Selective electroless metallization of non-conductive substrates enabled by a Fe3O4/Ag catalyst and a gradient magnetic field

The formation of printed circuit patterns on non-conductive substrates has many applications in high value sectors such as electronics manufacturing. Current semi-additive and subtractive circuit manufacturing processes use photolithography to pattern substrates coated with a thin or relatively thick metal film. This process is often wasteful and expensive. Using an innovative approach; composite Fe3O4-Ag nanoparticles were synthesized and attracted to a magnetic field. The nanoparticles catalysed electroless copper deposition. Such a catalyst is new to electroless plating and was deposited selectively on a dielectric substrate using a gradient magnetic field. In this way, subsequent electroless copper plating occurred exclusively where the magnetic field was applied, whilst the remaining surface was free of deposited metal. The advantage of this additive method of manufacture is that less material is needed and less waste is produced.