Characterization of adhesion of copper to poly(tetrafluoroethylene)

• Published in: Journal of materials science letters Vol. 18; no. 15; pp. 1205 - 1208
• Main Authors: SONWANE, C. G, BHATGADDE, L. G, BELLARE, J. R, LI, Q
• Format: Journal Article
• Language: English
• Published: Dordrecht Kluwer Academic Publishers 01-08-1999
• Subjects: Applied sciences; Coating, metallization, dyeing; Exact sciences and technology; Machinery and processing; Plastics; Polymer industry, paints, wood; Technology of polymers; Adhesivity; Tetrafluoroethylene polymer; Metallizing; Chemical etching; Experimental study; Coated material; Surface treatment; Deposition process; Morphology; Surface properties; Sensitization; Pretreatment; Copper; Electroless plating; Surface grinding
• ISSN: 0261-8028
• DOI: 10.1023/A:1006646117539

A process for depositing adherent copper coating on PTFE by making use of mechanical roughening, etching, sensitization, activation, electroless plating, annealing and electroplating is explained. The SEM, XRD, SRM, ICPT, ASM studies during different stages of processing revealed that (1) Mechanical roughening removes low molecular weight compounds thereby exposing the true surface of PTFE. (2) Etching with sodium naphthalene selectivity defluorinates the surface producing the required roughness. (3) After activation, both Sn and Pd oxychlorides along with Pd-Sn and Pd-Sn sub 3 colloids are present over the surface. (4) Development of Cu coating occurs via nucleation, growth of nuclei, coalescence of nuclei to form islands and coalescence of islands to form crystallites. (5) The as-deposited Cu had fcc structure. Traces of Cu sub 2 O suggest that the deposition takes place via formation of an intermediate Cu sub 2 O phase. (6) After annealing at 393K, the coating had a distinct columnar dendritic structure. The XRD peak broadening is attributed to non-unfiorm strains induced by reduction in free volume. The increased penetration of Cu at this temperature explains the increase in adhesion after annealing and (7) after electroplating to 20 mu m, both Cu(111) and Cu(200) phases were present in equal concentration.