Streamlining conductive film deposition
A simple electroless process for preparing nickel-phosphorus (Ni- P) film on wood veneers for electrical conductivity is being explored by Chinese researchers.
The streamlined plating process for electromagnetic shielding of the wood involves electroless deposition in a plating bath and eliminates the costly use of palladium.
Dr Lijuan Wang, at the Northeast Forestry University in China, who initiated the research, explains, ‘The benefits of electroless nickel plating for wood veneers is that it can obtain uniform and compact metal coating without electrical energy. The traditional process [ for Ni-P film plating] requires five steps with palladium colloid activation, which is expensive. This may eliminate traditional processes’.
So far, trials of the new Ni-P film deposition technique have been conducted on birch veneer. The plated specimens have been observed by scanning electron microscopy and the film has been shown to be ‘compact and continuous’. It is also crystalline and contains 3.32wt% phosphorus and 96.68wt% nickel.
Wang remarks, ‘It was found that the birch veneer plated with crystalline Ni-P coating has better electrical conductivity and electromagnetic shielding performance’. Yet she is keen to point out the research’s main benefits lie in the simplified method. She adds, ‘Veneers plated with the crystalline Ni–P coating have good electrical conductivity, with a surface resistivity less than 200 mΩ/cm2 and a firm adhesion of the Ni–P coating to the wood’.
The group also claims the process is suitable for most kinds of wood with good surface wettability. Furthermore, Wang argues the technique is cost effective and less energy intensive, as the pre-treatment is carried out at room temperature, and energy is consumed in heating the plating solution.
However, consultant Dr Chris Bocking, of Surface Technology Support, UK, says, ‘The uniformity is correct, but instead of [using] electrical energy to create the coating, it uses chemical energy. The cost of this process is about 15 times that of conventional nickel plating.’
The research is currently at laboratory scale and the technique is undergoing patent.