Solder composition and method for manufacturing electronic board

Abstract

To provide a solder composition which is excellent in tacking force after the lapse of a long period of time and is excellent in heating slump property.SOLUTION: A solder composition contains a flux composition containing (A) a rosin-based resin, (B) an activator and (C) a solvent, and (E) solder powder, wherein the component (B) contains (B1) a diglycolic acid, the component (C) has (C1) an alkyl chain having 12 or more an 22 or less carbon atoms and one hydroxyl group in one molecule, and the alkyl chain contains an alcohol compound having a branched chain.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a solder composition and a method for manufacturing an electronic substrate. [Background technology]

[0002] The solder composition is a paste-like mixture made by kneading a solder powder with a flux composition (rosin-based resin, an activator, a solvent, etc.) (see Patent Document 1). Electronic substrates are manufactured by reflow soldering using this solder composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5887330 Summary of the Invention [Problem to be solved by the invention]

[0004] By such a manufacturing method for electronic boards, module components such as communication modules or camera modules can also be manufactured. In addition, the miniaturization of module components is progressing, and the electronic components mounted are also fine 0402 chips or 0201 chips, and the mask opening is becoming finer. Furthermore, as the mounting of closely adjacent components progresses, the component intervals tend to become very narrow. And, as the mask openings become finer, the amount of solder composition printed also decreases, so it is susceptible to drying and it may be difficult to maintain the tackiness. In addition, since fine chips are prone to mounting defects due to the influence of static electricity, it is necessary to apply ion blow wind when mounting them on the board, making them more susceptible to drying. At this time, if the tackiness of the solder composition cannot be maintained, it may become impossible to mount the components halfway. Even if the components are mounted, the components may fly off due to the blower in the reflow furnace. Furthermore, as the component intervals become narrower, a bridge may occur after reflow, causing a short circuit. Furthermore, a module component may be manufactured, for example, by mounting electronic components on a large electronic board, and dividing the board into several hundred module components after reflow. A single large electronic board may have 10,000 or more components, and it may take 2 to 3 hours to mount electronic components on a single large electronic board. In such a case, the tack strength may decrease due to drying of the solder composition, causing a problem that the mounted electronic components cannot be held. On the other hand, if the boiling point of the solvent in the solder composition is increased to suppress the decrease in tackiness due to drying, there is a problem that the heat dripping property of the solder composition is decreased. Furthermore, the decrease in heat dripping property tends to make bridges more likely to occur. Thus, it has been difficult to achieve both tackiness and heat dripping property of the solder composition.

[0005] An object of the present invention is to provide a solder composition that has excellent tack strength even after a long period of time and excellent heat sagging properties, and a method for producing an electronic substrate using the same. [Means for solving the problem]

[0006] According to the present invention, there are provided the following solder composition and electronic substrate. [1] A flux composition comprising (A) a rosin-based resin, (B) an activator, and (C) a solvent, and (E) a solder powder, The component (B) contains (B1) diglycolic acid, The component (C) contains (C1) an alcohol compound having an alkyl chain with 12 to 22 carbon atoms and one hydroxyl group in one molecule, the alkyl chain having a branched chain. Solder composition. [2] The solder composition according to [1], The alkyl chain of the component (C1) has a branched chain at the C-2 position. Solder composition. [3] The solder composition according to [1] or [2], The flux composition further contains (D) a thixotropic agent, The component (D) contains (D1) an amide-based thixotropic agent and (D2) a dibenzylidene sorbitol-based thixotropic agent. Solder composition. [4] The solder composition according to any one of [1] to [3], the component (C) further contains (C3) a dicarboxylate diester which is an ester of a chain saturated dicarboxylic acid having 6 to 10 carbon atoms and an alcohol having 3 to 4 carbon atoms; Solder composition. [5] A flux composition comprising (A) a rosin-based resin, (B) an activator, and (C) a solvent, and (E) a solder powder, The component (B) contains (B1) diglycolic acid, The component (C) contains (C3) a dicarboxylate diester which is an ester of a chain saturated dicarboxylic acid having 6 to 10 carbon atoms and an alcohol having 3 to 4 carbon atoms. Solder composition. [6] A method for manufacturing an electronic substrate, comprising soldering using the solder composition according to any one of [1] to [5], applying the solder composition onto an electronic substrate; placing an electronic component on the solder composition; a step of mounting the electronic component on the electronic board by heating under predetermined conditions in a reflow furnace; and dividing the electronic substrate to obtain a module component. A method for manufacturing electronic boards. Effect of the Invention

