Sustainable technologies for the regeneration of acidic tin stripping solutions used in PCB fabrication

摘要

Electroplated tin deposits are used as etch resists during the processing of Printed Circuit Boards (PCB). The tin coating protects the copper tracks during etching but is subsequently removed (stripped), to expose the defined copper circuitry. The commonly used stripping solutions are based on nitric acid and after use they represent a very acidic waste product with a high metal content. The disposal of these spent strippers is typically via offsite neutralisation and precipitation followed by subsequent landfill. This is clearly a non-sustainable waste of valuable resources and a practice that is increasingly undesirable as environmental legislation becomes more stringent.