A Study On The Technology Of Electroless Copper Plating Of Wood With Sodium Hypophosphite As Reductant

In this study, Sodium Hypophosphite as a reducing agent instead of formaldehyde, nantokite as activating solution of the activation process to replace the traditional activation process of the precious metal palladium, the Cu2 + and Ni2 + as a catalyst for electroless copper plating timber. After a great deal of experimental research, an optimal activation process of electroless copper plating and sodium hypophosphite as a reducing agent in place of formaldehyde was adopted. It will be a great significance for the chemical copper plating field as well as the development of electromagnetic shielding, anti-static, surface decoration and other new types of functional wood-composite materials. Research results are summed up as follows:1. It placed a premium on the electroless copper plating reactivity on wood surface successfully, using the room temperature copper-activated method. The proper activation process parameter as follows: the copper sulfate hexhydrate concentration 15g/L, Hydrochloric acid concentration 10g/L,the Sodium borohydride concentration 10 g/L, the Sodium hydroxide concentration 10g/L, the activation time in A solution 10 min, the activation time in B solution 5 min.2. The electroless copper plating process using hypophosphite as reducing agent was investigated by orthogonal test. According to influencing sequence, the factors affecting the surface resistance and deposition rate are as followed: the concentration of nickel sulphate>pH value> the concentration of citrate > the concentration of hypophosphite >temperature. The perfect basic process of electroless copper plating is 10 g/L CuSO4, 1.75～2.00 g/L NiSO4, 40～45 g/L NaH2PO2, 25～30 g/L Na3C6H5O7, 30 g/L H3BO3, pH 8.5, 65～70℃and 10～15 min.3. The deposition rate of electroless copper plating at different concentration of Ni2+, NaH2PO2, Na3C6H5O7, pH and temperature respectively, were measured when maintaining other factors as constant. With the increasing about the concentration of nickel sulfate, the concentration of sodium hypophosphite, pH value and temperature, the rate of copper plating deposition increased continuously; and with the increasing of the concentration of sodium citrate, the rate of copper plating deposition is also decreased.4. The surface tension of coating was reduced when adding 40 mg/L polyethylene glycol (PEG) to the electroless copper plating, it is beneficial to H2 emission, in order to eliminate gas traces of the surface coating. However, the deposition rate increased obviously and the copper deposits became loose and porous, which resulting the surface resistance of copper-coated fabrics was raised; The deposition rate on the wood decreased from 7.59 to 4 g/ (m2·min) when adding 5 mg/L K4Fe(CN)6 to the electroless copper plating. The copper deposit became compact and the color turned to copper-bright from dark red or brownish black at the presence of 5 mg/L K4Fe(CN)6.