[0007] According to the present invention, it is possible to provide a solder composition that has excellent tack strength even after a long period of time and excellent heat sagging properties, and a method for manufacturing an electronic substrate using the same. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The solder composition according to the present embodiment contains a flux composition containing (A) a rosin resin, (B) an activator, and (C) a solvent, and (E) a solder powder. The (B) component contains (B1) diglycolic acid. The (C) component contains (C1) an alcohol compound having an alkyl chain with 12 to 22 carbon atoms and one hydroxyl group in one molecule, the alkyl chain having a branched chain.

[0009] According to this embodiment, a solder composition that has excellent tackiness even after a long time has elapsed and excellent heat sagging properties can be obtained. Although the reason for this is not entirely clear, the present inventors speculate as follows. That is, the flux composition according to the present embodiment is a so-called rosin-based flux containing (A) a rosin-based resin, and is excellent in printability after a long time has passed. The flux composition according to the present embodiment further uses (B1) diglycolic acid and (C1) an alcohol compound having an alkyl chain with 12 to 22 carbon atoms in one molecule and one hydroxyl group, the alkyl chain having a branched chain. The (C1) component can improve the tackiness after a long time has passed, but the heat sagging tends to decrease. However, it has been surprisingly found that the tackiness can be improved while maintaining the heat sagging by using the (B1) component in combination with the (C1) component. The present inventors presume that the above-mentioned effects of the present invention are achieved in the above-mentioned manner.

[0010] [Flux composition] First, the flux composition used in this embodiment will be described. The flux composition used in this embodiment is a component other than the solder powder in the solder composition, and contains (A) a rosin resin, (B) an activator, and (C) a solvent, which will be described below.

[0011] [Component (A)] The rosin-based resin (A) used in this embodiment includes rosins and rosin-modified resins. Examples of rosins include gum rosin, wood rosin, and tall oil rosin. Examples of rosin-modified resins include disproportionated rosin, polymerized rosin, hydrogenated rosin, and derivatives thereof. Examples of hydrogenated rosin include fully hydrogenated rosin, partially hydrogenated rosin, and hydrogenated products of unsaturated organic acid-modified rosins (also called "hydrogenated acid-modified rosin"), which are modified rosins of unsaturated organic acids (aliphatic unsaturated monobasic acids such as (meth)acrylic acid, aliphatic unsaturated dibasic acids such as α,β-unsaturated carboxylic acids such as fumaric acid and maleic acid, unsaturated carboxylic acids having aromatic rings such as cinnamic acid, etc.). These rosin-based resins may be used alone or in combination of two or more.

[0012] The blending amount of the (A) component is preferably 20% by mass or more and 70% by mass or less, more preferably 30% by mass or more and 65% by mass or less, and particularly preferably 40% by mass or more and 60% by mass or less, based on 100% by mass of the flux composition. If the blending amount of the (A) component is equal to or more than the lower limit, the oxidation of the copper foil surface of the soldering land is prevented, and the surface is made easy to wet with molten solder, so that the so-called solderability can be improved, and the solder ball can be sufficiently suppressed. Also, if the blending amount of the (A) component is equal to or less than the upper limit, the amount of flux residue can be sufficiently suppressed.

[0013] [(B) Component] The (B) activator used in this embodiment must contain (B1) diglycolic acid. This (B1) component allows the heat sagging properties to be maintained even when the (C1) component is used. The blending amount of the (B1) component is preferably 0.1% by mass or more and 5% by mass or less, and more preferably 0.2% by mass or more and 2% by mass or less, based on 100% by mass of the flux composition. If the blending amount of the (B2) component is equal to or more than the lower limit, the heat sagging property tends to be further improved, while if it is equal to or less than the upper limit, the insulating property of the flux composition tends to be maintained.

