CN108687463B

CN108687463B - Solder composition for precoating, method for producing printed wiring board, solder composition, and method for producing electronic board

Info

Publication number: CN108687463B
Application number: CN201810297135.7A
Authority: CN
Inventors: 饭岛纪成; 木村瞳; 原拓生; 酒井悠希; 柴崎正训; 石垣幸一; 臼仓伸一; 吉泽慎二; 岩渕充
Original assignee: Tamura Corp
Current assignee: Tamura Corp
Priority date: 2017-03-30
Filing date: 2018-03-30
Publication date: 2021-09-21
Anticipated expiration: 2038-03-30
Also published as: CN108687463A

Abstract

The present invention provides a solder composition for precoating, which contains a flux composition and (D) solder powder, wherein the flux composition contains (A) rosin resin, (B) an activator and (C) a solvent, the component (B) contains (B1) N, N, N ', N' -tetra (2-hydroxypropyl) ethylenediamine, and in the component (D), the particles with the particle diameter of less than 5 μm are more than 40 volume percent.

Description

Solder composition for precoating, method for producing printed wiring board, solder composition, and method for producing electronic board

Technical Field

The present invention relates to a solder composition for precoating and a method for manufacturing a printed wiring board. The present invention also relates to a solder composition used for, for example, reflow soldering, and a method for manufacturing an electronic substrate.

Background

In the printed wiring board, a solder coating (precoat) may be formed on the electrode from the viewpoint of preventing oxidation of the electrode surface. Therefore, as a method for forming such a precoat layer, for example, the following method can be employed: a solder composition for a precoat layer is printed on an electrode of a printed wiring board, and then a reflow process is performed to form a precoat layer on the electrode. Further, as a solder composition for precoating, for example, a lead-free solder paste for precoating containing 60 to 85 wt% of an Sn-based lead-free solder powder (a) containing a powder having a particle diameter of 20 μm or less in a range of 90 wt% or more and 15 to 40 wt% of a flux (b) containing a bromine-based compound has been proposed (see document 1: Japanese patent laid-open No. 2007 222932).

However, when the lead-free solder paste for precoat described in document 1 is used, pores not wetted with solder may be formed in the electrode, and the solder wettability may be insufficient.

Disclosure of Invention

A first object of the present invention is to provide a solder composition for a precoat layer which has excellent solder wettability and sufficient storage stability, and a method for producing a printed wiring board.

In addition, in the solder composition for reflow soldering, a halogen-containing compound in the existing flux composition is used as an activator having excellent properties. However, in the halogen-free flux composition, it is necessary to supplement the activation by an activator other than halogen. Therefore, as the activator composition, for example, a combination use of an organic acid and an amine has been studied. However, such an activator composition can complement activation action to improve solder wettability, but has a problem that storage stability is lowered and solder balls are likely to be generated.

A second object of the present invention is to provide a solder composition which is excellent in solder wettability and storage stability and can sufficiently suppress solder balls, and a method for manufacturing an electronic substrate using the solder composition.

In order to solve the above problems, a first aspect of the present invention provides a solder composition for a precoat layer and a method for producing a printed wiring board as described below.

The solder composition for precoating comprises a flux composition and (D) solder powder, wherein the flux composition comprises (A) rosin resin, (B) an activator and (C) a solvent, the component (B) comprises (B1) N, N, N ', N' -tetra (2-hydroxypropyl) ethylenediamine, and in the component (D), the volume percentage of particles with the particle diameter of less than 5 μm is more than 40%.

In the solder composition for precoating of the present invention, it is preferable that the solder composition has a chlorine concentration of 900 mass ppm or less, a bromine concentration of 900 mass ppm or less, an iodine concentration of 900 mass ppm or less, and a halogen concentration of 1500 mass ppm or less.

In the solder composition for precoat layer of the present invention, it is preferable that the component (B) further contains a halogen-based activator (B2), and the component (B2) contains an iodocarboxylic acid compound.

In the solder composition for precoat layer of the present invention, the amount of the component (B1) is preferably 12 mass% or more with respect to 100 mass% of the flux composition.

The method for manufacturing a printed wiring board of the present invention is a method for manufacturing a printed wiring board using the solder composition for a precoat layer, and the method includes the steps of: a coating step of coating the solder composition on an electrode of the printed wiring board; and a precoating layer forming step of heating the printed wiring board after the coating step to melt the solder powder in the solder composition, thereby forming a solder coating film on the electrode.

The reason why the solder composition for precoating of the present invention has excellent solder wettability and sufficient storage stability is not clear, but the present inventors presume as follows.

That is, the solder composition for precoating of the present invention contains (B1) N, N' -tetrakis (2-hydroxypropyl) ethylenediamine as (B) an activator. The (B1) component has a strong effect of improving solder wettability as compared with an activator such as an organic acid. On the other hand, since the amine-based activator generally tends to have a low storage stability, the upper limit of the amount to be blended is limited. However, component (B1) has a small influence on storage stability even when the amount thereof is added to a certain extent. In the solder powder (D) of the present invention, since the amount of particles having a particle diameter of 5 μm or less in the component (D) is 40 vol% or more, the amount of the solder powder is large, and the number of starting points at which the solder powder starts to melt increases when reflow is performed. Therefore, there are a large number of starting points of the molten solder on the electrode, and the molten solder does not wet and spread, and a defect such as a void is not easily generated. In addition, when the amount of the solder powder having a fine particle diameter is large as in the component (D) of the present invention, the surface area of the solder powder is large, and there is a possibility that the oxide on the surface thereof is difficult to remove, but the oxide on the surface of the solder powder can be removed by the component (B1) even if the component (D) of the present invention is used. The present inventors presume that the above-described effects of the present invention are achieved thereby.

The present inventors have intensively studied to achieve the second object and found the following findings. That is, although the number of amines having an activating action is large, when an amine compound having a specific chemical structure and an organic acid are used in combination in such a large number of amines, surprisingly, it has been found that the problem of reduction in storage stability and the easy generation of solder balls is very small, and the second invention of the present invention has been completed.

That is, the solder composition of the present invention comprises a flux composition comprising (a) a rosin-based resin, (B) an activator, (C) a solvent, and (D) a thixotropic agent, and (E) a solder powder, wherein the component (B) comprises (B1)1 amine compound having 1 or more hydroxyalkyl groups in the molecule, and (B2) an organic acid.

