemical Co., Ltd., product name: Gelall MD), and N,N'-methylenebis(stearamide) (manufactured by Mitsubishi Chemical Corporation, product name: Bisamide LA).

[0055] (4) Activator (D) Since the activator (D) has a function of removing a metal oxide film, the inclusion of the activator (D) in the resin composition for flux (X) can impart a fluxing effect to the resin composition for flux (X). Here, the "fluxing effect" refers to the reducing effect of removing an oxide film formed on a metal surface to which solder is applied, and the effect of reducing the surface tension of the molten solder to promote the wettability of the solder to the joining metal surface.

[0056] The activator (D) preferably contains at least one of an organic acid (D1) having a carboxyl group equivalent of 40 g / mol to 400 g / mol and a melting point of 220°C or less, and an amine (D2) having a nitrogen atom equivalent of 10 g / mol to 300 g / mol and a melting point of 220°C or less. Since the activator (D) has a melting point of 220°C or less, even when a solder having a melting point of around 200°C or more is used, the oxide film of the solder can be removed before the solder is melted. Here, the "carboxyl group equivalent" means a value expressed by the molar molecular weight (g) / the number of carboxyl groups (mol) per molecule, and the "nitrogen atom equivalent" means a value expressed by the molar molecular weight (g) / the number of nitrogen atoms (mol) per molecule.

[0057] The organic acid (D1) may include at least one selected from the group consisting of rosin component materials, adipic acid, glutaric acid, succinic acid, malonic acid, citric acid, suberic acid, sebacic acid, and pimelic acid. The organic acid (D1) may include, in particular, succinic acid (carboxyl group equivalent: 59 g / mol), glutaric acid (carboxyl group equivalent: 66 g / mol), adipic acid (carboxyl group equivalent: 73 g / mol), suberic acid (carboxyl group equivalent: 87 g / mol), sebacic acid (carboxyl group equivalent: 101 g / mol), and Tsunodyme 395 (carboxyl group equivalent: 288 g / mol).

[0058] The amine (D2) is not particularly limited as long as it is an amine used as a flux, and may include, for example, at least one selected from the group consisting of various amine salts, alkanolamines, and guanidines. The amine (D2) preferably includes, in particular, diethanolamine (nitrogen atom equivalent: 105 g / mol), triethanolamine (TEA) (nitrogen atom equivalent: 149 g / mol), triisopropanolamine (nitrogen atom equivalent: 191 g / mol), 1,3-diphenylguanidine (nitrogen atom equivalent: 70 g / mol), and 1,3-di-o-tolylguanidine (nitrogen atom equivalent: 80 g / mol).

[0059] The activator (D) may contain components other than the organic acid (D1) and the amine (D2). The activator (D) may contain an organic acid or amine having a melting point of more than 220°C.

[0060] (5) Phenolic compounds (E) The phenol compound (E) is liquid at room temperature. The phenol compound (E) contains phenol novolac (novolac-type phenol resin). As the phenol novolac, for example, one shown in formula (13) can be used. The phenol compound (E) may contain a phenol compound other than phenol novolac. That is, as the phenol compound (E), a phenol novolac and a phenol compound other than phenol novolac can be used in combination. A phenol compound that is solid at room temperature can be used by dissolving or dispersing it in a phenol compound that is liquid at room temperature.

[0061] The flux resin composition (X) of the present embodiment is liquid at room temperature and contains phenol novolac, so that the coverage of the cured product can be increased compared to a flux resin composition not containing a liquid phenol compound and a flux resin composition not containing phenol novolac. For example, the flux resin composition (X) of the present embodiment has an improved coverage compared to a case where diaryl bisphenol A shown in formula (14) is used as the phenol compound.

[0062] The weight average molecular weight of the phenol novolac is preferably 200 to 10000, more preferably 225 to 8000, and further preferably 250 to 6000. By using such a phenol novolac, the coverage of the flux resin composition (X) is improved. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) in terms of polystyrene.

[0063] The OH group equivalent (g / mol) of the phenol novolac is preferably 50 to 1500, more preferably 50 to 1000, and further preferably 100 to 500. By using such a phenol novolac, the coverage of the resin composition for flux (X) is improved. The OH group equivalent was measured according to JIS K 0070.

[0064] The phenol compound (E) mainly acts to improve the coverage of the cured product of the resin composition for flux (X), but a part of the phenol compound (E) also acts as a curing agent for the epoxy resin (A).

[0065] In this disclosure, the term "coverage ratio" refers to the ratio of the height of the reinforcing part to the height of the bump in electronic components and mounting structures. The higher the coverage ratio, the higher the reinforcing part covers the bump, and the larger the area of ​​the bump covered by the reinforcing part, allowing the joint between the conductor and the bump to be sufficiently reinforced. Therefore, the reinforcing effect of the reinforcing part on the bump is improved.

[0066] As shown in FIG. 3C, if the height (dimension) from the surface of a circuit board such as electrical component body 200 to the top of bump 30 joined to conductor 210 is HB, and the height (dimension) from the surface of a circuit board such as electrical component body 200 to the top of reinforcing portion 4 is HR, the coverage rate is calculated by the following formula.

