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
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