JP2015160233A - Flux composition, solder composition and printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux composition excellent in viscosity stability during continuous printing and capable of sufficiently controlling occurrence of chip side balls when preparing a solder composition.SOLUTION: A flux composition contains a rosin-based resin (A), a flux (B), an activator (C), a thixotropic agent (D) and an antioxidant (E). The component (E) contains a compound (E1) represented by a general formula (1) mentioned below (wherein L, L, Land Lmay be the same or different, are a group represented by -CH-, and m is an integer of 0 to 4).

Description

  The present invention relates to a solder composition (so-called solder paste) for mounting a component on a printed wiring board of an electronic device, a flux composition for the solder composition, and a printed wiring in which an electronic component is mounted using the solder composition. Regarding the substrate.

  The solder composition (solder paste) is a mixture in which a solder powder is kneaded with a flux composition (such as a rosin resin, an activator, and a solvent) to form a paste. This solder composition is required to suppress chip side balls and to be printable, as well as solder melting properties and the property of solder being easily spread (solder spread). Note that the chip side ball differs from the normal solder ball (the solder ball remaining between the pads after reflow), the solvent in the solder paste volatilizes under the chip, this gas repels the solder, and the ball Means what happened to the side of the chip. These chip side balls are larger than ordinary solder balls. Among these required characteristics, in particular, high printability (viscosity stability during continuous printing and other characteristics) may be required from the viewpoint of productivity such as a mounting substrate. Further, from the viewpoint of downsizing the mounting substrate, there is a case where more reliable suppression of the chip side balls is also required. In order to solve these problems, studies have been made on an activator in the flux composition (for example, Patent Document 1).

JP 2006-110580 A

However, the solder paste described in Patent Document 1 is not always sufficient in terms of viscosity stability during continuous printing and chip side ball suppression.
From the viewpoint of viscosity stability and chip side ball suppression, not only the type of activator but also the blending amount is examined. From the viewpoint of printability, the type and blending amount of the thixotropic agent in the flux composition are also examined. However, even by these studies, thickening during continuous printing can be suppressed only to a certain extent, viscosity stability is insufficient, and chip side balls cannot be sufficiently suppressed.

  Therefore, when the present invention is a solder composition, the flux composition is excellent in viscosity stability during continuous printing and can sufficiently suppress the generation of chip side balls, a solder composition using the same, and It aims at providing the printed wiring board using this solder composition.

As a result of intensive studies to solve the above problems, the present inventors have found that, in the flux composition, when an activator, a thixotropic agent, and a specific antioxidant are used in combination, viscosity stability during continuous printing is determined. It has been found that the performance can be drastically improved and the occurrence of chip side balls can be sufficiently suppressed. The present invention has been completed based on such knowledge, and provides the following flux composition, solder composition, and printed wiring board.
That is, the flux composition of the present invention contains (A) a rosin resin, (B) a solvent, (C) an activator, (D) a thixotropic agent, and (E) an antioxidant, (E1) It contains the compound represented by following General formula (1), It is characterized by the above-mentioned.

In the general formula (1), L ¹ , L ² , L ³ and L ⁴ may be the same or different and each represents a group represented by —C _m H _2m —, where m is an integer of 0 to 4. Indicates.
In the flux composition of the present invention, the molecular weight of the component (E1) is preferably 700 or less.
In the flux composition of the present invention, the melting point of the component (E1) is preferably 160 ° C. or higher and 185 ° C. or lower.
In the flux composition of this invention, it is preferable that the compounding quantity of the said (E1) component is 1 to 10 mass% with respect to 100 mass% of flux compositions.
In the flux composition of the present invention,
The component (E1) is preferably N, N′-bis [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) ethylcarbonyloxy] ethyl] oxamide.

  In the flux composition of the present invention, the component (E) further contains (E2) a compound represented by the following general formula (2), the component (E1) in the component (E) and the component ( The mass ratio with the component E2) is preferably in the range of 1:10 to 10: 1.

In the general formula (2), L ⁵ and L ⁶ may be the same or different, each represents a group represented by —C _m H _2m —, _m represents an integer of 0 to 4, and n represents 1 The integer of -3 is shown, p shows the integer of 1-4.
In the flux composition of this invention, it is preferable that melting | fusing point of the said (E2) component is 70 degreeC or more and 85 degrees C or less.
In the flux composition of the present invention, the component (E2) is bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)]. Is preferred.

