JP5490959B1 - Rosin for solder flux and solder flux using the same - Google Patents

Abstract

Provided is a rosin for solder flux that can suppress solder scattering and that is less likely to generate voids and can impart excellent cleaning properties to the flux.
The rosin for solder flux of the present invention contains methyl dehydroabietic acid and other resin acid other than methyl dehydroabietic acid, and the methyl dehydroabietic acid is 20 to 70% by mass with respect to the entire rosin. Included in the ratio. Preferably, methyl dehydroabietic acid and other resin acids are contained in a total proportion of 99% by mass or more based on the whole rosin. Further, the solder flux of the present invention contains the above rosin for solder flux.
[Selection figure] None

Description

  The present invention relates to a rosin for solder flux that can suppress solder scattering and that is less likely to generate voids and can impart excellent cleaning properties to the flux.

  Rosin is a non-volatile component of pine resin contained in a pine family plant and contains various isomers of diterpene carboxylic acid (resin acid) as a main component. Rosin is a relatively inexpensive and renewable plant resource that can be supplied in large quantities. For example, it is converted into various derivatives and used as tackifiers, resins for printing inks, emulsifiers for synthetic rubber, sizing agents for papermaking, etc. Yes.

  Examples of the method for derivatizing rosin include a method of reacting rosin with formaldehyde. This rosin derivative is known to contain methyl dehydroabietic acid (Patent Document 1 and Non-Patent Document 1), in addition to the dehydration condensate of resin acid, resin acid derived from raw material rosin, resin acid Degradation products and isomers.

  Although methyl dehydroabietic acid contained in such rosin derivatives has a structure similar to dehydroabietic acid, the use of methyl dehydroabietic acid itself is hardly known. Non-Patent Document 1 does not describe the specific use of methyl dehydroabietic acid, and Patent Document 1 only describes that it is used for the production of a molded product as a crystalline thermoplastic resin composition. Absent.

JP 2004-231484 A

Jeffery M. McGuire, Richard R. Suchanec, Journal of Chromatographic Science, 32 (4), 139-143 (1994)

  As a result of intensive studies on novel uses of methyl dehydroabietic acid, the present inventors have found that methyl dehydroabietic acid is a main component of hydrogenated rosin and disproportionated rosin that are generally used as solder flux resins. It has been found that certain dehydroabietic acid (formula (I)) is not as crystalline as it is. Therefore, when methyl dehydroabietic acid is used as a resin for solder flux, it can suppress solder scattering and is excellent in flux because it is less likely to generate voids than conventional hydrogenated rosin and disproportionated rosin. It was found that it was possible to impart a good cleaning property.

  That is, an object of the present invention is to provide a solder flux rosin that can suppress solder scattering and that is less likely to generate voids and can impart excellent cleaning properties to the flux, and a solder flux containing this rosin. .

As a result of intensive studies to solve the above problems, the present inventors have found a solution means having the following configuration, and have completed the present invention.
(1) A rosin for solder flux containing methyl dehydroabietic acid and a resin acid other than methyl dehydroabietic acid, wherein the methyl dehydroabietic acid is in a proportion of 20 to 70% by mass with respect to the entire rosin Rosin for solder flux contained in
(2) The rosin for solder flux according to (1), wherein the methyl dehydroabietic acid and other resin acids are contained in a ratio of 99% by mass or more in total with respect to the entire rosin.
(3) The rosin for solder flux according to (1) or (2), wherein the other resin acid contains at least one of dihydroabietic acid and tetrahydroabietic acid.
(4) A solder flux containing the rosin for solder flux according to any one of (1) to (3) above.
(5) A solder paste containing solder alloy powder and the solder flux according to (4).
(6) An electronic circuit board provided with a soldered portion by the solder paste as described in (5) above.
(7) A method for producing a rosin for solder flux as described in (1) above, wherein 0.4 mol or more of a formaldehyde donating substance is added to a mixture of rosin and an acid catalyst with respect to 1 mol of the rosin. A method for producing a rosin for solder flux, comprising a step of heating and reacting the mixture to obtain a reaction product after the step and the step of adding.
(8) The production method according to (7), further comprising a step of purifying a resin acid from the reaction product after the step of obtaining the reaction product.
(9) The process according to (7) or (8), further comprising a step of hydrogenating a resin acid contained in the reaction product after the step of obtaining the reaction product.

