JP7554294B2 - Flux composition, solder composition, and method for manufacturing electronic board - Google Patents

Description

The present invention relates to a flux composition, a solder composition, and a method for manufacturing an electronic substrate.

The solder composition is a mixture of solder powder and a flux composition (rosin-based resin, an activator, a solvent, etc.) kneaded together to form a paste (see Patent Document 1).
When soldering is performed using a solder composition, flux residue remains around the joint after soldering. This residue contains activator components, etc., and there is a concern that moisture may enter the residue distributed across the electrodes due to condensation, etc., and cause ion migration. In addition, the presence of flux residue on the surface may cause defects in the molding process or coating process, or cause poor bonding in wire bonding. Therefore, it is desirable to remove this residue by cleaning after bonding.

Conventionally, cleaning has been carried out using cleaning agents whose main component is organic solvents with high cleaning power. However, because these agents contain a large amount of solvent, regulations have been strengthened from the viewpoints of preventing water pollution, fire and air pollution, and from the viewpoint of occupational health.
In recent years, the amount of solvent used has been reduced and water-based cleaning chemicals, which are mainly composed of water, have come to be used. However, due to the change in the cleaning chemicals' ingredients, the cleaning performance of flux residues has tended to deteriorate, which has become a problem.
Also, from the viewpoint of equipment costs, there is an increasing need to perform soldering by reflow under atmospheric conditions. In the case of air reflow, oxidation of the solder powder progresses, and solder melting property decreases. This tendency is more pronounced in the joints of small components where the amount of solder composition printed is small. Furthermore, in air reflow, the metal salts contained in the flux residue after soldering increase due to the effect of metal oxidation, and the cleanability of the flux residue also tends to deteriorate.

Patent No. 5887330

The present invention aims to provide a flux composition and a solder composition that have excellent cleaning properties for flux residues in aqueous cleaners and excellent solder melting properties in air reflow, as well as a method for manufacturing electronic substrates.

According to one aspect of the present invention, there is provided a flux composition comprising (A) a rosin-based resin, (B) an activator, (C) a solvent, and (D) a hindered amine compound, the (B) component comprising (B1) a dicarboxylic acid having 4 to 18 carbon atoms, and the (D) component having a structure represented by the following general formula (D1):

In the general formula (D1), R ¹ is independently a methyl group or an ethyl group, and X is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.

According to one aspect of the present invention, there is provided a solder composition containing the flux composition according to the above aspect of the present invention and (E) solder powder.

According to one aspect of the present invention, there is provided a method for manufacturing an electronic board by performing soldering using a solder composition according to one aspect of the present invention, the method comprising the steps of applying the solder composition onto an electronic board, arranging electronic components on the solder composition, mounting the electronic components on the electronic board by heating under predetermined conditions in a reflow furnace, and cleaning flux residues on the electronic board with a water-based cleaner.

The present invention provides a flux composition and solder composition that are excellent in cleaning properties for flux residues with aqueous cleaners and excellent in solder melting properties during air reflow, as well as a method for manufacturing electronic substrates.

[Flux composition]
First, the flux composition according to the present embodiment will be described. The flux composition according to the present embodiment is a solder composition containing components other than the solder powder, which are (A) a rosin resin, (B) an activator, (C) a solvent, and (D) a hindered amine compound, which will be described below.

[Component (A)]
Examples of the rosin-based resin (A) used in this embodiment include rosins and rosin-modified resins. Examples of rosins include gum rosin, wood rosin, and tall oil rosin. Examples of the rosin-modified resin include disproportionated rosin, polymerized rosin, hydrogenated rosin, and derivatives thereof. Examples of the 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. From the viewpoint of cleaning properties of flux residue, it is preferable to use at least one of polymerized rosin and hydrogenated acid-modified rosin among these rosin-based resins, and it is more preferable to use polymerized rosin. It is also more preferable to use at least one of polymerized rosin and hydrogenated acid-modified rosin in combination with another rosin-based resin (such as disproportionated rosin, formylated rosin, or hydrogenated rosin).

