JP2014024116A - Flux for soldering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flux for soldering which enables flux residues to be removed by water washing even when a soldering temperature is high.SOLUTION: A flux for soldering contains (A) an ester compound of polyglycerol and 8-12C fatty acid, (B) 12-18C fatty acid, (C) solvent with a boiling point of 120°C or more.

Description

  The present invention relates to a soldering flux, and more particularly, to a soldering flux capable of removing flux residue after soldering by washing with water.

  When soldering using a flux, the non-volatile organic component (so-called flux residue) in the flux remains in the soldered portion. In the so-called non-cleaning flux in which the flux residue is left as it is, the risk of short-circuit between lands increases due to alteration of flux residue or inclusions. Therefore, non-cleaning flux cannot cope with short package parts between lands. Therefore, when soldering in the package component, the flux residue is washed with an organic solvent. However, it is unavoidable that the organic solvent for cleaning is volatilized in the air, and there is a risk of fire, and air pollution (such as volatilization of volatile organic compounds (VOC)) is likely to occur. In addition, from the viewpoint of occupational health, regulations on the use of organic solvents have been strengthened. Furthermore, in order to prevent water pollution (such as an increase in biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in wastewater), advanced wastewater treatment is required.

In order to solve the above-described problems, a shift to a so-called water-washing flux in which the flux residue is washed with water or warm water is being promoted (for example, Patent Document 1).
On the other hand, with the lead-free solder, high melting point solder tends to be used. In particular, for solder used in the package component, it is necessary to withstand heat when the package component is mounted, and therefore solder having a higher melting point is used.

JP 2004-158728 A

  However, in the flux as described in Patent Document 1, when the soldering temperature is too high, there is a problem that it is difficult to remove the flux residue by washing with water.

  Therefore, an object of the present invention is to provide a soldering flux capable of removing the flux residue by washing even when the soldering temperature is high (for example, 250 ° C. or higher).

In order to solve the above problems, the present invention provides the following soldering flux.
That is, the soldering flux of the present invention comprises (A) an ester compound of polyglycerin and a fatty acid having 8 to 12 carbon atoms, (B) a fatty acid having 12 to 18 carbon atoms, and (C) a boiling point of 120 ° C. or higher. And a solvent.

In the soldering flux of the present invention, the (B) fatty acid is preferably myristic acid.
In the soldering flux of the present invention, the content of the ester compound (A) is preferably 50% by mass to 90% by mass with respect to 100% by mass of the flux.

According to the present invention, it is possible to provide a soldering flux capable of removing flux residue by washing even when the soldering temperature is high.
Therefore, compared with the case where the flux residue is washed with an organic solvent, the risk of fire and the influence on air pollution can be reduced. In addition, problems related to occupational health are improved, and the management burden in wastewater treatment can be reduced.

The soldering flux of the present invention contains (A) an ester compound, (B) a fatty acid, and (C) a solvent described below.
The (A) ester compound used in the present invention is an ester compound of polyglycerol and a fatty acid having 8 to 12 carbon atoms.

  The polyglycerin refers to one having a structure in which a plurality of glycerins are polymerized. The average polymerization number of glycerol units in the polyglycerol is preferably 6 or more, 12 or less, more preferably 8 or more and 11 or less, and particularly preferably 10 from the viewpoint of water washability of the flux.

  The fatty acid needs to have 8 to 12 carbon atoms. When the carbon number is out of the above range, the water washability of the flux becomes insufficient. Examples of such fatty acids include caprylic acid, pelargonic acid, capric acid, and lauric acid.

  Examples of the (A) ester compound include decaglyceryl compounds (decaglyceryl monocaprylate, decaglyceryl monopelargonate, decaglyceryl monocaprate, decaglyceryl monolaurate, etc.), octaglyceryl compounds (octaglyceryl monocaprylate) , Octaglyceryl monopelargonate, octaglyceryl monocaprate, octaglyceryl monolaurate), hexaglyceryl compounds (hexaglyceryl monocaprylate, hexaglyceryl monopelargonate, hexaglyceryl monocaprate, hexaglyceryl monolaurate, etc.) Is mentioned.