[0067] Coverage rate (%) = (reinforcement height / bump height) x 100 = HR / HB x 100

[0068] [ka]

[0069] (6) Other ingredients (F) The flux resin composition (X) may contain components other than the epoxy resin (A), the imidazole compound (B), the thixotropic agent (C), the activator (D) and the phenol compound (E), such as a component modifier such as rosin, a filler, a solvent, etc.

[0070] (7) Content of each ingredient The flux resin composition (X) of this embodiment contains, relative to the total amount of the flux resin composition (X), an epoxy resin (A) in the range of 60% by weight to 80% by weight, an imidazole compound (B) in the range of 0.01% by weight to 2% by weight, a thixotropic agent (C) in the range of 1% by weight to 5% by weight, an activator (D) in the range of 4% by weight to 20% by weight, and a phenol compound (E) in the range of 7% by weight to 30% by weight. Here, the total amount of the flux resin composition (X) is obtained by adding up the weights of the epoxy resin (A), the imidazole compound (B), the thixotropic agent (C), the activator (D), the phenol compound (E), and the other components (F).

[0071] The flux resin composition (X) of the present embodiment contains the rigid epoxy resin (A1) in a range of 15% by weight or more and 40% by weight or less based on the total amount of the flux resin composition (X). In this case, the glass transition point of the cured product of the flux resin composition (X) can be increased. The epoxy resin (A1) is more preferably contained in a proportion of 25% by weight or more, and particularly preferably contained in a proportion of 30% by weight or more, based on the total amount of the flux resin composition (X).

[0072] If the entire epoxy resin (A) is composed of the epoxy resin (A1), it may become solid and become impossible to supply, so the epoxy resin (A1) is preferably 80% by weight or less of the entire epoxy resin (A). The remainder of the entire epoxy resin (A) other than the epoxy resin (A1) may be composed of the epoxy resin (A2).

[0073] The flux resin composition (X) of the present embodiment has the above-mentioned content of each component, and therefore the cured product has a high glass transition point and good storage stability, and can increase the coverage of the reinforcing part, which is the cured product.

[0074] In the resin composition for flux (X), when the content ratio of the epoxy resin (A) is 60% by weight or more and 80% by weight or less based on the total amount of the resin composition for flux (X), the glass transition temperature of the cured resin composition for flux (X) can be increased, and the storage stability of the resin composition for flux (X) becomes good.

[0075] In the resin composition for flux (X), when the content ratio of the imidazole compound (B) is 0.01% by weight or more and 2% by weight or less based on the total amount of the resin composition for flux (X), the storage stability of the resin composition for flux (X) becomes good.

[0076] In the resin composition for flux (X), when the content of the thixotropic agent (C) is 1% by weight or more and 5% by weight or less with respect to the total amount of the resin composition for flux (X), the viscosity at 25°C and 2.5 rpm is easily set to 10 Pa·s or more and 130 Pa·s or less, and the thixotropic ratio (25°C, 0.25 rpm / 2.5 rpm) is easily set to 1.5 or more and 8 or less, and the resin composition for flux (X) can be applied to a supply method such as printing, transfer, dispenser, etc. If the thixotropic ratio is less than 1.5, the resin composition for flux (X) is difficult to maintain its shape after being supplied by printing, and bridging is easily generated. On the other hand, if the amount of the thixotropic agent (C) is large and the thixotropic ratio exceeds 8, the resin composition for flux (X) is difficult to remove from the printing mask, and chipping is easily generated.

[0077] In the resin composition for flux (X), when the content ratio of the activator (D) is 4% by weight or more and 20% by weight or less based on the total amount of the resin composition for flux (X), the resin composition for flux (X) can be easily endowed with flux properties and can have good storage stability.

[0078] When the content of the phenol compound (E) in the resin composition for flux (X) is 7% by weight or more and 30% by weight or less, the coverage of the resin composition for flux (X) can be easily made good (for example, 20 to 30%).

[0079] (8) Properties The flux resin composition (X) according to this embodiment has a time period of 24 hours or more from the start of storage at 25°C until the value calculated from (viscosity after storage / viscosity at the start of storage) x 100(%) reaches 120% (property corresponding to "life" described below), which provides excellent storage stability. The flux resin composition (X) according to this embodiment also has a solder ball wettability of 50% or more before and after reflow (property corresponding to "wettability" described below), which provides excellent solder wettability during reflow. Furthermore, the flux resin composition (X) according to this embodiment has a glass transition temperature of 85°C or more after curing (property corresponding to "glass transition point (Tg)" described below), which provides excellent reinforcing effect of the cured product at the solder joint.

[0080] 2-2. Electronic components and their manufacturing methods The configuration of an electronic component 100 to which the flux resin composition (X) is applied and the manufacturing method thereof will be described below.

[0081] (1) Electronic component configuration The electronic component 100 of this embodiment will be described with reference to Fig. 2. Note that the configuration of the electronic component 100 described below is merely an example, and the configuration of the electronic component 100 is not limited to the following content.