[0014] It is preferable that the component (B) further contains (B2) an organic acid (excluding diglycolic acid). Examples of the component (B1) include other organic acids in addition to monocarboxylic acids and dicarboxylic acids, etc. These may be used alone or in combination of two or more. Monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and glycolic acid. Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, fumaric acid, maleic acid, and tartaric acid. Other organic acids include 1,2,3-propanetricarboxylic acid, 3-hydroxy-2-naphthoic acid, dimer acid, trimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

[0015] The blending amount of the (B2) component is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 7% by mass or less, and even more preferably 2% by mass or more and 5% by mass or less, based on 100% by mass of the flux composition. If the blending amount of the (B2) component is equal to or more than the lower limit, the activation action tends to be improved, whereas if it is equal to or less than the upper limit, the insulating property of the flux composition tends to be maintained.

[0016] In addition to the components (B1) and (B2), the component (B) may further contain another activator (hereinafter also referred to as the component (B3)) within the scope of the present invention. Examples of the component (B3) include halogen-based activators and amine-based activators. However, the total amount of the components (B1) and (B2) is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on 100% by mass of the component (B).

[0017] The blending amount of the (B) component is preferably 1% by mass or more and 15% by mass or less, more preferably 2% by mass or more and 10% by mass or less, and particularly preferably 3% by mass or more and 8% by mass or less, based on 100% by mass of the flux composition. If the blending amount of the (B) component is equal to or more than the lower limit, the activation action tends to be improved, whereas if it is equal to or less than the upper limit, the insulating property of the flux composition tends to be maintained.

[0018] [(C) component] The solvent (C) used in this embodiment must contain (C1) an alcohol compound having an alkyl chain with 12 to 22 carbon atoms and one hydroxyl group in one molecule, the alkyl chain being branched. This component (C1) can improve the tackiness even after a long period of time. In the component (C1), the number of carbon atoms in the alkyl chain is preferably from 16 to 20, and particularly preferably 18. In addition, the alkyl chain preferably has a branched chain at the C-2 position. Examples of the component (C1) include 2-hexyldecanol, isostearyl alcohol, 2-heptylundecanol, 2-octyldecanol, 2-hexyldodecanol, and 2-octyldodecanol.

[0019] The blending amount of the (C1) component is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 40% by mass or less, based on 100% by mass of the (C) component. If the blending amount of the (C1) component is equal to or more than the lower limit, the tackiness after a long time can be further improved. On the other hand, if the blending amount of the (C1) component is equal to or less than the upper limit, the heat sagging property can be maintained. From the same viewpoint, the blending amount of the (C1) component 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 10% by mass or less, based on 100% by mass of the flux composition.

[0020] Component (C) may contain a solvent other than component (C1) and component (C3) described below (hereinafter, component (C2)). Examples of component (C2) include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, 1,5-pentanediol, 2,5-dimethyl-2,5-hexanediol, methyl carbitol, butyl carbitol, 2-ethylhexyl diglycol (EHDG), phenyl glycol, hexyl diglycol (DEH), tetraethylene glycol dimethyl ether, and dibutyl maleate.

[0021] The component (C) preferably contains (C3) a dicarboxylate diester which is an ester of a chain saturated dicarboxylic acid having 6 to 10 carbon atoms and an alcohol having 3 to 4 carbon atoms. The present inventors have discovered that the component (C3) exerts almost the same effect as the component (C1). In other words, the effect of this embodiment can be exerted even if the component (C3) is used instead of the component (C1). Examples of the component (C3) include diisopropyl sebacate and dibutyl adipate. From the viewpoint of tack strength after a long time has elapsed, the blending amount of the (C3) component is preferably from 1 to 20% by mass, more preferably from 3 to 15% by mass, and particularly preferably from 5 to 10% by mass, relative to 100% by mass of the flux composition. When the (C1) component and the (C3) component are used in combination, the mass ratio of the (C3) component to the (C1) component ((C3) component / (C1) component) is preferably 1 / 10 or more and 10 or less, more preferably 1 / 4 or more and 4 or less, and particularly preferably 1 / 2 or more and 2 or less.

