JPH05185283A - Flux for soldering and cream solder - Google Patents

Abstract

PURPOSE:To provide the flux for soldering and cream solder which have excellent solderability even in an atmosphere of a relatively high oxygen concn. of about 10000ppm to 20.9%(atm.) oxygen content and are low in residues without requiring washing. CONSTITUTION:This flux for soldering and cream solder contain one or more kinds of antioxidants contg. one or more phenol skeleton attached with a 3rd butyl group within the molecule.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering flux which can be soldered in an atmosphere having a relatively high oxygen concentration of about 10000 ppm to 20.9% (atmosphere) of oxygen content and has a low residue and does not require cleaning. And cream solder.

[0002]

2. Description of the Related Art Due to technological innovation in recent years, various types of low-residue type soldering flux and cream solder have been developed. However, in all products, the residue after soldering, that is, the solid content is reduced, so that one of the functions of the solid content, the reoxidation prevention function during the flow and reflow cannot be expected. Therefore, it is necessary to prevent reoxidation of the board, components and solder by a method other than adding a large amount of solid content.

Therefore, instead of setting the atmosphere of the flow solder and the reflow furnace to a highly oxidizing atmosphere (atmosphere), purging with an inert gas such as nitrogen is generally performed. However, in order to purge the flow solder and reflow furnace, a large amount of inert gas such as nitrogen is required,
It is more costly than flowing and reflowing in the atmosphere, and special safety considerations are required.

[0004]

The problem to be solved by the present invention is to add an antioxidant containing a phenol skeleton having a tertiary butyl group in the molecule to a soldering flux and a cream solder. Realizes highly reliable solderability in a relatively high oxygen concentration atmosphere,
The purpose is to reduce the consumption of the inert gas in the inert gas purge flow solder and the reflow furnace to reduce the cost.

[0005]

According to the present invention, a low-residue type soldering flux and a cream solder are mixed with an antioxidant containing a phenol skeleton having a tert-butyl group in the molecule to obtain a low solid content. However, it is intended to supply a soldering flux and a cream solder capable of preventing reoxidation of the substrate and components and solder during the flow and reflow.

During flow soldering and reflow soldering, as an antioxidant containing a phenol skeleton with a tert-butyl group in the molecule having a reoxidation-preventing effect,
2,6-di-tert-butyl-4-methylphenol, tert-butylhydroxyanisole, n-octadecyl-3- (3,5-di-tert-butyl-4-
Hydroxyphenyl) propionate, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-te)
rt-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 4 , 4'-thiobis (3-methyl-6-tert-
Butylphenol), 2- (2'-hydroxy-3 ',
5'-di-tert-butylphenol) benzotriazole, 2,4-di-tert-butylphenol-
3 ', 5'-di-tert-butyl-4-hydroxybenzoate, triethylene glycol bis [3- (3-
tert-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] and the like.

The antioxidant containing a phenol skeleton having a tert-butyl group in the molecule is contained in the flux for soldering and the flux for cream solder in an amount of 1 to 30% by weight.
Is added in the range of. 1% by weight
If the amount is 30% by weight or more, no significant effect can be expected and the cost becomes high.

Natural resins and synthetic resins such as rosin, which are added to the conventional high solid content type soldering flux and cream soldering flux, have only a slight reducing action and a coating effect, so that it is sufficient to reduce the addition amount. However, the antioxidant containing a phenol skeleton with a tert-butyl group in the molecule added in the present invention has not only a simple coating effect but also a positive antioxidant effect. Therefore, even if the addition amount is suppressed to a small amount, a sufficient reoxidation preventing action is exhibited, and therefore it can be applied to low solid content (low residue) type soldering flux and cream solder flux.

As other components, additives usually used in soldering flux, for example, activators such as amine hydrohalide, amine organic acid salt, natural and synthetic resins and isopropanol, ethanol, Solvents such as toluene are mentioned, and as the flux component for cream solder, the general activator, thixotropic agent such as castor wax, natural and synthetic resin, thickener and butyl carbitol, propylene glycol monophenyl ether, etc. Solvents may be mentioned. In addition, the solder powder added to the cream solder may be usual eutectic solder, bismuth-containing solder, silver-containing solder, or the like.

