It would seem that vent regulation could be used to control pH; however, what then happens to the fine control of chlorides? The reason this is asked is vendor etchant contains varied amounts of ammonia gas (i.e., control of one means loss to the other?). How about ammonia gas controllers and oxygen input devices with fixed vents for chloride regulation? Where are these purchased? Thanks, Paul Wilson -----Original Message----- From: Sarah Boutwell [SMTP:[log in to unmask]] Sent: Thursday, August 26, 1999 11:44 AM To: [log in to unmask] Subject: [TN] etching pH controllers Hello everybody I would like to add a pH control system to my ammoniacal copper etcher that would open and close a vent based on the pH of the bath. Does anyone know of a company that supply me with something like that? Thanks Sarah Boutwell Manufacturing Engineer Johnson Matthey Advanced Circuits [log in to unmask] 612-684-5079 ############################################################## 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. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ############################################################## ############################################################## 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. If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or 847-509-9700 ext.5365 ##############################################################