Pink lonco? It solders everything.  As long as you clean it fast, its a beauty.
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----- Original Message -----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Wednesday, February 29, 2012 02:48 AM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] halides in water soluble fluxes

You have roused my curiosity, Phil. What are the parts that can 
withstand halide-free WS fluxes but not halide-containing ones, and why? 
I could understand it for some chemical sensors but optical??? Have you 
discussed this with your parts manufacturer? Does he give a reason for 
eschewing halides or is it aqueous processes that he does not like? What 
is his view on halide-containing rosin fluxes?

Please let me warn you that you would need to re-qualify your process 
because you may find that the halide-free fluxes may be a lot more 
difficult to clean, especially with a DI-water only wash. You may find 
that there may be more corrosive residues on the washed boards.

For me, assuming that my thoughts are justified, using your current 
process with one small modification, perhaps not requiring 
re-qualification, will fill the bill. That is to have a static bath 
containing a chelating neutraliser (not a saponifier) between the 
soldering and cleaning operations. A couple of minutes or so will 
solubilise any heavy metal halides or organic halides and will "kill" 
the excess acidity of any WS flux. I used to recommend Lonco 2051-B-3 
but I think this is no longer available. I think Alpha have one called 
Rinse-Aid and I suppose Kester, Multicore etc. may have equivalents.

Have you thought that many components are supplied with halides galore? 
Component manufacturers often use halide fluxes for tinning their 
products, often with little or even no cleaning. Much tinned copper wire 
uses a zinc chloride/hydrochloric acid flux and the only cleaning is 
running it through a damp sponge followed by a sponge with a waxy substance!

If your components are really sensitive to halide ions, I would say that 
ion chromatography will be an essential part of your qualification 
process, no matter which flux you use.

Finally, have you thought about using your existing process but adding 
the sensitive components by hand, soldering with an evaporative 
halide-free no-clean flux, after cleaning? this may a simple cheap way 
round your problem, especially if the quantities are small.

Brian

PS Inge: Thanks for the plug. The IPC were kind enough to allow me to 
mention the availability of the book on this forum a few months ago but 
I don't want to abuse their hospitality, other than to say there is now 
a download version as well as the hard copy. I'm now the publisher as 
well as the author!



On 28/02/2012 21:12, Phil Nutting wrote:
> We have some parts that are sensitive to halides in flux, specifically some thru-hole opto devices.  We are currently using a water soluble flux that contains halides.  In doing some very quick research it looks like the WS fluxes have halides and the NC fluxes do not.
>
> Is there a halide free WS flux for lead-free wave soldering (foam application)?
>
> We need the WS fluxes because we currently use a DI water only batch wash system.  Washing the boards is mandatory for our applications.
>
> Thanks in advance,
>
> Phil Nutting
> Design for Manufacturing Engineer
> Kaiser Systems, Inc.
> 126 Sohier Road
> Beverly, MA 01915
> Phone: 978-922-9300 x1310
> Fax: 978-922-8374
> e-mail: [log in to unmask]<mailto:[log in to unmask]>
> www.kaisersystems.com<http://www.kaisersystems.com>
> www.linkedin.com/in/philnutting<http://www.linkedin.com/in/philnutting>
>
>
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