Abstract

A simple method has been developed to synthesize Cu/Pd nanoparticles in aqueous solution in ambient condition with the addition of complexing agent, trisodium citrate. UV–vis spectra confirmed the complexing behavior of trisodium citrate and metal ions. The particles synthesized with trisodium citrate were well dispersed with particle size ranging between 3–4 nm while the particles without trisodium citrate were larger and aggregated, as demonstrated by transmission electron microscopy (TEM). X-ray diffraction patterns (XRD) indicated the formation of bimetallic nanoparticles without impurities in the complexing agent-supplemented system. In contrast, large amounts of PdO and Cu(OH)₂ were precipitated along with the formation of particles in the complexing agent-free system. X-ray photoelectron spectroscopy (XPS) revealed small amounts of oxidized Pd on the surface of particles and the existence of zerovalent Cu and oxidized Cu in particles with trisodium citrate. With a simpler process for electroless copper deposition, the Cu/Pd nanoparticle activator with less Pd metal used exhibited comparable catalytic activity to conventional Pd/Sn colloidal activator. In summary, application of Cu/Pd nanoparticles synthesized with the complexing agent as an activator suggested a novel, simpler and inexpensive process in PCB industry.

Graphical abstract

The Cu/Pd nanoparticles synthesized with complexing agent can be applied as an activator for electroless copper deposition in PCB industry.

Full-size image (28K)

Keywords: PVP; Cu/Pd nanoparticles; Electroless deposition; Catalyst; Activator

Article Outline

1. Introduction

2. Materials and methods

2.1. Preparation of nanoparticles

2.2. Characterization

2.3. Electroless copper deposition and determination of catalytic ability

3. Results and discussion

3.1. Confirmation of complexation induced by trisodium citrate

3.2. Preparation and characterization of the Cu/Pd nanoparticles

3.3. Catalytic activity of Cu/Pd nanoparticles for electroless copper deposition

4. Conclusion

Acknowledgements

References