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June 2013

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Subject:
From:
"Nutting, Phil" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Nutting, Phil
Date:
Thu, 20 Jun 2013 15:43:40 +0000
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Russell,

No-clean has good applications, unfortunately when working with very high voltages (above 3kV to 240kV) funny things happen if there is residual flux on the boards.  Also have seen issues with leakage in circuits caused by leftover fluxes.  We have been "successfully" using OA flux and DI closed loop cleaning since 2006.

Did we do a DOE or other documented testing/qualification... well no, but it's still working as the best process for us.

Just my opinion though.

Phil

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nowland, Russell Howard (Russell)
Sent: Thursday, June 20, 2013 11:06 AM
To: [log in to unmask]
Subject: [TN]

Just an FYI,

Telcordia GR-78 no longer allows water soluble fluxes.  They use to have a provision that allows you to use it as long as you are performing adequate testing but with the introduction of BGAs and QFN, and such they determined that you would be unable to clean efficiently and therefore no more.  So unless you got some really difficult to solder situations I would go with a Telcordia compliant no-clean flux.  To do WSF correctly you have too much upkeep. 

Dr. Munie (aka Moonman, and a few other aliases' not to be disclosed) is an expert on the subject.  He actually co-developed a saponifier used by a leading telecommunication company ;-) and holds one of his many patents.  We just don't use it any more.  Sorry Greg.

 
RUSSELL NOWLAND
ALCATEL-LUCENT
REPAIR STRATEGY & SUPPLIER MANAGEMENT
14000 Quail Spring Parkway, Suite 100
Oklahoma City, OK 73134
T: +1 405 302 1660
F: +1 405 302 1622
M: +1 405 203 0034
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of greg
Sent: Thursday, June 20, 2013 9:21 AM
To: [log in to unmask]
Subject: [TN]

It is true that WS flux should be removed in the cleaning process. 

However, many glycols actually bond to FR-4 epoxy through their -OH groups. Hence the surface after soldering and cleaning is hydrophillic. (Frank Zado showed this back in the early 80s.)

An easy test is take a board that is clean but not WS soldered and drop DI water on it. It should bead up.

If after WS soldering and cleaning a drop of DI spreads you have glycols bonded to the epoxy.

Adding a no-clean (with dibasic acids) to a hydrophobic mix may be an iffy proposition. 

Better to use a Bellcore compliant flux for your final soldering. 


>  -------Original Message-------
>  From: Steven Kelly <[log in to unmask]>
>  To: [log in to unmask]
>  Subject: [TN]
>  Sent: 20 Jun '13 09:02
>  
>  Thanks Dave - customer has not done any testing and for years we have 
> only used no-clean for both operations so now I have some parts to be 
> done one way and some another for Class 3 medical. Not good in my 2 
> cent opinion. Regards Steve Kelly
>  
>  From: [log in to unmask] 
> [mailto:[log in to unmask]]
>  Sent: June-20-13 9:15 AM
>  To: TechNet E-Mail Forum; Steven Kelly
>  Cc: TechNet
>  Subject: Re: [TN] Mixing solders,
>  
>  Hi Steve - I'll have to pay Doug and use his tag line - "It depends"! Anytime you mix two different flux systems, especially a water soluble and a low residue (aka no clean), there may be an issue of incompatibility that could result in a really hard lacquer (best case) or a really cool corrosion cell (worst case).  My recommendation would be to advise the customer that the mixing of the two flux systems would not be advised unless some testing can be conducted to ensure no detrimental reactions would occur. A second option would be to check with the flux supplier to see if they have any compatibility data. If the fluxes come from two different suppliers, don't waste your time asking that question as they won't have the answer. Good Luck.
>  
>  Dave Hillman
>  Rockwell Collins
>  [log in to unmask]<mailto:[log in to unmask]>
>  
>  
>  
>  From:        Steven Kelly 
> <[log in to unmask]<mailto:[log in to unmask]>>
>  To:        <[log in to unmask]<mailto:[log in to unmask]>>
>  Date:        06/20/2013 08:02 AM
>  Subject:        [TN] Mixing solders,
>  Sent by:        TechNet <[log in to unmask]<mailto:[log in to unmask]>>
>  ________________________________
>  
>  
>  
>  Hi All,
>  I have been looking in the archives but can't seem to find what I 
> want an answer to . I have a customer who wants us to use water 
> soluble RoHS for the SMT process but wants no-clean RoHS for the 
> touch-up. Is this recommended? Regards Steve Kelly
>  
>  
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