The amount of component (A) is preferably 30% by mass or more and 70% by mass or less, more preferably 35% by mass or more and 60% by mass or less, and particularly preferably 40% by mass or more and 50% by mass or less, relative to 100% by mass of the flux composition. If the amount of component (A) is equal to or more than the lower limit, oxidation of the copper foil surface of the soldering land can be prevented, making the surface more easily wetted by molten solder, improving so-called solderability, and sufficiently suppressing solder balls. Also, if the amount of component (A) is equal to or less than the upper limit, the amount of flux residue can be sufficiently suppressed.

[Component (B)]
The activator (B) used in this embodiment is required to contain (B1) a dicarboxylic acid having 4 to 18 carbon atoms. From the viewpoints of cleaning properties for flux residue and solder melting properties, the component (B1) is preferably a dicarboxylic acid having 4 to 12 carbon atoms, more preferably a dicarboxylic acid having 8 to 12 carbon atoms, and particularly preferably a dicarboxylic acid having 9 to 12 carbon atoms.
Examples of the (B1) component include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Among these, azelaic acid, sebacic acid, and dodecanedioic acid are preferred from the viewpoint of cleaning properties of flux residue and solder melting properties. These may be used alone or in combination of two or more.

The amount of the (B1) component is preferably 2% 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 4% by mass or more and 12% by mass or less, relative to 100% by mass of the flux composition. If the amount of the (B1) component is equal to or more than the lower limit, the solder melting property tends to be improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

From the viewpoints of cleaning properties for flux residues and solder melting properties, it is preferable that the component (B) further contains an aromatic carboxylic acid (B2).
As the component (B2), a known aromatic carboxylic acid can be appropriately selected. From the viewpoint of cleaning property and activity of flux residue, the component (B2) is preferably an aromatic carboxylic acid having a hydroxyl group and an amino group in one molecule or having a heterocycle in one molecule.
Examples of the (B2) component include 2-naphthoic acid, 3-hydroxy-2-naphthoic acid, benzoic acid, anthranilic acid, salicylic acid, and picolinic acid. Among these, from the viewpoint of cleaning properties and activation of flux residue, 3-hydroxy-2-naphthoic acid, anthranilic acid, salicylic acid, and picolinic acid are preferred, 3-hydroxy-2-naphthoic acid, salicylic acid, and picolinic acid are more preferred, and 3-hydroxy-2-naphthoic acid and picolinic acid are particularly preferred. These may be used alone or in combination of two or more.

The amount of the (B2) component is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 8% by mass or less, and particularly preferably 3% by mass or more and 5% by mass or less, relative to 100% by mass of the flux composition. If the amount of the (B2) component is equal to or more than the lower limit, the solder melting property tends to be improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

From the viewpoint of cleaning ability of flux residue and solder melting ability, it is preferable that the (B) component further contains (B3) a dicarboxylic acid having 19 to 24 carbon atoms. Examples of the (B3) component include eicosane diacid and 8,13-dimethyl-8,12-eicosadienedioic acid. This (B3) component can improve solder melting ability while maintaining the cleaning ability of flux residue. In contrast, long-chain dicarboxylic acids with branched chains such as dimer acid have a negative effect on the cleaning ability of flux residue, although the reason is unclear.

The amount of the (B3) component is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 8% by mass or less, and particularly preferably 3% by mass or more and 5% by mass or less, relative to 100% by mass of the flux composition. If the amount of the (B3) component is equal to or more than the lower limit, the solder melting property tends to be improved, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

The (B) component may further contain other activators (hereinafter also referred to as (B4) component) in addition to the (B1), (B2) and (B3) components, within the scope of the present invention. Examples of the (B4) component include organic acids, halogen-based activators, and amine-based activators other than the (B1), (B2) and (B3) components. However, from the viewpoint that the (B4) component may adversely affect the cleaning properties of the flux residue, it is preferable to use the (B1), (B2) and (B3) components as the (B) component. In addition, the total amount of the (B1), (B2) and (B3) components is preferably 80% by mass or more, and more preferably 90% by mass or more, relative to 100% by mass of the (B) component.