In the solder composition of the present invention, it is preferable that the component (B1) further has two amino groups in 1 molecule.

In the solder composition of the present invention, it is preferable that the hydroxyalkyl group in the component (B1) is a hydroxypropyl group.

In the solder composition of the present invention, the component (B1) is preferably a compound represented by the following structural formula (1).

In the solder composition of the present invention, the amount of the component (B1) is preferably 0.01 mass% or more and 2 mass% or less with respect to 100 mass% of the flux composition.

In the solder composition of the present invention, it is preferable that the solder composition has a chlorine concentration of 900 mass ppm or less, a bromine concentration of 900 mass ppm or less, an iodine concentration of 900 mass ppm or less, and a halogen concentration of 1500 mass ppm or less.

The method for manufacturing an electronic substrate according to the present invention is a method for manufacturing an electronic substrate using the solder composition, and includes the steps of: a coating step of coating the solder composition on a wiring substrate; a mounting step of mounting an electronic component on the solder composition; and a reflow step of heating the wiring board on which the electronic component is mounted.

According to the first aspect of the present invention, there can be provided a solder composition for a precoat layer which has excellent solder wettability and has sufficient storage stability, and a method for producing a printed wiring board.

Further, according to the second aspect of the present invention, it is possible to provide a solder composition which is excellent in solder wettability and storage stability and can sufficiently suppress solder balls, and a method for manufacturing an electronic substrate using the solder composition.

Drawings

Fig. 1 is a graph showing a relationship between time and temperature when reflow soldering is performed in an evaluation test of a solder composition.

Detailed Description

< first embodiment >

First, a first embodiment of the present invention will be explained.

Hereinafter, embodiments of the solder composition for precoat layer and the method for manufacturing a printed wiring board according to the present embodiment will be described.

[ flux composition ]

The solder composition for precoating according to the present embodiment contains the flux composition described below and (D) solder powder described below.

First, a flux composition used in the present embodiment will be described.

The flux composition used in the present embodiment contains (a) a rosin resin, (B) an activator, and (C) a solvent, which are described below.

[ (A) component ]

Examples of the rosin-based resin (a) used in the present embodiment include rosins and rosin-based modified resins. Examples of the rosin include: gum rosin, wood rosin, tall oil rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and their derivatives, and the like. Examples of the rosin-based modified resin include: rosin acids such as the above rosin-based unsaturated organic acid-modified resins ((aliphatic unsaturated monobasic acids such as (meth) acrylic acid, aliphatic unsaturated dibasic acids such as alpha, beta-unsaturated carboxylic acids such as fumaric acid and maleic acid, and modified resins such as unsaturated carboxylic acids having an aromatic ring such as cinnamic acid)) and modified products thereof, which are reaction components of the Diels-Alder reaction, and substances containing these modified products as main components. These rosin resins may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The amount of the component (a) is preferably 30 to 70 mass%, more preferably 35 to 60 mass%, based on 100 mass% of the flux composition. When the amount of component (A) is not less than the lower limit, the oxide film on the copper foil surface of the solder pad can be removed, and the surface of the pad can be easily wetted with the molten solder. When the amount of component (a) is not more than the upper limit, the residual flux amount can be sufficiently suppressed.

[ (B) component ]

The activator (B) used in the present embodiment needs to contain (B1) N, N' -tetrakis (2-hydroxypropyl) ethylenediamine. When the component (B1) is not contained, solder wettability and storage stability cannot be both achieved.

From the viewpoint of improving solder wettability, the amount of the component (B1) is preferably 1 mass% or more and 35 mass% or less, more preferably 5 mass% or more and 30 mass% or less, particularly preferably 12 mass% or more and 25 mass% or less, and most preferably 15 mass% or more and 20 mass% or less, relative to 100 mass% of the flux composition.

In the present embodiment, it is preferable that the component (B) further contains (B2) a halogen activator. The solder wettability can be further improved by the (B2) component. Among these, the amount of the component (B2) is preferably 0.01 mass% or more and 3 mass% or less, and more preferably 0.1 mass% or more and 1 mass% or less, relative to 100 mass% of the flux composition, from the viewpoint of reducing the amount of halogen in the solder composition.

The component (B2) may be a compound formed by covalent bonds of individual elements such as chlorine, bromine, and fluorine, such as chloride, bromide, and fluoride, or a compound having covalent bonds of any two or all of chlorine, bromine, and fluorine. In order to improve the solubility in an aqueous solvent, these compounds preferably have a polar group such as a hydroxyl group or a carboxyl group, for example, a halohydrin or a halogenated carboxylic acid compound. Examples of the halogenated alcohol include: bromoalcohols such as 2, 3-dibromopropanol, 2, 3-dibromobutanediol, trans-2, 3-dibromo-2-butene-1, 4-diol, 1, 4-dibromo-2-butanol, and tribromoneopentyl alcohol; chlorohydrins such as 1, 3-dichloro-2-propanol and 1, 4-dichloro-2-butanol; fluoroalcohols such as 3-fluorocatechol, and other similar compounds. Examples of the halogenated carboxylic acid compound include: iodocarboxylic acid compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid; chloro carboxylic acid compounds such as 2-chlorobenzoic acid and 3-chloropropionic acid; bromo-carboxylic acid compounds such as 2, 3-dibromopropionic acid, 2, 3-dibromosuccinic acid, and 2-bromobenzoic acid, and other compounds similar to these compounds. Among them, from the viewpoint of solder wettability, iodocarboxylic acid compounds are preferable, and 2-iodobenzoic acid and 3-iodobenzoic acid are more preferable. These compounds may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

In the present embodiment, the component (B) may further contain (B3) an organic acid. The component (B3) can improve the activation. When the component (B3) is used, the amount thereof is preferably 0.1 mass% or more and 10 mass% or less, more preferably 0.5 mass% or more and 7 mass% or less, and particularly preferably 1 mass% or more and 5 mass% or less, relative to 100 mass% of the flux composition.

The component (B3) may be other organic acids in addition to monocarboxylic acids and dicarboxylic acids.

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

Acids, tetracosanoic acids, and glycolic acids, and the like.

Examples of dicarboxylic acids include: 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 other organic acids, there may be mentioned: dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, picolinic acid, and the like.

