Yes, but they are not deliberately added to disinfect the water, as was
implied. I was trying to make a distinction between ionic chlorides and
elemental chlorine, that many people tend to confuse.
Brian
On 06/04/2011 18:15, Karen Tellefsen wrote:
> Won't some of the non-ionic chlorine be reduced to ionic chloride in city
> water? Also, chlorides are often among the various dissolved minerals in
> tap water.
>
> Karen Tellefsen - Electrical Testing
> [log in to unmask]
> 908-791-3069
>
>
>
>
>
>
> Re: [TN] [TechNet] DI water and plating
>
>
> Brian Ellis
> to:
> TechNet
> 04/06/2011
> 10:09 AM
>
>
>
>
> Sent by:
> TechNet<[log in to unmask]>
> Please respond to TechNet E-Mail Forum, Brian Ellis
>
>
>
>
>
>
>
>
>
> I agree that there will be no difference because of the CO2. The ionics
> in any plating solution will be such that they will 'drown' the CO2,
> probably by 4 or 5 orders of magnitude.
>
> However, I disagree that chlorides are added to tap water for
> disinfection. It is chlorine that is added, not at all the same thing,
> in most places (UV-generated ozone in a few places, especially after
> desalination). Chlorine is non-ionic, although it can react with organic
> impurities and some of the reaction by-products may end up as chloride
> ions. In Europe, much of the tap water has a conductivity of 100-500
> �S-cm, but this is because of dissolved minerals, not the chlorine.
>
> Brian
>
> On 06/04/2011 15:42, Paul Reid wrote:
>> 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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