[0022] The blending amount of the (C) component is preferably 10% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less, based on 100% by mass of the flux composition. When the blending amount of the solvent is within the above range, the viscosity of the obtained solder composition can be appropriately adjusted to an appropriate range.

[0023] [(D) component] From the viewpoint of print dripping and heat dripping, the flux composition used in this embodiment preferably further contains a thixotropic agent (D). In addition, the (D) component preferably contains an amide-based thixotropic agent (D1) and a dibenzylidene sorbitol-based thixotropic agent (D2). The combination of the (D1) component and the (D2) component can further improve the heat dripping. As the component (D1), a known fatty acid amide can be used. The blending amount of the (D1) component is preferably from 0.5 to 8% by mass, and more preferably from 1 to 6% by mass, based on 100% by mass of the flux composition. Examples of the component (D2) include 1,3:2,4-bis-O-benzylidene-D-glucitol. The blending amount of the (D2) component is preferably from 0.1 to 3 mass %, and more preferably from 0.5 to 2 mass %, relative to 100 mass % of the flux composition.

[0024] From the viewpoint of printability, the (D) component may further contain a thixotropic agent other than the (D1) and (D2) components (hereinafter also referred to as the (D3) component). Examples of the (D3) component used here include hydrogenated castor oil, kaolin, colloidal silica, organic bentonite, and glass frit. These may be used alone or in combination of two or more.

[0025] The blending amount of the (D) component is preferably 2% by mass or more and 15% by mass or less, and more preferably 5% by mass or more and 10% by mass or less, based on 100% by mass of the flux composition. If the blending amount is less than the lower limit, thixotropy is not obtained and printing dripping tends to occur easily, while if the blending amount exceeds the upper limit, the thixotropy is too high and printing defects tend to occur easily.

[0026] [Other ingredients] In addition to the components (A), (B), (C), and (D), the flux composition used in this embodiment may contain other additives and other resins as necessary. Examples of the other additives include antioxidants, antifoaming agents, modifiers, matting agents, and foaming agents. The amount of these additives is preferably 0.01% by mass or more and 5% by mass or less with respect to 100% by mass of the flux composition. Examples of the other resins include acrylic resins.

[0027] [Solder composition] Next, the solder composition according to the present embodiment will be described. The solder composition according to the present embodiment contains the flux composition used in the present embodiment described above and the solder powder (E) described below. The amount of the flux composition is preferably 5% by mass or more and 35% by mass or less, more preferably 7% by mass or more and 15% by mass or less, and particularly preferably 8% by mass or more and 12% by mass or less, relative to 100% by mass of the solder composition. When the amount of the flux composition is less than 5% by mass (when the amount of the solder powder exceeds 95% by mass), the flux composition as a binder is insufficient, so that it tends to be difficult to mix the flux composition and the solder powder. On the other hand, when the amount of the flux composition is more than 35% by mass (when the amount of the solder powder is less than 65% by mass), when the obtained solder composition is used, it tends to be difficult to form a sufficient solder joint.

[0028] [(E) component] The solder powder (E) used in this embodiment is preferably made of only lead-free solder powder, but may be lead-containing solder powder. The solder alloy in this solder powder preferably contains at least one selected from the group consisting of tin (Sn), copper (Cu), zinc (Zn), silver (Ag), antimony (Sb), lead (Pb), indium (In), bismuth (Bi), nickel (Ni), cobalt (Co) and germanium (Ge). The solder alloy in the solder powder is preferably an alloy mainly composed of tin. More preferably, the solder alloy contains tin, silver, and copper. Furthermore, the solder alloy may contain at least one of antimony, bismuth, and nickel as an additive element. According to the flux composition of the present embodiment, even when a solder alloy containing an additive element that is easily oxidized, such as antimony, bismuth, and nickel, is used, the generation of voids can be suppressed. Here, lead-free solder powder refers to a powder of solder metal or alloy to which no lead is added. However, the presence of lead as an unavoidable impurity in the lead-free solder powder is permitted, but in this case, the amount of lead is preferably 300 ppm by mass or less.

