Abstract: The invention provides a process for electroless plating tin, lead or tin-lead alloy on copper or copper alloy using an electroless plating bath containing a water soluble tin and/or lead salt, an acid capable of dissolving the salts, and a complexing agent. The tin and/or lead content in the bath is maintained high enough to chemically deposit thick films by replenishing the tin and/or lead salt in proportion to an increase in concentration of copper ion dissolving out in the bath. Also provided is an electroless tin, lead or tin-lead alloy plating process in which a water soluble copper salt is added to a fresh bath.

Abstract: For replenishing a metal ion to a plating bath, a soluble electrode of the same type of metal as in the bath and a counter electrode of a metal material having a nobler standard electrode potential than the soluble electrode are immersed in the bath. Electricity is conducted between the soluble electrode and the counter electrode, thereby dissolving the soluble electrode to replenish an ion of the metal of the soluble electrode to the bath. The potential of the counter electrode is measured using a reference electrode of the same metal as the soluble electrode. The quantity of electricity is controlled such that the measured potential may not be negative with respect to the reference electrode, thereby preventing deposition of the dissolving metal ion on the counter electrode while ensuring a high rate of metal ion dissolution.

Abstract: A gold plating bath having potassium aurous cyanide and thiourea complexing agent dissolved in water and adjusted to an acidity of pH 3 or lower can be used as either electroplating or electroless plating bath. Bright gold electroplating is possible when a brightener is added to the bath. Electroless plating is possible when a reducing agent, typically sodium hypophosphite is added to the bath.

Abstract: An amine, such as a triethanol amine or ethylenediamine is added to an alkaline electroless gold plating solution comprising a gold salt and a boron-based reducing agent to deposit a gold film having good appearance and high throwing power on a workpiece at a high deposition rate.