Attack CPLD Chip program memory and data memory, cut off the security fuse bit by focus ion beam which is one of the most technique in microcontroller unlocking, and readout the firmware from CPLD memory;

Attack CPLD Chip program memory and data memory, cut off the security fuse bit by focus ion beam which is one of the most technique in microcontroller unlocking, and readout the firmware from CPLD memory

The process of manual decapsulation usually starts with milling a hole in the package so that the acid will affect only the desired area above the chip die (Figure 50). The tools necessary for this operation are available from any DIY shop for less than £10.

The commonly used etching agent for plastic packages is fuming nitric acid (>95 %), which is a solution of nitrogen dioxide NO2 in concentrated nitric acid HNO3. It is very strong nitrifying and oxidizing agent; it causes plastic to carbonise, and it also affects copper and silver in the chip carrier island and pins. Sometime a mixture of fuming nitric acid and concentrated sulphuric acid H2SO4 is used. This speeds up the reaction with some types of packages and also prevents the silver used in bonding pads and chip carrier from reacting.

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