JP2692029B2 - Flux for soldering - Google Patents

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 in the electronics industry.

[0002]

2. Description of the Related Art Conventionally, when soldering an electronic component to a printed wiring board, flux is applied to a soldered portion to remove an oxide film on the soldered portion and reduce the surface tension of molten solder. The part is uniformly covered with molten solder metal. After soldering, the flux residue has been removed by washing.

Recently, from the idea that the flux residue acts as a protective film for the solder joint, the flux residue may be positively left as a protective film for the soldering part without washing. Therefore, in such a case, it is necessary that the flux residue is not corrosive and that the flux residue does not peel off.

Conventionally, the flux composition used in the electronic industry is generally a mixture of a natural rosin or a synthetic rosin as a main component and an activator. Or, the impact due to vibration may cause cracks on the surface of the flux residue, and the flux residue may come off. Then, the peeled flux residue may be peeled off from the printed wiring board and mixed into a volume, a contact point, a motor or the like to cause a trouble such as conduction failure. 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 flux composition for soldering, which does not cause cracks in the coating film of the flux residue due to the impact of cold heat or vibration of the temperature, it has a hydroxyl group, a carboxyl group, and a carbonyl group and has a molecular weight of 1500 to 1500. The use of 4000 polyolefin as a flux has been found to ameliorate the aforementioned drawbacks and has led to the completion of the invention. The object of the present invention is to use the flux residue coating in the soldered portion during use without causing surface cracks,
Another object is to provide a soldering flux that does not cause peeling.

[0006]

The gist of the present invention is to provide a polyolefin having a hydroxyl group, a carboxyl group and a carbonyl group, and having a molecular weight of 1500 to 4000.
A soldering flux containing , and also a soldering flux composition containing a natural rosin or a synthetic rosin or a derivative thereof and an activator, a hydroxyl group, a carboxyl group,
And has a carbonyl group and a molecular weight of 1500 to 4
It is a flux for soldering, characterized in that at least 10% by weight of a polyolefin of 000 is added to the composition.

That is, in the flux composition of the present invention, a polyolefin containing three functional groups of a hydroxyl group, a carboxyl group and a carbonyl group is used as a flux, and a natural rosin or a synthetic rosin or its derivative and an activator are used. By adding the above-mentioned polyolefin containing three kinds of functional groups to the flux composition for soldering, the flux residue after soldering is made to have flexibility, and the flux residue is shocked by cold heat or vibration of temperature. Has the property that no cracks are generated on the surface of, and as a result, the flux residue does not peel off.

The flux used in the present invention is, for example, a flux used for a core of a cored solder, a post flux for a jet solder, a surface mount solder space, and the like. The polyolefin having a functional group such as a group and a carboxyl group needs to have a molecular weight of 1500 to 4000. When the molecular weight is 1500 or less, the viscosity of the flux residue decreases and becomes sticky, while on the other hand, the molecular weight is 40%.
If it is 00 or more, the flexibility of the flux residue is lost,
Cracks easily occur. The polyolefin having a functional group of a hydroxyl group, a carbonyl group, and a carboxyl group used in the present invention is, for example, one in which a hydroxyl group, a carbonyl group, and a carboxyl group are bonded to a main chain made of polyethylene, and usually polyethylene is air-oxidized or the like. It is obtained by means of. In the present invention, a polyolefin having a functional group of a hydroxyl group, a carbonyl group, and a carboxyl group can be used alone as a flux, but this is added to a flux composition for soldering containing a natural rosin or a synthetic rosin or a derivative thereof and an activator. It can also be used. And, the addition amount at that time is at least 10 (weight)% or more of the entire flux,
% Or less, the film sticking property after soldering is lowered, and cracks are likely to occur particularly at -20 to 0 ° C.

The flux composition to which the polyolefin is added in the present invention is not different from the conventionally used flux composition. That is, it consists of a flux for soldering in which an activator is added to one or more of natural rosin or synthetic rosin or its derivative. As natural rosin, usual gum tols and wood rosins are used, and as derivatives thereof, heat-treated polymerized rosin, hydrogenated rosin, fully hydrogenated rosin, rosin ester, rosin-modified phenol resin, rosin-modified maleic acid resin are used. , Rosin-modified alkyd resin and the like. 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 0.1 to 20 (weight)% of the entire flux. If it is less than 0.1% by weight, the activity will be insufficient and the solderability will be deteriorated, and if it is more than 20% by weight, the flux film adhesion will be reduced and the hydrophilicity will become stronger, resulting in corrosion. In addition, the insulating property is reduced.

When the flux of the present invention is used in a liquid state, a solvent is further added to these compositions.
As this solvent, one or two or more kinds of natural rosin or synthetic rosin or a derivative thereof and a component having an activator are dissolved in a polyolefin having a hydroxyl group, a carboxyl group or a carbonyl group, to prepare a solution, a usual alcohol is used. -Le system,
It is particularly 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]

Examples and Comparative Examples Hereinafter, the present invention will be described specifically with reference to Examples. The PO used in the examples is a polyolefin having a hydroxyl group, a carboxyl group, and a carbonyl group, and its molecular weight is 2,000 to 3,
000. Example 1 PO 39.0 wt% Polymerized rosin 60.0 Cyclohexylamine hydrobromide 1.0 Example 2 PO 43.5 Maleic acid modified rosin 55.0 Cyclohexylamine / hydrochloride 1.0 adipic acid 0.5 Example 3 PO 99.0 Cyclohexylamine hydrobromide 1.0

The case where PO is not added is shown below as a comparative example. Comparative Example 1 Natural rosin 99.0 Cyclohexylamine hydrobromide 1.0 Comparative Example 2 Polymerized rosin 99.0 Cyclohexylamine hydrobromide 1.0 Comparative Example 3 Natural rosin 49.5 Polymerized rosin 49.5 Cyclohexyl Amine hydrobromide The flux obtained with a compounding ratio of 1.0 or more is 30 mm.
A steel plate having a size of 30 mm and a thickness of 0.3 mm was used as a test piece, and the performance was measured by the following test method at a temperature of 25 ° C and -20 ° C. Pin test A pin was put on the flux residue on the test piece and the presence or absence of cracks was visually confirmed. Tape test A tape was attached on the flux residue on the test piece, and the tape was peeled off with a constant force to visually confirm the occurrence of cracks. Table 1 shows the test results.

[0014]

[Table 1]

[0015]

As described above, in the present invention,
The soldering flux composition has a hydroxyl group, a carboxyl group, and a carbonyl group, and has a molecular weight of 15
By blending the polyolefin of 00 to 4000, cracks did not occur on the surface of the flux residue, and as a result, troubles due to peeling could be eliminated. As a result, the flux residue can be strongly protected without being peeled off from the soldered portion, and a high insulation resistance value can be maintained. Furthermore, since the conventional washing step can be omitted, the cost based on the washing step can be saved, and CFC 11 as a washing liquid can be omitted.
It has also been possible to solve the problems such as environmental pollution that occur when an organic solvent based on 3 is used.

Claims (2)

(57) [Claims] 1. A soldering flux containing a polyolefin having a hydroxyl group, a carboxyl group, and a carbonyl group and having a molecular weight of 1500 to 4000. 2. A soldering flux composition containing a natural rosin or a synthetic rosin or its derivative and an activator, and a polyolefin having a hydroxyl group, a carboxyl group and a carbonyl group and having a molecular weight of 1500 to 4000, A soldering flux, characterized in that at least 10% by weight is added to the composition.