Tech For Fun have a how-to guide and walkthrough on some simple home techniques for decapsulating integrated circuits for discovery and observation.
Decapsulating is the process of removing the epoxy capsule that protects the integrated circuit. The purpose of removing this epoxy is to access to the silicon die in order to analyse it under microscope or perform a live attack.
There are several ways to remove the encapsulation, but the most commons are chemical attack with acid, softening the epoxy with heat or removing it mechanically with, for example, sand paper (very useful when a ceramic encapsulation is used instead of epoxy). Normally we apply several of these procedures in order to decapsulate the IC.
The guide comes with a strong red-text disclaimer so proceed with caution as you will be doing some risky chemistry procedures like so:
This process of opening things up, and boiling away all the obtrusive epoxy, can you lead you down pretty remarkable avenues of discovery.
Here’s a photo of a decapsulated PIC16F84:
Even with naked eyes you can distinguish the microcontroller blocks like the Flash, EEPROM, RAM and the ALU. This photo has been made with a 12 megapixel camera from a distance of 70 cm, without a macro objetive, and some blocks are recognizable
And from there you can get even closer to the brain of the IC. For example here’s a close-up of a 74HC04 hex inverter:
From there certain aspects of the ICs design or datasheet may begin to become more apparent, or make sense visually as you can observe the paths and layout of the internals of the IC directly!
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