The component (B) may contain an activator ((B4) component) other than the component (B1), the component (B2), and the component (B3) within a range in which the object of the present invention can be achieved. Examples of the component (B4) include amine activators and the like other than the component (B1).

The amount of the component (B) is preferably 1 to 40 mass%, more preferably 5 to 35 mass%, particularly preferably 12 to 30 mass%, and most preferably 15 to 25 mass% with respect to 100 mass% of the flux composition. When the amount of component (B) is not less than the lower limit, sufficient solder wettability cannot be secured. When the amount of component (B) is not more than the upper limit, storage stability can be ensured.

[ (C) ingredient ]

As the solvent (C) used in the present embodiment, a known solvent can be suitably used. As such a solvent, a solvent having a boiling point of 170 ℃ or higher is preferably used.

Examples of such solvents include: diethylene glycol, dipropylene glycol, triethylene glycol, hexanediol, diethylene glycol monohexyl ether, 1, 5-pentanediol, methyl carbitol, butyl carbitol, diethylene glycol-2-ethylhexyl ether, octanediol, phenyl glycol, diethylene glycol monohexyl ether, tetraethylene glycol dimethyl ether, and dibutyl maleic acid. These solvents may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The amount of the component (C) is preferably 10 to 60 mass%, more preferably 15 to 40 mass%, and particularly preferably 20 to 30 mass% with respect to 100 mass% of the flux composition. When the amount of the solvent is within the above range, the viscosity of the obtained solder composition can be appropriately adjusted to an appropriate range.

The flux composition of the present embodiment may further contain a thixotropic agent from the viewpoint of printability and the like. As the thixotropic agent used herein, there may be mentioned: hydrogenated castor oil, polyamines, polyamides, bisamides, dibenzylidene sorbitol, kaolin, colloidal silica, organic bentonite, glass powder and the like. These thixotropic agents may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

When the thixotropic agent is used, the amount thereof is preferably 1% by mass or more and 15% by mass or less, and more preferably 5% by mass or more and 10% by mass or less, relative to 100% by mass of the flux composition. When the blending amount is not less than the lower limit, sufficient thixotropy can be obtained, and dripping can be sufficiently suppressed. When the amount is not more than the upper limit, printing defects due to excessively high thixotropy are not caused.

[ other ingredients ]

In the flux composition used in the present embodiment, other additives and other resins may be added as necessary in addition to the component (a), the component (B), the component (C), and the thixotropic agent. As other additives, there may be mentioned: defoaming agent, antioxidant, modifier, delustering agent, foaming agent, curing accelerator and the like. As other resins, there may be mentioned: epoxy resins, acrylic resins, urethane resins, polyimide resins, and the like.

[ solder composition for precoating ]

Next, the solder composition for precoat layer of the present embodiment will be described. Which contains the flux composition and (D) solder powder described below.

The amount of the flux composition is preferably 10 mass% or more and 50 mass% or less, more preferably 15 mass% or more and 40 mass% or less, and particularly preferably 20 mass% or more and 35 mass% or less, based on 100 mass% of the solder composition. When the amount of the flux composition to be mixed is 10 mass% or more (the amount of the solder powder to be mixed is 90 mass% or less), the flux composition as a binder is sufficient, and therefore the flux composition and the solder powder can be easily mixed. When the amount of the flux composition is 50 mass% or less (the amount of the solder powder is 50 mass% or more), a uniform precoat layer can be formed when the obtained solder composition is used.

The solder composition for precoating according to the present embodiment has excellent solder wettability and sufficient storage stability. Therefore, even a non-halogenated solder composition for a precoat layer that can cope with a printed wiring board can ensure the same solder wettability as when a halogen activator is used, and is therefore particularly suitable as a solder composition for a precoat layer containing low halogen.

The low-halogen-content solder composition for a precoat preferably has a chlorine concentration of 900 mass ppm or less, a bromine concentration of 900 mass ppm or less, an iodine concentration of 900 mass ppm or less, and a halogen concentration of 1500 mass ppm or less. Examples of the halogen include: fluorine, chlorine, bromine, iodine, and the like.

The chlorine concentration, bromine concentration and halogen concentration in the precoat solder composition were measured according to the method described in JEITA ET-7304A. In addition, the calculation can be easily performed based on the blending components and the blending amount of the solder composition for precoat layer.

[ (D) component ]

The solder powder (D) used in the present embodiment is preferably composed of only a lead-free solder powder, but may be a lead-containing solder powder. As the solder alloy in the solder powder, an alloy containing tin (Sn) as a main component is preferable. Further, as the second element of the alloy, there can be mentioned: silver (Ag), copper (Cu), zinc (Zn), bismuth (Bi), indium (In), antimony (Sb), and the like. Further, other elements (third and above elements) may be added to the alloy as necessary. As other elements, there may be mentioned: copper, silver, bismuth, indium, antimony, cobalt (Co), chromium (Cr), nickel (Ni), germanium (Ge), iron (Fe), aluminum (Al), and the like.

Here, the lead-free solder powder refers to a powder of a solder metal or alloy to which lead is not added. However, in the lead-free solder powder, the presence of lead as an inevitable impurity is allowed, and in this case, the amount of lead is preferably 100 mass ppm or less.

Specific examples of the lead-free solder powder include: Sn-Ag, Sn-Ag-Cu, Sn-Ag-Bi, Sn-Ag-Cu-Bi, Sn-Sb, Sn-Zn-Bi, Sn-Zn-Al, Sn-Zn-Bi-Al, Sn-Ag-Bi-In, Sn-Ag-Cu-Bi-In-Sb, In-Ag and the like. Among them, from the viewpoint of soldering strength, Sn — Ag — Cu based solder alloys are preferably used. The melting point of the Sn-Ag-Cu based solder is usually 200 ℃ or higher and 250 ℃ or lower. In the Sn — Ag — Cu based solder, the solder having a low silver content has a melting point of 210 ℃ or higher and 250 ℃ or lower. In such a solder alloy, the silver content is usually 4 mass% or less, and the copper content is usually 1 mass% or less. In addition, from the viewpoint of low melting point, a Sn — Bi based solder alloy is preferably used. The melting point of the Sn-Bi solder is usually 130 ℃ or higher and 170 ℃ or lower.