The amount of component (B) is preferably 3% by mass or more and 25% by mass or less, more preferably 5% by mass or more and 23% by mass or less, even more preferably 7% by mass or more and 21% by mass or less, and particularly preferably 10% by mass or more and 20% by mass or less, relative to 100% by mass of the flux composition. If the amount of component (B) is equal to or more than the lower limit, the activation action tends to be improved, while if it is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[Component (C)]
As the solvent (C) used in the present embodiment, a known solvent can be appropriately used. As such a solvent, it is preferable to use a solvent having a boiling point of 170° C. or higher.
Examples of such solvents include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, 2-ethylhexyl diglycol, octanediol, phenyl glycol, diethylene glycol monohexyl ether (DEH), tetraethylene glycol dimethyl ether, dibutyl maleic acid, etc. These solvents may be used alone or in combination of two or more.

The amount of component (C) is preferably 10% by mass or more and 60% by mass or less, and more preferably 20% by mass or more and 50% by mass or less, relative to 100% by mass of the flux composition. If the amount of the solvent is within the above range, the viscosity of the resulting solder composition can be appropriately adjusted to an appropriate range.

[Component (D)]
The hindered amine compound (D) used in this embodiment has a structure represented by the following general formula (D1). This component (D) can improve the solder melting property in air reflow. Furthermore, the combination of this component (D) with component (B1) can improve the solder melting property in air reflow while maintaining the cleaning property of the flux residue.

In formula (D1), R ¹ is independently a methyl group or an ethyl group, and is preferably a methyl group.
X is hydrogen, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms. When X is hydrogen, the structure is represented by the following general formula (D1-1). When X is an alkyl group having 1 to 12 carbon atoms, the structure is represented by the following general formula (D1-2). When X is an alkoxy group having 1 to 12 carbon atoms, the structure is represented by the following general formula (D1-3).
In addition, in component (D), the structure of the portion beyond the wavy line is not particularly limited.
The number of structures represented by general formula (D1) in one molecule of the component (D) is preferably 1 or more and 10 or less, and more preferably 2 or more and 4 or less.

In formula (D1-1), R ¹ is independently a methyl group or an ethyl group, and is preferably a methyl group.
Examples of the compound having a structure represented by general formula (D1-1) include bis(2,2,6,6-tetramethyl-4-piperidyl)sebacicate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate.

In formula (D1-2), R ¹ is independently a methyl group or an ethyl group, and is preferably a methyl group.
^R2 is an alkyl group having 1 to 12 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, and particularly preferably a methyl group.
Examples of the compound having a structure represented by general formula (D1-2) include bis(1,2,2,6,6-pentamethyl-4-piperidyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]ethyl]butyl malonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 1-(methyl)-8-(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, and 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate.

In formula (D1-3), R ¹ is independently a methyl group or an ethyl group, and is preferably a methyl group.
^R3 is an alkyl group having 1 to 12 carbon atoms, preferably an alkyl group having 4 to 11 carbon atoms, more preferably an alkyl group having 8 to 11 carbon atoms, and particularly preferably an octyl group or an undecyl group.
Examples of the compound having a structure represented by general formula (D1-3) include bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate and bis(1-undecaoxy-2,2,6,6-tetramethylpiperidin-4-yl)carbonate.

The amount of component (D) is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less, even more preferably 1% by mass or more and 7% by mass or less, and particularly preferably 2% by mass or more and 4% by mass or less, based on 100% by mass of the flux composition. If the amount of component (D) is equal to or more than the lower limit, the solder meltability during air reflow tends to be improved, especially when the time required to reach the melting temperature during reflow is long, while if the amount is equal to or less than the upper limit, the insulating properties of the flux composition tend to be maintained.

[Thixilation agent]
In the flux composition of the present embodiment, it is preferable to further contain a thixotropic agent from the viewpoint of printability, etc. Examples of the thixotropic agent used here include hardened castor oil, amides, kaolin, colloidal silica, organic bentonite, and glass frit. These may be used alone or in combination of two or more.

The amount of the thixotropic agent is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 12% by mass or less, relative to 100% by mass of the flux composition. If the amount is less than the lower limit, thixotropy is not obtained and sagging tends to occur easily, while if the amount is more than the upper limit, the thixotropy is too high and printing defects tend to occur.

