Guru Andy - Based on your "ps": How does zinc chromate passivation fit into the general picture of copper solderability? Could it be used instead of or along with OSP coatings to reduce copper oxidation? - LeRoy -----Original Message----- From: Andy Magee [SMTP:[log in to unmask]] Sent: Saturday, July 24, 1999 8:08 AM To: [log in to unmask] Subject: Re: [TN] Copper oxide removal Sulfuric is preferred over Hydrochloric for oxide removal because HCl tends to increase in etch activity as the dissolved copper concentration goes up with use. 10% H2SO4 will be a much more stable and reliable process for oxide removal. Save the nitric for things like stripping copper off your plating racks. Andy Magee Flex Guru - Consulting [log in to unmask] (937) 435-3629 ps. Initially copper foil is provided from the supplier with a zinc chromate passivation coating to prevent oxidation. Since this angstroms thick, relatively brittle, layer may not be uniformly intact it should be removed with a process that will not attack the copper before microetching. 10% H2SO4 is clearly the preferred choice over HCl, but there are also a number of proprietary acid/surfactant mixtures that are widely used for this. LeRoy wrote, Subject: Re: Copper oxide removal Date: Fri, 23 Jul 1999 15:56:52 -0400 From: LeRoy Forney <[log in to unmask]> My understanding of the usual oxide removal procedure is a 3-minute soak with 5%HCl. The goal is a very mild etch, and I've heard that nitric acid will cause pitting instead - and this is in line with some laboratory oxidation studies I did some time ago. Variability in solderability data was much higher on aged coupons I had treated with dilute HNO3 than on coupons treated with 5%HCl. LeRoy -----Original Message----- From: nishath yasmeen [SMTP:[log in to unmask]] Sent: Friday, July 23, 1999 3:34 PM To: [log in to unmask] Subject: [TN] Copper oxide removal Hello everyone! Is Nitirc acid ( dilute) a better acid than sulfuric for cleaning the oxide on plated copper? Any information provided will be appreciated. Yasmeen ############################################################## 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 ##############################################################