Traditionally, copper additives are broken into three fairly distinct groups:1
• Carriers (suppressors)
• Brighteners
• Levelers
While many chemical groups can be used, the art has generally evolved into carrier species that are polyglycols.1 Carriers form a film on the cathode and increase the potential necessary for deposition. In simple terms, this film suppresses the plating rate and is the reason carriers are also referred to as suppressors.