[Other ingredients]
In addition to the (A), (B), (C), (D) and thixotropic agent, other additives and even other resins can be added to the flux composition used in this embodiment as necessary. Examples of the other additives include antioxidants other than the (D) component, antifoaming agents, modifiers, matting agents, and foaming agents. The amount of these additives to be added 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 and polybutadiene.

[Solder Composition]
Next, the solder composition of the present embodiment will be described. The solder composition of the present embodiment contains the flux composition of 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 18% by mass or less, and particularly preferably 8% by mass or more and 15% 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.

[Component (E)]
The solder powder (E) used in the present invention is preferably composed of only lead-free solder powder, but may be lead-containing solder powder. The solder alloy in the 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), gold (Au), 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 a 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.

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

The average particle diameter of component (E) is usually 1 μm or more and 40 μm or less, but from the viewpoint of being compatible with electronic boards with narrow pitches of solder pads, it is more preferably 1 μm or more and 35 μm or less, even more preferably 2 μm or more and 35 μm or less, and particularly preferably 3 μm or more and 32 μm or less. The average particle diameter can be measured by a dynamic light scattering particle size measuring device.

[Method of manufacturing solder composition]
The solder composition of the present 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.

[Electronic Substrate Manufacturing Method]
Next, a method for producing an electronic board according to the present embodiment will be described. The method for producing an electronic board according to the present embodiment is characterized by using the solder composition described above. According to the method for producing an electronic board according to the present embodiment, an electronic board can be produced by mounting electronic components on an electronic board (such as a printed wiring board) using the solder composition.
The solder composition of the present embodiment described above has excellent cleaning properties for flux residues with an aqueous cleaner and excellent solder melting properties in air reflow, so that flux residues can be easily cleaned with an aqueous cleaner after soldering.
In the method for producing an electronic substrate according to the present embodiment, first, a solder composition is applied onto the electronic substrate by a coating device.
Examples of the coating device used here include a screen printer, a metal mask printer, a dispenser, and a jet dispenser.
In addition, an electronic component can be mounted on an electronic board by a reflow process in which an electronic component is placed on the solder composition applied by the application device and heated under specified conditions in a reflow furnace to mount the electronic component on a printed wiring board.

In the reflow process, the electronic component is placed on the solder composition and heated under predetermined conditions in a reflow furnace. 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 atmosphere during reflow may be a nitrogen atmosphere, but since the solder composition of the present embodiment described above has excellent solder melting properties in air reflow, it may be left in air.
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 more and 200° C. or less, and more preferably 150° C. or more and 160° C. or less. The preheat time is preferably 60 seconds or more and 120 seconds or less. The peak temperature is preferably 230° C. or more and 270° C. or less, and more preferably 240° C. or more and 255° C. or less. The holding time at a temperature of 220° C. or more is preferably 20 seconds or more and 60 seconds or less.

After the reflow process, flux residues on the electronic substrate are cleaned using a water-based cleaner.
The cleaning method may be a dipping method, a jet method, or the like.
For example, in the immersion method, the electronic substrate is immersed in a water-based cleaning agent. At this time, ultrasonic waves may be applied.
As the aqueous cleaning agent, a known aqueous cleaning agent for flux residue can be used. Here, aqueous means that the main component is water (water is 50 mass% or more). Commercially available products include "VIGON US" manufactured by ZESTRON JAPAN.
The temperature of the aqueous cleaner during cleaning is, for example, 30° C. or higher and 70° C. or lower.
The cleaning time is, for example, from 1 minute to 10 minutes.
After cleaning with the aqueous cleaner, rinsing may be performed. The conditions for rinsing are not particularly limited, and the rinsing may be performed with water at 20° C. to 50° C. for about 0.5 minutes to 5 minutes. Rinsing may be performed two or more times.

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 method for manufacturing an electronic board, the printed wiring board and the electronic components 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 components may be bonded by a process (laser heating process) in which the solder composition is heated 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, CO ₂ , and excimer, etc.).

