The difference between electroless and immersion is in the chemistry and what drives the reduction of palladium in solution to pure metal. Electroless solutions contain reducing chemicals that cause the palladium to go from an oxidized state to elemental (zero). If you keep adding ionic palladium and more reducing agent, the reaction will keep on going, and going, etc. Immersion reactions dissolve some of the metal being plated to drive the reduction reaction of the palladium in solution. That is, once the deposited elemental palladium covers the underlying metal, the reaction stops. Immersion reactions only work based on the electromotive series of elements. Think of it as a reverse battery. Electroless reactions do not depend strictly on the electromotive series of elements - a strong reducing chemical system can drive anything - even gold. Denny Fritz MacDermid - Waterbury ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################