SOLUTION AND METHOD FOR CURRENTLESS DEPOSITION OF GOLD COATING

摘要

Various methods exist for currentless deposition of gold coating on metal surfaces. In one method, the coating can be deposited on a base metal by means of cementing charge exchange. In other methods, the depositing solutions can additionally contain a reducing agent such that a gold coating can also be deposited on a precious metal e.g. gold. Known solutions, however, have a disadvantage in that the depositing rate is very slow when the pH value of the solution is between 6 and 7 and when the temperature is adjusted below 50 DEG C. However, such coating conditions are not suitable for processing, for example, alkali-soluble resistant conducting plates. To this end, a depositing bath is provided. According to the invention, said bath contains: a) at least one gold (I) compound, b) at least one reducing agent for the gold (I) compounds, and c) at least one solvent. d1) The gold (I) compound contains a complexity of gold (I) ions with a compound comprised of the amino acids group and the salts thereof, said compound having a formation constant of at least 10<10> for the complexation of gold (I) ions. d2) The solution additionally contains at least one compound comprised of the amino acids group or the salts thereof, said compound having a formation constant of at least 10<10> for the complexation of gold (I) ions.