[0082] The electronic component 100 is, but is not limited to, a surface-mount semiconductor chip, for example. The semiconductor chip is, but is not limited to, a BGA (ball grid array), a WLP (wafer level package), or the like.

[0083] The electronic component 100 includes an electronic component body 200, a conductor 210, a solder bump 30, and a reinforcing portion 4.

[0084] The conductor 210 is formed on the surface of the electronic component body 200, and therefore the conductor 210 is exposed to the outside at the surface of the electronic component body 200. When the electronic component 100 is a WLP, the electronic component body 200 includes, for example, a silicon substrate provided with a rewiring layer, and the conductor 210 is, for example, a pillar electrically connected to the rewiring layer. When the electronic component 100 is a BGA, the electronic component body 200 is, for example, a package configured by sealing a die mounted on a substrate with a sealing resin, and the conductor 210 is, for example, an electrode pad electrically connected to the die. The structure of the electronic component body 200 is not limited to the above, and may be any appropriate structure according to the type of electronic component 100.

[0085] The bump 30 is disposed on the conductor 210 and is electrically connected to the conductor 210. Therefore, a joint 20 is formed between the bump 30 and the conductor 210. The bump 30 is not particularly limited, and may be made of, for example, SAC solder or tin-copper (Sn-Bi) solder. The Sn-Bi solder may contain at least one material selected from the group consisting of Ag, Ni, Fe, Ge, Cu, and In in addition to Sn and Bi. In order to improve the mechanical performance of the Sn-Bi solder, it is preferable that the Sn-Bi solder contains at least one material selected from the group consisting of Ag, Ni, Fe, and Ge.

[0086] The reinforcing portion 4 is a cured product of the resin composition for flux (X). In the electronic component 100, the reinforcing portion 4 is attached to the outside of the joint 20 between the bump 30 and the conductor 210. That is, in the electronic component 100, the cured product of the resin composition for flux (X) is attached to the outside of the joint 20 between the bump 30 and the conductor 210. Therefore, the reinforcing portion 4 can reinforce the joint 20 between the bump 30 and the conductor 210, and the connection reliability of the electronic component 100 can be improved.

[0087] (2) Manufacturing methods for electronic components A method for manufacturing electronic component 100 will now be described with reference to FIGS. 3A to 3C.

[0088] First, an electronic component body 200 including a conductor 210 is prepared, and a flux resin composition (X) is arranged so as to cover the conductor 210 (see FIG. 3A). The method for arranging the flux resin composition (X) is not particularly limited, but can be performed by, for example, a printing method such as an inkjet method, a transfer method, or the like.

[0089] Next, the bump 30 is disposed above the conductor 210 so that the bump 30 is in contact with the flux resin composition (X) (see FIG. 3B). As the bump 30, for example, a solder ball can be used.

[0090] Next, the bump 30 and the flux resin composition (X) are heated in the state shown in Fig. 3B. The heating method is not particularly limited, but for example, heating in a reflow furnace can be used. In this case, the bump 30 and the flux resin composition (X) can be heated according to a reflow profile such as that shown in Fig. 1.

[0091] The fluxing properties of the flux resin composition (X) and the method for producing a reinforcing portion for reinforcing the joint between a conductor and a solder bump will be described below.

[0092] Bumps made of solder are arranged on the conductor, and by melting these bumps, the conductor and the bumps can be electrically connected. By attaching a cured product of the flux resin composition (X) to the joint between the conductor and the bumps, the joint between the conductor and the bumps can be reinforced. For example, with the flux resin composition (X) arranged between the conductor and the bumps, the bumps and the flux resin composition (X) are heated. As the viscosity of the flux resin composition (X) decreases with heating, the flux resin composition (X) acts as a flux while flowing. As the flux resin composition (X) flows, the bumps come into contact with the conductor. With the flux resin composition (X) maintaining fluidity, the bumps melt and adhere to the conductor. At this time, the flux resin composition (X) adheres to the outside of the joint between the conductor and the bumps and cures in that state, thereby producing a reinforcing portion. Thereby, the conductor and the bumps are electrically connected, and reinforcement can be achieved by fixing a reinforcing portion, which is a cured product of the flux resin composition (X), to the outside of the joint between the conductor and the bumps. To melt the bumps, the bumps and the flux resin composition (X) are heated to a temperature higher than the melting point of the solder.

[0093] Examples of the heating temperature profile and the viscosity change of the flux resin composition (X) when electrically connecting the conductor and the bumps and producing a reinforcing portion are shown in the graph of FIG. 1. In the graph of FIG. 1, the dashed line indicates the heating temperature, and the solid line indicates the viscosity of the flux resin composition (X). T3 (°C) in the figure is the melting point of the bumps, and T1 (°C) and T2 (°C) are specific temperatures that satisfy the relationship room temperature < T1 < T2 < T3.

[0094] As shown in FIG. 1, first, the heating temperature is raised from room temperature to T1 (°C). Subsequently, the heating temperature is raised to T2 (°C). Subsequently, the heating temperature is raised to a temperature (peak temperature) higher than T3 (°C). Subsequently, the heating temperature is lowered to room temperature.

