Hi Paul, You can build an ammonia gas injection system the same way as you would design a vent control system. You can purchase electric gas valves to activate ammonia cylinders via a pH controller. But again, as in the case of automatic vent control, the system will only be as good as the maintenance put in around it. These valves stick open or closed and can cause a great deal of pain. Not to mention the probe itself. In this environment they need plenty of care and preventive maintenance to keep them calibrated. As for oxygen introduction, most equipment I've been associated with takes in enough oxygen from the conveyor's entrance and exit openings. I've never had the need for an additional oxygen feed system. I think the trick in creating a well balanced ammoniacal etch system is machine design, placement of the venting, evenly matching the exhaust stacks with the right fan size, relatively constant work flow, a VERY good specific gravity controller for fresh etch feed and spent bleed, and a VERY good PM program for keeping all of this maintained. Not to mention good operators who are well trained and know how to look after the systems. I would suggest to Sarah, and anyone else looking for information on ammoniacal etch systems, to contact Chuck Mosolf (Insulectro) and/or Marty Leiberman (Phibrotech). Marty is probably one of the most knowledgable fellows I've ever met regarding ammoniacal etch systems. Good luck. Mark Mazzoli Eng. Mgr. Circuit Technologies, Inc. 3622 Clearview Pkwy. Atlanta, GA 30340 770-458-1700 [log in to unmask] ----- Original Message ----- From: Paul Wilson <[log in to unmask]> To: <[log in to unmask]> Sent: Thursday, August 26, 1999 4:11 PM Subject: Re: [TN] etching pH controllers > 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 > ############################################################## ############################################################## 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 ##############################################################