Surface treatment of PA6 and ABS with oxygen plasma for molded interconnect devices

Polymer materials are widely used in electronic packaging. Especially adhesion properties are of interest for the bonding polymer-metal and their peel strength. The adhesion of copper on polymer substrates is more and more importance. A lot of polymer materials have low energy surfaces whereas metals have high energy surfaces. In order to reach adhesion between these two kinds of materials, polar groups must be produced at the low-energy surface. By plasma treatment with different gases or gas mixtures, for example CO₂, Ar, N₂ or Ar+O₂, polar groups can be produced on the polymer surfaces. The oxygen plasma or the plasma with oxygen containing gas mixtures represents the standard plasma for the treatment of polymer surfaces. It is well known that the oxygen plasma can react with most polymer materials and can produce a multiplicity of oxygen containing functional groups on the polymer surface. Such functional groups are for example C-O, C=O, O-C=O and C-OH. The increase of polar groups can be proven on the polymer surface by using XPS measurement. This paper gives an overview of the principles of plasma treatment and of the results by XPS measurements of plasma treated polymers.