He said he wasn’t sure if it had to be fuming nitric or if it could just be good old “regular” 68% concentrated nitric?
I would love to give this a go as your results look so cool but don’t stock any RFNA / WFNA and don’t really like making it (68% is more than good enough for my uses! ) ![Tongue :P](https://www.eevblog.com/forum/Smileys/default/tongue.gif)
If you don't feel like reading the whole thread linked by Noopy, and I'm not even 100% sure if I ever described it in detail:
Pour 1~2ml into a 5ml beaker, drop the chip, cover with watch glass or at least HDPE bottle cap (for vapor reflux, reduces fuming and loss of acid).
Boil gently for a few minutes. Nitric acid remains transparent, allowing you to watch progress, only turns green from dissolved copper.
68% will eat exposed aluminium bonding pads, but won't reach under the passivation glass in short time. FNA passivates aluminium, hence the preference.
edit: Hopefully you know it already, but NO₂ is poison and stinks ugly like chlorine, so don't be an idiot, do it outside ![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
Awesome! Thanks so much to both you and Noopy
![Cheesy :D](https://www.eevblog.com/forum/Smileys/default/cheesy.gif)
I’ve been reading through all the info and am super keen to give this a go! Thank you
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
I would probably go down the chemical route as am more confident in my chemistry skills than I am with my electronics ones at this point think
![Tongue :P](https://www.eevblog.com/forum/Smileys/default/tongue.gif)
To be completely honest, I think I would probably be far more likely to kill myself wiring up a furnace than I would working with most chemicals with a LD50 higher than cyanide
![Laughing :-DD](https://www.eevblog.com/forum/Smileys/default/smiley_laughing.gif)
I am already thinking of maybe experimenting with a few different acids or solutions such as maybe testing out if H3PO4 works (might be an easy-to-find replacement for people in countries that don’t have access to HNO3 / H2SO4?)
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Agree! NO2 is some pretty nasty stuff! I have caught a lung full from being stupid once or twice and straight up thought I was dying
That said, Noopy mentioned HF in the other thread… now that stuff… that stuff proper terrifies me!!!
![Tweak :-/O](https://www.eevblog.com/forum/Smileys/default/smiliey_cal.gif)