1,181,422. Soldering. LEAR SIEGLER Inc. 30 Jan., 1967 [25 Feb., 1966], No. 36210/69. Divided out of 1,181,421. Heading B3R. [Also in Divisions C7 and H1] A firmly-adhering layer of solder is produced on a metal substrate, e.g. a coating of solder on a copper conductor of a printed circuit board, by forming a layer of solder thereon and spraying it with a liquid not miscible with the alloy when the alloy is molten, at a temperature above the melting point of the alloy, so that a layer intermediate in composition forms at the junction of the metal substrate and solder layer, and bonds them together. The initial solder layer may be deposited by electro-plating or by hot dipping.