  The content of the ester compound (A) is preferably 20% by mass or more and 95% by mass or less, more preferably 40% by mass or more and 92% by mass or less, with respect to 100% by mass of the flux. It is particularly preferable that the content is from mass% to 90 mass%. If the content is outside the above range, the pin transferability of the flux tends to be reduced.

  The fatty acid (B) used in the present invention has 12 to 18 carbon atoms. If the carbon number is less than the lower limit, the flux residue tends to be burnt and tends to be insufficiently washed, whereas if it exceeds the upper limit, the wettability of the solder tends to decrease. (B) The fatty acid may be a saturated fatty acid or an unsaturated fatty acid. Examples of such (B) fatty acid include lauric acid, myristic acid, palmitic acid, stearic acid, myristoleic acid, palmitoleic acid, and oleic acid.

  The content of the (B) fatty acid is preferably 4% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less with respect to 100% by mass of the flux. If the content is less than the above lower limit, the water washability and activity of the flux tend to decrease. On the other hand, if the content exceeds the above upper limit, the fatty acid in the flux tends to precipitate by recrystallization and the water washability of the flux. Tend to decrease.

  The (C) solvent used in the present invention is a solvent having a boiling point of 120 ° C. or higher. When the boiling point is less than the lower limit, when soldering at a high temperature, the volatility of the solvent is too high, so that the water washability of the flux decreases. Moreover, from the viewpoint of the volatility of the solvent, the boiling point of the solvent (C) is preferably 200 ° C. or higher and 300 ° C. or lower, and more preferably 230 ° C. or higher and 270 ° C. or lower.

  Examples of the solvent (C) include glycol solvents (triethylene glycol monomethyl ether (boiling point: 249 ° C.), ethylene glycol monophenyl ether (boiling point: 245 ° C.), diethylene glycol dibutyl ether (boiling point: 256 ° C.), triethylene. Glycol butyl methyl ether (boiling point: 261 ° C), hexyl diglycol (boiling point: 259 ° C), diethylene glycol monobutyl ether (boiling point: 230 ° C), propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, tetraethylene Glycol dimethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol dimethyl ether, 2-ethylhexyl diglycol Triethylene glycol monobutyl ether, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, 1,3-butanediol, diethylene glycol monoethyl ether acetate, butyl glycol, isobutyl diglycol, mixed glycol ether mainly composed of ethylene glycol monophenyl ether ( Trade name: phenyl glycol H), methyl polyglycol, butyl propylene glycol, etc.), alcoholic solvent (α-, β-, γ-terpineol isomer mixture (trade name: terpineol C), octanediol, etc.), petroleum Examples thereof include a solvent (trade name: Solvesso 150). Among these, a glycol solvent is preferable from the viewpoint of compatibility with other components.

  The content of the (C) solvent is preferably 1% by mass or more and 70% by mass or less, and more preferably 2% by mass or more and 50% by mass or less with respect to 100% by mass of the flux. If the content is less than the lower limit, the water washability of the flux tends to be reduced. On the other hand, if the content exceeds the upper limit, the component (A) is insufficient, and the activity of the flux tends to be reduced.

The flux of the present invention may contain other general active agents other than the (B) fatty acid within the range in which the effects of the present invention can be achieved.
Examples of other activators include organic acids other than fatty acids (such as succinic acid, adipic acid, and sebacic acid), halides (such as halogenated alcohols), amines, amino acids, and amide compounds.
When these other activators are used, the content thereof is preferably 0.01% by mass or more and 10% by mass or less with respect to 100% by mass of the flux.

  In addition to the (A) ester compound, the (B) fatty acid, the (C) solvent, and the other activator, the flux of the present invention includes an antioxidant, an antifoaming agent, and an antirust as necessary. An additive such as an agent and a surfactant may be contained. The content of these additives is preferably 0.01% by mass or more and 10% by mass or less with respect to 100% by mass of the flux.

The flux of the present invention described above can remove the flux residue by washing even when the soldering temperature is high. Here, the soldering temperature is not particularly limited as long as it is higher than 184 ° C. which is the melting point of eutectic solder (Pb / Sn). Even if the soldering temperature is, for example, 250 ° C. or higher, 270 ° C. or higher, or 300 ° C. or higher, the flux residue can be removed by washing with water using the flux of the present invention.
Examples of the high melting point solder composition include Au—Sn, Au—Ge, Pb—Sn, Pb—Sn—Sb, Pb—Sn—Sb—Bi, Pb—Sn—Bi, Pb— Sb type is mentioned.
Moreover, when washing a flux residue with water, water may be used and warm water may be used. The water temperature at the time of washing the flux residue may be 15 ° C. or more and less than 100 ° C.

