JP3334376B2 - 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 for soldering an electronic component in a manufacturing process of the electronic component.

[0002]

2. Description of the Related Art
When soldering an electronic component in a manufacturing process of the electronic component or the like, generally, a soldering flux having the following composition is used. Rosin: 10 to 30% by weight Activator (such as hydrochloride of organic amine): 0.1 to 1.0% by weight Solvent (such as isopropyl alcohol): Remaining

[0003] By the way, the flux using a low-boiling alcohol solvent such as isopropyl alcohol as a solvent has the following problems. (1) In order to prevent cracks due to thermal shock of parts, preheating is often performed before soldering, but since the solvent has a low boiling point, it evaporates before reaching the soldering temperature (usually 180 to 300 ° C). The properties such as the wraparound property are reduced. (2) When the solvent evaporates, only the rosin and the activator remain, so that the rosin and the activator directly receive heat during preheating, and the activity of the flux during soldering decreases. (3) If a strong activator such as an organic amine remains after soldering, it may cause corrosion of the electrode and decrease in insulation resistance.Therefore, solder with a chlorofluorocarbon-based solvent such as trichloroethane or trichloroethane. Although it is necessary to clean the part, the use of these solvents is gradually being banned in recent years due to the problem of ozone layer depletion and the problem of groundwater contamination, and it becomes difficult to efficiently clean the solvent.

The present invention has been made to solve the above problems, and it is possible to exhibit sufficient activity even when the amount of use of a strong activator such as an organic amine is reduced or its use is stopped. Possible, with little residue after soldering,
An object of the present invention is to provide a soldering flux that can eliminate the need for cleaning.

[0005]

[0006]

The soldering flux of the present invention (claim 1 ) is characterized by comprising stearic acid or sebacic acid, glycerin and benzyl alcohol.

[0007]

[Act as solvent, benzyl alcohol is a high boiling primary alcohol: when using (bp 205 ° C.), the benzyl alcohol is, before soldering, during soldering, the following at each stage after soldering It behaves like this.

(1) First, a film is formed on a soldered portion without evaporation or volatilization during preheating before soldering.

(2) At the time of soldering, it is thermally decomposed to generate benzoic acid, and exerts an active action of removing an oxide film formed on an electrode metal surface or the like as a soldered portion.
That is, benzyl alcohol, while being a diluting solvent, self-decomposes to benzoic acid at the time of soldering and exhibits an activating action.

(3) After soldering, benzoic acid is volatilized gradually, so that no residue remains and cleaning can be made unnecessary.

Therefore, the use of the flux for soldering of the present invention makes it possible to reduce the dependence on a strong activator such as an organic amine-based flux, and to obviate the use of the flux. As a result, removal of the activator after soldering
The intended cleaning can be eliminated.

Further, as the solvent, if used <br/> benzyl alcohol, although the use of rosin as in the conventional soldering flux becomes unnecessary, which is benzyl <br/> alcohol The fact that rosin remains until the time of soldering plays a role of preventing re-oxidation and improving the fluidity of the solder, which were conventionally performed by rosin. Further, when rosin is not used, it is not necessary to remove rosin remaining after soldering, so that washing for removing rosin after soldering can be made unnecessary.

[0013] Incidentally, a solvent benzyl alcohol is,
It is preferable that the content is 20 to 99% by weight. When the content of the solvent is less than 20% by weight, the effect of the solvent, which is a feature of the present invention, is reduced. If the ratio exceeds the above range, the ratio of the activator becomes relatively too small, so that the solderability deteriorates.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described, and features thereof will be described in more detail.

[0015] In this embodiment, stearate, sebacic acid, as well as providing a material such as glycerin, as a solvent, to prepare a benzyl alcohol which is a high-boiling primary alcohol, these in proportions shown in Table 1 This was mixed to produce a soldering flux (Examples 1 and 2).

[0016]

[Table 1]

For comparison, other components were the same as in Examples 1 and 2, and a soldering flux (Comparative Examples 1 and 2) using isopropyl alcohol instead of benzyl alcohol as a solvent was prepared.

Regarding these fluxes, JI
A “solder spread test” was performed based on SZ3197, and flux using benzyl alcohol (Example
1,2 ) and a flux using isopropyl alcohol (Comparative Examples 1,2 ).

Table 1 shows the measurement results for the solder spread rate.
Are shown together.

As shown in Table 1, when comparing the flux of the flux and Comparative Examples 1 and 2 of Examples 1 and 2, in the case of Examples 1 and 2 with benzyl alcohol as a solvent,
The solder spread rate is significantly higher than in Comparative Examples 1 and 2 using isopropyl alcohol, and a soldering flux having sufficient activity can be obtained without using an organic amine-based activator. It was confirmed that.

Further, the flux of Example 1 and 2, Do not be using any of the active agents and rosin organic amine
Therefore, after soldering, an organic amine-based activator or rosin
Residues are generated due to corrosion of the electrodes and low insulation resistance.
After soldering without causing any
It is possible to eliminate the need for cleaning.

[0022] Note that the high-voltage capacitor in produced by soldering with a flux and flux in Comparative Example 1 of Example 1, 1000 hours humidity load test (60 ℃, 90% RH, 1kV is applied) the Do
The insulation resistance was measured. As a result, it shows the non-washed product using the flux of Example 1, the cleaning article equivalent insulation resistance (1 × 10 ⁹ Ω · cm or more) using the flux in Comparative Example 1, i.e., equal trust It was confirmed that the property was obtained.

[0023] The present invention is not limited to the above embodiment relates to such a set composition ratio, within the scope of the invention, it is possible to add various applications and modifications.

As described above, in the soldering flux of the present invention, the solvent does not substantially evaporate before soldering (during preheating), forms a film on the soldered portion, and forms a film at the time of soldering. by thermal decomposition showed an activity to reduce and remove the oxide film on the soldering surface, gradually volatilized after soldering, include benzyl alcohol have been used, and none of the rosin and the organic amine activator Since the cleaning is not performed, cleaning after soldering, which is conventionally required, can be eliminated, and cost can be reduced. Ozone depleting substances (O
The use of DC) is unnecessary, and the burden on the environment can be reduced.

Continuation of the front page (56) References JP-A-5-185282 (JP, A) JP-A-6-79491 (JP, A) JP-A-6-41601 (JP, A) JP-A-4-66291 (JP) , A) JP-A-2-290693 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 35/363

Claims (1)

(57) [Claims] 1. A soldering flux comprising stearic acid or sebacic acid, glycerin and benzyl alcohol.