[TriEmbed] soldering oxidized pins - QFN part

[Brian]

That's a (T)QFP, not a QFN (QFN means Quad Flat No-lead).  Pedantry 
aside, try a good blast of flux remover, or a soak in a weak acid such 
as H2SO4 (sulfuric acid, available as "battery acid" in auto parts 
stores) to try to dissolve the oxide.  Light wiping with a lint-free 
swab will help the process along.  Be sure to rinse well in deionized 
water afterward and allow to dry thoroughly for at least 24 hours.  Wear 
gloves!

Most plastics hold up well in sulfuric acid; epoxies are fair (keep the 
bath below room temperature).  Not knowing the exact makeup of the 
plastic of the part, I can only say don't keep it in the bath for long 
(as in hours or days).

Note: I have never tried this; I'm inventing this suggestion based on 
the chemistry.

Or just try soldering it anyway.

Good luck!


On 1/27/2016 10:57 AM, Alex Davis via TriEmbed wrote:
> I have a QFN part which shows signs of oxidation on the pins, and I'm
> wondering if there's anything I can or should do to clean it up.
> Unfortunately, it's an old-stock part, so I can't just get a new one.
>
> I have some photos here of the part:
> https://hackaday.io/project/9150-68040-upgrade-for-powerbook-520c/log/30827-68040-has-arrived
>
> I am hoping there's enough un-oxidized metal on each leg that the solder
> and flux will wet the legs properly. I'll be point soldering a few pins
> on each side before drag soldering the rest, so I should be able to
> evaluate if it's going to work before committing to soldering the whole
> thing.
>
> Alex
>
>