An ecofriendly electroless copper plating process

Abstract

The conventional electroless copper plating process poses environmental problems owing to toxicity and the resultant health hazards of formaldehyde. An alternative process employing sodium hypophosphite as a reducing agent and Ni++ ions as a mediator was reported in 1980s. However, there are no reports on commercial application of this process. Thereafter in 1990, a direct metallization system (DMS), which replaces electroless copper thereby eliminating the use of formaldehyde, was developed for PCB industry. This process also has limited uses. An attempt has been made to deposit electroless copper from a bath containing sodium hypophosphite and cobalt ions as a mediator. The properties of copper coatings obtained from this bath are compared with those of formaldehyde-reduced bath for electronic applications.