  The rosin for solder flux of the present invention can suppress solder scattering and can easily generate voids and can impart excellent cleaning properties to the flux. Therefore, the flux containing the rosin for flux of the present invention is less susceptible to solder scattering and voids, and has excellent cleaning properties.

In an Example, in order to evaluate generation | occurrence | production of a void, it is the photograph at the time of observing the board | substrate after soldering with a soft X-ray fluoroscope. (A) is a substrate having a void area ratio of approximately 5%, (B) is a substrate having a void area ratio of approximately 15%, and (C) is a substrate having a void area ratio of approximately 30%. , (D) is a substrate having a void area ratio of about 40%.

(Rosin for solder flux)
The rosin for solder flux of the present invention contains methyl dehydroabietic acid and a resin acid other than methyl dehydroabietic acid (hereinafter sometimes simply referred to as “other resin acid”). The rosin for solder flux of the present invention contains methyl dehydroabietic acid in a proportion of 20 to 70% by mass with respect to the entire rosin for solder flux. By including methyl dehydroabietic acid in such a ratio, the crystallinity of the rosin for solder flux becomes low, and it is possible to suppress solder scattering and void generation without affecting the cleaning performance.

  When the rosin and formaldehyde donating substance are heated and reacted in the presence of an acid catalyst, for example, a hydroxymethyl group is formed at the 7-position of abietic acid (formula (II)) which is the main component of rosin. Next, dehydration by an acid catalyst occurs to generate an exomethylene group, and at the same time, an aromatic ring is formed by movement of a hydrogen atom, and 7-methyldehydroabietic acid represented by the formula (III) is generated. Further, when a hydroxymethyl group is formed at the 14th position of abietic acid, 14-methyldehydroabietic acid shown in (III ') is generated through the same route as described above.

  Methyl dehydroabietic acid represented by the formulas (III) and (III ') is a monosubstituted product of the methyl group. However, in the present specification, a polysubstituted product such as a disubstituted product in which a methyl group is bonded to both the 7-position and the 14-position is also encompassed in the “methyl dehydroabietic acid”. Methyl dehydroabietic acid is preferably contained in a proportion of 25 to 60% by mass, more preferably 40 to 60% by mass.

  Other resin acids are not particularly limited, and examples thereof include resin acids contained in rosin used as a raw material, hydrides, dehydrogenates, and other isomers of these resin acids. Examples of such resin acids include abietic acid, pastric acid, neoabietic acid, pimaric acid, isopimaric acid, sandaracopimalic acid, dehydroabietic acid, dihydroabietic acid, and tetrahydroabietic acid.

  The rosin for solder flux of the present invention contains methyl dehydroabietic acid in a specific ratio, and further contains other compounds such as a decomposition product and a condensate of the resin acid as long as it contains other resin acids. Also good. In consideration of color tone, detergency and suppression of void generation, these other compounds are preferably in small amounts. Therefore, the rosin for solder flux of the present invention preferably contains methyl dehydroabietic acid and other resin acids in a ratio of 99% by mass or more based on the total rosin for solder flux. It is more preferable that other compounds such as decomposition products and condensates are not contained (that is, the total of methyl dehydroabietic acid and other resin acids is 100% by mass).

  The rosin for solder flux of the present invention preferably contains at least one of dihydroabietic acid and tetrahydroabietic acid as another resin acid. Dihydroabietic acid and tetrahydroabietic acid are resin acids obtained, for example, by hydrogenating abietic acid. By including such a resin acid, the rosin for solder flux of the present invention improves the effect of imparting detergency to the flux and the oxidation stability, and the color tone becomes thin. The rosin for solder flux of the present invention preferably contains dihydroabietic acid and tetrahydroabietic acid in a proportion of 10 to 65% by mass, and preferably contains 15 to 35% by mass. More preferred.