The solder composition of the present invention is characterized by containing the flux composition and solder powder.
The printed wiring board of the present invention is characterized in that an electronic component is mounted on a printed wiring board using the solder composition.

  According to the present invention, when a solder composition is used, a flux composition that is excellent in viscosity stability during continuous printing and that can sufficiently suppress the generation of chip side balls, a solder composition using the same, and A printed wiring board using this solder composition can be provided.

[Flux composition]
First, the flux composition of the present invention will be described. The flux composition used in the present invention is a component other than the solder powder in the solder composition, and (A) a rosin resin, (B) a solvent, (C) an activator, (D) a thixotropic agent, and (E) an antioxidant. It contains an agent.

[(A) component]
Examples of the (A) rosin resin used in the present invention include rosins and rosin modified resins. Examples of rosins include gum rosin, wood rosin, tall oil rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, and derivatives thereof. As rosin-based modified resins, unsaturated organic acid-modified resins of the above rosins that can be reactive components of Diels-Alder reactions (aliphatic unsaturated monobasic acids such as (meth) acrylic acid, fumaric acid, maleic acid, etc.) adietic acids such as aliphatic unsaturated dibasic acids such as α, β-unsaturated carboxylic acids, and unsaturated carboxylic acids having an aromatic ring such as cinnamic acid) and abietic acids such as modified products thereof, and these The thing which has a modified substance as a main component is mentioned. These rosin resins may be used alone or in combination of two or more.

  The blending amount of the component (A) is preferably 30% by mass or more and 70% by mass or less, and more preferably 35% by mass or more and 60% by mass or less with respect to 100% by mass of the flux composition. When the blending amount of the component (A) is less than the lower limit, oxidation of the copper foil surface of the soldering land is prevented and the molten solder is easily wetted on the surface, so-called solderability is lowered, and solder balls are easily generated. On the other hand, if the upper limit is exceeded, the amount of residual flux tends to increase.

[Component (B)]
As the solvent (B) used in the present invention, a known solvent can be appropriately used. As such a solvent, a water-soluble solvent having a boiling point of 170 ° C. or higher is preferably used.
Examples of such solvents include diethylene glycol, dipropylene glycol, triethylene glycol, hexylene glycol, hexyl diglycol, 1,5-pentanediol, methyl carbitol, butyl carbitol, and 2-ethylhexyl diglycol (EHDG). , Octanediol, phenyl glycol, diethylene glycol monohexyl ether, and tetraethylene glycol dimethyl ether. These solvents may be used alone or in combination of two or more.

  The blending amount of the component (B) is preferably 20% by mass or more and 60% by mass or less, and more preferably 30% by mass or more and 50% by mass or less with respect to 100% by mass of the flux composition. If 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.

[Component (C)]
Examples of the (C) activator used in the present invention include organic acids, non-dissociative activators composed of non-dissociable halogenated compounds, and amine-based activators. These activators may be used individually by 1 type, and may mix and use 2 or more types.
Examples of the organic acid include other organic acids in addition to monocarboxylic acid and dicarboxylic acid.
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, glycolic acid and the like.
Examples of the dicarboxylic acid 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.
Examples of other organic acids include dimer acid, levulinic acid, lactic acid, acrylic acid, benzoic acid, salicylic acid, anisic acid, citric acid, and picolinic acid.

  Examples of the non-dissociable activator comprising the non-dissociable halogenated compound include non-salt organic compounds in which halogen atoms are bonded by a covalent bond. The halogenated compound may be a compound formed by covalent bonding of chlorine, bromine and fluorine, such as chlorinated, brominated and fluoride, but any two or all of chlorine, bromine and fluorine may be used. The compound which has the following covalent bond may be sufficient. 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 such as a halogenated alcohol or a halogenated carboxyl. Examples of the halogenated alcohol include 2,3-dibromopropanol, 2,3-dibromobutanediol, trans-2,3-dibromo-2-butene-1,4-diol, 1,4-dibromo-2-butanol, Brominated alcohols such as tribromoneopentyl alcohol, chlorinated alcohols such as 1,3-dichloro-2-propanol and 1,4-dichloro-2-butanol, fluorinated alcohols such as 3-fluorocatechol, and the like Compounds. Examples of the halogenated carboxyl include 2-iodobenzoic acid, 3-iodobenzoic acid, 2-iodopropionic acid, 5-iodosalicylic acid, 5-iodoanthranilic acid, etc., 2-chlorobenzoic acid, 3-chloropropion Examples thereof include carboxyl chloride such as acid, brominated carboxyl such as 2,3-dibromopropionic acid, 2,3-dibromosuccinic acid and 2-bromobenzoic acid, and other similar compounds.

