In prodn. of a PCB, comprising: (1) cleaning by: (1a) opt. treating with organic solvent; (1b) treating in alkaline permanganate soln.; (1c) reducing permanganate; and (2) metallising walls of holes by; (2a) conditioning walls, (2b) etching Cu surfaces, (2c) treating precatalytically, (2d) treating catalytically, (2e) metallising by nongalvanic deposition of Cu, (1c), (2a) and (2b) are carried out in one operation. Pref. (ia) solvent is N-methyl-2-pyrrolidone, dimethylformamide, or aq. alkaline soln. of propylene glycol or dipropylene glycol mono-Me ethers. (1b) Soln. contains NaMnO4 or KMnO4, partic. 150-250 g/l KMnO4 and 15-30 g/l NaOH or 40-80 g/l KMnO4 and 30-50 g/l NaOH. (1c) Permanganate is reduced by H2O2 in acid medium, H2O2 also oxidising Cu surfaces. (2a) Walls are conditioned by water-sol. (I). (2c) Walls are treated with soln. contg. 200 g/l NaCl and 20 ml/l 37 % HCl or contg. 300 ml/l 37 % HCl. (2d) Catalyst is acid soln. contg. 0.05-0.20 g/l Pd and 5-20 g Sn chloride; alkaline soln. contg. ionic Pd; or soln. based on Cu, Cu, and Pd, or noble metal, partic. Pt. Au, or Ag.
