Mike

Generally, I would agree with you, however I would like to point out 
that your "rosin-based fluxes" require some qualification. Using the old 
denomination, activated rosin fluxes can provide the wherewithal to 
start "a nice little corrosion cell", if it is an RA type or even an RMA 
type. Only pure rosin could be considered as more or less benign, from 
the point of view of corrosion. However, I don't think that leadfree 
solder fluxes are likely to be based on unmodified rosin for thermal 
reasons.

Brian

On 27/04/2015 17:04, Mike Fenner wrote:
> You asked two questions, Figuratively:
> Q1 - Are all LF solder fluxes created equal?
> A1 - No. See other answers
>
> Q2 - What happens to residues in actual life or life testing?
> A2 - To answer this even in the most general terms you would need to be more
> specific about the type of flux you are looking at. For example, rosin based
> fluxes can effloresce with damp heat to give what looks like a corrosion
> product. However if heated the "growth" can melt and revert back to normal
> appearance. A cosmetic in other words. Alternatively some other flux types
> could start a nice little corrosion cell which will self perpetuate as long
> as there is a supply of damp and oxygen and that would be a concern.
> This is, as you can see, a long way round to avoid saying ... it depends...
>
>
> Best Wishes
>
>
>
> Mike
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
> Sent: Friday, April 24, 2015 8:31 PM
> To: [log in to unmask]
> Subject: [TN] LF Solder flux
>
> Fellow TechNetters:
>
>     Are all LF solder fluxes created equal?   I often see m/b with more flux
> residue, dry-crusty-yellowish, accumulated around the solder joint.  Yet
> others are almost free of flux residue.   I do see that either solder form a
> glassy halo around the solder joint at the solder mask surface.   What are
> the Pros & Cons.   The solder flux residue is more pronounced on Filed
> return assemblies or those which have been subject to reliability testing,
> HALT, HASS, S&V & T/C
>
> Victor,
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>

______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________