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) Ester compound a: decaglycerin monolaurate, trade name “ML-750”, Sakamoto Yakuhin Kogyo Co., Ltd. (A) ester compound b: decaglycerin monocaprylate, trade name “MCA-750”, Sakamoto Industrial company ester compound c: decaglycerin monocaproic acid ester, trade name “MC6G-10”, Japanese emulsion ester compound d: decaglycerin monomyristic acid ester, trade name “MM-750”, manufactured by Sakamoto Pharmaceutical Co., Ltd. (B) Fatty acid: Myristic acid (C) Solvent: Triethylene glycol monomethyl ether, trade name “Hi-Mall TM”, manufactured by Toho Chemical Industry Co., Ltd.

[Example 1]
(A) 50% by mass of ester compound a, (B) 7% by mass of fatty acid, and (C) 46% by mass of solvent were put into a container and mixed using a rough machine to obtain a flux.

[Examples 2-7, Comparative Examples 1-3]
A flux was obtained in the same manner as in Example 1 except that each material was blended according to the composition shown in Table 1.

<Evaluation of flux>
The characteristics of the flux (water washability, pin transferability) were evaluated by the following methods. The results obtained for the examples are shown in Table 1, and the results obtained for the comparative examples are shown in Table 2.
(1) Water washability Test substrate: 0.03 g of flux was dropped onto a ceramic plate (size: 25 mm × 25 mm, thickness 0.635 mm) to obtain a test piece. The test piece is heated on a hot plate at 300 ° C. for 60 seconds. The test piece after heating is immersed in water at a temperature of 60 ° C. for 15 minutes, and then dried at a temperature of 80 ° C. for 20 minutes. The obtained test piece was visually observed, and water washability was evaluated according to the following criteria.
○: There is no organic residue (flux residue).
X: There is an organic matter residue (flux residue).
(2) Pin transferability A flux is applied on a substrate so as to have a thickness of 15 μm. Then, a needle tip (needle toothpick tip diameter: 0.2 to 0.8 mmφ, diameter: 1 to 4 mmφ, material: wood) is stabbed perpendicularly to the flux, and then the needle tip is placed on another substrate. Place it vertically and try to transfer the flux. The presence or absence of flux transfer was visually observed, and pin transferability was evaluated according to the following criteria.
The material of the needle is not particularly limited as long as it does not adsorb a large amount of flux internally, and may be a natural material such as bamboo or stainless steel such as SUS304 or SUS316.
○: Good transfer.
Δ: Transfer is slightly insufficient.
X: Not transferred.

As is clear from the results shown in Table 1, when the flux of the present invention was used (Examples 1 to 7), it was confirmed that the flux residue could be removed by washing even when the soldering temperature was 300 ° C. It was done. Moreover, in Examples 6-7, since pin transcription | transfer property is a little inferior, content of (A) ester compound shall be 50 to 90 mass% with respect to 100 mass% of flux of this invention. Was confirmed to be preferable.
On the other hand, when (B) the flux not containing fatty acid is used (Comparative Example 1) or when (A) the flux not containing an ester compound is used (Comparative Examples 2-3), the soldering temperature is low. It was confirmed that the water washability at 300 ° C. was insufficient.

  The soldering flux of the present invention can be particularly suitably used for soldering lead-free solder (particularly high melting point solder).

Claims (3)

  (A) An ester compound of polyglycerin and a fatty acid having 8 to 12 carbon atoms, (B) a fatty acid having 12 to 18 carbon atoms, and (C) a solvent having a boiling point of 120 ° C. or more. Soldering flux. In the soldering flux according to claim 1,
Said (B) fatty acid is myristic acid. The soldering flux characterized by the above-mentioned. In the soldering flux according to claim 1 or 2,
Content of the said (A) ester compound is 50 to 90 mass% with respect to 100 mass% of the said flux. The soldering flux characterized by the above-mentioned.