[0095] The melting point T3 (°C) of the bumps depends on the composition of the solder constituting the bumps. For example, in the case of Sn-Ag-Cu (SAC) solder, T3 (°C) is 217°C or higher and 230°C or lower.

[0096] T1 (°C) is preferably set to be close to the temperature at which the resin composition for flux (X) starts to melt. T1 (°C) is not particularly limited, but is, for example, 140°C or higher and 160°C or lower.

[0097] T2 (°C) is preferably defined as a temperature higher than T1 (°C) and lower than the temperature at which the resin composition for flux (X) starts curing. T2 is not particularly limited, but is, for example, 160°C or higher and 200°C or lower. The peak temperature is preferably defined as a temperature higher than T3 (°C) and higher than the temperature at which the resin composition for flux (X) starts curing. The peak temperature is not particularly limited, but is, for example, 232°C or higher and 255°C or lower. The heating rate when the heating temperature rises from room temperature to T1 (°C) is not particularly limited, but is, for example, 5°C / sec or lower. The time required for the heating temperature to rise from T1 (°C) to T2 (°C) is not particularly limited, but is, for example, 60 seconds or more and 100 seconds or less. The heating rate when the heating temperature rises from T2 (°C) to the peak temperature (°C) is, for example, 4°C / sec or less. The time during which the heating temperature is equal to or higher than T3 (°C) is not particularly limited, but is, for example, 30 seconds or more and 90 seconds or less.

[0098] As shown in FIG. 1, the viscosity of the flux resin composition (X) decreases around T1 (°C) and the flux resin composition (X) starts to flow. The melting in FIG. 1 refers to the melting of the epoxy resin (A). By controlling the rate of temperature rise from room temperature to T1 (°C), the time from the start of heating to when the flux resin composition (X) starts to flow can be controlled. As shown in FIG. 1, even if the heating temperature is raised from T1 (°C) to T2 (°C), the flux resin composition (X) maintains a low viscosity. Therefore, by controlling the rate of temperature rise from T1 (°C) to T2 (°C), the time during which the flux resin composition (X) maintains its fluidity can be controlled. This allows the flux resin composition (X) to flow sufficiently, thereby suppressing the generation of voids in the reinforcing part 4.

[0099] As shown in FIG. 1, when the heating temperature rises from T2 (°C) toward the peak temperature, the viscosity of the flux resin composition (X) is not likely to increase for a while even if the heating temperature exceeds T3 (°C), and the flux resin composition (X) maintains a state of having fluidity, followed by a sudden increase in viscosity. That is, even if the heating temperature exceeds the melting point of the solder, the flux resin composition (X) is likely to maintain a state of having fluidity for a while. Therefore, the flux resin composition (X) flows, and the bumps are easily brought into contact with the conductor, and the bumps are easily fused to the conductor. In addition, the self-alignment effect of the molten bumps is not easily inhibited by the flux resin composition (X). Furthermore, since the flux resin composition (X) contains an activator (D), the oxide film of the solder can be quickly removed by the fluxing action of the activator (D) during the time when the heating temperature rises from T2 (°C) to T3 (°C) and before the curing. As shown in Figure 1, the activity of the activator (D) continues even after the viscosity of the flux resin composition (X) increases due to the ring-opening and polymerization of the epoxy resin (A). This allows the conductor and the solder to be well connected, and the occurrence of poor electrical continuity can be further suppressed.

[0100] With the resin composition for flux (X) attached to the joint between the conductor and the solder, polymerization occurs due to ring opening of the epoxy group. Therefore, the resin composition for flux (X) hardens to form a reinforcing part that is fixed to the outside (outer surface) of the joint between the conductor and the solder. As shown in FIG. 1, even when the heating temperature drops from the peak temperature to room temperature, the viscosity of the resin composition for flux (X) continues to increase. Therefore, the resin composition for flux (X) can be quickly hardened while remaining attached to the outside of the joint between the conductor and the solder.

[0101] The reason why the flux resin composition (X) can achieve such viscosity behavior is believed to be due to the high melting point of the imidazole compound (B). Since the melting point of the imidazole compound (B) is 130°C or higher, the curing reaction of the flux resin composition (X) is unlikely to proceed between T1 (°C) and T3 (°C), and the flux resin composition (X) can maintain a low viscosity.

[0102] In addition, even if the heating temperature drops from the peak temperature to room temperature, the flux resin composition (X) cures quickly because the temperature of the flux resin composition (X) does not drop suddenly, but remains at a temperature sufficient for the curing reaction of the epoxy resin (A) and the imidazole compound (B) to proceed for a certain period of time. Therefore, an ideal three-dimensional crosslinked structure is formed, and a cured product with a high glass transition temperature (Tg) is obtained. If the flux resin composition (X) is applied to the electronic component 100 shown in Fig. 2, the reinforcing part 4 attached to the outside of the joint 20 between the conductor 210 and the bump 32 of the electronic component body 200 can be produced.