  Examples of the amine activator include amines (polyamines such as ethylenediamine), amine salts (amines such as trimethylolamine, cyclohexylamine, diethylamine, and organic acid salts such as amino alcohols and inorganic acid salts (hydrochloric acid, sulfuric acid, odors). Hydroacid, etc.)), amino acids (glycine, alanine, aspartic acid, glutamic acid, valine, etc.), amide compounds and the like. Specifically, diphenylguanidine hydrobromide, cyclohexylamine hydrobromide, diethylamine salt (hydrochloride, succinate, adipate, sebacate, etc.), triethanolamine, monoethanolamine, etc. And the hydrobromide of the amine.

  The amount of the component (C) 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, with respect to 100% by mass of the flux composition. The content is particularly preferably 3% by mass or more and 8% by mass or less. When the blending amount of the component (C) is less than the lower limit, chip side balls tend to be generated, and when the upper limit is exceeded, the insulating property of the flux composition tends to decrease.

[(D) component]
Examples of the thixotropic agent (D) used in the present invention include hardened castor oil, amides, kaolin, colloidal silica, organic bentonite, and glass frit. These thixotropic agents may be used alone or in combination of two or more.

  The blending amount of the component (D) is preferably 1% by mass or more and 15% by mass or less, and more preferably 2% by mass or more and 10% by mass or less with respect to 100% by mass of the flux composition. If the blending amount is less than the lower limit, thixotropy cannot be obtained and the sagging tends to occur. On the other hand, if the amount exceeds the upper limit, the thixotropy tends to be too high and the coating tends to be poor.

[(E) component]
The (E) antioxidant used in the present invention contains (E1) a compound represented by the following general formula (1).

In the general formula (1), L ¹ , L ² , L ³ and L ⁴ may be the same or different, and represent a group represented by —C _m H _2m —. M represents an integer of 0 to 4 (preferably 1 to 3, more preferably 2).
The molecular weight of the component (E1) is preferably 700 or less, and more preferably 650 or more and 700 or less. When the molecular weight exceeds the upper limit, it tends to precipitate from the flux.
The melting point of the component (E1) is preferably 160 ° C. or higher and 185 ° C. or lower, and more preferably 170 ° C. or higher and 180 ° C. or lower. When the melting point is within the above range, the solder melting property can be further improved when using a solder powder having a high melting point (for example, 200 ° C. or higher and 240 ° C. or lower) such as lead-free solder powder.

  Examples of the component (E1) include N, N′-bis [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) methylcarbonyloxy] ethyl] oxamide, N, N′-bis. [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) ethylcarbonyloxy] ethyl] oxamide, N, N′-bis [2- [2- (3,5-di-tert -Butyl-4-hydroxyphenyl) propylcarbonyloxy] ethyl] oxamide, N, N′-bis [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) butylcarbonyloxy] ethyl] Oxamide etc. are mentioned. Among these, N, N′-bis [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) ethylcarbonyloxy] ethyl] oxamide represented by the following structural formula (3) is preferable. These may be used alone or in combination of two or more.

  The blending amount of the component (E1) is preferably 1% by mass or more and 10% by mass or less, more preferably 1% by mass or more and 8% by mass or less, with respect to 100% by mass of the flux composition. It is particularly preferred that the content is not less than 4% by mass. When the blending amount of the component (E1) is less than the lower limit, the viscosity tends to increase during continuous printing. On the other hand, when the amount exceeds the upper limit, the printability tends to deteriorate.

  In addition to the component (E1), the component (E) preferably contains (E2) a compound represented by the following general formula (2).

In the general formula (2), L ⁵ and L ⁶ may be the same or different and each represents a group represented by —C _m H _2m —, where m is 0 to 4 (preferably 1 to 3, More preferably, it represents an integer of 2). n represents an integer of 1 to 3 (preferably 2 to 3, more preferably 2), and p represents an integer of 1 to 4 (preferably 2 to 3, more preferably 2).
Such a combination of the component (E2) and the component (E1) achieves a synergistic effect on the viscosity stability and solder meltability during continuous printing. The reason for this is not clear, but (i) the action caused by the low melting point (E2) component contributing to the activity at low temperature and the high melting point (E1) component contributing to the activity at high temperature, or (ii) The above effect is achieved by the action of the component (E1) having a hindered phenol structure represented by the following structural formula (S1) and the component (E2) having a half hindered phenol structure represented by the following structural formula (S2). The present inventors speculate that this is done.

