Getting Inside A Microcontroller - Page 1
Forum section: electronics / projects

author: Lance
author_rank: Frequent Contributor
timestamp: February 03, 2011, 02:22:53 am
content: Okay, so this was my second attempt at getting inside a chip, specifically a dead PIC18f4525. It didn't go well. I tried using a handheld propane torch to burn the plastic off, as opposed to sanding this time. It failed. The plastic just bubbled a little. I got green fire, which I know is copper, so I'm fairly certain I trashed whatever is in there.Does anyone know of a method I could do at home which would let me get at the die?

author: Hypernova
author_rank: Unknown
timestamp: February 03, 2011, 03:54:51 am
content: Acid? Forgot which type that only eat away at the plastic.Might wanna do it out side of course.

author: Jon Chandler
author_rank: Frequent Contributor
timestamp: February 03, 2011, 04:03:08 am
content: Sparkfun did a series of posts on this subject while investigating some fake chips. There are at least 3 posts in the series:http://www.sparkfun.com/news/350http://www.sparkfun.com/news/364http://www.sparkfun.com/news/395There are also some additional columns on dissecting fake SD cards on Sparkfun.Jon

author: Lance
author_rank: Frequent Contributor
timestamp: February 03, 2011, 05:45:55 am
content: Wait, so why did fire not burn off the plastic?

author: Simon
author_rank: Unknown
timestamp: February 03, 2011, 06:22:55 am
content: must be fairly heat resistant but plastic will melt before burning at which point you have already made a mess. Who said the chip inside is fire proof ?

author: DJPhil
author_rank: Frequent Contributor
timestamp: February 03, 2011, 08:25:15 am
content: Quote from: Hypernova on February 03, 2011, 03:54:51 amNitric or maybe sulfuric should work. It'll need to be strong enough to require lots of protective gear and a fume hood. I might try this with a few old chips I have next summer.

author: Hypernova
author_rank: Unknown
timestamp: February 03, 2011, 02:12:46 pm
content: Quote from: Simon on February 03, 2011, 06:22:55 amNot all plastic melt, some will simply burn. That's why not all of them are recyclable as you can't melt them down to make new things.

author: Lance
author_rank: Frequent Contributor
timestamp: February 03, 2011, 05:48:02 pm
content: Quote from: Simon on February 03, 2011, 06:22:55 amI was getting green flames. I'm fairly sure I trashed whatever was inside that case. There was a paper sticker that had pin labels on it which I couldn't get fully off. The fire stripped the remaining paper right off! It did form a really cool effect though. Imagine a microchip, reentering the atmosphere. It looked awesome.So lesson learned, they don't pick cheap plastic for these things. Is acid really the only way to go here?

author: armandas
author_rank: Frequent Contributor
timestamp: February 03, 2011, 09:07:26 pm
content: Quote from: Lance on February 03, 2011, 05:48:02 pmI've said it before, and I'll say it again: if you just want to extract the die, burning is the easiest way. I've never seen a chip package that melts instead of burning to ashes, can you post pics of what it looked like?When the chip is sufficiently charred, you should be able to use a hammer or pliers to break the package and find a little piece of silicon inside.

author: Lance
author_rank: Frequent Contributor
timestamp: February 03, 2011, 10:15:18 pm
content: Unfourtinately I binned it. The plastic literally just sat there. It bent and expanded a little in the middle, and my attempts at removing the plastic failed. Is there a specific type of fire source that works better? I used a handheld propane torch.

author: armandas
author_rank: Frequent Contributor
timestamp: February 03, 2011, 11:08:17 pm
content: I've got a cheapy torch from ebay, so nothing special. You could try your luck with different chips you have any. IC's are not hard to come by.

author: TopherTheME
author_rank: Regular Contributor
timestamp: February 03, 2011, 11:20:52 pm
content: You need to use a high molar nitric acid to remove the encasing. I don't know of any other method besides sanding or sandblasting that will give you any real results.

author: Lance
author_rank: Frequent Contributor
timestamp: February 04, 2011, 12:03:03 am
content: Quote from: armandas on February 03, 2011, 11:08:17 pmTrue enough, but I'd prefer to not destroy any working technology, at least until I get a viable technique going. So far I've been experimenting with dead chips.Quote from: TopherTheME on February 03, 2011, 11:20:52 pmI tried sanding already, it trashed the die.

