[sdiy] PCB manufacturers for SMD

[ASSI]

On Friday 07 September 2012, 14:08:31, Eric Brombaugh wrote:
> I'm looking at OSHPark for a 4-layer design that I've got coming up, but
> they use ENIG (gold) finish rather than HASL (solder) which I'm used to.
> Other guys I talk to who use OSHPark assemble with stencil/paste/reflow,
> but I'm not interested in that. Any suggestions on what hand soldering
> techniques work best for fine pitch parts on a gold-finish board?

I've never had any problems soldering to gold-finished boards.  If they are 
_really_ old with fingerprints all over the place, I might first go over 
them with a plastic eraser to get the shine back on.  On copper boards I use 
those white "miracle" sponges dipped in isopropyl/water mixture, but I've 
not needed to use those on gold finish yet and it might actually be too much 
for very thin gold flash.  Then flux the board (still using rosin in 
isopropyl for that) or just the footprint you want to solder and just solder 
like you normally would.  Make sure you heat both the pad and the pin, but 
that problem is there for HASL as well — you just don't see it as easily.  
If the pad footprint is very small, tinning the footprints first might work 
better, but it's tricky to get them non-bumpy with just a soldering iron.  
For the parts themselves, remember to fix one or two corners first before 
doing the rest of the pins.  Exposed paddle variants or BGA (which you're 
probably not using) must be soldered with paste/reflow, YouTube will show 
you how to do it with a heat gun if you're in a pinch.

For when I need a bit more flux in a defined spot I've used a 
rosin/isopropyl "paste", but it's very tricky to get the consistency right 
and it solidifies really fast… so I'm now using planters' grafting wax (the 
translucent, yellow version) instead.  It is mostly rosin as your nose can 
tell you, but the waxy consistency makes sure it stays in place.  If you're 
not too liberal in application, it doesn't even leave much of a residue and 
you can easily clean it with isopropyl/water mixture if necessary.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

SD adaptation for Waldorf microQ V2.22R2:
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