One of the concerns I have is what happens if this gets onto the board.  This doesn't seem as unlikely as it may seem if you let the solder level get low and start sucking the compound into the impeller. Good chance that it is based on an ionic surfactant system. Suitable choice due to their inherent heat stability, but they also tend to be rather hygroscopic.  Potential for some SIR failures I suppose.  

When everyone used to wash, this wasn't such a big deal, but with no-cleans...?

Rich K / KEDS


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Wednesday, April 26, 2006 10:32 AM
To: [log in to unmask]
Subject: Re: [TN] Molten Solder Surfactant for Dross Elimination

This subject was discussed at length in a thread of 10 March. Have a 
look through the archives.

I contributed the following to this thread on 14 March:

OK, I've had a good look at the P. Kay MS2. Framnkly, I see no grounds 
for sufficient originality for a patent to be granted. Let me go into 
the history of solder blankets. The original one was vegetable oil, 
usually peanut oil. This was effective at reducing dross formation and 
the acid decomposition products actually chemically reduced some of the 
dross back to metal. Two disadvantages: flammability and odour, which 
rendered it unpopular. Also, it had a short lifetime because of 
polymerisation, requiring skimming twice/day.

To overcome this, van t'Hoen helped develop a mineral soldering oil 
which was marketed as Shell Peblum A, initially for the tinplate market 
and later for soldering. This was a pure blanket product with no 
chemical reduction. It had a reasonable lifetime of a few days.

Then came the most significant development in the 1960s, by the 
erstwhile London Chemical Company in Bensenville, IL (later taken over 
by Alpha Metals). This was marketed as Lonco Fusecote 240. This was a 
blend of carboxyl alkanes and their polymers. This was popular for 
immersion reflow of electroplated tin/lead alloys, as well as being a 
clean substitute for soldering oils. It was easily cleaned with either 
water or the usual organic solvents. It was very stable with waves up to 
~245°C and was safe with a flash point of ~265°C. Typical lifetime was 
about one week. Some of the components of this had surfactant properties.

A different technique was offered by Fry's Metals, in Mitcham. They 
offered orange tablets of a hard wax blended with a reducing agent. This 
looked like a chocolate bar and I suspect that this was a deliberate 
ploy as there was also a chocolate company called Fry's. The two 
companies were founded independently by two branches of the same Quaker 
family in the 19th c. A small piece of the wax floated on a drossy 
solder bath reduced the volume of dross and some of the metal was 
recovered. The gunge resulting from this was then skimmed off, but the 
technique left no or little blanket.

Other techniques used for static baths was floating pine sawdust on the 
solder. This was actually quite good at reducing dross by means of the 
slow exudation of rosin.

As for machinery, the most significant was the Hollis machine which 
sucked a small volume of the "oil" and mixed it into the solder at the 
bottom of the wave, which did not oxidise. The disadvantage was that 
micro-droplets of oil were sometimes found in solder joints. This did 
not appear to affect the reliability but did cause some worry. Other 
manufacturers just offered an oil blanket so the wave itself was 
unprotected. Another technique was to drop a few drops of oil across the 
wave as each pallet or circuit approached it. Fry's recommended 
occasionally rubbing their orange "chocolate" along the nozzles with the 
  wave off, of course.

One of the most important factors to consider is the "cleanability" of 
the oil residues on the assembly. The vegetable and mineral oils 
required solvent cleaning, while Fusecote, being water-soluble, could 
also be water-cleaned, but was prone to foaming and additions of octylic 
alcohol and soft soap were required in the wash water.

The P.Kay MS2 appears to be quite similar to Fusecote in all ways, 
except that it has a higher flash point, possibly because of longer 
chain alkane molecules. I have little doubt it is effective. What 
worries me is the toxicity to water wildlife and the long lifetime. This 
suggests (my speculation) that it may contain nonyl- or 
deca-phenoxylates or something similar which are non-ionic detergents 
that are not looked on too kindly in waste water by some authorities. If 
so, this may require the need for elimination before emission into a 
waste water stream.

Hope this helps.

Brian

Todd, Richard wrote:
> TechNet,
> 
> 
> 
> I have come to the Oracle seeking wisdom.  Has anyone had any experience
> with using a molten solder surfactant for dross elimination in a wave solder
> process?  There is a (fairly) new product on the market which makes some
> exciting claims.  Although, as the adage goes, if it sounds too good to be
> true, it probably is!
> 
> I am not a chemist or metallurgist but, I think I understand in principal
> how this stuff works, but I am hesitant to add anything to my solder pot for
> fear of contamination issues, etc.  Any and all comments are welcome.  I am
> especially concerned about long-term solder joint reliability issues.  I
> will do my own testing and validation both in lab and on the production
> floor but I want to understand any process concerns, etc.
> 
> 
> 
> Oh, by the by, I am running standard Sn/Pb in my waves; we do not solder in
> an inert environment and we do not clean our boards (no-clean flux).
> 
> 
> 
> Thanks in advance,
> 
> 
> 
> Rick Todd
> 
> Senior Engineer
> 
> Process Quality Engineering
> 
> 
> 
> Panasonic Automotive Systems Company of America
> 
> Division of Panasonic Corporation of North America
> 
> 776 Highway 74 South, Peachtree City, GA 30269
> 
> 770-515-1087 Direct
> 
> 678-458-2887 Cell
> 
> 770-486-2248 Fax
> 
> [log in to unmask] <mailto:[log in to unmask]>
> 
> 
> 
> 
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