The Research On Non-cyanide Chemical Deposition Of Gold

Nowadays chemical deposition of gold is widely used in the field of microelectronics, and it is the key procedure to plate gold in the PCB industry,because of its high reliability, high electrical conductivity,good solderability and high corrosion resistance.Up to now chemical deposition of gold is from Potassium dicyanoaurate in our country,But the cyanide is very poisonous and dangerous in the producing process and the disposal process of waste water and waste gas.With more attention about environmental protection, to find a process of non-cyanide chemical deposition gold become a way to develop the techniques of chemical deposition gold.The target of this paper is to study a new non-cyanide gold plating composition,and use it in the chemical deposition of gold in the PCB industry. The non-cyanide gold plating solution is characterized by containing chloroauric acid and organic amine as the main ingredients in this paper.Electrochemical method, ultraviolet visible spectrum, solution analysis,coating thickness test, coating binding force test were used to get the optimum composition and operating conditions.In addition, EIA(Environmental Impact Assessment) is compared for this process and the traditional way from the safety in production and environmental protection point.The optimum compositions and operating parameters have been obtained after massive experiments,there are:The gold salt (content of gold) concentration 1g/L,organic amine concentration 0.2 mol/L,citric acid 5 g/L,the operating temperature is 50～60℃,solution pH is 9～10,timing control in 5-10 min;Its found that this chemical deposition is stable under the operating condition,and the binding force,luster,stability can achieve the PCB professional specification.It can be concluded this techniques can meet the standard of chemical deposition of gold in the existing PCB production and will benefit the society by safe operation and less harm to the environment.