author: Wim_L
author_rank: Regular Contributor
timestamp: February 04, 2011, 02:34:57 am
content: It's very unlikely that a small blowtorch would reach sufficient temperatures to really damage the silicon. Worst case you'd oxidise the surface a bit further. Do make sure you have a plastic and not a ceramic DIP. Ceramic won't burn, though the glue holding the parts together probably would.For acid, nitric is certainly more versatile. Sulfuric has a reputation for burning very hard, but that's mostly for biological matter (it certainly damages humans quickly). Nitric usually is the better bet if you want to dissolve something. Or in some cases specialised mixtures like aqua regia.Oh, and ventilate well. If concentrated nitric acid gets too warm or digests a lot of metal, it will form NO2, which is a nasty poison with effects (lung edema) that can be delayed for hours. Something to be careful with if you value your lungs.

author: Lance
author_rank: Frequent Contributor
timestamp: February 04, 2011, 06:34:47 am
content: Quote from: Wim_L on February 04, 2011, 02:34:57 amMy lungs are kind of important. The more I learn, the more I see I'm NOT equipped to deal with this at home. It's definitely plastic, unless Microchip's PIC18 devices are made out of some ceramic that really feels a lot like plastic.It wasn't a small torch, but it wasn't particularly huge. How hot do you need to get before you damage the silicon? Also, if I remember correctly aren't these semiconductors encased in a thin layer of glass?

author: RayJones
author_rank: Frequent Contributor
timestamp: February 04, 2011, 07:28:04 am
content: Many ceramic chips simply had a lid soldered on following wafer installation and lead bonding. Lead as in the fine gold wires, not the heavy metal!They would be real easy to expose.

author: Lance
author_rank: Frequent Contributor
timestamp: February 05, 2011, 02:33:58 am
content: Okay, so it turns out that I have a readily available source of Z80's available. I wonder if getting inside those would be any easier.

author: Zero999
author_rank: Super Contributor
timestamp: February 05, 2011, 10:20:13 am
content: Careful removal of the package can be used to disable code protection and enable reverse engineering.http://www.cl.cam.ac.uk/~sps32/mcu_lock.html

author: Lance
author_rank: Frequent Contributor
timestamp: February 05, 2011, 06:52:13 pm
content: Be that as it may, I'm not interested in reverse engineering. I just wanna get at some dies. So it's looking like nitric acid is the only way to go. Acetone apparently won't work on this stuff, and they're apparently built to survive some really stupidly high temperatures.

author: Wim_L
author_rank: Regular Contributor
timestamp: February 05, 2011, 09:54:11 pm
content: Quote from: Lance on February 04, 2011, 06:34:47 amVery hot. Melting point of pure silicon is over 1400 degrees, so if it isn't glowing bright red, it'll keep its shape. But it will be chemicall altered somewhat at the surface.And yes, just about every silicon semicondictor is encased in "glass", if you can call it that. It's really surface oxidation of the silicon, through a high temperature with oxygen and/or water, forming silicon dioxide, the main component of glass. When heating the chip with a burner, you'll grow this layer some more, making it thicker. This will affect the visual appearance somewhat, mostly by making the colours different, because the colour of reflected light depends on the thickness of that thin layer. The effect is rather obvious when heating a silicon wafer over a small area. It discolours visibly because the oxide layer becomes thicker.

author: Lance
author_rank: Frequent Contributor
timestamp: February 07, 2011, 08:55:40 pm
content: Good news everyone! I managed to crack open a ceramic intel chip by driving a flathead screwdriver into the side with a hammer. It broke the top right off, and the IC is undamaged! There's a few microscopic bits of ceramic on it, but other then that it looks fine. I'm going to see if a similar method will work for a plastic device.

author: osmosis321
author_rank: Regular Contributor
timestamp: February 08, 2011, 06:08:07 pm
content: QuoteWords of exceptional wisdom.

author: Lance
author_rank: Frequent Contributor
timestamp: February 08, 2011, 06:22:47 pm
content: Quite. I would love to take some pictures of this thing with my microscope, but I don't have the hardware for it.