On Chemical Deposition Techniques Of Silver And Silver-tungsten

Nowadays immersion silver has received a great deal of interest inmicroelectronics. And the use of Immersion Silver has been one of the key tasks. Theobjective of this paper is to obtain the fine structure silver and silver-tungsten coatings bythe way of chemical depositing on copper substrates.The copper substrates used in experimentwere pretreated to produce catalytic activity before the chemical silver deposition. And thendepositing was carried out at middle temperature/ low temperature and ultrasonic radiation. Themorphology of coatings was observed by using SEM; TEM was used to examine the coatings; XRDwas used to analyze the phases of the coatings. It was found that before the plating, there is section time to gestating, that we callthe "gestating time". The pretreatment is the vital to the chemical deposition. Thedepositing rate was increased when the pH, the temperature of the bath were increasedand the ultrasonic radiation introduced. It was also increased by increasing theconcentration of silver nitrade, but decreased by increasing the concentration ofEDTA-2Na and ammonia liquor. The X-ray analysis showed that EDTA-2Na andammonia liquor can effectively decrease the content of the silver oxidation in thecomposite material. That is important factor to get better structure coatings. Theobservation by SEM indicated that the size of grains coated at room temperature inchemical silver depositing bath was about 80nm and in chemical silver-tungstendepositing bath was about 50nm. The X-ray analysis showed that the coatings was silver.The EDS analysis showed that tungsten and oxygen formatted WO3. And TEM alsofound WO3. Bockris equation is applied to the reaction of chemical silver deposition.Thermodynamics functions ?Gθdep,?Hθdep,?Sdep are obtained by surveying the weight θfor deposition in unit time and on unit area. In addition, the effect of each factor onchemical silver deposition is given through experiments. From these, the kineticparameters are obtained, experimental equation of deposition rate is presented.[Ag+] ≤0.055mol/L v = 6.5888×10?4[Ag+]0.5732[L1]?0.97153[L2]?1.49722[H+]?0.3218exp[298 (T Ea ?298)] R T [Ag+] >.055mol/L v = 6.343×10?6[Ag+]?0.98163[L1]?0.97153[L2]?1.49722[H+]?0.3218exp[298 (T Ea ?298)] R T...