Electroless copper plating on Fraxinus mandshurica veneer using glyoxylic acid as reducing agent

Abstract

Copper coating was deposited on Fraxinus mandshurica veneers for preparing EMI shielding composite by electroless plating using glyoxylic acid as reducing agent in the solution. XPS and SEM were used to analyze the activation process. It was found that a continuous chitosan membrane was loaded on the wood surface. XPS results showed that Pd(II) ions were chemically adsorbed on a chitosan membrane on the wood surface through an N-Pd σ coordination bond. After reduction, part of Pd(II) absorbed formed very little Pd(0) particles on the chitosantreated wood surface. The activated wood veneers were immersed into a plating bath in which copper film was successfully initiated. The coatings were characterized by SEM-EDS, XPS, and XRD. The metal deposition, surface resistivity, and electromagnetic shielding effectiveness were measured. The morphology of the coating was uniform, compact, and continuous. The wood grains were preserved on the plated wood veneer, which had a copper-like color and sheen. EDS, XPS, and XRD results indicated that the coating consisted of Cu 0 with crystalline structure. The surface resistivity and copper deposition reached 175.14 mΩ·cm- -2 and 21.66 g/m 2 when the veneer was pretreated with 0.8 % chitosan for 8 min and plated for 30 min at 55 oC. The plated veneers exhibited good electromagnetic shielding effectiveness of over 60 dB in frequency ranging from10 MHz to 1.5 GHz.