(Method for producing rosin for solder flux)
The method for producing the solder flux rosin of the present invention is not particularly limited. For example, a method of reacting rosin as a raw material with a formaldehyde donating substance can be mentioned.
The rosin is not particularly limited, and is mainly composed of, for example, a diterpene monocarboxylic acid (for example, a resin acid such as abietic acid, pultrinic acid, neoabietic acid, pimaric acid, isopimaric acid, sandaracopimalic acid, dehydroabietic acid). Examples include gum rosin, tall oil rosin, wood rosin, and purified products thereof. The purified product is, for example, rosin from which impurities other than a polymer compound and resin acid are removed. Among these, rosins (for example, Chinese horsetail pine gum rosin and the like) that are rich in abietic acid, which is a precursor of methyl dehydroabietic acid, are preferable.

Formaldehyde donating substance is a concept including a compound that generates formaldehyde by decomposition or the like in a reaction system in addition to formaldehyde (formalin). Examples of formaldehyde donating substances include formaldehyde (formalin), paraformaldehyde, trioxane and the like. Among these, paraformaldehyde is preferable from the viewpoint of easy handling. The formaldehyde donor is used in a ratio of, for example, 0.4 mol or more, preferably 0.5 mol or more, more preferably 0.9 mol or more, preferably 1.5 mol or more, in terms of formaldehyde, with respect to 1 mol of rosin. It is used in a proportion of not more than mol, more preferably not more than 1.3 mol. For example, 1 mol of trioxane corresponds to 3 mol in terms of formaldehyde. In the present specification, the molecular weight of rosin is calculated by the following formula. In the formula, “56.108” is the molecular weight of potassium hydroxide (KOH).
Molecular weight of rosin = (56.108 × 1000) / acid value of rosin (neutralization value)

  The formaldehyde donor material is preferably added in small portions over about 2 to 4 hours, rather than being charged all at once. By adding little by little, the content of methyl dehydroabietic acid can be further increased.

  The reaction between rosin and formaldehyde donor is performed in the presence of an acid catalyst. Examples of the acid catalyst include known catalysts. Preferably, sulfonic acid catalysts such as paratoluenesulfonic acid, methanesulfonic acid, and 4-sulfophthalic acid are used. The acid catalyst is preferably used in an amount of 0.02% by mass or more, more preferably 0.05 to 0.5% by mass with respect to rosin.

  The reaction between the rosin and the formaldehyde donor material is preferably performed at 150 ° C. or higher, more preferably 170 to 220 ° C. In particular, when the reaction is carried out at 170 to 220 ° C., side reactions such as decomposition and condensation of the resin acid are unlikely to occur, and unreacted raw materials are unlikely to remain. The reaction is carried out for about 2 to 8 hours after the addition of the formaldehyde donor material. In the reaction, an aromatic hydrocarbon solvent such as toluene or xylene may be appropriately used.

  The reaction between rosin and formaldehyde donor will be described by taking as an example the case where formaldehyde (paraformaldehyde) is used as the formaldehyde donor. When rosin and formaldehyde (paraformaldehyde) are heated and reacted in the presence of an acid catalyst, first, at least a part of carbon atoms of abietic acid (formula (II)) contained in rosin (for example, 7-position, 12-position or A hydroxymethyl group is formed at the 14th carbon atom). Thereafter, an exomethylene group is generated by a dehydration reaction, and at the same time, hydrogen transfer occurs to form an aromatic ring, whereby methyl dehydroabietic acid represented by formulas (III) and (III ') is obtained. In this reaction, it is presumed that high molecular weight by dehydration condensation of resin acid, isomerization and decomposition of resin acids, etc. are proceeding simultaneously.

The content of methyl dehydroabietic acid in the obtained reaction product should be measured by gas chromatography / mass spectrometry (GC-MS), gas chromatography, etc. after methylation or trimethylsilylation by a conventional method, for example. Can do.
On the other hand, the content of the non-volatile dehydration condensate (high molecular weight compound) obtained by the side reaction can be measured by gel permeation chromatography (GPC), high performance liquid chromatography (HPLC) or the like.

  If the resulting reaction product contains methyl dehydroabietic acid in a proportion of 20 to 70% by mass and other resin acids, it can be used as it is as the rosin for solder flux of the present invention. However, considering the suppression of color tone, solder scattering, and void generation, for example, a small amount of non-volatile dehydration condensate generated by side reaction is preferably small, and the reaction product may be purified. Examples of purification include distillation, high performance liquid chromatography, column chromatography, and solvent extraction. For example, distillation is performed under reduced pressure conditions of 200 to 280 ° C. and 5 Torr or less.

