SMD Soldering Question

Started by vigilante397, January 28, 2015, 09:53:54 AM

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Jdansti

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R.G. Keene: EXPECT there to be errors, and defeat them...

pickdropper

I use one of those Amscope microscopes as well.  The optics are quite decent for an inexpensive Chinese scope.

Snowbird laid it out pretty well.  The only point I disagree with is the water soluble flux.  For board houses, it's fine as they have board washing included as part of their standard processes.  For DIY builds, an RMA flux is a lot safer.  Most RMA fluxes can be left on the board if desired (although I still wash SMT boards built with it) whereas the water based will eat away at the board if left on.

You can get a Kester 186 flux pen very inexpensively and they are easy to use when hand-populating SMT parts.

snowbird

I hate no clean fluxes. In my experience, they are not active enough and the residue looks awful.

Fluxes have certainly gotten better in recent years. IT IS ABSOLUTELY TRUE that you need to remove water soluble flux or it will attack your board.

Production shops generally use de-ionized water. This is very pure water and works great. The catch for DIYers is that you probably don't have access to it.

If you don't have access to di water, then I would start with reasonably good tap water and an old tooth brush. You can buy distilled water at the grocery for final rinse.
Sometimes a cheap ultrasonic cleaner helps. You can buy these for little money at places like Harbor Freight.

Obviously point to point wiring may not work so well. This would be a place for the RMA type.

Al

pickdropper

I totally agree about No Clean fluxes.  I find them to be borderline useless.

Kester 186 is an RMA flux that can be removed but doesn't need to be (per Kester).

Water soluble can work quite well, it's just important to get it right and offers unnecessary risk for DIY applications.  Obviously, just my opinion.