SU1551503A1 - Flux for low-temperature soldering - Google Patents

Abstract

The invention relates to soldered production, in particular, to the composition of the flux for low-temperature soldering of mounted components of printed wiring. The purpose of the invention is to improve the quality of soldering and washing of flux residues. The flux contains as an active component a complexone selected from the group: iminodacidic acid, N ₁ , N-bis (hydroxyethyl) aspartic acid, N-hydroxyethylglutamic acid, ethylenediamine-N ₁ N-dictic acid. The ratio of flux components, wt.%: Complexone 5-15, an organic solvent - the rest. The flux may contain a surfactant in an amount of 0.1-10.0% to increase its wetting ability. Good fluxing activity of the flux is provided in the absence of the corrosive effect of both the flux itself and its residues after soldering. 1 hp f-ly, 3 tab.

Description

The invention relates to soldering, in particular to fluxes for low-temperature soldering of mounted elements of printed wiring.

The purpose of the invention is to improve the quality of soldering and washing of flux residues.

The flux contains as an active component a complex selected from the group:

iminodi succinic acid, N, N-6nc (hydroxyethyl) aspartic acid, N-hydroxyethylglutamic acid, N-hydroxyethylamine dicodic acid, ethylene-di-M-M, H-di-succinic acid, and as a solvent - a mixture of ethanol with glycerol or ethylene glycol.

Flux contains components in the following ratio, wt.%:

Complexes 5-15

Organic Solvent Remaining Flux Additionally, the flux may contain a surfactant in an amount of 0.1-1.00% to determine the wetting ability of the flux.

Use as an active component of chelating agents -. derivatives of dicarboxylic acids, allows to obtain a non-corrosive flux, which possesses high fluxing activity and allows to obtain brilliant solder compounds, since the complexons interact only with metal ions, and not with metals at zero oxidation state.

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According to thermogravimetric studies, complexones (derivatives of dicarboxylic acids) are resistant to temperatures of 200-260CDC. Its amount of 5-15 wt.% Is sufficient for obtaining high-quality soldering. An increase in the activator above 15 wt.% Does not lead to a further increase in activity; however, itco alone makes it difficult to remove the flux residues after soldering. Flux thinner slupit mixture of ethanol with glycerin or ftileglycol. Glycerol and ethylene glycol dissolve the complexones and at the same time serve as thickeners, reducing the required viscosity of the flux.

Anionic surfactants, such as DNS-AZ, ijibix cation surfactants, such as katamin AB, leveler A, as well as high-molecular surfactants, such as polyethylene glycol ShEG-300, PEG-400, can be used as a substance that increases the “wettability”. These substances are combined with the components of the flux, which is a clear solution, which is not practical for other classes of surfactants, for example, non-ionic. They provide wettability of printed glass boards made of fiberglass, protective masks SPFZ and EP - 379. Their number is 0.1-1.00% enough to charge a uniform film of flux on the printed circuit board.

The preparation of the flux is carried out as follows.

A certain amount of complexones is mixed with glycerol and the mixture is stirred to 150-100 ° C for 3-4 hours to obtain a true solution, then the solution is cooled and ethyl alcohol is added to it. Under these conditions of dissolution, the partially substituted esters of polyamino polycarboxylic acids with glycerin are formed, which significantly affects the solubility in polyhydric alcohols.

A surfactant may be added with the solvent after cooling.

Examples of the flux are presented in table. 1 and 2,

The finished flux is tested in techno-logical soldering and washing processes in order to determine the quality of soldering.

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and cleanliness washes. Qualitative indicators are determined visually by the presence of icicles, fistulas, non-solders, shine of solder. The purity of washing is judged by the value of insulation resistance of dielectrics – printed circuit boards after exposure to a hygrostat (YQTH 9.8 ± 2%, t 20 ± 5 ° C) for 1 hour.

The results of the flux test are presented in table. 3

The flux of example 10 has insufficient activity, which leads to unsatisfactory soldering quality. The quality of soldering with flux in example 11 is similar to the quality of soldering with flux in example 9.

A further increase in the content of the activator in the flux does not lead to an increase in its activity, therefore it should be limited to 15 wt.%. The test results of the fluxes in examples 10 and 11 show that the limits of variation of the components of the fluxes are selected correctly.

The proposed flux for soldering has a combination of such characteristics as sufficient fluxing activity in the absence of the corrosive effect of both the flux itself and its residues after soldering,

Claims (1)

Invention Formula 1, Flux for low-temperature soldering of hinged printed circuit board components containing an active component and an organic solvent, characterized in that in order to improve the quality of soldering and washing of flux residues, it contains as its active component a complex selected from the imino-di-succinic acid group, K, M-bis (hydroxyethyl) aspartic acid, M-hydroxyethylimine succinic acid, ethylenediamine N N-di-succinic acid, K-hydroxyethylglutamic acid, in the following ratio, wt.%: Complex 5-15 Organic solventErest 2, the flux according to claim 1, distinguishing toot and also in that it additionally contains a surfactant in an amount of 0.1-10%. Table 1 one 2 3 4 5 6 7 8 7 5 Table 2 1 Continuation of table 2 25 25 22 25 31 25 31 20 63 63 63 55 59 63 59 55 Soldering quality Good Same m .- P . it Unsatisfactory Good Table3 Isolation resistance of the printed circuit board after soldering and washing and 1 hour of exposure in a hygrostat, Ohm 1010 10 10yu 10 h 8-Ю7 9 5 9-Ю9 U1 10 W 5-1 (G 3-Yu9