  Furthermore, the obtained reaction product may be hydrogenated for the purpose of imparting detergency to the flux, improving oxidation stability, and reducing the color tone. In the hydrogenation reaction, a noble metal catalyst such as palladium carbon, nickel, rhodium carbon, or platinum is added in an amount of 0.01% by mass or more (preferably 0.05 to 1% by mass) as an active ingredient to the reaction product, Using a sealed container, stirring is performed at a hydrogen pressure of 5 MPa or more (preferably 7 to 10 MPa) and 200 ° C. or more (preferably 220 to 270 ° C.) for about 2 to 8 hours. In hydrogenation, alicyclic hydrocarbon solvents such as cyclohexane and decalin, and aromatic hydrocarbon solvents such as toluene and xylene may be used as appropriate.

  When performing both purification and hydrogenation, the order is not particularly limited. The reaction product may be purified and then hydrogenated, or the reaction product may be hydrogenated and purified. By performing both refining and hydrogenation, a rosin for solder flux that is nearly colorless and transparent has a methyldehydroabietic acid content of 50% by mass or more and a Hazen color number of 250 or less.

(Solder flux)
The solder flux of the present invention includes the above-described rosin for solder flux. The above-described rosin for solder flux is preferably used at a rate of 20 to 60% by mass. The solder flux of the present invention may contain components usually used for solder flux such as an activator, a thixotropic agent, and an organic solvent.

  Examples of the activator include amines (diphenylguanidine, naphthylamine, diphenylamine, triethanolamine, monoethanolamine, etc.), amine salts (polyamines such as ethylenediamine, and organic acids of amines such as cyclohexylamine, ethylamine, diethylamine, and allylamine). Salts, inorganic acids (mineral acids such as hydrochloric acid and sulfuric acid) salts, hydrohalides, etc., organic acids (dicarboxylic acids such as succinic acid, adipic acid, glutaric acid, sebacic acid, maleic acid; myristic acid, palmitic acid , Fatty acids such as stearic acid and oleic acid; hydroxycarboxylic acids such as lactic acid, dimethylolpropionic acid and malic acid; benzoic acid, phthalic acid, trimellitic acid, etc., amino acids (glycine, alanine, aspartic acid, glutamic acid, valine) Etc.), and the like hydrohalide aniline (aniline hydrobromide). The activator is preferably used in a proportion of 1 to 25% by mass.

  Examples of the thixotropic agent include hydrogenated castor oil, beeswax, carnauba wax, stearamide, hydroxystearic acid ethylenebisamide, and the like. The thixotropic agent is preferably used at a ratio of 1 to 8% by mass.

  Examples of the organic solvent include alcohol solvents (ethyl alcohol, isopropyl alcohol, ethyl cellosolve, butyl carbitol, hexyl carbitol, etc.), ester solvents (ethyl acetate, butyl acetate, etc.), hydrocarbon solvents (toluene, terpine) Oil). The organic solvent is preferably used at a ratio of 10 to 35% by mass.

  Furthermore, the solder flux may contain additives such as other base resins, antioxidants, chelating agents, and rust inhibitors as long as the effects of the present invention are not impaired. Examples of other base resins include acrylic resins, styrene-maleic acid resins, epoxy resins, urethane resins, polyester resins, phenoxy resins, and terpene resins. The additive may be added when the flux and the solder alloy powder are mixed.

(Solder paste)
The solder paste of the present invention contains solder alloy powder and the above-described solder flux. The solder alloy powder is not particularly limited. For example, an Sn—Pb alloy, an alloy obtained by adding silver, bismuth, indium or the like to an Sn—Pb alloy, an Sn—Ag alloy, an Sn—Cu alloy, an Sn—Ag—Cu Based alloys. Considering the influence on the environment, lead-free alloys such as Sn—Ag alloys, Sn—Cu alloys, Sn—Ag—Cu alloys are preferable. The average particle diameter of the solder alloy powder is not particularly limited, and is preferably about 10 to 40 μm, for example.