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: polymerized rosin, trade name "Chinese polymerized rosin", manufactured by Arakawa Chemical Industries, Ltd. Rosin-based resin B: acrylic acid modified hydrogenated rosin, trade name "Pine Crystal KE-604", manufactured by Arakawa Chemical Industries, Ltd. Rosin-based resin C: formylated rosin, trade name "FORAL-AX", manufactured by Eastman Chemical Co. Rosin-based resin D: special modified rosin, trade name "Haritac FG-90", manufactured by Harima Chemical Industries, Ltd. (component (B1))
Dicarboxylic acid A: azelaic acid Dicarboxylic acid B: sebacic acid Dicarboxylic acid C: dodecanedioic acid (component (B2))
Aromatic carboxylic acid: 3-hydroxy-2-naphthoic acid (component (B3))
Eicosanedioic acid: trade name "SL-20", manufactured by Okamura Oil Mills (component (B4))
Organic acid A: dimer acid, trade name "UNIDYME 14", manufactured by Arizona Chemical Company Organic acid B: palmitic acid Organic acid C: dodecanoic acid (component (C))
Solvent: Diethylene glycol monohexyl ether (DEH, hexyl diglycol)
(Component (D))
Hindered amine compound A: a compound having two structures represented by the general formula (D1-2) in one molecule, bis(1,2,2,6,6-pentamethyl-4-piperidyl)-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]ethyl]butyl malonate, trade name "Tinuvin PA144", manufactured by BASF Hindered amine compound B: a compound having two structures represented by the general formula (D1-1) in one molecule, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, trade name "Tinuvin 770DF", manufactured by BASF Hindered amine compound C: a compound having two structures represented by the general formula (D1-3) in one molecule, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, trade name "Tinuvin 123", manufactured by BASF Corporation; hindered amine compound D: a compound having four structures represented by the general formula (D1-1) in one molecule; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylate, trade name "ADEKA STAB LA-57", manufactured by ADEKA Corporation (other components)
Thixotropic agent: Trade name "Slipax H", manufactured by Nippon Kasei Chemical Industry Co., Ltd. (component (E))
Solder powder: alloy composition is Sn-3.0Ag-0.5Cu, particle size distribution is 15-25 μm, solder melting point is 217-220°C

[Example 1]
45% by mass of rosin-based resin A, 2% by mass of dicarboxylic acid B, 4% by mass of aromatic carboxylic acid, 4% by mass of eicosanedioic acid, 36.5% by mass of solvent, 2% by mass of hindered amine compound D, and 6.5% by mass of a thixotropic agent were charged into 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.

[Examples 2 to 13]
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 5]
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.
[Examples 14 to 19]
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 2.