  Examples of the component (E2) include bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)], bis [3- (3-tert-butyl). -4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxypropylene)], bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) acetic acid] [ethylenebis (oxyethylene) )] And the like. Among these, bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)] represented by the following structural formula (4) is preferable. These may be used alone or in combination of two or more.

  The mass ratio of the (E1) component and the (E2) component in the (E) component is in the range of 1:10 to 10: 1 from the viewpoint of viscosity stability during continuous printing and solder meltability. It is preferable that the ratio is in the range of 1: 3 to 3: 1.

  The amount of the component (E) 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, with respect to 100% by mass of the flux composition. The content is particularly preferably 3% by mass or more and 6% by mass or less. When the blending amount of the component (E) is less than the lower limit, the viscosity tends to increase during continuous printing. On the other hand, when the amount exceeds the upper limit, the storage stability of the solder composition tends to deteriorate.

[Other ingredients]
In addition to the component (A), the component (B), the component (C), the component (D), and the component (E), the flux composition used in the present invention includes other components as necessary. Additives, and other resins can be added. Examples of other additives include antifoaming agents, modifiers, matting agents, and foaming agents. Examples of other resins include acrylic resins.

[Solder composition]
Next, the solder composition of the present invention will be described. The solder composition of the present invention contains the flux composition of the present invention and (F) solder powder described below.

[(F) component]
The solder powder (F) used in the present invention is preferably composed only of lead-free solder powder, but may be lead-containing solder powder. As the solder alloy in the solder powder, an alloy containing tin as a main component is preferable. Examples of the second element of the alloy include silver, copper, zinc, bismuth, and antimony. Furthermore, you may add another element (after 3rd element) to this alloy as needed. Examples of other elements include copper, silver, bismuth, antimony, aluminum, and indium.
The flux composition of the present invention exhibits the effect of the present invention remarkably when it has a high melting point such as lead-free solder powder. Therefore, the melting point of the component (F) is preferably 200 ° C. or higher and 240 ° C. or lower.
Specific examples of the lead-free solder powder include Sn / Ag, Sn / Ag / Cu, Sn / Cu, Sn / Ag / Bi, Sn / Bi, Sn / Ag / Cu / Bi, Sn / Sb, Sn / Zn / Bi, Sn / Zn, Sn / Zn / Al, Sn / Ag / Bi / In, Sn / Ag / Cu / Bi / In / Sb, In / Ag, and the like.

  The average particle diameter of the solder powder is preferably 1 μm or more and 40 μm or less, more preferably 5 μm or more and 35 μm or less, and particularly preferably 15 μm or more and 25 μm or less. If the average particle diameter is within the above range, it can be applied to the recent printed wiring board in which the pitch of the soldering lands is narrow. The average particle size can be measured with a dynamic light scattering type particle size measuring device.

[Method for producing solder composition]
The solder composition of the present invention can be produced by blending the above-described flux composition and the above-described (F) solder powder at the predetermined ratio and stirring and mixing them.

[Printed wiring board]
Next, the printed wiring board of the present invention will be described. The printed wiring board of the present invention is characterized in that an electronic component is mounted on a printed wiring board using the solder composition described above. Therefore, in the printed wiring board of this invention, discoloration of the copper foil under the flux residue after soldering can fully be suppressed.
Examples of the coating apparatus used here include a screen printer, a metal mask printer, a dispenser, and a jet dispenser.
Further, the electronic component is placed on the solder composition applied by the coating apparatus, heated under a predetermined condition by a reflow furnace, and the electronic component is printed by a reflow process in which the electronic component is mounted on the wiring board. Can be mounted on a board.

In the reflow process, the electronic component is placed on the solder composition and heated in a reflow furnace under predetermined conditions. By this reflow process, sufficient soldering can be performed between the electronic component and the wiring board. As a result, the electronic component can be mounted on the wiring board.
What is necessary is just to set reflow conditions suitably according to melting | fusing point of solder. For example, when using a Sn—Ag—Cu-based solder alloy, preheating may be performed at a temperature of 150 to 190 ° C. for 60 to 120 seconds, and a peak temperature may be set to 240 to 270 ° C.

