JPH10305391A - Flux for soldering - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a flux composition for soldering, which is used particularly when manufacturing a printed wiring board in the electronics industry. A flux composition for soldering containing a natural rosin or a synthetic rosin or a derivative thereof and an activator,
A flux for soldering, characterized by containing a long-chain dibasic acid or an anhydride thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering flux used in the manufacture of printed wiring boards, particularly in the electronics industry.

[0002]

2. Description of the Related Art Conventionally, when an electronic component is soldered to a printed wiring board, a flux is applied to a soldered portion to remove an oxide film on the portion and reduce the surface tension of the molten solder. Is uniformly covered with the molten solder metal. The property of lowering the surface tension of the molten solder and uniformly blending it on the metal surface to be soldered is generally regarded as wettability, but such property is important as a flux.

[0003] Furthermore, after soldering, flux residues have conventionally been removed by washing.
Without considering that the flux residue after soldering recently acts as a protective coating on the solder joint,
In some cases, the flux residue was positively left as a protective film at the soldered portion. In such a case, the flux residue is not corrosive to the metal surface to be soldered, and furthermore, the flux residue does not peel off and does not crack in the flux residue due to the impact of temperature cooling or vibration. Has been requested.

[0004] Conventional flux compositions used in the electronics industry generally contain natural rosin or synthetic rosin as a main component, mixed with an activator, and have a high insulating property. Alternatively, cracks may be generated on the surface of the flux residue due to shock due to vibration, and the flux residue may be peeled off. Then, the separated flux residue may be separated from the printed wiring board and mixed into a volume, a contact, a motor, or the like to cause a trouble such as poor conduction. Therefore, the printed wiring board and the in-vehicle printed wiring board are generally cleaned as before.

[0005]

Therefore, the present inventor has proposed:
Improving the above disadvantages in conventional flux compositions,
As a result of various studies on a soldering flux composition that does not generate cracks in the flux residue coating due to the impact of temperature cooling or vibration, as a result of adding a certain long-chain dibasic acid or anhydride thereof, It has been found that the above-mentioned drawbacks are improved, and the present invention has been completed.The object of the present invention is to provide a coating of a flux residue in a soldered portion without causing surface cracks during use, and An object of the present invention is to provide a soldering flux that does not cause peeling.

[0006]

The gist of the present invention is to make a flux composition for soldering containing a natural rosin or a synthetic rosin or a derivative thereof and an activator contain a branched long-chain dibasic acid or an anhydride thereof. It is a flux for soldering characterized by the above.

That is, the flux composition of the present invention contains a branched long-chain dibasic acid or an anhydride thereof, thereby improving the wettability to the metal surface of the half and preventing the surface of flux residue from cracking. Imparting properties,
As a result, an excellent flux composition for soldering without flux residue peeling is provided.

In the present invention, the flux to which a branched long-chain dibasic acid or an anhydride thereof is added is used, for example, for a core of solder, a post flux for a jet solder, and a surface mount solder / pace. Flux. The components constituting these fluxes do not differ from the flux compositions conventionally used. That is,
It consists of a soldering flux to which one or more of natural rosin or synthetic rosin or a derivative thereof and an activator are added.

As a natural rosin, ordinary gum toll and wood rosin are used, and as its derivatives, heat-treated polymerized rosin, hydrogenated rosin, completely hydrogenated rosin,
Rosin esters, rosin-modified phenol resins, rosin-modified maleic resins, rosin-modified alkyd resins, and the like are included. These may be used as a mixture.

Examples of the activator include hydrohalides such as ethylamine, propylamine, butylamine, hexylamine, diethylamine, dipropylamine, dibutylamine, triethylamine, ethylenediamine, chloroxylamine and aniline, succinic acid, adipic acid, and the like.
The use of organic carboxylic acids such as spearic acid, azelaic acid, sebacic acid and stearic acid is preferred. The amount used is preferably 0.01 to 20 (weight)% of the entire flux. When the content is less than 0.01% by weight, the activating force is insufficient and the solderability is deteriorated. When the content is more than 20% by weight, the coating property of the flux is reduced and the hydrophilicity becomes strong, so that corrosion is caused. In addition, the insulating property decreases.

When the flux of the present invention is used in a liquid state, a solvent is further added to these compositions.
Examples of the solvent include a conventional alcohol for dissolving one or more of natural rosin or synthetic rosin or a derivative thereof and a component of the activator in a polyolefin having a hydroxyl group, a carboxyl group, and a carbonyl group to form a solution. system,
Particularly, it is preferable to use a polar solvent such as isopropyl alcohol and butyl acetate. The amount of solvent used is 30-9
9% by weight is preferred. When the amount of the solvent is 30% by weight or less, the flux has a high viscosity, so that the coatability of the flux is deteriorated.

[0012] Although branched long chain dibasic acid or anhydride thereof for use in the present invention are, or anhydrides thereof C ₁₂ -C ₂₂ about branched long-chain dibasic acid, in particular represented by the following general formula Compound (1) or (2) is preferred.

[0013]

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Such a compound can be obtained, for example, by subjecting cyclohexanone, which is a C ₆ cyclic ketone, to ring-opening dimerization by the action of a solution comprising hydrogen peroxide and a ferrous salt. Further, when the above reaction is performed in the presence of an olefin, that is, cyclohexanone is subjected to ring-opening dimerization by acting on a solution comprising hydrogen peroxide and a ferrous salt, one to two molecules of the olefin are interposed, The following dibasic acid mixtures in which carboxyl groups have been added to both ends are also used in a similar manner.

[0015]

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The amount of the long-chain dibasic acid or anhydride added is 0.1 to 20% by weight, preferably 1%, in the flux composition.
If it is present in an amount of not more than 0.1% by weight, it is not possible to achieve the intended purpose.

[0017]

Examples and Comparative Examples Hereinafter, the present invention will be described specifically with reference to Examples. Example 1 Polymerized rosin (softening point 137 ° C.) 97.0% by weight Activator diethylamine HBr salt 1.0 Compound (1) 2.0 Example 2 Polymerized rosin (softening point 137 ° C.) 97.0% by weight Activator diethylamine HBr salt 1.0 Compound (2) 2.0 Comparative Example 1 Polymerized rosin (softening point: 137 ° C.) 99.0% by weight Activator diethylamine HBr salt 1.0 Obtained by the blending ratio of the above Examples and Comparative Examples. When soldering was performed using a comb-shaped electrode specified in JIS-2 as a test piece using a flux, and a change in the electric resistance value with time was examined, a result as shown in FIG. 1 was obtained. . The conductor width of the comb-shaped electrode defined in JIS-2 type is 0.318 mm, and the conductor gap is 0.318 mm.
In mm, the overlap margin is 15.76 mm.

[0018]

As described above, in the present invention,
By adding a long-chain dibasic acid or its anhydride to the soldering flux composition, the solder wettability is improved, and the flux residue does not crack, and as a result, as shown in FIG. Over a long period of time, there was little change in the electric resistance value.

[Brief description of the drawings]

FIG. 1 shows a change in electric resistance value with respect to time in Examples 1 and 2 and Comparative Example 1.

Claims (3)

[Claims] 1. A soldering flux comprising a branched long-chain dibasic acid or an anhydride thereof in a soldering flux composition containing a natural rosin or a synthetic rosin or a derivative thereof and an activator. 2. The soldering flux according to claim 1, wherein the branched long-chain dibasic acid or its anhydride is a compound represented by the following chemical formulas 1-3. Embedded image Embedded image Embedded image 3. The soldering flux according to claim 1, wherein the branched long-chain dibasic acid or anhydride thereof is a mixture of the following dibasic acids.