Although many companies have worked on or are working on water borne solder masks, the results to date have not been that positive. Some of the problems are: 1. Critters like to live and breed in water borne organic materials (fungus, mostly) and putting in anti fungal ingredients into the formulas do not usually enhance the performance of the solder masks. 2. Its hard enough to get a good performing solder mask in a solvent borne system. Much harder in a water borne system. Any water borne mask would have to be soluble in water and, therefore, would be more susceptible to any aqueous system even after final cure. The average PWB is subjected to all kinds of high temperature aqueous systems, both alkaline and acid and solder mask breakdown can be a major concern. 3. Water borne systems tend to be based on emulsions and are notorious for difficulty in controlling these emulsions, batch to batch inconsistencies, stability problems, freezing during shipping (like into upstate New York in February), etc. Don't mean to throw "cold water" on water borne masks, but I don't think they are there yet. If someone has a good one, more power to them and I'd love tolearn more about it. Larry Fisher Dexter Electronic Materials [log in to unmask] *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************