[0029] Specific examples of alloy systems for lead-free solder powder include Sn-Ag-Cu systems, Sn-Cu systems, Sn-Ag systems, Sn-Bi systems, Sn-Ag-Bi systems, Sn-Ag-Cu-Bi systems, Sn-Ag-Cu-Ni systems, Sn-Ag-Cu-Bi-Sb systems, Sn-Ag-Bi-In systems, and Sn-Ag-Cu-Bi-In-Sb systems.

[0030] From the viewpoint of compatibility with electronic boards having narrow pitches of solder pads, the average particle size of component (E) is preferably 1 μm or more and 20 μm or less, and more preferably 2 μm or more and 15 μm or less. The average particle size can be measured by a dynamic light scattering particle size measuring device.

[0031] [Method of manufacturing solder composition] The solder composition according to this embodiment can be produced by blending the above-described flux composition and the above-described (E) solder powder in the above-described predetermined ratio, and stirring and mixing them.

[0032] [Electronic board manufacturing method] Next, a method for manufacturing an electronic substrate according to this embodiment will be described. The method for manufacturing an electronic board according to this embodiment is a method for manufacturing an electronic board in which soldering is performed using the solder composition described above, and includes the steps of applying the solder composition onto an electronic board (application step), arranging electronic components on the solder composition (mounting step), mounting the electronic components on the electronic board by heating under specified conditions in a reflow furnace (reflow step), and dividing the electronic board to obtain module components (dividing step). According to the method for manufacturing an electronic board according to this embodiment, several hundred modular components can be manufactured from one large electronic board.

[0033] In the application step, the solder composition is applied onto the electronic substrate, and in the mounting step, the electronic components are placed on the solder composition. Examples of the coating device used here include a screen printer, a metal mask printer, a dispenser, and a jet dispenser. In addition, the electronic substrate may be a large substrate that can be divided into several hundred modular components and can mount many electronic components. Since the solder composition according to the present embodiment described above has excellent tack strength even after a long time has elapsed, it is possible to suppress the problem of the mounted electronic components being unable to be held even when many electronic components are mounted over a long period of time.

[0034] In the reflow process, the electronic component is placed on the solder composition and heated in a reflow furnace under predetermined conditions. This reflow process allows sufficient solder bonding between the electronic component and the printed wiring board. As a result, the electronic component can be mounted on the printed wiring board. The reflow conditions may be appropriately set according to the melting point of the solder. For example, the preheat temperature is preferably 140°C or higher and 200°C or lower, and more preferably 150°C or higher and 160°C or lower. The preheat time is preferably 60 seconds or higher and 120 seconds or lower. The peak temperature is preferably 230°C or higher and 270°C or lower, and more preferably 240°C or higher and 255°C or lower. The holding time at a temperature of 220°C or higher is preferably 20 seconds or higher and 60 seconds or lower.

[0035] In the dividing step, the electronic substrate is divided to obtain modular components. Here, the electronic substrate can be divided using a router type substrate divider, a dry slicer type substrate divider, a dicer, etc. Also, the electronic substrate may be provided with cuts in advance.