In the present embodiment, it is necessary that the particles having a particle diameter of 5 μm or less in the component (D) be 40% by volume or more. If this condition is not satisfied, solder wettability is insufficient. The particle size distribution of the solder powder can be measured by, for example, a dynamic light scattering type particle size measuring device (manufactured by COULTER corporation, "laser diffraction type particle size analyzer LS 130"). Then, the ratio of particles having a particle diameter of 5 μm or less in the component (D) [ (volume of particles having a particle diameter of 5 μm or less in the component (D)/(total volume of the component (D)). times.100) can be calculated from the particle diameter distribution.

Further, as a method for adjusting the particle size of 5 μm or less in the component (D) to the above range, the following method can be mentioned.

For example, the conditions (raw material supply rate, composition of the solder alloy) of the centrifugal powder production apparatus may be changed to adjust the conditions. The adjustment can be made by mixing 2 or more kinds of solder powders having different particle size distributions at a given ratio.

[ method for producing solder composition ]

The solder composition of the present embodiment can be produced by mixing the flux composition described above and the solder powder (D) described above at the above-mentioned predetermined ratio and then stirring and mixing them.

[ method for producing printed Wiring Board ]

Next, a method for manufacturing the printed wiring board of the present embodiment will be described. The method for manufacturing a printed wiring board according to the present embodiment is a method for using the above-described solder composition for precoating according to the present embodiment, and includes the steps of: a coating step of printing the solder composition on an electrode of the printed wiring board; a precoat layer forming step: and heating the printed wiring board after the printing step to melt the solder powder in the solder composition, thereby forming a solder coating on the electrode.

In the coating step, the solder composition for the precoat layer is coated on the electrode of the printed wiring board.

As the coating apparatus used here, there are exemplified: screen printers, metal mask printers, dispensers, etc.

The thickness of the coating film is usually 20 μm or more and 50 μm or less.

In the precoat layer forming step, the printed wiring board after the coating step is heated to melt the solder powder in the solder composition, thereby forming a solder coating film on the electrode.

As a means for heating the printed wiring board, a reflow furnace can be used. The reflow furnace includes: an air reflow apparatus, a vacuum reflow apparatus, a formic acid reflow apparatus, a plasma reflow apparatus, and the like. Among these, from the viewpoint of equipment cost, an air reflow apparatus is preferable.

The reflow conditions may be appropriately set according to the melting point of the solder. For example, when a Sn — Ag — Cu based solder alloy is used, the preheating temperature is preferably 140 ℃ or more and 200 ℃ or less, and more preferably 150 ℃ or more and 160 ℃ or less. The preheating time is preferably 60 seconds or more and 120 seconds or less. The peak temperature is preferably 230 ℃ or more and 270 ℃ or less, and more preferably 240 ℃ or more and 255 ℃ or less. The holding time at a temperature of 220 ℃ or higher is preferably 20 seconds or longer and 60 seconds or shorter.

< second embodiment >

Next, a second embodiment of the present invention will be explained.

The solder composition of the present embodiment contains the flux composition described below and (E) solder powder described below.

[ flux composition ]

First, the flux composition used in the present embodiment will be described. The flux composition used in the present embodiment is a component other than solder powder in the solder composition, and contains (a) a rosin-based resin, (B) an activator, (C) a solvent, and (D) a thixotropic agent.

[ (A) component ]

Examples of the rosin-based resin (a) used in the present embodiment include rosins and rosin-based modified resins. Examples of the rosin include: gum rosin, wood rosin, tall oil rosin, and the like. Examples of the rosin-based modified resin include: disproportionated rosin, polymerized rosin, hydrogenated rosin (completely hydrogenated rosin, partially hydrogenated rosin, and hydrogenated rosin of unsaturated organic acid-modified rosin (also referred to as "hydrogenated acid-modified rosin"), which is a modified rosin of unsaturated organic acid ((aliphatic unsaturated monobasic acid such as (meth) acrylic acid), aliphatic unsaturated dibasic acid such as α, β -unsaturated carboxylic acid such as fumaric acid, maleic acid, and unsaturated carboxylic acid having aromatic ring such as cinnamic acid), and derivatives thereof, and the like. These rosin resins may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The amount of component (a) is preferably 20 to 60 mass%, more preferably 25 to 50 mass%, based on 100 mass% of the flux composition. (A) When the amount of the component is not less than the lower limit, solderability, which is a property of preventing oxidation of the copper foil surface of the solder pad and making the surface of the solder pad easily wet with molten solder, can be improved and the solder ball can be sufficiently suppressed. When the amount of the component (a) is not more than the upper limit, the residual flux amount can be sufficiently suppressed.

[ (B) component ]

The activator (B) used in the present embodiment needs to contain (B1) an amine compound having 1 or more hydroxyalkyl groups in 1 molecule and (B2) an organic acid.

(B1) The component (A) is an amine compound having 1 or more hydroxyalkyl groups in 1 molecule. The (B1) component can improve solder wettability without lowering storage stability and the like.

From the viewpoint of improving solder wettability, the number of hydroxyalkyl groups in 1 molecule is preferably 1 or more and 8 or less, more preferably 2 or more and 6 or less, and particularly preferably 3 or more and 4 or less. From the viewpoint of improving solder wettability, it is preferable that the component (B1) further has 2 amino groups in 1 molecule. In addition, the hydroxyalkyl group in the component (B1) is preferably a hydroxypropyl group from the viewpoint of improving solder wettability.

Examples of the component (B1) include: n, N '-tetrakis (2-hydroxypropyl) ethylenediamine, and N, N' -tetrakis (2-hydroxyethyl) ethylenediamine.

N, N' -tetrakis (2-hydroxypropyl) ethylenediamine is a compound represented by the following structural formula (1).

The amount of the component (B1) is preferably 0.01 to 2 mass%, more preferably 0.05 to 1 mass%, and particularly preferably 0.1 to 0.5 mass% with respect to 100 mass% of the flux composition. When the blending amount is not less than the lower limit, the solder wettability can be further improved. When the amount is not more than the upper limit, the storage stability of the flux composition can be further improved.

The component (B2) may be other organic acids besides monocarboxylic acids and dicarboxylic acids. These can be used alone in 1 kind, also can be mixed with more than 2 kinds of use.

Acids, tetracosanoic acids, and glycolic acids, and the like.

As other organic acids, there may be mentioned: dimer acids, trimer acids, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, picolinic acid, and the like. Among these, dimer acid is more preferably used from the viewpoint that solder wettability can be improved.