Further, the solder composition and the printed wiring board of the present invention are not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention.
For example, in the printed wiring board, the wiring board and the electronic component are bonded by the reflow process, but the invention is not limited to this. For example, instead of the reflow process, the wiring board and the electronic component may be bonded by a process of heating the solder composition using laser light (laser heating process). In this case, the laser light source is not particularly limited, and can be appropriately selected according to the wavelength matched to the metal absorption band. As the laser light source, for example, a solid laser (ruby, glass, YAG, etc.), semiconductor laser (GaAs, InGaAsP, etc.), (such as a dye) liquid laser, a gas laser (He-Ne, Ar, CO 2, etc. excimer) is Can be mentioned.

EXAMPLES Next, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited at all by these examples. In addition, the material used in the Example and the comparative example is shown below.
((A) component)
Rosin resin: hydrogenated acid-modified rosin, trade name “Pine Crystal KE-604”, manufactured by Arakawa Chemical Industries, Ltd. (component (B))
Solvent: 2-ethylhexyl diglycol (EHDG)
((C) component)
Activator A: glutaric acid activator B: adipic acid activator C: picolinic acid (component (D))
Thixotropic agent A: Trade name “Sripacs ZHH”, Nippon Kasei Co., Ltd. thixotropic agent B: Hardened castor oil, trade name “Hima-Kade”, manufactured by KF Trading (component (E1))
Antioxidant A: antioxidant represented by the following structural formula (3), melting point 170-180 ° C.
((E2) component)
Antioxidant B: antioxidant represented by the following structural formula (4), melting point: 76 to 79 ° C.
((F) component)
Solder powder: average particle diameter 20 μm, solder melting point 216-220 ° C., solder composition Sn / Ag / Cu
(Other ingredients)
Antioxidant C: antioxidant represented by the following structural formula (5), melting point 260 to 267 ° C.
Antioxidant D: Antioxidant represented by the following structural formula (6), melting point 104 ° C.
Antioxidant E: Hydroquinone

[Example 1]
Rosin resin 41% by mass, solvent 38% by mass, activator A 5% by mass, activator B 2% by mass, activator C 1% by mass, thixo agent A 6% by mass, thixo agent B 3% by mass, antioxidant A 3% by mass, and Antioxidant B1 mass% was put 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 solder powder (100% by mass in total) were put into a container and mixed with a planetary mixer to prepare a solder composition.

[Examples 2 to 8]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.
[Comparative Examples 1-6]
A solder composition was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 2.

<Evaluation of solder composition>
Evaluation of the solder composition (rolling test, printability, meltability, spread spread, chip side ball) was performed by the following method. The obtained results are shown in Tables 1 and 2.
(1) Rolling test (viscosity stability during continuous printing)
Using a printing machine (“SP-70” manufactured by Panasonic Corporation), the solder composition is placed on a plate having no pattern, and printing is repeated for 24 hours under the conditions of a printing speed of 50 mm / sec and a printing pressure of 0.2 N. A rolling test was performed. The viscosity change rate (thickening rate) before and after this rolling test was measured, and the thickening during continuous printing was evaluated according to the following criteria.
A: Thickening rate is within ± 3%.
○: The thickening rate is not within ± 3%, but within ± 10%.
Δ: The viscosity increase rate is not within ± 10%, but within ± 15%.
X: Thickening rate is outside the range of ± 15%.
(2) Printability 49 holes having a diameter of 0.2 mmφ are provided, a plate having a thickness of 0.12 mm is used, and the solder composition is applied on the substrate at a printing speed of 50 mm / sec and a printing pressure of 0.2 N. Printed. And the plate after printing was observed visually, the ratio (missing rate) of the part which pierced was measured, and printability was evaluated according to the following references | standards.
A: The dropout rate is 90% or more.
A: The dropout rate is 80% or more and less than 90%.
Δ: The dropout rate is 60% or more and less than 80%.
X: The dropout rate is less than 60%.
(3) Meltability 49 holes having a diameter of 0.2 mmφ are provided, a plate having a thickness of 0.12 mm is used, and the solder composition is applied on the substrate at a printing speed of 50 mm / sec and a printing pressure of 0.2 N. Printed. Then, reflow was performed under the conditions of preheating 180 ° C. for 60 seconds and peak temperature 260 ° C. for 10 seconds to prepare a test substrate. Of the printed parts (49) of the test substrate, the melted part where the solder was melted was measured, and the meltability was evaluated according to the following criteria.
A: There are 40 or more melting points.
◯: The number of melting points is 35 or more and less than 40.
(Triangle | delta): A melt location is 25 or more and less than 35 pieces.
X: The number of melting points is less than 25.
(4) Spreading spread The spreading spread was evaluated by a method based on the JIS Z 3197 solder spreading method. And the spread spread was evaluated according to the following criteria.
A: The spreading rate is 80% or more.
○: The spreading rate is 70% or more and less than 80%.
Δ: The spread rate is 50% or more and less than 70%.
X: The spreading rate is less than 50%.
(5) Chip side ball A metal mask having a corresponding pattern is used on a substrate having an electrode (size: 0.5 mm × 0.8 mm) on which a chip (size: 1.6 mm × 0.8 mm) can be mounted. The solder composition was printed under the conditions of a printing speed of 50 mm / sec and a printing pressure of 0.2 N. Thereafter, a chip (size: 1.6 mm × 0.8 mm) is mounted on the solder composition, and reflow is performed under conditions of preheating 180 ° C. for 60 seconds and peak temperature 260 ° C. for 10 seconds to produce a test substrate. did. The test substrate was visually observed to measure the number of solder balls on the side of the chip (number of balls on the side of the chip), and the chip side balls were evaluated according to the following criteria.
A: The number of side balls per chip is 2 or less.
○: The number of balls beside the chip per 10 chips is more than 2 and 5 or less.
Δ: The number of chips side balls per 10 chips is more than 5 and 8 or less.
X: The number of chip side balls is more than 8 per 10 chips.

