JP2902572B2 - Flux for flux cored solder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flux for a cored solder.

[0002]

2. Description of the Related Art It is known that a flux having a composition of 99% by weight of polymerized rosin and 1% by weight of an activator is filled in a central portion of a cored solder.

[0003]

The flux residue after soldering is required to have characteristics such as non-corrosion, high insulation, long-term stability, heat resistance, moisture resistance, and non-toxicity. In the conventional example as well, the above characteristics are satisfied in a generally used environment, but remain in a special environment (low temperature, high temperature and high humidity conditions, vibration or other conditions where external force is applied, etc.). Since the flux cannot maintain the above characteristics, there is a concern that the reliability may decrease.

[0004] In view of the above, the present invention adapts to changes in the surrounding environment to some extent, has excellent heat resistance, has little scattering of flux, and is less likely to crack in flux residues.
An object of the present invention is to provide a flux for cored solder having good jointability.

[0005]

In order to achieve the above object, the flux for a cored solder according to the present invention has a composition of 5 to 25% by weight of the following high melting point wax and 5 to 30% by weight of the following high molecular compound. %, 0.5 to 1.5% by weight of an activator, and the remainder of rosin.

The high melting point wax is any of a polyethylene wax derivative, a paraffin wax derivative, a hydrogenated castor oil derivative, and a derivative of 12-hydroxystearic acid.

[0007] The high molecular compound is a propylene-based polymer. As the propylene-based polymer, it is preferable to use a copolymer of propylene and ethylene or a copolymer of propylene and butene.

The rosin is preferably contained in an amount of 50 to 65% by weight.

The content of the high melting point wax is 15 to 22.
Most preferably, the content of the polymer compound is 15 to 25% by weight.

As the activator, it is preferable to use a hydrobromide of an organic amine such as diethylamine hydrobromide, or an organic acid such as malonic acid, succinic acid or adipic acid.

As the rosin, natural rosin, disproportionated rosin, polymerized rosin, hydrogenated rosin, purified rosin and the like are preferable.

[0012]

According to the present invention, by setting the above-mentioned high melting point wax, the above-mentioned polymer compound, activator and rosin in the above-mentioned ranges, the heat resistance is excellent, the flux is less scattered, and the flux residue is hardly cracked. It is possible to provide a highly reliable flux having good bonding properties.

That is, by adding the above-mentioned high melting point wax, the heat resistance of the flux can be improved and the scattering of the flux can be prevented. If the amount is less than 5% by weight, the effect is small, and if it exceeds 25% by weight, the melting point is increased and the wettability of the solder is reduced. Most preferably, the content of the high melting point wax is 15 to 22% by weight.

By adding the above-mentioned polymer compound, the heat resistance of the flux is improved, and deformation due to heat is prevented. If the addition amount is less than 5% by weight, the effect is small, and if it exceeds 30% by weight, the melting point increases and the wettability of the solder decreases. High polymer compound content of 15 to 25
It is optimal that the content is% by weight.

In particular, the present invention has a unique composition in which a high melting point wax and a high molecular compound are added in the above-mentioned proportions as a flux composition. As a result, heat resistance, prevention of flux scattering and crack generation of flux residue are obtained. The remarkable effect was able to be exhibited in prevention.

The addition of an activator is necessary to improve the wettability of the solder. However, if the addition amount is less than 0.5% by weight, the effect is small, and if it exceeds 1.5% by weight, the effect is small. Reliability decreases.

Rosin has the function of improving the flowability of the solder and preventing oxidation. When the rosin is less than 50% by weight, its effect is small. The effect of the inventive flux cannot be expected.

[0018]

FIG. 1 shows a cored solder 3 having a central portion filled with a flux 1 of the present invention and a main body 2 made of a 63Sn-37Pb eutectic solder alloy. The outer diameter of the solder 3 is 1 mm, and the content of the flux 1 is 3 mm.
% By weight.

Table 1 shows the compositions of the flux 1 for the cored solder of Examples 1 to 3 and those of Comparative Examples 1 to 3.

[0020]

[Table 1]

Table 2 shows the results of a heat resistance test performed on each flux having the above composition. In this heat resistance test, a certain amount of flux was heated and melted on a copper plate, allowed to cool naturally, and then reheated to examine the temperature at the time when the flux around the solder metal flowed. .