The component (B) may further contain other activators (e.g., (B3) halogen activators and (B4) organic acid amines) in addition to the component (B1) and the component (B2) within a range in which the object of the present invention can be achieved. However, from the viewpoint of being halogen-free, the component (B) is preferably composed of only the component (B1) and the component (B2). The total amount of the component (B1) and the component (B2) is preferably 85 mass% or more, more preferably 90 mass% or more, and particularly preferably 95 mass% or more, based on 100 mass% of the component (B).

The component (B3) may be a compound formed by covalent bonds of individual elements such as chlorine, bromine, and fluorine, such as chloride, bromide, and fluoride, or a compound having covalent bonds of any two or all of chlorine, bromine, and fluorine. In order to improve the solubility in an aqueous solvent, these compounds preferably have a polar group such as a hydroxyl group or a carboxyl group, for example, a halohydrin or a halocarboxylic acid compound. Examples of the halogenated alcohol include: bromoalcohols such as 2, 3-dibromopropanol, 2, 3-dibromobutanediol, trans-2, 3-dibromo-2-butene-1, 4-diol, 1, 4-dibromo-2-butanol, and tribromoneopentyl alcohol; chlorohydrins such as 1, 3-dichloro-2-propanol and 1, 4-dichloro-2-butanol; fluoroalcohols such as 3-fluorocatechol, and other similar compounds. Examples of the halogenated carboxylic acid compound include: iodocarboxylic acid compounds such as 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, and 5-iodoanthranilic acid; chloro carboxylic acid compounds such as 2-chlorobenzoic acid and 3-chloropropionic acid; bromo-carboxylic acid compounds such as 2, 3-dibromopropionic acid, 2, 3-dibromosuccinic acid, and 2-bromobenzoic acid; and other compounds similar to these compounds. These compounds may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The amount of component (B) is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, and particularly preferably 5% by mass or more and 12% by mass or less, based on 100% by mass of the flux composition. When the amount of incorporation is not less than the lower limit, the solder ball can be more reliably suppressed. When the amount is not more than the upper limit, the insulation reliability of the flux composition can be ensured.

[ (C) ingredient ]

Examples of such solvents include: diethylene glycol, dipropylene glycol, triethylene glycol, hexanediol, 1, 5-pentanediol, methyl carbitol, butyl carbitol, diethylene glycol-2-ethylhexyl ether, octanediol, phenyl glycol, diethylene glycol monohexyl ether, tetraethylene glycol dimethyl ether, and dibutyl maleic acid. These solvents may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

When the component (C) is used, the amount thereof is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, relative to 100% by mass of the flux composition. When the amount of the solvent is within the above range, the viscosity of the obtained solder composition can be appropriately adjusted to an appropriate range.

[ (D) component ]

Examples of the thixotropic agent (D) used in the present embodiment include: hydrogenated castor oil, polyamides, amides, kaolin, colloidal silicon dioxide, organic bentonite, glass powder and the like. These thixotropic agents may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The amount of component (D) is preferably 1 to 20 mass%, more preferably 5 to 10 mass%, based on 100 mass% of the flux composition. When the amount is not less than the lower limit, sufficient thixotropy can be obtained, and dripping can be sufficiently suppressed. When the amount is not more than the upper limit, printing defects due to excessively high thixotropy are not caused.

[ other ingredients ]

In the flux composition used in the present embodiment, other additives and other resins may be added as necessary in addition to the component (a), the component (B), the component (C), and the component (D). As other additives, there may be mentioned: defoaming agent, antioxidant, modifier, flatting agent, foaming agent, etc. Examples of the other resin include acrylic resins.

[ solder composition ]

Next, the solder composition of the present embodiment will be explained. The solder composition of the present embodiment contains the flux composition of the present embodiment described above and (E) solder powder described below.

The amount of the flux composition to be blended is preferably 5 mass% or more and 35 mass% or less, more preferably 7 mass% or more and 15 mass% or less, and particularly preferably 8 mass% or more and 12 mass% or less with respect to 100 mass% of the solder composition. When the amount of the flux composition blended is less than 5 mass% (when the amount of the solder powder blended exceeds 95 mass%), the flux composition as the binder is insufficient, and therefore, it tends to be difficult to mix the flux composition and the solder powder, whereas when the amount of the flux composition blended exceeds 35 mass% (when the amount of the solder powder blended is less than 65 mass%), it tends to be difficult to form a sufficient solder joint when the obtained solder composition is used.

The solder composition of the present embodiment is excellent in solder wettability and storage stability, and can sufficiently suppress solder balls. Therefore, even a non-halogenated solder composition that can cope with a printed wiring board can ensure the same solder wettability as when a halogen activator is used, and therefore, it is particularly suitable as a solder composition containing low halogen.

The low-halogen solder composition preferably has a chlorine concentration of 900 ppm by mass or less, a bromine concentration of 900 ppm by mass or less, an iodine concentration of 900 ppm by mass or less, and a halogen concentration of 1500 ppm by mass or less. Examples of the halogen include: fluorine, chlorine, bromine, iodine, and the like.

The chlorine concentration, bromine concentration, and halogen concentration in the solder composition can be measured according to the method described in JEITA ET-7304A. Further, the calculation can be easily performed according to the components and the amounts of the components to be mixed in the solder composition.

[ (E) ingredient ]

The solder powder (E) used in the present embodiment is preferably composed of only a lead-free solder powder, but may be a lead-containing solder powder. As the solder alloy in the solder powder, an alloy containing tin (Sn) as a main component is preferable. Further, as the second element of the alloy, there can be mentioned: silver (Ag), copper (Cu), zinc (Zn), bismuth (Bi), indium (In), antimony (Sb), and the like. Further, other elements (third and above elements) may be added to the alloy as necessary. As other elements, there may be mentioned: copper, silver, bismuth, indium, antimony, aluminum (Al), and the like.

Here, the lead-free solder powder refers to a powder of a solder metal or alloy to which lead is not added. However, in the lead-free solder powder, the presence of lead as an inevitable impurity is allowed, and in this case, the amount of lead is preferably 300 mass ppm or less.

