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Date:	Tue, 29 Nov 2011 21:05:33 -0500
Message-ID:	<CAPYb0EG6tgWv4bvjq_0e-d3TkanHv9yM5f7X7490DxytTiqi3w@mail.gmail.com>
Subject:	Re: [geda-user] Re: I want to do BGA prototype soldering
From:	Bob Paddock <bob DOT paddock AT gmail DOT com>
To:	geda-user AT delorie DOT com
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>> But modified with a ramp controller?
>
> The elektor oven already has one:
> https://www.elektor.com/projects/smt-oven.1372709.lynkx

http://www.grainger.com/ has several temperature controllers that can
be put to work with a toaster oven.
I'll have to see what the model number on ours is when I get to work.


>> Is there a technique for doing those first few prototypes
>> washout well, or just plan on them not being usable long?

Flux needs to be removed or deactivated.  A lot of fluxes are
deactivated by the heat of the soldering.
If you don't reach that temperature the flux will eat away the joints.
 Aggressive fluxes can do that in days.

No-Cleans can absorb junk from the atmosphere over long periods of
time (months to years) that can raise sleep-currents.
Trying to clean some No-Cleans turn them into goo. :-(

> Also a few types of DFN/QFN packages have leads which are not only on the
> under side of the package, but also continue a little bit up the sides.
> Which makes soldering a lot easier.

Be careful with castlations.  Actually look at the bottom of the part,
sometimes those are there for mechanical strength,
they are *not* always electrically connected to the pads on the
bottom.  Can get a falls sense of soldered-well security from those
type of pads on the edge.


>> 140 degrees F is what I've been told about water washout of flux.
>> maybe a water pik pump would survive that temperature?
>> Else, is pouring a stream of hot water from 2 feet up good for
>> dislodging flux under BGA's?
>
> How about using better solvents? Like pure petrol or alkohol...
> Aceton is also not bad. What works depends on the exact type
> of flux.

In the past I saw some solvents attack the Meniscus  (sp?) Coatings on
Through-Hole Tantalum capacitors.
Point is trying random solvents can lead to unexpected problems.  Test
*everything* on *small* quantities first.

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