[0103] Furthermore, by applying the flux resin composition (X) to the mounting structure 1 shown in FIG. 4A, it is possible to produce a reinforcing portion 4 that adheres to the joint 20 between the first conductor 21 and the bump 32 when connecting the first conductor 21 of the circuit board 2 and the bump 32.

[0104] The flux resin composition (X) of this embodiment may be used to produce a reinforcing portion that covers the joint between the conductor and the bump after the conductor and the bump are electrically connected.

[0105] As described above, the flux resin composition (X) maintains a low viscosity until the bump 30 melts. Even when the bump 30 starts to melt, the viscosity of the flux resin composition (X) does not increase immediately, but increases rapidly after a while. Therefore, the flux resin composition (X) can be cured after it is attached to the outside of the joint 20 between the conductor 210 and the bump 30. This allows the conductor 210 and the bump 30 to be well connected. Therefore, poor conduction between the conductor 210 and the bump 30 can be suppressed. In addition, the cured product of the flux resin composition (X) can be fixed to the outside of the joint 20 between the conductor 210 and the bump 30. Therefore, the joint 20 between the conductor 210 and the bump 30 can be reinforced.

[0106] 2-3. Mounting structure and its manufacturing method (1) Mounting structure The mounting structure 1 of the present embodiment will be described with reference to Figures 4A to 4C. Note that the configuration of the mounting structure 1 shown below is merely an example, and the configuration of the mounting structure 1 is not limited to the following content.

[0107] The mounting structure 1 includes a circuit board 2 , an electronic component 3 , bumps 32 , and a reinforcing portion 4 .

[0108] The circuit board 2 is, for example, a mother board, a package board, or an interposer board. For example, the circuit board 2 is an insulating board made of glass epoxy, polyimide, polyester, ceramic, or the like. A first conductor 21 is formed on the surface of the circuit board 2. Therefore, the circuit board 2 includes the first conductor 21. The first conductor 21 is, but is not particularly limited to, a wiring formed of a conductor containing a metal such as copper or a copper alloy. The first conductor 21 may also include a plating layer, such as a nickel plating layer, a nickel-gold plating layer, or a gold plating layer, on the surface.

[0109] The electronic component 3 is, for example, a semiconductor chip, and more specifically, a flip-chip type chip such as a BGA (ball grid array), an LGA (land grid array), or a CSP (chip size package). The electronic component 3 may be a PoP (package on package) type chip. A second conductor 31 is formed on the surface of the electronic component 3. Therefore, the electronic component 3 includes the second conductor 31. The second conductor 31 is, but is not limited to, an electrode pad formed of a conductor containing a metal such as copper or a copper alloy. The second conductor 31 may also include a plating layer such as a nickel plating layer, a nickel-gold plating layer, or a gold plating layer on the surface.

[0110] The bump 32 is fixed between the first conductor 21 of the circuit board 2 and the second conductor 31 of the electronic component 3. The bump 32 electrically connects the first conductor 21 and the second conductor 31. The bump 32 can be made of solder. In this case, the type of solder is not particularly limited, but may be, for example, SAC solder (lead-free solder) or tin-copper (Sn-Bi) solder.

[0111] The reinforcing part 4 is a cured product of the flux resin composition (X). In the mounting structure 1, the reinforcing part 4 is attached to the outside of the joint 20 between the bump 32 and the first conductor 21. Therefore, the reinforcing part 4 can reinforce the joint 20 between the bump 32 and the first conductor 21, and can improve the connection reliability of the mounting structure 1. If the connection reliability is low, stress caused by environmental temperature changes or the like is repeatedly applied, and fatigue failure may occur.

[0112] In the mounting structure 1 shown in Fig. 4A, the reinforcing portion 4 is attached to the outside (outer surface) of the joint 20 between the first conductor 21 and the bump 32 of the circuit board 2, but is not limited thereto. For example, as in the mounting structure 1 shown in Fig. 4B, the reinforcing portion 4 may be attached to the outside of the joint 20 between the second conductor 31 and the bump 32 of the electronic component 3. Also, as in the mounting structure 1 shown in Fig. 4C, for example, the reinforcing portion 4 may be attached to the outside of the joint 20 between the first conductor 21 and the bump 32 of the circuit board 2, and the reinforcing portion 4 may be attached to the outside of the joint 20 between the second conductor 31 and the bump 32 of the electronic component 3.

[0113] 4A and 4C, when the interval between adjacent first conductors 21 is small (narrow pitch), or when the interval between adjacent second conductors 31 is small in the mounting structure 1 shown in FIGS. 4B and 4C, adjacent reinforcing portions 4 may be connected to each other and integrated. In addition, in the mounting structure 1 shown in FIGS. 4A to 4C, all reinforcing portions 4 may be connected to each other. That is, the surface of the circuit board 2 may be covered with reinforcing portions 4, or the surface of the electronic component 3 may be covered with reinforcing portions 4.