With the above composition, the oxygen content is 10,000
Supplying a low-residue type soldering flux and cream solder that can maintain sufficient solderability even in a flow solder and reflow furnace set to a relatively high oxygen concentration of about ppm to atmospheric (20.9%). You can The conventional low-residue type soldering flux and cream solder were not able to obtain sufficient solderability unless the oxygen concentration was as low as tens to thousands of ppm, but the present invention provided a relatively high oxygen concentration. However, since sufficient solderability can be obtained, the purge amount of the inert gas can be remarkably reduced, and the cost can be remarkably reduced.

The effects of the soldering flux and cream solder according to the present invention will be described below in more detail with reference to comparative examples and examples. The test methods and results are shown in Tables 1 and 2.

[0012]

[Table 1]

(Examples 1 and 2 and Comparative Examples 1 and 2) Table 1
Is the test result of the soldering flux. For solderability, the solder spread test described in JISZ-3197 6.10 was performed, and the solder spread was compared by the quality of the spread ratio.

The soldering flux of the present invention (Examples 1 and 2) has a relatively low oxygen concentration (500) as compared with the conventional type soldering flux (Comparative Examples 1 and 2).
(ppm) atmosphere, the solder spreading ratio is
2, 96%, 97%, Comparative Examples 1, 2 93%, 95
There is no big difference between the two, and the results are good. But,
In a relatively high oxygen concentration (50000 ppm) atmosphere, the soldering flux of the present invention (Examples 1 and 2)
93%, 94%, Comparative Examples 1 and 2 81%, 82%
As described above, the spreading flux of the soldering flux of the present invention is obviously better. In the atmosphere, Examples 1 and 2 are 90% and 91%, and Comparative Examples 1 and 2 are 69% and 7%.
The difference further widens to 1%, and the effect of adding an antioxidant containing a phenol skeleton with a tert-butyl group in the molecule is remarkably exhibited.

[0015]

[Table 2]

(Examples 3 and 4 and Comparative Examples 3 and 4) Table 2
Is the test result of cream solder. For solderability, a solder spread test described in JIS Z-3197 6.10 was performed, and the solder spread ratio was compared according to the quality.

Cream solder of the present invention (Examples 3 and 4)
In comparison with the conventional type cream solder (Comparative Examples 3 and 4), the solder spreading ratio is 92% in Examples 3 and 4 in an atmosphere having a relatively low oxygen concentration (500 ppm).
2%, and Comparative Examples 3 and 4 are 90% and 89%, which are not so different from each other, and good results are obtained. However, in an atmosphere having a relatively high oxygen concentration (50000 ppm), the cream solder of the present invention (Examples 3 and 4) had 89% and 87%, and the comparative examples 3 and 4 had 72% and 73%. The spread rate of the cream solder of the present invention is obviously better. In the atmosphere, Examples 3 and 4 were 85%, 86%, Comparative Example 3,
4 further spreads to 65% and 64%, and the effect of adding an antioxidant containing a phenol skeleton with a tert-butyl group in the molecule is remarkable. Moreover, in Examples 3 and 4, there is almost no residue as long as it is observed with the naked eye.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Matsumoto 7-21 Chikkohama Nishimachi, Sakai City, Osaka Prefecture Ishikawa Metal Co., Ltd. (72) Naoki Muraoka 7-21 Nishicho Chikamahama Nishimachi, Sakai City, Osaka Ishikawa Metal Co., Ltd. (72) Inventor Midori Nomura 7-21, Chikkohamaji Nishimachi, Sakai City, Osaka Prefecture Ishikawa Metal Co., Ltd.

Claims (2)

[Claims] 1. A soldering flux containing 1 to 30% by weight of one or more antioxidants containing one or more phenolic skeletons with a tert-butyl group in the molecule. .. 2. A cream solder containing the soldering flux according to claim 1 and a solder powder.