[NLRS] DB6NT assembly soldering tools

[Doug Reed]

At 10:58 AM 2/12/2003 -0600, you wrote:
>I've found flux residue to be sensitive indicators (though uncalibrated)
>of humidity. ...snip...... I suspect
>flux cleaners are more than just alcohol and are more effective than
>plain alcohol on some fluxes. Flux cleaners I've found to be effective
>on cleaning rosin from circular saw blades too.
>73, Jerry, K0CQ

I've repaired many boards where just the least little bit of flux residue
caused the product to fail during manufacturing tests. Any amount of flux
residue in a high impedance circuit is likely to cause trouble. As Jerry
says, flux tends to be hydroscopic and will attract moisture out of the
air. Not only does this cause leakage problems but it can also cause
corrosion due to re-activating the chemicals in the flux. Once upon a time
our "torture test" for high temp and high humidity problems was our dealers
in Bermuda. If it worked there it would work almost anywhere..... 

I will say that for the most part the old style rosin core flux was not as
much of a problem as all the new water-wash or no-clean fluxes. But most
manufacturers switched to water-wash years ago to get away from the
cleaning chemicals and are now switching to no-clean flux to get away from
waste water disposal issues. As a repair tech, I still clean the PCB when
I'm using no-clean solder flux...... Tri-clor was an excellent cleaner but
alcohol is much safer. 

At home I've used electric motor cleaner as flux remover. I've also used
Birchwood Casey Gun Scrubber as flux remover. Both are very aggressive so
don't use them around plastic. Plain old 95%+ alcohol is much less
aggressive and is less likely to damage things too. Just pour it on, brush
it around and pour it off. If you have compressed air available, you can
blow it clean and dry very quickly. (Don't do it around an open flame.....)
I reapply and brush it again if I see any white residue on the board or can
still see flux on the board. 

"Follow all applicable safety precautions." No open flames or sparks when
working with flammable liquids. Have ventilation if there will be a lot of
vapor. Wash your hands when done cleaning the board to get the chemicals
off your skin. (Don't say I didn't warn you.<g>)

73, Doug Reed, N0NAS.