Specific examples of the solder alloy in the lead-free solder powder include: Sn-Ag, Sn-Ag-Cu, Sn-Ag-Bi, Sn-Ag-Cu-Bi, Sn-Sb, Sn-Zn-Bi, Sn-Zn-Al, Sn-Ag-Bi-In, Sn-Ag-Cu-Bi-In-Sb, In-Ag and the like. Among them, from the viewpoint of soldering strength, Sn — Ag — Cu based solder alloys are preferably used. The melting point of the Sn-Ag-Cu based solder is usually 200 ℃ or higher and 250 ℃ or lower. In the Sn — Ag — Cu based solder, the solder having a low silver content has a melting point of 210 ℃ or higher and 250 ℃ or lower (more preferably 220 ℃ or higher and 240 ℃ or lower).

(E) The average particle size of the component (A) is usually 1 to 40 μm, and from the viewpoint of coping with an electronic substrate having a narrow pad pitch, it is more preferably 1 to 35 μm, and still more preferably 2 to 30 μm. The average particle diameter can be measured by a dynamic light scattering particle diameter measuring apparatus.

[ method for producing solder composition ]

The solder composition of the present embodiment can be produced by mixing the flux composition described above and the solder powder (E) described above at the above-mentioned predetermined ratio and then stirring and mixing them.

[ method for producing electronic substrate ]

Next, the electronic substrate of the present embodiment will be explained.

The method for manufacturing an electronic board according to the present embodiment is a method using the solder composition according to the present embodiment, and includes a coating step, a mounting step, and a reflow step described below. By the method for manufacturing an electronic substrate of the present embodiment, an electronic component can be mounted on an electronic substrate (such as a printed wiring board) using the solder composition described above.

In the coating step, the solder composition is coated on the wiring substrate.

As the coating apparatus used here, there are exemplified: screen printers, metal mask printers, dispensers, and jetting dispensers, among others.

The thickness of the coating film (coating film thickness) can be appropriately set.

In the mounting step, the electronic component is mounted on the solder composition.

Examples of the electronic component include: chip components, BGA packages, chip scale packages, etc.

As the device used in the mounting step, a known chip mounting apparatus can be suitably used.

In the reflow step, the wiring board on which the electronic component is mounted is heated to melt the solder powder, thereby joining the electronic component to the electrode terminal.

As the apparatus used here, a known reflow furnace can be suitably used.

The reflow conditions may be appropriately set according to the melting point of the solder. For example, when a Sn-Au-Cu based solder alloy is used, the solder alloy may be preheated at a temperature of 150 to 180 ℃ (preferably 150 to 160 ℃) for 60 to 120 seconds, and the peak temperature may be set to 220 to 260 ℃ (preferably 230 to 250 ℃).

[ modified examples ]

The solder composition and the method for manufacturing an electronic substrate according to the present invention are not limited to the above-described embodiments, and modifications, improvements, and the like that are performed within a range that can achieve the object of the present invention are included in the present invention.

For example, in the above-described method for manufacturing an electronic substrate, the printed wiring board and the electronic component are bonded by a reflow step, but the method is not limited thereto. For example, the printed wiring board and the electronic component can be bonded by a step of heating the solder composition with a laser (laser heating step) instead of the reflow step. In this case, the laser light source is not particularly limited, and can be appropriately used according to the wavelength corresponding to the metal absorption band. As the laser light source, for example: fixing deviceBulk laser (ruby, glass, YAG, etc.), semiconductor laser (GaAs, InGaAsP, etc.), liquid laser (dye, etc.), and gas laser (He-Ne, Ar, CO)₂And excimer molecules, etc.).

Examples

< examples and comparative examples of the first embodiment >

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Materials used in examples and comparative examples are shown below.

(component (A))

Rosin resin a: hydrogenated acid-modified rosin available under the trade name "Pine crystal KE-604", available from Mitsuwa chemical industries, Ltd

Rosin resin B: hydrogenated rosin ester, trade name "M-HDR", manufactured by Tanshichen chemical Co., Ltd

((B1) component)

Amine activator A: n, N, N ', N' -tetrakis (2-hydroxypropyl) ethylenediamine

((B2) component)

Halogen-based activator a: 2-iodobenzoic acid

Halogen-based activator B: dibromobutenediol

((B3) component)

An organic acid A: suberic acid

Organic acid B: malonic acid

((B4) component)

Amine activator B: octadecaneamine

(component (C))

Solvent: diethylene glycol monohexyl ether, manufactured by Nippon emulsifier Co., Ltd

(component (D))

Solder powder a: the particle size distribution is 2-6 μm (average particle size is 4 μm), the melting point of the solder is 217-220 ℃, and the solder composition is Sn-Ag3.0-Cu0.5

Solder powder B: the particle size distribution is 1-12 μm (average particle size is 6 μm), the melting point of the solder is 217-220 ℃, and the solder composition is Sn-Ag3.0-Cu0.5

(other Components)

Thixotropic agent: hydrogenated castor oil, product name "HIMAKO (ヒマコウ)", manufactured by KF writing Co

[ example 1-1]

As a flux composition, 40 mass% of rosin-based resin a, 10 mass% of rosin-based resin B, 14 mass% of amine activator a, 2.6 mass% of organic acid a, 0.6 mass% of organic acid B, 0.5 mass% of halogen-based activator a, 0.3 mass% of halogen-based activator B, 8 mass% of thixotropic agent, and 24 mass% of solvent were mixed and mixed as appropriate, thereby obtaining a flux composition.

The obtained flux composition 30 mass%, solder powder a 35 mass%, and solder powder B35 mass% (total 100 mass%) were mixed and mixed appropriately to prepare a solder composition.

Examples 1-2 to 1-8 and comparative examples 1-1 to 1-6

Flux compositions and solder compositions were obtained in the same manner as in example 1-1, except that the materials were mixed in accordance with the compositions shown in table 1.

< evaluation of solder composition >

The solder composition was evaluated by the following method (solder wettability, flux residue cleanability, storage stability). The obtained results are shown in table 1.

Further, the physical properties of the solder composition (the ratio of solder powder of 5 μm or less (unit: volume%), the average particle diameter of the solder powder (unit: μm), and the bromine concentration, iodine concentration and halogen concentration in the solder composition (unit: mass ppm, values calculated from the amounts blended)) are shown in table 1.

(1) Solder wettability

The solder composition was printed on a substrate under the following substrate preparation conditions, and a reflow process was performed to prepare an evaluation substrate for solder wettability.

