[sdiy] PCB manufacturers for SMD

[Matthew Smith]

Quoth Eric Brombaugh at 08/09/12 06:38...
...
> 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 wipe the pads (and some components) with an Electrolube SMF12P flux 
pen. This actually makes the board a wee bit sticky, which I find helps 
hold parts in position.

For 2-3 lead parts, I apply solder to the iron bit, then iron to part, 
whilst holding the part down with tweezers.

For multi-lead parts, I do the same for the first leg, secure the 
opposite leg, then drag-solder the rest. Biggest (in terms of leads) 
part I've done this with so far is a 0.5mm pitch 100 QFP - reasonably 
easy with the microscope.

I tend to find more missed legs than solder bridges, but the 'scope 
locates these pretty quickly.

For removing solder bridges, I first apply the same flux to my braid.

Solder is 0.4mm (0.015") Kester Sn63/Pb37 - as I'm prototyping, I have 
yet to have a need to fight Pb-free stuff.

Doing all this with a Hakko FX-888 with the pointy tip it comes with.


-- 
Matthew Smith

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