As is clear from the results shown in Tables 1 and 2, the solder compositions of the present invention (Examples 1 to 8) are all excellent in rolling test, printability, meltability, spread of spread, and evaluation of chip side balls. It was confirmed that. Therefore, it was confirmed that the solder composition of the present invention has excellent viscosity stability during continuous printing and can sufficiently suppress the generation of chip side balls.
On the other hand, when using the solder composition which does not contain the component (E1) (Comparative Examples 1 to 6), it was found that either the rolling test or the evaluation of the chip side ball is insufficient. .
Moreover, when the results of Example 1 and Example 8 were compared, these were examples using a combination of antioxidants, but it was found that the evaluation results of Example 1 were remarkably superior. From this, it was found that the combination of the component (E1) and the component (E2) has a synergistic effect.

  The flux composition and the solder composition of the present invention can be suitably used as a technique for mounting components on a printed wiring board of an electronic device.

Claims (10)

(A) containing a rosin resin, (B) a solvent, (C) an activator, (D) a thixotropic agent and (E) an antioxidant,
The said (E) component contains the compound represented by (E1) following General formula (1). The flux composition characterized by the above-mentioned.

(In the general formula ^{(1), L 1, L} 2, L 3 and ^{L 4} may be the same or _different, -C _{m H 2m} - indicates a group represented by, m is 0-4 Indicates an integer.) The flux composition according to claim 1, wherein
The flux composition, wherein the molecular weight of the component (E1) is 700 or less. In the flux composition according to claim 1 or claim 2,
The melting point of said (E1) component is 160 degreeC or more and 185 degrees C or less. The flux composition characterized by the above-mentioned. In the flux composition according to any one of claims 1 to 3,
The compounding quantity of the said (E1) component is 1 mass% or more and 10 mass% or less with respect to 100 mass% of flux compositions. The flux composition characterized by the above-mentioned. In the flux composition according to any one of claims 1 to 4,
The flux (E1) is N, N′-bis [2- [2- (3,5-di-tert-butyl-4-hydroxyphenyl) ethylcarbonyloxy] ethyl] oxamide. Composition. In the flux composition according to any one of claims 1 to 5,
The component (E) further contains (E2) a compound represented by the following general formula (2),
The flux composition characterized by the mass ratio of the (E1) component and the (E2) component in the (E) component being in the range of 1:10 to 10: 1.

(In the general formula (2), L ⁵ and L ⁶ may be the same or different and each represents a group represented by —C _m H _2m —, _m represents an integer of 0 to 4, and n represents An integer of 1 to 3, and p represents an integer of 1 to 4.) The flux composition according to claim 6, wherein
The melting point of said (E2) component is 70 degreeC or more and 85 degrees C or less. The flux composition characterized by the above-mentioned. In the flux composition according to claim 6 or 7,
The flux composition, wherein the component (E2) is bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionic acid] [ethylenebis (oxyethylene)].   A solder composition comprising the flux composition according to any one of claims 1 to 8 and a solder powder.   An electronic component is mounted on a printed wiring board using the solder composition according to claim 9.