  The mass ratio between the flux and the solder alloy powder (flux: solder alloy powder) is not particularly limited as long as it is appropriately set according to the application of the solder paste. For example, about 10:90 to 15:85 is preferable.

  The solder paste of the present invention is applied onto a substrate by a dispenser, screen printing or the like when soldering an electronic device component or the like. For example, when a solder alloy powder having a metal composition of Sn-3Ag-0.5Cu is used, preheating is performed at about 140 to 190 ° C, and reflow is performed at a maximum temperature of about 230 to 245 ° C. In this way, an electronic circuit board on which electronic device components are mounted is obtained.

  As described above, according to the present invention, solder scattering can be suppressed and voids are less likely to be generated than the conventionally used hydrogenated rosin and disproportionated rosin, and excellent cleaning performance is imparted to the flux. Can be obtained.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to these Examples.

Example 1
Place 1000 g of Chinese gum rosin (acid number: 165, softening point: 87 ° C., Gardner color number: 7) into a four-necked flask equipped with a stirrer, thermometer, condenser, drain tube and nitrogen inlet tube And melted at 150 ° C. in a nitrogen atmosphere. Next, 0.5 g of paratoluenesulfonic acid was added while stirring, and 109 g of paraformaldehyde (concentration 92 mass%) was added in small portions over 2 hours. The paraformaldehyde used was 1.1 moles per mole of rosin. After the addition, the temperature was raised to 180 ° C. and reacted for 4 hours to obtain 1021 g of rosin for solder flux (acid value: 150, softening point: 90 ° C., Gardner color number: 12).

The obtained solder flux rosin was subjected to GPC analysis and GC-MS analysis. GPC analysis and GC-MS analysis were performed using the following apparatus.
(GPC analysis)
Device: GPC101, manufactured by Shodex
Column: manufactured by Shodex, KF803, KF802 and KF801
Solvent: Tetrahydrofuran (GC-MS analysis)
Equipment: Agilent Technologies, Agilent 7890GC / 5975MSD
Column: Agilent Technologies, DB-5

  When the GPC analysis was performed about the obtained rosin for solder flux, the non-volatile dehydration condensate was contained in the ratio of 16 mass%. Furthermore, when GC-MS analysis was performed, methyl dehydroabietic acid was contained at a ratio of 55% by mass. However, since a non-volatile substance is not detected by GC-MS analysis, this ratio is a ratio when the total of other components excluding the non-volatile substance (dehydration condensate) is 100% by mass. Therefore, when the content of methyl dehydroabietic acid in the solder flux rosin was calculated from these values, it was about 46% by mass (55% by mass × 0.84).

(Example 2)
700 g of the rosin for solder flux obtained in Example 1 was subjected to vacuum distillation (1 Torr) under a nitrogen atmosphere to recover the main fraction (406 g, acid value: 168, softening point: 84 ° C., Gardner color number: 6). As a result of GPC analysis, no non-volatile dehydration condensate was detected in the recovered main fraction (rosin for solder flux). Further, the main fraction was subjected to GC-MS analysis for qualitative and quantitative analysis. The obtained solder flux rosin contained 57% by mass of methyl dehydroabietic acid and 43% by mass of other resin acids. Other resin acids were resin acids derived from Chinese gum rosin as a raw material such as abietic acid, dehydroabietic acid, and pimaric acid, and resin acids produced by isomerization during the reaction.

(Example 3)
200 g of rosin for solder flux obtained in Example 2 was put into an induction stirring autoclave and melted. Next, 2 g of 5 mass% palladium carbon (containing 50% water) was added to remove oxygen in the reaction system. Next, hydrogen was introduced into the reaction system, pressurized to 10 MPa, heated to 250 ° C. with stirring, and a hydrogenation reaction was performed for 4 hours. After the reaction, the reaction mixture was subjected to pressure filtration to remove the catalyst to obtain a rosin for solder flux (191 g, acid value: 167, softening point: 82 ° C., Hazen color number: 220). Since the solder flux rosin is almost colorless, the Hazen color number is used instead of the Gardner color number.
The obtained solder flux rosin was subjected to GC-MS analysis for qualitative and quantitative determination. The obtained solder flux rosin contained 55% by weight of methyl dehydroabietic acid and 45% by weight of other resin acids. Other resin acids were dehydroabietic acid, dihydroabietic acid and tetrahydroabietic acid produced by the hydrogenation reaction. Dihydroabietic acid and tetrahydroabietic acid were contained in a total proportion of 25% by mass.