[0022]

[Table 2]

As is apparent from Table 2, Examples 1 and 2 in which the content ratio of the high molecular compound (propylene polymer) is high and a predetermined amount of the high melting point wax (hardened castor oil derivative) is added thereto are as follows. It showed very good heat resistance. In Example 3 in which the content of the high-melting-point wax was high and a predetermined amount of the high-molecular-weight compound was added thereto, Comparative Example 1 in which the high-molecular-weight compound and the high-melting-point wax were not added at all,
Excellent heat resistance was shown as compared with Comparative Example 3 to which only the high melting point wax was added. Further, it was equivalent to Example 3 and Comparative Example 2 in which the polymer compound was added at a high ratio.

Next, Table 3 shows the results of a heat cycle test performed on each flux having the above composition. In this heat cycle test, a certain amount of flux was applied to a substrate in which a copper wire was embedded and arranged in a comb mold, and one cycle was performed at + 70 ° C.
(30 minutes) → −30 ° C. (30 minutes) → + 70 ° C. It is observed whether or not cracks occur in the flux when a heat test of a predetermined cycle is performed.

[0025]

[Table 3]

As is clear from Table 3, Examples 1 to 3 all have good heat cycle resistance.
In particular, Example 1 in which the high melting point wax (hardened castor oil derivative) was 20% by weight and the polymer compound (propylene-based polymer) was 19% by weight was found to have remarkably excellent heat cycle resistance. Comparative Example 2 and Comparative Example 3 in which only one of the polymer compound and the high melting point wax was added.
Had poor heat cycle resistance similarly to Comparative Example 1 to which these were not added.

Next, the results of a flying test performed on each flux having the above composition are shown in Table 4. In this scattering test, as shown in FIG. 2, a soldering iron 4 having a tip temperature of 330 ° C.
The solder 3 shown in FIG. 1 is brought into contact with the solder wire feed pulley 5 to observe the state of the scattered flux, and evaluated from the number of scattered flux.
The transport speed of the solder 3 is 5, 10, 15 mm /
The three types of experiments that were performed in sec were performed.

[0028]

[Table 4]

As is clear from Table 4, all of Examples 1 to 3 were able to reduce the flux scatter as compared with Comparative Examples 1 to 3, but in Example 1, especially the flux scatter was observed. Can be set to 0, which is much better.

Table 5 shows the results of a peeling test performed on each flux having the above composition. This peel test was performed by JI
A flux film was formed on a copper plate by using a matrix test (test for evaluating a paint film) based on SK-5400.6.15, and approximately at the center of the film,
11 each of vertical and horizontal directions orthogonal to the shape of the base using a cutter knife
A line-shaped cut is made in each case, and the state of peeling of the flux film at the scratch is observed and evaluated. Test No. 1 to No. Three tests of three were performed.

[0031]

[Table 5]

As is evident from Table 5, in Examples 1 to 3, the peeling of the flux film (residual flux) was smaller than in Comparative Examples 1 to 3. In No. 1, no peeling was observed, and the peel resistance was remarkably improved.

[0033]

According to the present invention, a high melting point wax (any one of a polyethylene wax derivative, a paraffin wax derivative, a hydrogenated castor oil derivative, and a derivative of 12-hydroxystearic acid) and a high molecular compound (propylene polymer) are used in predetermined amounts. Since it is provided as a flux composition, it is possible to provide a highly reliable flux cored solder having excellent heat resistance, less scattering of the flux, less occurrence of cracks in the flux residue, good bonding properties, and high reliability.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows a cored solder, (a) is a longitudinal sectional view, and (b) is a transverse sectional view.

FIG. 2 is a schematic diagram showing a flux scattering test.

[Explanation of symbols]

 1 flux for cored solder 2 body 3 cored solder

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takahiko Omoto 7-21 Chikuhama-ji Nishimachi, Sakai City, Osaka Prefecture Inside Ishikawa Kinzoku Co., Ltd. No. 21 Ishikawa Metal Co., Ltd. (56) References JP-A-62-34696 (JP, A) JP-A-7-100690 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) ) B23K 35/14 B23K 35/363

Claims (3)

(57) [Claims] 1. A composition comprising 5 to 25% by weight of a high melting point wax, 5 to 30% by weight of a polymer compound, and 0.5 to 1.
Wherein the high molecular weight compound is a propylene polymer, and the high melting point wax is any of a polyethylene wax derivative, a paraffin wax derivative, a hydrogenated castor oil derivative, and a derivative of 12-hydroxystearic acid. Flux for cored solder, characterized in that: 2. The flux for a cored solder according to claim 1, wherein the flux contains 50 to 65% by weight of rosin. 3. The flux for a cored solder according to claim 1, wherein the flux contains 15 to 22% by weight of the high melting point wax and 15 to 25% by weight of the high molecular compound.