[coreboot] smd work

Tim S tim.strommen at gmail.com
Sat Dec 30 00:45:55 CET 2017

Personally I like hot air reflow for multi-pin parts.

Something cheapish like an Ayoue works fine - I think Walmart has the 888A
hot-air/solder-iron station listed for <$70 (I use the Ayoue 852 myself at
home, because I have a very nice solder station already).  The trick with
hot air is not getting the air speed too high, do that and you'll start
blowing off small SMD resistors and caps all over your workspace.  Get it
too hot and you scorch the plastic packaged parts.

Can't beat hot air though for re-attaching parts, get some solder paste
from (anywhere really), and put the paste in a small modeling or plastic
gluing syringe, and under a decent magnification, you can apply solder
paste directly to the bare cold pads (don't drink coffee that day).  Drop
the part on the paste (just like a pick an place machine), and it'll stick
there with surface tension until you reflow (heat) the part.  IMHO the
nicest thing about this method is that even if you drop the part a bit off
alignment, the surface tension of the heated paste will pull the legs onto
the pads.  There are good YouTube videos for this method.

If you need to reattach a larger part like an IO controller or a
chipset/BGA, you'll want to heat both sides of the board so it doesn't
warp.  Also for holding things in place you don't intend to remove, get
some Kapton tape (the brownish-orange transparent stuff) and cover the
"keep out" areas.  Kapton sticks at temperatures up to 500°C is
non-conductive, just make sure you let the board cool down again before you
remove the tape, or you'll have tape covered in the parts you were trying
not to remove...

Get used to this stuff, the leg-less parts are becoming the norm in the
thinner form factors especially.


Date: Thu, 28 Dec 2017 17:47:54 +0000
> From: ron minnich <rminnich at gmail.com>
> To: coreboot <coreboot at coreboot.org>
> Subject: [coreboot] smd work
> Message-ID:
>         <CAP6exY+K-9UJizGxQd3QJaOOw+XsaPR13sW44dPzasSQJKZUYg at mail.
> gmail.com>
> Content-Type: text/plain; charset="utf-8"
> A friend of mine wants to do some SPI rework. He wants a  16M part in his
> chromebook, not 8M. (hmm, so do I). Given the huge expertise of this group,
> I wonder if you have advice about equipment he should get.
> Soldering irons? hot air guns? magic wands?
> thanks
> ron
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