SU1318374A1 - Flux for tinning and soldering with low-melting solders - Google Patents

Abstract

The invention relates to the field of soldering, in particular, to the composition of the flux for tinning and soldering by low-melting solders of electronic equipment units. The aim of the invention is to expand the temperature range of flux activity. The flux contains the following components, wt%: butyl polyphosphoric acid 10-45, glycerin 20-25, ethylene glycol - the rest. Butylpolyphosphoric acid starts deoxidizing the oxide film of the serviceable surface at a lower temperature of 180 C. As a result, the composition of the flux allows the temperature range of its activity to be extended to be within 180-300 ° C and to ensure high-quality tinning and brazing of nickel surfaces and silver-coated plastic fusible pastes. 1 tab. § CO 00 X) with

Description

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The invention relates to soldering, in particular to water washable fluxes for tinning and punks with low-melting solders for electronic equipment, including for tinning solders POIN-52.

The purpose of the invention is to expand the temperature range of the active flux.

The flux contains the following components, wt%:

Butyl polyphosphoric acid 10-45

Glycerin20-25

Ethylene glycol Else The use of butyl polyphosphoric acid allows the temperature range of flux activity to be expanded by increasing its fluxing activity and, as a result, optimizes the process of tinning and soldering POIN-52, PSrOSZ-58 with nickel surfaces and surfaces obtained by firing silver and palladium pastes in

ceramic substrate. t

Examples of flux performance and its properties are presented in the table.

The quality of the tinning is estimated by the area of the flow of weighed solder POIN-52, PSROSZ-58 on copper and nickel-plated substrates. The quality of the washing is determined by the change in the insulation resistance of the test boards in the initial state before the tinning, after the tinning and washing of the flux residues and keeping the moisture in the chamber for 1 hour.

In accordance with the requirements of GOST, in the case of complete washing of flux residues, the insulation resistance of the boards after exposure to moisture in the chamber for 1 hour must be at least 700 M ohms.

To ensure the quality of the tinning, the spreading area of 0.1 g of the solder must be at least 35 mm.

From the obtained results, it can be seen that the flux with the content of the active component from 10 to 15% provides a qualitative tinning of the surfaces obtained by firing silver and palladium pastes into the ceramic substrate by soldering the PSWOS-58, while the active component decreases to 8%; with a content of 18% - quality tinning.

Glycerin performs the role of a plasticizer in the composition of the flux, which gives it high fluidity in temperature

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the modes of tinning, soldering and thereby promotes better wetting by the flux of the trimmed surface and its rapid displacement by molten solder from the trimmed portion. 15% glycerol does not affect the tinning process. With the introduction of the. a flux of 20% glycerol, a decrease in areas of poor quality is observed

tinning Increasing the amount of glycerin leads to increased flux smoking, which is undesirable and does not affect the improvement of its fluxing properties.

At the same time, the flux with the content of the active component in the range of 10–15% does not contribute to the creation of a process of qualitative tinning of nickel surfaces with POIN-52 solder.

Qualitative tinning is provided with a content of butyl polyphosphoric acids in the range of 40–45%. A higher concentration does not contribute to the process of improving the quality of tinning,

therefore, an increase in the concentration of the active component above the upper boundary limit is not advisable. Thus, the flux provides high-quality tinning, soldering, in addition to

Commonly used copper, silver, tin-lead and others, as well as nickel surfaces and leading silver-palladium pastes with low-melting solders, including PS, OSZ-58, POIN-52 solders. Leftovers

The flux is washed with water at 60 ° C for 2 minutes, followed by rinsing in distilled water.

Butylpolyphosphoric acid starts deoxidizing the oxide film of the surface to be laid at a lower temperature (180 ° C), which means that optimization of the tinning process is possible

It is at this temperature, and not at 220 ° C, as in the case of applying the known composition. This phenomenon is due to the fact that the hydrocarbon radical in butyl polyphosphoric acid

much shorter and contains only 4 hydrocarbon groups, and not 10-13, as in the triethanolamine salt of dialkyl-polyphosphoric acids. The migration of electrons from the outer shell of the phosphorus atom is much slower and the ability of the phosphorus radical to oxidize oxides increases significantly and begins to appear at lower temperatures.

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As a result, the composition of the flux allows to expand the temperature range of its activity in the range of 180-300 ° C and thereby ensure the quality of the tinning of nickel and other surfaces with solder PSROSZ-58, POIN-52.

Claims (1)

Invention Formula A flux for tinning and brazing with low-melting solders, containing the active component, glycerin and a solvent, characterized in that, in order to extend the temperature range of the flux activity, it is 15 20 2: 25 27 20 20 20 20 20 10 12 15 " 18 38 40 42 45 48 77 30 36 60 55 i2 40 38 35 32 ten . About About About About Ltd oh oh 318374. four  as an active component, butyl polyphosphoric acid of formula ABOUT RO-P-0-P-OR | I OH he where R is a hydrocarbon radical with chain length C, and ethylene glycol as a solvent, in the following ratio of components, wt.%: Butyl polyphosphoric acid 10-45 Glycerin20-25 This glycol Rest 45 56 56 56 56 60 YO 60 60 60 40 40 40 40 40 40 60 60 60 60 28 28 30 30 30 36 40 40 40 40 1000 1000 1000 1000 1000 1000 1000 1000 1000 1000