[sdiy] Which solder is safer for home projects ?

[Richie Burnett]

---- Tom Wiltshire wrote ----
> 
> Do I *really* *actually* need to worry about any of this stuff?

The only time I've actually seen a problem that was traced back to poor flux cleaning was around a 32.768kHz watch crystal that had been manually replaced on a large batch of boards made for a company where I worked.  The real-time clocks in all of the product that was shipped to Asian markets started to fail in the humid season. Other world markets were unaffected. This was apparently due to flux residue absorbing water from the humid atmosphere, forming a conductive path with salts present in the flux and damping the crystal enough to stop oscillation.

This happened on hundreds of boards, so it is a real phenomenon, and the ensuing recall and rework was very costly for the company. 

High impedance nodes are most susceptible to stay leakage paths, like the low-power watch crystal in this example, or something like an analogue sample and hold circuit.

-Richie,