(Example 4)
A reaction was carried out in the same manner as in Example 1 except that an autoclave equipped with a stirrer was used instead of the four-necked flask to obtain 1025 g of rosin for solder flux (acid value: 154, softening point: 94 ° C. Gardner color number: 11).
The obtained solder flux rosin was subjected to GPC analysis and GC-MS analysis. The obtained rosin for solder flux contained 10% by mass (GPC analysis) of a non-volatile dehydration condensate. In the GC-MS analysis, methyl dehydroabietic acid was contained at a ratio of 68% by mass. Therefore, in the same manner as in Example 1, the content of methyl dehydroabietic acid in the solder flux rosin was calculated to be 61% by mass (68% by mass × 0.9).

(Example 5)
Except for using the solder flux rosin obtained in Example 4, vacuum distillation was performed in the same procedure as in Example 2 to recover the main fraction (455 g, acid value: 171; softening point: 82 ° C; Gardner Number of colors: 5). As a result of GPC analysis, no non-volatile dehydration condensate was detected in the recovered main fraction (rosin for solder flux). Further, the main fraction was subjected to GC-MS analysis for qualitative and quantitative determination. The obtained solder flux rosin contained 65% by mass of methyl dehydroabietic acid and 35% by mass of other resin acids. Other resin acids were resin acids derived from Chinese gum rosin as a raw material such as abietic acid, dehydroabietic acid, and pimaric acid, and resin acids produced by isomerization during the reaction.

(Example 6)
Except for using the solder flux rosin obtained in Example 5, a hydrogenation reaction was performed in the same procedure as in Example 3 to obtain a solder flux rosin (190 g, acid value: 170, softening point: 81). ° C, Hazen color number: 210).
The obtained solder flux rosin was subjected to GC-MS analysis for qualitative and quantitative determination. The obtained solder flux rosin contained 67% by mass of methyl dehydroabietic acid and 33% by mass of other resin acids. Other resin acids were dehydroabietic acid, dihydroabietic acid and tetrahydroabietic acid produced by the hydrogenation reaction. Dihydroabietic acid and tetrahydroabietic acid were included in a proportion of 20% by mass in total.

(Example 7)
Solder flux rosin obtained in Example 1 and commercially available disproportionated rosin (trade name: manufactured by Harima Chemicals, Bandis G-100F, acid value: 158, softening point: 80 ° C., Gardner color number: 7 ) Was mixed at a mass ratio of 1: 1. The obtained rosin for solder flux contains, in calculation, 23% by mass of methyl dehydroabietic acid and 69% by mass of other resin acids. Dihydroabietic acid and tetrahydroabietic acid are contained in a proportion of 20% by mass in total.

(Example 8)
The solder flux rosin obtained in Example 2 and the disproportionated rosin used in Example 7 were mixed at a mass ratio of 1: 1. The obtained solder flux rosin includes 29% by mass of methyl dehydroabietic acid and 71% by mass of other resin acids in calculation. Dihydroabietic acid and tetrahydroabietic acid are contained in a proportion of 20% by mass in total.

Example 9
The solder flux rosin obtained in Example 3 and the disproportionated rosin used in Example 7 were mixed at a mass ratio of 1: 1. The obtained solder flux rosin includes 28% by mass of methyl dehydroabietic acid and 72% by mass of other resin acids in calculation. Dihydroabietic acid and tetrahydroabietic acid are contained in a proportion of 32% by mass in total.

(Comparative Example 1)
Except for using 27 g of paraformaldehyde (concentration 92 mass%), the reaction was performed in the same procedure as in Example 1 to obtain 980 g of rosin for solder flux (acid value: 155, softening point: 88 ° C., Gardner color) Number: 11). The paraformaldehyde used was 0.28 mole per mole of rosin.
The obtained solder flux rosin was subjected to GPC analysis and GC-MS analysis. The obtained rosin for solder flux contained 7% by mass of a non-volatile dehydration condensate (in proportion of GPC analysis. In GC-MS analysis, methyl dehydroabietic acid was contained in a proportion of 13% by mass. Therefore, when the content of methyl dehydroabietic acid in the rosin for solder flux was calculated in the same manner as in Example 1, it was 12% by mass (13% by mass × 0.93).

