SU724606A1 - Silver plating electrolyte - Google Patents

Description

The invention relates to electroplating, in particular, to electrolytic deposition of silver on copper products and its alloys (brass bronze). A silver electrolyte is known that contains silver and potassium iodides and glycerin. The electrolyte also contains desirable tin and water as a solvent ij. The main obstacle for industrial use of the known electrolyte is the adsorption of iodine by silver precipitation, which degrades their quality: it increases the transient resistance (Oh, OOO815 Ohm), impairs the capacity (coefficient spreadability Cr) and gives yellowness. In the ard solutions of iodides, complex silver salts are stable only in concentrated solutions. However, aqueous concentrated solutions of iodides are susceptible to decomposition of air by oxygen with the formation of the complex anion Jj, due to which large amounts of iodine accumulate in electrolytes, which is adsorbed by silver precipitates. As the electrolyte accumulates, the dissolved iodine begins to recover on the cathode, as a result of which the cathodic output decreases to the current. A mismatch between the cathode and anode current outputs leads to an increased consumption of silver anodes, as well as to a violation of the electrolyte composition. The purpose of the invention is to improve the packet filtering path and reduce their transient resistance. The goal is achieved by the fact that the electrolyte additionally contains potassium bromide in the following ratio of components: silver iodide, g25-80 potassium iodide, g15O-ZOO potassium bromide, g12-40 Glycerol, dDo 1 Using glycerol as a solvent and introducing bromine drip leads to the formation of mixed bromoiodide complex silver ions in

glydergual solution, characterized by increased stability, by contrast with homogeneous iodide complex ions in aqueous solutions. In the proposed

Lectra Olte; C cpaiBHeHiBO with Known, decreases the activity of iodide ions, which makes it resistant to CMM: reducing the iodine and thus eliminating the adsorption of iodide by silver precipitates, which results in bright silver precipitation, reducing transient resistance and improving heat absorption.

In addition, in the proposed electropower when electroplating silver is additional, compared with the known electrolyte, energy difficulties in discharging the complex ions of the server, which contributes to the deposition of more small electrons, as a result coatings of iOfeHncTbix electrolytes, and in terms of their length: properties, such as transient resistance and absorption, are superior to them.

When choosing the composition of the electrolyte is necessary and MO; so that the ratio of tapogides of potassium to silver iodide is: 1 for bromide, not less than 5 for iodide to form stable

complex ions cepeiSpa, along the way. fine crystalline precipitation and stable operation of the bath. The molar ratio of potassium iodide to silver iodide is supported by

WnMlTClTTB npieflenax 5- @.

Electricity is prepared in the following way. .

Glycerin is heated to 6 ° -10 ° C, bromide and potassium iodide are dissolved in it, then silver iodine is added. Dissolving the salts with stirring, KopifeK-rigx) -i Vanyo sobyva electrolyte wire rfOi

according to the analysis,,.;

The dispersing capacity of the electrolyte is 41-53%. The deposition process is carried out at 60-100 O, the current density of 0.1-0.3 A / dm using silver anodes, -.

Cathodic to anodic outputs The current is close to 100% and does not change during electrolysis, which. provides a high, stable operation of the bath. The electrolyte is characterized by high stability and stability. In operation, it is possible to obtain light crystalline silver deposits directly on copper and its alloys. At the same time, the lifetime of the CoJOTfleT electrolyte is at least two years and is determined by the accumulation of copper, tin and zinc ions, the permissible concentrations of which are, g / l: 1.0, 0.3 0.4 °. The electrolyte regeneration is performed at High Density. by direct current using a random cathode, the Electrolyte is non-toxic, due to the absence of professionally harmful exposures, there is no need for an on-board fan bath,

The permissible water content in the electrolyte is ke more than 50 g / l, and an excess amount of water is easily removed when the electrolyte is heated.

From the proposed electrolyte, good adherence to the substrate is observed (no swelling and exfoliation is observed) with 15-30 µm togacine, practically porous, corrosion-resistant, the resistance is 0, OOP583-0 000726 Ohm, darkening resistance is 1 point -yt system OST 4GO, 054.076),

The invention can be illustrated by several examples presented in the table.

T about. about l and c

Table continuation

Glycerin, l Deposition mode Temperature, C80 Current density,, 2 Diffusing power,% 53 Current output,% 100 Coating thickness mkm15 Transient resistance. Om0,000588 O, Ltd. Experimental data Ratio capacity 1% coefficient of spreading by OSTN GO 033 000 / at three measuring points, Cr 71 0, O00583 O, O00578 0,00057 5

Claims (1)

SUMMARY OF THE INVENTION A silver electrolyte containing silver and potassium iodides and glycerin, characterized in that, in order to improve the solderability of the coatings and reduce their transient resistance, it additionally contains potassium bromide in the following ratio of components: 25-80 150-300. 12-40 to 1.