You should see no difference in the two ... all things being equal (like the same volumes etc.) Electroplating baths are ionic solutions. They are acid based solutions with metal ions. So resistivity of the water used in bath maintenance is not so important as what is in the water. In incoming water may contain contaminants, or even additives, additives like chlorine. Chloride concentration will have an effect on things like anode corrosion. City water in the fall is laced with chlorides which the municipality increases to fight intestinal disease (at least in New England). I could maintain chloride levels in the fall without making additions in New Hampshire. Plating bath maintenance changes seasonally based on the water contaminants, additives and temperature. Many companies use RO and ionic exchange colums to remove the variables inherent in "City" water. Treating the incoming water also allows the water to warm up to room temperature. When I was working in a shop outside of Boston (in a city that starts with W) the incoming water was not pure enough to be dumped down the drain and meet EPA requirements. The city water was clean enough to drink but not clean enough to go directly into the sewer without treatment. PS. I think I am not able to post to technet again. Might be an email issue at our end. If this bounce back from TechNet I'll ask to have it fixed. Paul Reid Sincerely, Paul Reid Program Coordinator PWB Interconnect Solutions Inc. 235 Stafford Rd., West, Unit 103 Nepean, Ontario Canada, K2H 9C1 613 596 4244 ext. 229 Skype paul_reid_pwb [log in to unmask] <mailto:[log in to unmask]> -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls Sent: April 6, 2011 8:33 AM To: [log in to unmask] Subject: Re: [TN] [TechNet] DI water and plating I am being vague on purpose. Lets try this. Lets say I have two scenarios. In the first scenario, DI water is generated at about 16 megohm-cm and is fed directly into the plating tanks. Chemically clean and high resistivity. Second situation, the DI water goes into a large holding tank (plastic) where the 16 megohm-cm water becomes 2 megohm-cm water just from sitting around, and gets piped into the plating tank. Still clean chemically, but now has lower resistivity from CO2 mixing. Lets say the tank is silver plating, just for fun. Am I going to see any difference in plating between the two scenarios, all other factors being equal, because one has lower resistivity than the other? Doug Pauls Dennis Fritz <[log in to unmask]> 04/05/2011 08:08 PM To [log in to unmask], [log in to unmask] cc Subject Re: [TechNet] DI water and plating Hmm, Doug, I too must ask for some clarification for your question. All electroplating baths I know have high concentrations of acids or highly conductive salts, to the point that the bath should have essentially zero resistance. The voltage registered when electroplating is that used to reduce metallic ions to elemental metal, not to drive current through the bath. That This voltage is the basis of the electomotive scale or electromotive force. It is always good to use DI water to make up an electroplating bath, because some common anions - like chloride - need to be well controlled. For instance in a sulfate copper electroplating bath, the chloride acts as the "anode corroder" causing the metallic copper electrode to be "etched" with a film of cupric chloride and go into solution. Are you thinking about the rinse water after plating? Denny -----Original Message----- From: Douglas Pauls <[log in to unmask]> To: TechNet <[log in to unmask]> Sent: Tue, Apr 5, 2011 12:04 pm Subject: [TechNet] DI water and plating Good morning all. I have a general question for those of you who deal with electroplating. How critical is the resistivity of the water to the plating process? I am not talking about impurities in the water, only the resistivity of it? Doug Pauls ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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