(Comparative Example 2)
Except for using the solder flux rosin obtained in Comparative Example 1, vacuum distillation was performed in the same procedure as in Example 2 to recover the main fraction (504 g, acid value: 170, softening point: 85 ° C., Gardner Number of colors: 6). As a result of GPC analysis, no non-volatile dehydration condensate was detected in the recovered main fraction (rosin for solder flux). Further, the main fraction was subjected to GC-MS analysis for qualitative and quantitative analysis. The obtained solder flux rosin contained 13% by weight of methyl dehydroabietic acid and 87% by weight of other resin acids. Other resin acids were resin acids derived from Chinese gum rosin as a raw material such as abietic acid, dehydroabietic acid, and pimaric acid, and resin acids produced by isomerization during the reaction.

(Comparative Example 3)
A rosin for solder flux was obtained by performing a hydrogenation reaction in the same manner as in Example 3 except that 300 g of the rosin for solder flux obtained in Comparative Example 2 was used and 3 g of 5 mass% palladium carbon (containing 50% water) was used. (290 g, acid value: 169, softening point: 81 ° C., Hazen color number: 200).
The obtained solder flux rosin was subjected to GC-MS analysis for qualitative and quantitative determination. The obtained solder flux rosin contained 14% by mass of methyl dehydroabietic acid and 86% by mass of other resin acids. Other resin acids were dehydroabietic acid, dihydroabietic acid and tetrahydroabietic acid produced by the hydrogenation reaction. Dihydroabietic acid and tetrahydroabietic acid were contained in a total amount of 55% by mass.

(Comparative Example 4)
Commercially available hydrogenated rosin (trade name: manufactured by Eastman Chemical, Foral AX-E, acid value: 165, softening point: 80 ° C., Hazen color number: 230) was used as a rosin for solder flux. When this hydrogenated rosin was subjected to GC-MS analysis, methyl dehydroabietic acid was not contained, and it was composed only of other resin acids. Dihydroabietic acid and tetrahydroabietic acid were contained in a total amount of 74% by mass. Resin acids other than these (dehydroabietic acid and the like) were contained in a total of 26% by mass.

(Comparative Example 5)
The disproportionated rosin used in Example 7 was used as a rosin for solder flux. When this disproportionated rosin was subjected to GC-MS analysis, methyl dehydroabietic acid was not contained, and it was composed only of other resin acids. The disproportionation product dehydroabietic acid was contained in a proportion of 58% by mass, and dihydroabietic acid and tetrahydroabietic acid were contained in a proportion of 39% by mass in total.

Using the rosin for solder flux obtained in Examples and Comparative Examples, (1) generation of voids, (2) the number of scattered solder, and (3) detergency were evaluated. First, in order to perform these evaluations, a solder paste composition was prepared.
The obtained solder flux rosin, thixotropic agent, antioxidant and solvent were mixed and heated to be dissolved. Next, a halogen compound and an organic acid were added to the dissolved mixture to obtain a flux. The obtained flux and solder alloy powder were mixed at a ratio (mass ratio) of 11.2: 88.8 to prepare a solder paste composition. The composition of the solder alloy powder used was Sn-3Ag-0.5Cu.
(Flux composition)
Rosin for solder flux: 54% by mass
Antioxidant (hindered phenol): 2% by mass
Solvent (Terpin oil): 38.6% by mass
Halogen compound (allylamine hydrobromide): 0.4% by mass
Organic acid (succinic acid): 1% by mass
Thixotropic agent (cured castor oil): 4% by mass