[0036] Furthermore, the solder composition and electronic substrate of the present embodiment are not limited to the above-described embodiment, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention. For example, in the electronic substrate, the printed wiring board and the electronic component are bonded by a reflow process, but the present invention is not limited thereto. For example, instead of the reflow process, the printed wiring board and the electronic component may be bonded by a process (laser heating process) of heating the solder composition using laser light. In this case, the laser light source is not particularly limited and can be appropriately adopted according to the wavelength that matches the absorption band of the metal. Examples of the laser light source include solid lasers (ruby, glass, YAG, etc.), semiconductor lasers (GaAs, InGaAsP, etc.), liquid lasers (dye, etc.), and gas lasers (He-Ne, Ar, CO2, excimer, etc.). EXAMPLES

[0037] The present invention will now be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. The materials used in the examples and comparative examples are shown below. (Component (A)) Rosin-based resin A: Hydrogenated acid-modified rosin, product name "Pine Crystal KE-604", manufactured by Arakawa Chemical Industries Co., Ltd. Rosin resin B: Fully hydrogenated rosin, product name "Foral AX", manufactured by Rika Finetech Co., Ltd. ((B1) component) Diglycolic acid: Diglycolic acid, manufactured by Midori Chemical Co., Ltd. ((B2) component) Organic acid A: Malonic acid Organic acid B: Succinic acid Organic acid C: Glutaric acid Organic acid D: 1,2,3-propanetricarboxylic acid, manufactured by New Japan Chemical Co., Ltd. Organic acid E: 3-hydroxy-2-naphthoic acid ((C1) component) Solvent A: 2-hexyldecanol, manufactured by Kokyu Alcohol Kogyo Co., Ltd. Solvent B: Isostearyl alcohol, manufactured by Kokyu Alcohol Kogyo Co., Ltd. Solvent C: 2-octyldodecanol, manufactured by Kokyu Alcohol Kogyo Co., Ltd. ((C2) component) Solvent D: Diethylene glycol monohexyl ether (hexyldiglycol (DEH)), manufactured by Nippon Nyukazai Co., Ltd. Solvent E: Diethylene glycol mono-2-ethylhexyl ether (2-ethylhexyl diglycol (EHDG)), manufactured by Nippon Nyukazai Co., Ltd. Solvent F: Tetraethylene glycol dimethyl ether, product name "Hisorb MTEM", manufactured by Toho Chemical Industry Co., Ltd. ((C3) component) Solvent G: Diisopropyl sebacate, manufactured by Tokyo Chemical Industry Co., Ltd. Solvent H: Dibutyl adipate, manufactured by Tokyo Chemical Industry Co., Ltd. (Component (D1)) Thixotropic agent A: Amide-based thixotropic agent (lauric acid amide), product name "Diamid Y", manufactured by Mitsubishi Chemical Corporation ((D2) component) Thixotropic agent B: dibenzylidene sorbitol-based thixotropic agent (1,3:2,4-bis-O-benzylidene-D-glucitol), trade name "Gelall D", manufactured by New Japan Chemical Co., Ltd. (Component (D3)) Thixotropic agent C: Castor oil (melting point 85-87°C), product name "Himakou", manufactured by KF Trading Co., Ltd. ((E) component) Solder powder: alloy composition is Sn-3.0Ag-0.5Cu, particle size distribution is 5-15μm (equivalent to type 7 of IPC-J-STD-005A), solder melting point is 217-220℃

[0038] [Example 1] 35 mass% rosin-based resin A, 15 mass% rosin-based resin B, 0.8 mass% diglycolic acid, 0.5 mass% organic acid A, 0.5 mass% organic acid B, 2 mass% organic acid C, 3 mass% organic acid E, 10 mass% solvent A, 23.2 mass% solvent B, 4 mass% thixotropic agent A, 1 mass% thixotropic agent B, and 5 mass% thixotropic agent C were placed in a container and mixed using a planetary mixer to obtain a flux composition. Thereafter, 12% by mass of the obtained flux composition and 88% by mass of the solder powder (total of 100% by mass) were placed in a container and mixed with a planetary mixer to prepare a solder composition.

[0039] [Examples 2 to 8] A solder composition was obtained in the same manner as in Example 1, except that the materials were mixed according to the composition shown in Table 1. [Comparative Examples 1 to 8] A solder composition was obtained in the same manner as in Example 1, except that the materials were mixed according to the composition shown in Table 1.