<Evaluation of Solder Composition>
The solder compositions were evaluated (cleaning properties, solder melting properties (air reflow), and property changes after rolling) by the following methods. The results are shown in Tables 1 and 2.
(1) Cleanability A solder composition was printed on a substrate capable of mounting chip components, chip components (size: 1.6 mm x 0.8 mm) were mounted, and the solder composition was melted in a reflow furnace (manufactured by Tamura Corporation) to perform soldering to obtain a substrate for evaluation. The reflow conditions were air reflow, a preheat temperature of 130 to 180°C (about 100 seconds), a time at a temperature of 220°C or higher for about 60 seconds, and a peak temperature of 240°C.
Next, the obtained evaluation substrate was immersed in a container containing a water-based cleaning agent (Zestron Japan's "VIGON US", 20% concentration) and cleaned with ultrasonic waves (liquid temperature: 60°C, cleaning time: 5 minutes). After that, the liquid was removed with an air knife, and the substrate was immersed in a container containing pure water at room temperature for a first rinse (rinsing time: 1 to 2 minutes), and further immersed in a container containing pure water at 45°C for a second rinse (rinsing time: 1 to 2 minutes). After that, the liquid was removed with an air gun, and the substrate was dried in a hot air drying furnace (furnace temperature: 70°C) for 10 minutes.
After cleaning with the aqueous cleaner, all chips were removed from the evaluation board, and the presence or absence of flux residue under the chips and the presence or absence of flux residue beside the chips were observed. The number of chips with residual flux and the ratio to the total number of chips (residual ratio) were then measured, and the cleanability (under the chips, beside the chips) was evaluated based on the residual ratio according to the following criteria.
A: The residual ratio is less than 10%.
Δ: The residual ratio is 10% or more and less than 20%.
×: The residual ratio is 20% or more.
(2) Solder melting property (air reflow)
A solder composition was printed on a substrate capable of mounting chip components, 1005 chip components (size: 1.0 mm x 0.5 mm) and 0603 chip components (size: 0.6 mm x 0.3 mm) were mounted, and the solder composition was melted and soldered in a reflow furnace (manufactured by Tamura Corporation) to obtain a substrate for evaluation. The reflow conditions were air reflow, a preheat temperature of 130 to 180°C (for about 100 seconds), a time at a temperature of 220°C or higher for about 60 seconds, and a peak temperature of 240°C.
The number of unmelted portions in the chip bonding portions of the evaluation board was then counted, and the solder melting property (air reflow) was evaluated according to the following criteria.
(a) 1005 chip component ◯: The unmelted ratio is less than 30%.
Δ: The unmelted ratio is 30% or more and less than 50%.
×: The unmelted ratio is 50% or more.
(b) 0603 chip component. ◯: The unmelted ratio is less than 50%.
Δ: The unmelted ratio is 50% or more and less than 70%.
×: The unmelted ratio is 70% or more.
(3) Changes in properties after rolling The obtained solder composition was used as a sample, and this sample was placed on a metal mask without any openings. This was set in a printing machine, and a rolling test was performed in which continuous printing was performed for 6 hours using a urethane squeegee. Then, the sample after the rolling test was evaluated for changes in properties after rolling according to the following criteria.
○: The sample maintains its original smooth state. For example, when a spatula is inserted and removed, a peak stands up and the tip falls back under its own weight.
△: The properties of the sample are slightly deteriorated. For example, when a spatula or the like is inserted and then removed, the horns remain erect for 10 seconds or more.
×: The properties of the sample are significantly deteriorated. For example, when a spatula or the like is inserted and then removed, no protrusion stands up and a hole remains.

As is clear from the results shown in Tables 1 and 2, it was confirmed that the solder compositions of the present invention (Examples 1 to 19) were good in all respects, including cleanability, solder melting property (air reflow), and property changes after rolling.
Therefore, it was confirmed that the solder composition of the present invention has excellent cleaning properties for flux residues when used with an aqueous cleaner, and also has excellent solder melting properties during air reflow.

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

Claims (5)

A flux composition comprising: (A) a rosin-based resin; (B) an activator; (C) a solvent; and (D) a hindered amine compound,
The component (B) contains (B1) a dicarboxylic acid having 4 to 18 carbon atoms,
The component (D) has a structure represented by the following general formula (D1):
The blending amount of the (A) is 30% by mass or more and 70% by mass or less with respect to 100% by mass of the flux composition,
The blending amount of the (B) component is 3 mass% or more and 25 mass% or less with respect to 100 mass% of the flux composition,
The blending amount of the (B1) component is 2 mass% or more and 20 mass% or less with respect to 100 mass% of the flux composition,
The blending amount of the (C) component is 10% by mass or more and 60% by mass or less with respect to 100% by mass of the flux composition,
The blending amount of the (D) component is 0.1 mass% or more and 20 mass% or less with respect to 100 mass% of the flux composition,
Flux composition.

(In the general formula (D1), R ¹ is independently a methyl group or an ethyl group, and X is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or an alkoxy group having 1 to 12 carbon atoms.) 2. The flux composition according to claim 1,
The component (B) contains an aromatic carboxylic acid (B2) ,
The blending amount of the (B2) component is 1 mass% or more and 10 mass% or less with respect to 100 mass% of the flux composition.
Flux composition. The flux composition according to claim 1 or 2,
The component (A) contains a polymerized rosin.
Flux composition. A flux composition according to claim 1 or 2, and (E) a solder powder.
Solder composition. A method for manufacturing an electronic substrate by soldering using the solder composition according to claim 4 , 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 cleaning the flux residue on the electronic substrate using a water-based cleaning agent.
A method for manufacturing electronic boards.