Substrate: FR-4 substrate (evaluation substrate for solder wettability and cleaning of flux residue)

Aperture of solder resist: 400 to 500 μm

Surface treatment: copper electrode (coating water-soluble flux)

The coating method comprises the following steps: screen printing

Thickness of the metal mask: 30 μm

Mask aperture: aperture of solder resist is 70%

Scraping a pulp board: metal scraping plate

A reflow furnace: TNP25-538EM manufactured by Tamura, K.K.) "

Oxygen concentration at reflow soldering: less than 100ppm

Reflow soldering curve: FIG. 1 shows a schematic view of a

Then, the entire precoat region of the obtained evaluation substrate was observed with a microscope, and solder wettability was evaluated according to the following criteria.

A: less than 5 pore-like non-wetting or non-wetting at solder resist occurred.

B: non-wetting occurs in a pore shape of 6 or more and 10 or less or non-wetting at the time of solder resist.

C: non-wetting occurs in a pore shape of 11 or more and 19 or less or non-wetting at the time of solder resist.

D: more than 20 pore-like non-wetting or non-wetting at solder resist occurred.

(2) Cleaning property of flux residue

An evaluation substrate was prepared in the same manner as in the solder wettability evaluation (1), and the flux residue on the evaluation substrate was cleaned under the following conditions.

Cleaning solution: "CLEANTHROUGH 750 HS" manufactured by Kao corporation "

Dipping and cleaning time: 120 seconds

Then, the evaluation substrate after cleaning was visually observed, and the flux residue cleanability was evaluated according to the following criteria.

A: no cleaning residue of the flux residue.

C: there is a cleaning residue of flux residue.

(3) Storage stability

The solder composition was filled in a polyethylene container, and the container was put into a thermostatic bath at a temperature of 30 ℃ and stored for 1 month. The solder composition after 1 month of storage was returned to room temperature, and then stirred with a spatula for 1 minute to observe the properties. Then, the storage stability was evaluated according to the following criteria.

A: the solder composition is in the form of a paste and is in a state of asexual change.

B: the solder composition remained pasty, but in a state in which the aggregation of the solder powder was confirmed.

C: the solder composition did not remain pasty and was in a matte state.

From the results shown in table 1, it was confirmed that the solder compositions for precoat layer (examples 1 to 8) of the present invention all had good solder wettability, flux residue cleaning property and storage stability, and had excellent solder wettability and sufficient storage stability.

< examples and comparative examples of the second embodiment >

(component (A))

Rosin resin: hydrogenated acid-modified rosin available under the trade name "Pine crystal KE-604", available from Mitsuwa chemical industries, Ltd

((B1) component)

Amine compound A: n, N, N ', N' -tetrakis (2-hydroxypropyl) ethylenediamine, manufactured by Tokyo chemical industries, Ltd

((B2) component)

An organic acid A: dimer acid, trade name "UNIDYME 14", manufactured by PELLE OIL CROSS

Organic acid B: malonic acid, Tokyo Kabushiki Kaisha

((B3) component)

Halogen-based activating agent: trans-2, 3-dibromo-2-butene-1, 4-diol

(component (C))

Solvent: diethylene glycol monohexyl ether

(component (D))

Thixotropic agent A: trade name "Slipax (スリパックス) H", manufactured by Nippon Kabushiki Kaisha

Thixotropic agent B: hydrogenated castor oil, product name "HIMAKO (ヒマコウ)", and KF tracing Co

((E) component)

Solder powder: the alloy composition is Sn-3.0Ag-0.5Cu, the particle size distribution is 20-38 mu m, the melting point of the solder is 217-220 DEG C

(other Components)

Amine compound B: modified aliphatic polyamine, trade name "FUJICURE FXR-1020", manufactured by T & K TOKA, Inc

Amine compound C: 2, 4-diamino-6- [2- (2-undecyl-1-imidazolyl) ethyl ] -1,3, 5-triazine, trade name "C11Z-A", antioxidant A manufactured by Shikoku Kabushiki Kaisha: trade name "Naugard XL-1", manufactured by SHIRAISHI CALCIUM Co

And (3) antioxidant B: tetramethylene (3, 5-di-tert-butyl-4-hydroxycinnamate) methane, available under the trade name "ANOX 20", SHIRAISHI CALCIUM

[ example 2-1]

45 mass% of rosin-based resin, 7 mass% of organic acid a, 0.5 mass% of organic acid B, 0.25 mass% of amine compound a, 1 mass% of halogen-based activator, 35.25 mass% of solvent, 6 mass% of thixotropic agent a, 1 mass% of thixotropic agent B, 1 mass% of antioxidant a, and 3 mass% of antioxidant B were put into a container and mixed by a planetary mixer to obtain a flux composition.

Then, 11 mass% of the obtained flux composition, 0.3 mass% of the solvent, and 88.7 mass% of the solder powder (total 100 mass%) were put into a container and mixed by a planetary mixer, thereby preparing a solder composition.

Note that, in the solder composition, the bromine concentration was 715 mass ppm, and the halogen concentration was 715 mass ppm.

[ examples 2-2 to 2-4]

Solder compositions were obtained in the same manner as in example 2-1, except that the materials were blended in accordance with the compositions shown in table 2.

Comparative examples 2-1 to 2-3

< evaluation of solder composition >

The solder composition was evaluated by the following method (wet spreading, storage stability, void area ratio, ball near chip). The obtained results are shown in table 2.

(1) Wet spreading

A solder composition was printed on an evaluation substrate on which QFN (quad Flat No lead) parts (pitch: 0.5mm) were mounted by using a 120 μm thick metal mask, the QFN parts were mounted, and the solder composition was melted and soldered by using a reflow oven (atmospheric reflow soldering, manufactured by Tankura K.K.) to prepare a board, which was used as a test substrate. Here, the reflow conditions are: preheating temperature is 150-180 deg.C (60 seconds), time is 50 seconds when temperature is above 220 deg.C, and peak temperature is 245 deg.C. The test substrate obtained was observed with a magnifying glass, and the wet spread area on the Cu end face of the QFN part was measured, and the wet spread was evaluated according to the following criteria.

A: the wet spreading area is more than 80%.

B: the wet spreading area is 50% or more and less than 80%.

C: the wet spread area was less than 50%.

