Francis: One additional comment in addition to those of Dennis Fritz: All acid copper baths, regardless of the brightener system, require carbon treating for the reasons mentioned. Since you're new to plating I thought that additional bit of information might be useful. Don Vischulis Dennis Fritz wrote: > In a message dated 99-06-04 18:09:12 EDT, [log in to unmask] writes: > > << I do not know why the Macdermid > 9241 acid copper plating bath needs carbon treatment after a certain > amp-hrs. of plating? >> > > 1. The brightners and grain refiners in acid coppers are organic molecules. > There is a continuous breakdown of these additives as electrical current > passes through them - more than the drag out of copper plating solution can > remove with today's pollution controls. So, the "Total Organic Carbon" > builds in the plating bath. At some point, the organics start to interfer > with the copper grain structure in the deposits. The tensile and elongation > properties fall off and you will get corner cracks in solder shock. Carbon > treatment removes (hopefully) all these organics, so that you can start over > with a new brightner add, just like on original make-up. > > 2. The plating resist you are using and the cleaner solution at the start of > the pattern plate line are both organics. These are other sources of > organic molecules, besides the breakdown products from the plating bath > brightner. They also are removed (hopefully) in carbon treatment. > > You can control an acid copper plating bath by running Hull cells to > determine brightner effectiveness -or the effect of the organic impurites, > run a total organic carbon frequently to see how much organic is building up, > run some sort of chromatograph (ionic, liquid, etc) to see what compound is > building up, and run frequent physical property samples of your copper plate. > > OR, you can use the guidelines we have established based on shop experience > around the world, and carbon treat after a specified number of amp hours per > gallon of plating bath solution to be safe. Unless you have access to a lot > of analytical equipment, better use the amp hour recommendation. > ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################ ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################