ABSTRACT
Electroless copper deposition is a key technology for fabricating of printed circuits. However, there is always concern regarding its bath control and the toxicity of the chemicals involved. So several processes have been developed as possible substitutes. They are usually referred to as “direct metallization” or “direct plating” since the nonconductive substrate can be copper electroplated directly after certain activation step without the need for a conductive electroless copper film. These processes can be classified into three groups. The first kind is based on the application of a conductive polymer film, whereby subsequent electrodeposition can be effected. The second kind uses colloidal dispersion of carbon instead. The underlying principle is similar since the carbon colloid can also form a conductive film on the nonconductor surface. Since the conductivity of the surface can be increased from another source, electroless copper can consequently be eliminated.