(2) Storage stability

The storage stability was evaluated in accordance with JIS Z3284-3 (2014). Specifically, first, the viscosity was measured using the solder composition as a sample. Then, the sample was placed in a sealed container, put into a thermostatic bath at a temperature of 30 ℃ and stored for 14 days, and the viscosity of the stored sample was measured. Then, the viscosity change rate { (η 2- η 1)/(η 1) } × 100% } of the viscosity value (. eta.2) after storage at 30 ℃ for 14 days relative to the viscosity value (. eta.1) before storage was determined.

Then, based on the results of the viscosity change rate, the storage stability was evaluated according to the following criteria.

A: the viscosity change rate is-10% or more and 10% or less.

B: the viscosity change rate is more than-15% and less than-10%, or more than 10% and less than 15%.

C: the viscosity change rate is less than-15%, or greater than 15%.

(3) Void area ratio

A solder composition was printed on an evaluation substrate on which QFN components (pitch: 0.5mm) were mountable by using a 120 μm thick metal mask, the QFN components were mounted, the solder composition was melted and soldered by using a reflow furnace (manufactured by atmospheric reflow, Kimura Corp.) and the thus-formed board was used as a test substrate. Here, the reflow conditions are: preheating temperature is 150-180 ℃ (60 seconds) under the atmosphere, time of more than 220 ℃ is 50 seconds, and peak temperature is 245 ℃. The solder joint portion of the obtained test substrate was observed using an X-ray inspection apparatus ("NLX-5000", manufactured by kokusha electric motor industries co., ltd.), and the maximum value of the QFN void area ratio [ (void area/land area) × 100% ] was measured.

(4) Ball near chip

A solder composition was printed on an evaluation substrate on which chip components (1608CR chips) can be mounted by using a metal mask having a thickness of 100 μm, 60 chip components were mounted, and the solder composition was melted and soldered by using a reflow oven (manufactured by atmospheric reflow, manufactured by tsukuwa corporation), and the thus-formed board was used as a test substrate. Here, the reflow conditions are: preheating temperature is 150-180 ℃ (60 seconds) under the atmosphere, time of more than 220 ℃ is 50 seconds, and peak temperature is 245 ℃. The test substrate obtained was observed with a magnifying glass, and the number (one) of solder balls generated in the vicinity of 60 chip components was measured.

From the results shown in Table 2, it was confirmed that the solder compositions of the present invention (examples 2-1 to 2-4) were excellent in wet spreading, storage stability, void area ratio, and evaluation results of balls in the vicinity of the chip. This confirmed that the solder composition of the present invention is excellent in solder wettability and storage stability, and can sufficiently suppress solder balls.

Claims

1. A solder composition for precoating comprising a flux composition and (D) a solder powder, the flux composition comprising (A) a rosin-based resin, (B) an activator and (C) a solvent, wherein,

the component (B) contains (B1) N, N, N ', N' -tetra (2-hydroxypropyl) ethylenediamine,

the amount of the component (A) is 30 to 70 mass% based on 100 mass% of the flux composition,

the amount of the component (B) is 5 to 35 mass% based on 100 mass% of the flux composition,

the amount of the component (C) is 10 to 60 mass% based on 100 mass% of the flux composition,

the amount of the component (B1) is 5 to 35 mass% based on 100 mass% of the flux composition,

in the component (D), the particles having a particle diameter of 5 μm or less are 40% by volume or more,

the amount of the flux composition is 10 to 50 mass% based on 100 mass% of the solder composition.

2. The solder composition for precoating according to claim 1,

the solder composition has a chlorine concentration of 900 mass ppm or less, a bromine concentration of 900 mass ppm or less, an iodine concentration of 900 mass ppm or less, and a halogen concentration of 1500 mass ppm or less.

3. The solder composition for precoating according to claim 1,

the component (B) further contains (B2) a halogen-based activator,

the component (B2) contains an iodocarboxylic acid compound.

4. The solder composition for precoating according to claim 1,

the component (B) further contains (B3) an organic acid.

5. The solder composition for precoating according to claim 1,

the amount of the component (B1) is 12% by mass or more based on 100% by mass of the flux composition.

6. The solder composition for precoating according to claim 1,

the flux composition also contains a thixotropic agent,

the thixotropic agent is at least 1 selected from hydrogenated castor oil, polyamine, polyamide, bisamide, dibenzylidene sorbitol, kaolin, colloidal silicon dioxide, organic bentonite and glass powder,

the amount of the thixotropic agent is 1 to 15 mass% based on 100 mass% of the flux composition.

7. The solder composition for precoating according to claim 1,

the component (A) contains hydrogenated acid modified rosin and hydrogenated rosin ester.

8. A method for producing a printed wiring board using the solder composition for precoating according to any one of claims 1 to 7, comprising the steps of:

a coating step of coating the solder composition on an electrode of the printed wiring board; and

and a precoating layer forming step of heating the printed wiring board after the coating step to melt the solder powder in the solder composition, thereby forming a solder coating film on the electrode.

9. A solder composition comprising a flux composition and (E) a solder powder, wherein the flux composition comprises (A) a rosin-based resin, (B) an activator, (C) a solvent and (D) a thixotropic agent,

the component (B) contains (B1) an amine compound having 1 or more hydroxyalkyl groups in 1 molecule and (B2) an organic acid,

the component (B1) is at least one member selected from the group consisting of N, N, N ', N' -tetrakis (2-hydroxypropyl) ethylenediamine and N, N, N ', N' -tetrakis (2-hydroxyethyl) ethylenediamine,

the amount of the component (A) is 20 to 60 mass% based on 100 mass% of the flux composition,

the amount of the component (B) is 1 to 20 mass% based on 100 mass% of the flux composition,

the amount of the component (B1) is 0.01 to 2 mass% based on 100 mass% of the flux composition,

the amount of the component (D) is 1 to 20 mass% based on 100 mass% of the flux composition,

the amount of the flux composition is 5 to 35 mass% based on 100 mass% of the solder composition.

10. The solder composition of claim 9,

the component (B1) is a compound represented by the following structural formula (1),

11. the solder composition of claim 9,

the component (B) further contains (B3) a halogen-based activator.

12. The solder composition of claim 9,

13. A method for manufacturing an electronic substrate using the solder composition according to any one of claims 9 to 12, the method comprising:

a coating step of coating the solder composition on a wiring substrate;

a mounting step of mounting an electronic component on the solder composition;

and a reflow step of heating the wiring board on which the electronic component is mounted.