tag:blogger.com,1999:blog-534708807576459669.post4500485572348404493..comments2024-03-10T17:45:30.851-07:00Comments on IC reverse engineering and other adventures: Sulphuric acid decapsulationJohn McMasterhttp://www.blogger.com/profile/11714069658809228929noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-534708807576459669.post-89909574338156837062011-07-08T21:16:19.303-07:002011-07-08T21:16:19.303-07:00e-mail is johndmcmaster at gmail dot com.e-mail is johndmcmaster at gmail dot com.John McMasterhttps://www.blogger.com/profile/11714069658809228929noreply@blogger.comtag:blogger.com,1999:blog-534708807576459669.post-44244874805558514342011-07-08T21:14:35.007-07:002011-07-08T21:14:35.007-07:00I have a post on more advanced H2SO4 techniques th...I have a post on more advanced H2SO4 techniques that I started to write before you posted but haven't got a chance to push out, I think you'll really like it. <br /><br />I've actually had very good results with H2SO4. I shoot for 150 - 160 C. It seems to work on almost all of the epoxies/chips I've tried so far with only one exception. Unfortunately I don't know who made it as it was part of a lot of chips I was never going to do anything with and didn't want to take the time to track them. Above this temperature fumes seem to increase a lot and I'm not sure if I gain a lot. So, ~150 has seemed to be a pretty good compromise between speed, safety, and results. What brand chips are you using? I have some good pictures of epoxies vs how hard they are to etch, I'll see if I can post them somewhere in near future. Basically, higher acid epoxy vs glass content means much harder to etch. If its too high it will form a hard sediment rather than dissolve. I have not tried oleum as I have not seen a need for it. <br /><br />One of the reasons why I've moved away from nitric is that it corrodes aluminium at lower concentrations where as H2SO4 is slow enough that you often don't notice. <br /><br />I use a 3M industrial respirator with acid gas cartridges to help with fumes (3M 7800, http://intruded.net:8080/siliconpr0n/lib/exe/fetch.php?cache=&media=hf_gas_mask.jpg) and do things outside. I also use watch glasses to cover beakers which reflows and considerably reduces fumes. I'm working on assembling or buying a fume hood but neither has gone through yet.<br /><br />I I've experimented a little with nitric/sulfuric but not real need for it. I've heard its useful for passivating (or at least helping) copper corrosion when using nitric, but I've found straight sulphuric good enough that it hasn't been necessary. You'll be limited by HNO3's decomposition point. H2SO4 won't work once contaminated by the excess water, so its really only good for assisting HNO3.<br /><br />Consider joining my wiki (just moved to http://intruded.net:8080/siliconpr0n/doku.php?id=start) if you have an interest in this stuff! I'd love more contributions / collaboration including things that you tried and didn't work. e-mail me at <@> for an account.John McMasterhttps://www.blogger.com/profile/11714069658809228929noreply@blogger.comtag:blogger.com,1999:blog-534708807576459669.post-78274337565837029962011-07-06T00:47:33.580-07:002011-07-06T00:47:33.580-07:00Hi,
so far I had only limited success with conc. ...Hi,<br /><br />so far I had only limited success with conc. (96%) sulfuric acid.<br />Like you, I threw a few chips into a beaker with the acid. I heated it up and at about 90°C the acid started to turn black (i.e. it started to etch away the epoxy).<br />However, I was only successful with one chip. All others (especially the DIP packages in which I also milled a small cavity to reduce the amount of epoxy over the die) were not affected very much.<br />I suppose that's because the epoxy composition is different for chips from different manufacturers.<br /><br />Since we're working with very similar acid concentrations, I would be interrested to which temperature you heated up the solution.<br />I was reading that for decapsulation with sulfuric acid, the acid is usually heated up to 225-250°C (boiling point is 337°C).<br /><br />What I would like to do is to drop the acid into the milled cavity on the chip package, so that the rest of the package is being conserved.<br /><br />Did you also try fuming sulfuric acid ?<br /><br />I would also have lower concentrations of nitric acid (53%).<br />However, so far I did not make any experiments involving heating up or mixing the acid, as my fume hood has not arrived yet and the NoX gases that can occur with nitric acid are pretty dangerous.<br />Did you already experiment with that (i.e. a mixture of sulfuric and nitric acid) ?<br />Did you try hot nitric acid ? Which concentrations ?<br /><br />cheers,<br />StefanAnonymousnoreply@blogger.com