Electroless Copper Plating On The Surface Of Asphaltene - Based Foam

Because of narrow aperture and deep hole, It has been an urgent and tough problem to coat copper on the inner surface of bulk carbon foam. Research a new electroless copper deposition processing or plating solution was the key, while electrochemical analysis was in need.The effect of electroless copper plating on mesophase pitch-based carbon foam was investigated. The optimal plating solution composition and process conditions was tested on graphite plate, the coated carbon foam was characterized by SEM, universal testing machine, four-probe conductivity, XRD, electrochemical workstation.The copper coating’s uniformity was improved by forcing plating solution inside the carbon foam on basis of vacuum and ultrasonic assistance during eletroless plating process. And the effect of the flow pattern on plated copper’s properties was investigated. Compared with one-direction flow of plating solution, a bidirectional flow made the weight gain rate of single cut piece>7.10% and the total increased weight of 7.68%. The copper coating with better uniformity was compact and smooth, having thickness>5μm;and no impurity was produced. The mechanical and electrical properties of Cu/carbon foam were evenly enhanced. The compression strength was increased from 0.70MPa to 1.54MPa, and the conductivity was increased from 700S/cm to 1724S/cm.Electrochemical analysis of electroless copper plating with methanal as reducing agent, and by using cyclic voltammetry and polarization curve method, the effect of methanal, copper sulfate, EDTA-2Na, potassium sodium tartrate,2,2’-dipyridyl, pH on anodic oxidation, cathodic reduction and redox reaction was investigated. The compositions and operation of the methanal solution gained by the electrochemical behavior were basically identical with previous conclusion.In order to achieve electroless copper plating under low pH, and meet environmental requirements, the toxic methanal was replaced by sodium hypophosphite as reducing agent. The compositions and operation were:copper sulfate 9g/L, nickel sulfate 0.8g/L, sodium hypophosphite 30g/L, sodium citrate 20g/L, potassium ferrocyanide 3mg/L, boric acid 30g/L, pH 9,75℃.Electrochemical analysis of electroless copper plating with sodium hypophosphite as reducing agent was investigated and the electrochemical study results were basically identical with previous conclusion.