[0114] In addition, in the mounting structure 1 shown in FIG. 4C, the reinforcing portion 4 attached to the outside of the joint 20 between the first conductor 21 and the bump 32 and the reinforcing portion 4 attached to the outside of the joint 20 between the second conductor 31 and the bump 32 may be connected and integrated. However, when the bump 32 is heated multiple times at a temperature equal to or higher than the melting point of the solder constituting the bump 32 (for example, in a reflow process or a repair process), the internal pressure may increase when the solder is remelted, and solder flash may occur. If solder flash occurs, the first conductor 21 and the second conductor 31 may be destroyed due to the expansion of the bump 32. For this reason, it is preferable that the reinforcing portion 4 attached to the outside of the joint 20 between the first conductor 21 and the bump 32 and the reinforcing portion 4 attached to the outside of the joint 20 between the second conductor 31 and the bump 32 are not integrated.

[0115] (2) Manufacturing method of mounting structure Hereinafter, a method for manufacturing the mounting structure 1 shown in FIG. 4A will be described with reference to FIGS. 5A to 5C.

[0116] First, a circuit board 2 having a first conductor 21 is prepared, and a flux resin composition (X) is arranged so as to cover the first conductor 21 (see FIG. 5A). The method for arranging the flux resin composition (X) is not particularly limited, and can be, for example, by a method such as printing, transferring, or coating.

[0117] Next, an electronic component 3 including a second conductor 31 is prepared. Bumps 32 are provided on the second conductor 31, and the second conductor 31 and the bumps 32 are electrically connected. This electronic component 3 is placed on the circuit board 2 such that the bumps 32 are in contact with the flux resin composition (X) (see FIG. 5B).

[0118] Next, the bumps 32 and the flux resin composition (X) are heated in the state shown in Fig. 5B. The heating method is not particularly limited, but for example, heating in a reflow furnace can be used. In this case, the bumps 32 and the flux resin composition (X) can be heated according to a reflow profile such as that shown in Fig. 1.

[0119] As described in the above section "2-2. Electronic component and its manufacturing method", the flux resin composition (X) maintains a low viscosity until the bump 32 melts. Even when the bump 32 starts to melt, the viscosity of the flux resin composition (X) does not increase immediately, but increases sharply after a while. Therefore, the flux resin composition (X) can be cured after covering the outside of the joint 20 between the first conductor 21 and the bump 32 with the flux resin composition (X). This allows the first conductor 21 and the bump 32 to be well connected, and the conduction failure between the first conductor 21 and the bump 32 can be suppressed. In addition, the cured product of the flux resin composition (X) can be fixed to the outside of the joint 20 between the first conductor 21 and the bump 32. Therefore, the joint 20 between the first conductor 21 and the bump 32 can be reinforced by the reinforcing part 4.

[0120] In the above-mentioned manufacturing method of the mounting structure 1, the bump 32 is provided on the second conductor 31, but the present invention is not limited thereto. For example, the bump 32 may be provided on the first conductor 21. In this case, the flux resin composition (X) is arranged so as to cover the second conductor 31, and when the second conductor 31 and the bump 32 are connected, the flux resin composition (X) can be cured after covering the outside of the joint 20 between the second conductor 31 and the bump 32. In this case, as in the mounting structure 1 shown in FIG. 4B, the outside of the joint 20 between the second conductor 31 and the bump 32 can be reinforced by the reinforcing part 4. EXAMPLES

