Re: new Bayou Jumper kit builder

Jim, N5IB

Hi Rod,

I would "dis-recommend" the solder with the no-clean flux. While it solders OK and leaves somewhat less residue than standard flux, its properties make rework more difficult if you need to remove and replace a component. Back in their early days Elecraft recommended using the no-clean for their kits but rescinded that recommendation when the folks who were doing repairs noticed the difficulties.

I'd suggest a standard rosin, multi-core solder with a tin lead ratio of 63/37, no larger than 0.025" for routine kit work, and smaller - maybe 0.020" or 0.015" for surface mount. And for surface mount, using a solder with a small silver content (62/36/2) is a good idea. The silver content prevents the silver plated contacts on some SMT components from dissolving into the molten solder.

The 63/37 alloy is "eutectic" meaning it has the lowest melting point for a tin/lead alloy. It passes directly from the liquid to solid phase without going through a "pasty" or "plastic" intermediate stage. Less chance of compromising a solder joint if a conductor should shift as the solder cools.

The standard rosin flux is inert after it cools and the residue generally need not be removed. That said, I have had a couple of occasions where flux residue affected a very high impedance part of a circuit. If you see globs of flux remaining, it's a sign of using too much solder. And if the flux residue is dark or discolored, too much heat.

BTW - in the matter of fluxes...

"mildly activated" and "activated" rosin fluxes are more aggressive than standard rosin, and are rarely needed when soldering clean conductors. Their residue should probably should be removed with solvent (acetone or ethanol) if used on PC boards.

"water soluble" flux sounds like such an environmentally friendly thing... but not so for the circuitry. It absorbs moisture from the air and becomes corrosive. It MUST be thoroughly cleaned off with a water spray. This flux is mostly used in industrial mass production settings

and of course "acid core" flux is strictly taboo for all things electronic

Jim, N5IB

---In 4sqrp@..., <rodhayes@...> wrote :

I have purchased the following items:

Kester 245 no clean solder

  60/40 solder

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