Tuesday, 14 June 2016

microcontroller - Can I cut an IC?


As far as I understand, the die of a DIP package is located at the center and the rest is just the lead frame. Given that I have unused pins, can I cut the top part of this microcontroller (ATmega16/32)? Will it still function afterwards?enter image description here


Edit: thank you for all the answers. I have realized that cutting an IC is a delicate process and there is a high risk of damaging the chip. But I've done it anyway, shear cutters worked a treat. I decided to go for the 3 lower pins instead of the upper ones since they are further away from the ISP connector. Here is a photo of the final result (My new DIP-34 package works just fine):


enter image description here



Answer



How do you intend to do this butchery?


Unless you have very specialized tools, a Dremel cutting disk or something like that could generate a lot of static charges. Well enough to kill the chip!



Moreover, mechanical stresses could damage the internal bond wires, or even the die. Let alone you would have the bond wires to the cut-off pins protruding flush from the cut side (8 of them), maybe shorted together due to harsh mechanical stresses during the butchering action.


People needing to reverse-engineer a chip do this kind of things, but they use much more "delicate" measures. Moreover, they want to expose the die, so they "cut" off the upper part of the package.


In particular see this link about decapsulation of the chip or this video showing LASER decapsulation.


Google for "chip decapsulation" and you'll find tons of references and you'll understand why it is a costly process if you want your die to survive! People pay big bucks to reverse engineer chips (both for legitimate and criminal purposes). Legitimate purposes comprise failure analysis ("Why our top notch IC failed unexpectedly?!? Let's crack it open and see what happened!") or retrieving lost designs ("OK, we acquired this little IC design house with these excellent parts. But, wait! Where are the design sheets of the groundbreaking HQC954888PXQ processor?!? Who fired the design engineers who knew?!?" - Yes these things happen!).


BTW, Did I mention all these methods are delicate?!? Side cutters are not what I could call delicate. When I was a boy I remember cutting a (dead) IC to see the die using a big side cutter: it splintered wildly!


YMMV!


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