[0121] 1. Preparation of resin composition Resin compositions were obtained by mixing the components shown in Tables 1 to 3 in the ratios shown in Tables 1 to 3. The details of the components shown in Tables 1 to 3 are as follows. HP-6000L: A mixture of naphthalene-type epoxy resins represented by formula (5) and formula (6), epoxy group equivalent 215, manufactured by DIC Corporation. HP-4032D: naphthalene type epoxy resin represented by formula (1), epoxy group equivalent 136 to 148, manufactured by DIC Corporation. HP-7250: Trisphenolmethane type epoxy resin represented by formula (8), epoxy group equivalent 162, manufactured by DIC Corporation. NC-3000-H: biphenyl aralkyl type epoxy resin represented by formula (10), epoxy group equivalent 280 to 300, manufactured by Nippon Kayaku Co., Ltd. YX4000H: biphenyl-type epoxy resin represented by formula (11), epoxy group equivalent 187 to 197, manufactured by Mitsubishi Chemical Corporation. HP-7200HHH: dicyclopentadiene type epoxy resin represented by formula (12), epoxy group equivalent 280 to 292, manufactured by DIC Corporation. YD8125: Bisphenol type epoxy resin that is liquid at 25℃, manufactured by Nippon Steel Chemical & Material Co., Ltd. YDF8170: Bisphenol-type epoxy resin that is liquid at 25℃, manufactured by Nippon Steel Chemical & Material Co., Ltd. 2PHZ-PW: 2-phenyl-4,5-dihydroxymethylimidazole, melting point 230°C, manufactured by Shikoku Chemical Industry Co., Ltd. 2P4MHZ-PW: 2-phenyl-4-methyl-5-hydroxymethylimidazole, melting point 191℃~195℃, manufactured by Shikoku Chemical Industry Co., Ltd. 2PZ-PW: 2-phenylimidazole, melting point 137℃~147℃, manufactured by Shikoku Chemical Industry Co., Ltd. · 2MAOK-PW: 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, melting point 260°C, manufactured by Shikoku Chemical Industry Co., Ltd. 1,2-DMZ: Melting point 36℃, manufactured by Shikoku Chemicals Corporation. Adipic acid: Manufactured by Tokyo Chemical Industry Co., Ltd. -Glutaric acid: Manufactured by Tokyo Chemical Industry Co., Ltd. TEA: Triethanolamine, manufactured by Tokyo Chemical Industry Co., Ltd. · 1,3-Diphenylguanidine: 1,3-Diphenylguanidine, manufactured by Tokyo Chemical Industry Co., Ltd. Tsunodyme 395: Contains 94% dimer acid. Manufactured by Tsuno Foods Co., Ltd. Gelall D: 1,3:2,4-Bis-O-benzylidene-D-glucitol (dibenzylidene sorbitol), manufactured by New Japan Chemical Co., Ltd. MEH-8000H: Phenol novolak (liquid phenolic resin) represented by formula (13), n=0-10, R 1 ~R 5 are hydrogen atoms, E-type viscometer (25°C) 1500-3500 [mPa·s] (low viscosity), OH equivalent [g / eq] 141, manufactured by Meiwa Kasei Co., Ltd. MEH-8005: Phenol novolak (liquid phenolic resin) represented by formula (13), mixture of n = 0 to 10, R 1 ~R 5 are hydrogen atoms, E-type viscometer (25°C) 4500~7500 [mPa s] (high viscosity), OH equivalent [g / eq] 133~138, manufactured by Meiwa Kasei Co., Ltd. ELPC75: Phenol novolak (liquid phenolic resin) represented by formula (13), n=0 to 10, R 1 ~R 5 are hydrogen atoms, E-type viscometer (25°C) 25 [mPa·s], OH equivalent [g / eq] 211, manufactured by Gun-ei Chemical Industry Co., Ltd. ELP83H: Phenol novolak (liquid phenolic resin) represented by formula (13), n=0-10, R 1 ~R 5 are hydrogen atoms, E-type viscometer (25°C) 25 [mPa·s], OH equivalent [g / eq] 226, manufactured by Gun-ei Chemical Industry Co., Ltd. Diallyl bisphenol A: Diallyl bisphenol A represented by formula (14) Gelall MD: 1,3:2,4-bis-O-(4-methylbenzylidene)-D-sorbitol, manufactured by New Japan Chemical Co., Ltd. Bisamide LA: N,N'-methylenebis(stearamide), Mitsubishi Chemical Corporation Made by. ·DEDG: Diethylene glycol diethyl ether, manufactured by Nippon Nyukazai Co., Ltd. · HEDG: Diethylene glycol monohexyl ether, manufactured by Nippon Nyukazai Co., Ltd.

[0122] 2. Evaluation (1) Viscosity The viscosity (Pa s) of the flux resin composition of each Example and Comparative Example was measured at 25°C and 2.5 rpm. An E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product number: RE-215U) was used for the viscosity measurement. The results are shown in Tables 1 to 3 below.

[0123] (2) Thixotropy The thixotropic ratio of the flux resin composition of each Example and Comparative Example was measured at 25° C. The thixotropic ratio was calculated by dividing the viscosity at 0.25 rpm by the viscosity at 2.5 rpm.

[0124] (3) Printability The printability was evaluated by printing the flux resin composition of each Example and Comparative Example on a substrate having a Ni-Pd-Au pad (conductor) of Φ300 μm and 0.5 mmP with a printer, and observing the printed state with a microscope. A: There is no problem with the shape. B: Bridges and chips are present, but do not cause any problems in practical use. C: Bridges, many chips.

[0125] (4) Glass transition temperature (Tg) The glass transition temperature of the cured resin composition for flux of each of the Examples and Comparative Examples was measured by thermomechanical analysis (TMA, in accordance with JIS K 7197:1991). A: Above 85℃. B: 80℃ or higher but less than 85℃. C:Below 80℃.

[0126] (5) Wetting and spreading rate In the flux resin compositions of each Example and Comparative Example, the wetting and spreading ratio is calculated from {(DH) / D}×100(%) on a copper plate, using the diameter D of the solder ball before reflow and the height H of the solder ball after reflow. The wetting and spreading ratio was calculated by a method in accordance with JIS Z 3198-3, and reflow was performed according to the reflow profile shown in FIG. A: More than 60%. B: 50% or more but less than 60%. C: Less than 50%.

[0127] (6) Life In each of the examples and comparative examples, the life of the flux resin composition is defined as the time from the start of storage to the end of storage. That is, the life was calculated by (viscosity after storage / viscosity at the start of storage)×100(%), and was judged as the time when the viscosity reached 120% (storage temperature: 25° C., viscosity was measured in the same manner as in (1)). A: More than 24 hours. B: More than 20 hours but less than 24 hours. C: Less than 20 hours.