[0040] <Evaluation of solder composition> The solder compositions were evaluated (component skipping test, heat dripping) by the following methods. The results are shown in Table 1. (1) Parts flying test A solder composition was printed on a test board using a 0201 chip pattern with an opening of 125 μm×85 μm, a 0402 chip pattern with an opening of 210 μm×150 μm, and a metal mask with a thickness of 25 μm. Then, the test board was exposed to air by a circulator in an environment of temperature 25° C. and humidity 50% RH. After 2 hours and 3 hours, 200 0201 chips and 200 0402 chips were mounted. After mounting the components, the test board was turned upside down to check whether the chips had fallen off, and the component flying test was evaluated according to the following criteria. ○: No chips were removed. ×: The chip fell off. (2) Heat dripping The solder composition was printed on the ceramic substrate using an IPC-A-20 pattern and a 100 μm thick metal mask. The substrate was then heated for 10 minutes in a hot air oven set at 150°C. A microscope was used to check for bridges in a test pattern with a pad size of 0.2 mm x 2.03 mm. Heat sagging was evaluated according to the following criteria. If bridges occur at 0.30 mm pitches, solder bridges will likely occur between components during reflow, causing a short circuit on the substrate. ◯: The minimum pitch is less than 0.15 mm. △: The minimum pitch is less than 0.25 mm. ×: The minimum pitch is 0.30 mm or more.

[0041] [Table 1]

[0042] As is clear from the results shown in Table 1, it was confirmed that the solder compositions of the present invention (Examples 1 to 8) were excellent in all results of the component flying test and heat dripping test. Therefore, it was confirmed that the solder composition of the present invention has excellent tack strength even after a long period of time and excellent heat sagging properties. [Industrial Applicability]

[0043] The solder composition of the present invention can be suitably used in a technique for mounting electronic components on electronic substrates such as printed wiring boards of electronic devices.

Claims

1. A flux composition including (A) a rosin-based resin, (B) an activator, and (C) a solvent, and (E) a solder powder, The component (B) contains (B1) diglycolic acid, The component (C) contains (C1) an alcohol compound having an alkyl chain with 12 to 22 carbon atoms and one hydroxyl group in one molecule, the alkyl chain having a branched chain, The blending amount of the (B1) component is 0.1 mass % or more and 5 mass % or less with respect to 100 mass % of the flux composition, The blending amount of the (C1) component is 1 mass% or more and 20 mass% or less with respect to 100 mass% of the flux composition, Solder composition.

2. The solder composition according to claim 1, The alkyl chain of the component (C1) has a branched chain at the C-2 position. Solder composition.

3. The solder composition according to claim 1 or 2, The flux composition further contains (D) a thixotropic agent, The component (D) contains (D1) an amide-based thixotropic agent and (D2) a dibenzylidene sorbitol-based thixotropic agent. Solder composition.

4. The solder composition according to claim 1 or 2, the component (C) further contains (C3) a dicarboxylate diester which is an ester of a chain saturated dicarboxylic acid having 6 to 10 carbon atoms and an alcohol having 3 to 4 carbon atoms; Solder composition.

5. A flux composition including (A) a rosin-based resin, (B) an activator, and (C) a solvent, and (E) a solder powder, The component (B) contains (B1) diglycolic acid, The component (C) contains (C3) a dicarboxylate diester which is an ester of a chain saturated dicarboxylic acid having 6 to 10 carbon atoms and an alcohol having 3 to 4 carbon atoms, The blending amount of the (B1) component is 0.1 mass % or more and 5 mass % or less with respect to 100 mass % of the flux composition, The blending amount of the (C3) component is 1 mass% or more and 20 mass% or less with respect to 100 mass% of the flux composition, Solder composition.

6. A method for manufacturing an electronic substrate by soldering using the solder composition according to claim 1 or 2, comprising the steps of: applying the solder composition onto an electronic substrate; placing an electronic component on the solder composition; a step of mounting the electronic component on the electronic board by heating under predetermined conditions in a reflow furnace; and dividing the electronic substrate to obtain a module component. A method for manufacturing electronic boards.

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