Peter Swanson wrote:
> 
> In message <[log in to unmask]> Karen Tellefsen writes:
> > Alpha sells Solder Stop 110.  Do not use pealable masks
> > with no-clean assembly.  Both Solder Stop 110 and Wondermask
> > are highly ionic and real bad SIR killers.
> 
> Could you please give an explanation or data to back up your advice to not use
> peelable masks with a no-clean process? We have been supplying latex-based
> temporary solder masks for many years to companies who do not clean after
> soldering, with no complaints. I agree that these types of materials do contain
> low levels of halides. However, I have no evidence that a properly cured
> material (which will be removed leaving no (visible) residue) has caused any
> problem. I believe your advice to be at odds with actual practice at many
> thousands of companies.
> 
> Peter

I can't speak for the pealable mask your company makes.  However,
I did a short study of Solder Stop 110, which my company sells, 
and one Wondermask formulation.  I crosshatched stripes of both 
masks across SIR combs, allowed them to sit several hours, 
wave soldered with and organic acid-type 
low residue flux, pulled off the stripes  of mask with clean forceps.  
No visible residues was left behind (this does not mean no residue).
These coupons had very low SIR values.  These latex masks had basic 
formation, either with ammonia/amine or alkali metal.  Ionic residue 
was left behind after the mask was pealed.

Perhaps your company's products perform better than the two materials
I tested for no clean assembly.  If you can provide SIR or cationic  
(not just anionic) IC data to prove this, many no-clean assemblers would 
be impressed. However, Solder Stop 110 should be washed after pealing.

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