Through-hole plating

A process for the manufacture of a printed circuit board having a plurality of metal plated holes interconnecting at least two circuits comprising the steps of, in either order, forming holes in an epoxy printed circuit board material and forming the circuits and thereafter, metallizing the holes, said metallization comprising a pretreatment sequence between the steps of forming the holes and metal plating including the steps of contact of the holes with a first aqueous alkaline solution of an oxygenated epoxy solvent at a pH greater than 10 and at a temperature and for a time sufficient to soften the hole walls, contact with a second solution comprising an aqueous alkaline solution of permanganate ions maintained at an elevated temperature and a pH in excess of 13, and contact with a third solution of a reducing agent for permanganate ions at a temperature and for a time sufficient to remove any manganese residues remaining on the walls of the holes.