(1) Generation | occurrence | production of a void On the copper electrode of FR4 board | substrates, the obtained solder paste composition was apply | coated with the thickness of 0.15 mm, and the power transistor component of 12x8 mm was mounted. Next, preheating was performed at 140 ± 5 ° C. for 100 ± 5 seconds in a nitrogen atmosphere, and melting was performed at a maximum temperature of 235 ± 5 ° C. to perform soldering. The substrate after soldering was observed with a soft X-ray fluoroscope (NLX-3500F2 manufactured by Nagoya Denki Kogyo Co., Ltd.) and photographed. The photograph taken was analyzed with image analysis software (Azo-kun, manufactured by Asahi Engineering Co., Ltd.), and the void area ratio (%) in the solder metal was measured. FIG. 1 shows a photograph when the substrate after soldering is observed with a soft X-ray fluoroscope. Gray spots are voids, and the substrates of FIGS. 1A to 1D have void area ratios shown below.
(A) is a void area ratio of about 5%.
(B) is a void area ratio of about 15%.
(C) is a void area ratio of about 30%.
(D) is a void area ratio of about 40%.

Void process capability index (Cpk) was calculated by setting the void standard to an area ratio of 30% or less, and evaluated according to the following criteria. If “評 価”, “◯” and “Δ” are evaluated, it can be evaluated that the generation of voids is suppressed although there is a difference in degree, and there is no practical problem. The results are shown in Table 1.
A: More than 2.00 B: 1.33-2.00
Δ: 1-1.33
×: Less than 1

(2) Number of scattered solder The obtained solder paste composition was printed with a diameter of 6.5 mm and a thickness of 200 μm on the center of a copper plate (50 mm × 50 mm × 0.3 mm). Next, preheating was performed at 140 ± 5 ° C. for 100 ± 5 seconds in a nitrogen atmosphere, and melting was performed at a maximum temperature of 235 ± 5 ° C. to perform soldering. In the copper plate after soldering, the range of 25 mm around the soldered portion was observed with a microscope (magnification 20 times), and the total number of fluxes and solder scattered was counted. If “評 価”, “◯” and “Δ” are evaluated, it can be evaluated that solder scattering is suppressed although there is a difference in degree, and there is no practical problem. The results are shown in Table 1.
◎: 10 or less ○: 11-15 △: 16-20 ×: 21 or more

(3) Detergency The copper plate after soldering used in the number of scattered solder was washed with a glycol ether solvent (Clinthru 750HS, manufactured by Asahi Kasei Corporation). The washed substrate was observed with a microscope (magnification 20 times) and evaluated according to the following criteria. If “評 価”, “◯” and “Δ” are evaluated, it can be evaluated that the cleaning property is excellent although there is a difference in degree, and there is no practical problem. The results are shown in Table 1.
A: When the metal surface has a sufficient metallic luster.
○: There is no residue, but the metal surface is dull.
Δ: A small amount of residue is present.
X: When a large amount of residue exists.

  As shown in Table 1, when the solder flux rosin obtained in the examples is used, it is understood that solder scattering can be suppressed, and voids are hardly generated, and the flux has excellent cleaning properties. .

Claims (9)

A solder flux rosin containing methyl dehydroabietic acid and a resin acid other than methyl dehydroabietic acid,
A rosin for solder flux, wherein the methyl dehydroabietic acid is contained in a proportion of 20 to 70% by mass with respect to the whole rosin.   2. The rosin for solder flux according to claim 1, wherein the methyl dehydroabietic acid and the other resin acid are contained in a ratio of 99 mass% or more in total with respect to the entire rosin.   The rosin for solder flux according to claim 1 or 2, wherein the other resin acid contains at least one of dihydroabietic acid and tetrahydroabietic acid.   The solder flux containing the rosin for solder flux in any one of Claims 1-3.   Solder paste containing solder alloy powder and the solder flux according to claim 4.   An electronic circuit board provided with a soldering part by the solder paste according to claim 5. A method for producing a solder flux rosin according to claim 1,
A step of adding 0.4 mol or more of a formaldehyde donating substance to 1 mol of the rosin to the mixture of rosin and an acid catalyst, and after the adding step, the mixture is heated to react to react the reaction product. The manufacturing method of the rosin for solder flux including the process to obtain.   The production method according to claim 7, further comprising a step of purifying a resin acid from the reaction product after the step of obtaining the reaction product.   The production method according to claim 7 or 8, further comprising a step of hydrogenating a resin acid contained in the reaction product after the step of obtaining the reaction product.