[0128] (7) Coverage rate In the flux resin composition of each Example and Comparative Example, the coverage is calculated by (HR / HB) x 100(%) using the height (HB) of the bump (ball after mounting) and the height (HR) of the reinforcing part (fillet) of a substrate having a Ni-Pd-Au pad (conductor) of Φ300μm and 0.5mmP, which is formed by mounting a 300μm solder ball. The flux resin composition was supplied onto the pad using a metal mask with an opening of 300μm and a thickness of 60μm, and reflow was performed according to the reflow profile shown in Figure 1. A: Coverage rate is 10% or more C: Coverage rate is less than 10%

[0129] (8) Overall rating The overall evaluation was made based on the results of the evaluation of the printability, the wetting and spreading rate, the life and the coverage rate, according to the following criteria. A: The printability, wetting and spreading rate, life and coverage rate were all rated A. B: In the evaluations of printability, wetting and spreading rate, life and coverage, there was one or more B ratings and no C ratings. C: One or more C ratings in the evaluations of printability, wetting spread rate, life and coverage rate.

[0130] The above evaluation results are shown in Tables 1 to 3 below.

[0131] [Table 1]

[0132] [Table 2]

[0133] [Table 3]

[0134] In Examples 1 to 11, the coverage can be improved as compared to Comparative Example 1 that does not contain a phenol compound and Comparative Example 2 that does not contain a phenol novolak.

[0135] Since the glass transition point of Examples 1-3 is better than that of Comparative Examples 3 and 4, it is preferable that the flux resin composition (X) contains the epoxy resin (A1) in a predetermined range.

[0136] In Examples 4 and 5, the phenol compound (E) is contained within a predetermined range, and therefore the coverage is good.

[0137] Since Examples 6 and 7 have better printability and wet spreadability than Comparative Examples 10 and 11, it is preferable that the flux resin composition (X) contains the activator (D) within a predetermined range.

[0138] In Examples 8 and 9, the wetting and spreading rate is higher than that in Comparative Examples 5 and 6, so it is preferable that the flux resin composition (X) contains the thixotropic agent (C) in a predetermined range.

[0139] Since Examples 10 and 11 have better printability and wet spreadability than Comparative Examples 7 to 9, it is preferable that the flux resin composition (X) contains the imidazole (B) within a predetermined range. [Explanation of symbols]

[0140] 1 Implementation structure 2 Circuit Board 3. Electronic Components 20 Joint 21 First Conductor 30, 32 Bump 31 Second Conductor 100 Electronic Components 200 Electronic component body 210 Conductor

Claims

1. Contains an epoxy resin in the range of 60% by weight or more and 80% by weight or less, The imidazole compound is contained in an amount of 0.01% by weight or more and 2% by weight or less, The thixotropic agent is contained in an amount of 1% by weight or more and 5% by weight or less, The content of the activator is in the range of 4% by weight to 20% by weight, The content of a phenol compound is within a range of 7% by weight or more and 30% by weight or less, the epoxy resin contains at least one selected from the group consisting of naphthalene type epoxy resins, biphenyl aralkyl type epoxy resins, trisphenol methane type epoxy resins, biphenyl type epoxy resins, and dicyclopentadiene type epoxy resins in an amount of 15% by weight or more and 40% by weight or less; The phenol compound is a phenol novolak that is liquid at room temperature, The imidazole compound has a melting point of 130° C. or higher. Resin composition for flux.

2. The viscosity (25°C, 2.5 rpm) is 10 Pa·s or more and 250 Pa·s or less, and the thixotropic ratio (25°C, 0.25 rpm / 2.5 rpm) is 1.5 or more and 8 or less. The resin composition for flux according to claim 1 .

3. The glass transition temperature (Tg) of the cured product is 85° C. or higher. The resin composition for flux according to claim 1 or 2.

4. The time required for the value calculated from (viscosity after storage / viscosity at the start of storage)×100(%) to reach 120% after the start of storage at 25° C. is 24 hours or longer. The resin composition for flux according to any one of claims 1 to 3.

5. An electronic component body; a conductor formed on a surface of the electronic component body; a solder bump disposed on the conductor and electrically connected to the conductor; A cured product of the flux resin composition according to any one of claims 1 to 4, comprising a reinforcing part that reinforces a joint between the conductor and the bump. Electronic components.

6. A method for manufacturing the electronic component according to claim 5, comprising: The flux resin composition according to any one of claims 1 to 4 is applied to the joint between the conductor and the bump, and then cured. A method for manufacturing electronic components.

7. A circuit board having a first conductor; an electronic component including a second conductor; a solder bump disposed between the first conductor and the second conductor and electrically connecting the first conductor and the second conductor; A cured product of the resin composition for flux according to any one of claims 1 to 4, comprising a reinforcing part that reinforces at least one of a joint between the first conductor and the bump and a joint between the second conductor and the bump. The implementation structure.

8. A method for manufacturing the mounting structure according to claim 7, comprising: The flux resin composition according to any one of claims 1 to 4 is applied to at least one of a joint between the first conductor and the bump and a joint between the second conductor and the bump, and then cured. A method for manufacturing a mounting structure.

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