Abstract: A protective coating for an electronic assembly on a circuit board is made from a pre-fabricated, roll-flattened plastic ribbon having desired pre-determined thickness. From the ribbon, a suitably shaped membrane piece is produced, e.g., by stamping or by water-jet cutting, with openings as may be desired for circuit components to be left uncovered. The membrane is placed onto the circuit board, softened by heating, and pressed on by means of a silicone stamp, for close contact with electronic modules to be protected. The membrane is then adhered to the circuit board by further heating. The starting material for the membrane is a mixture of a thermoplastic material and of a wax including a significant amount of branched-chain and cycloaliphatic hydrocarbons.