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| tutorial:tutorial_on_epoxy_decapsulation [2014/02/04 02:46] – azonenberg | tutorial:tutorial_on_epoxy_decapsulation [2014/02/04 02:46] (current) – [Decapsulation] azonenberg | ||
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| * Acetone and wash bottle | * Acetone and wash bottle | ||
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| Nitric acid is quite dangerous so proper safety equipment is a must. I wear a lab coat, splash goggles, and neoprene or Norfoil gloves at all times when doing decapping work. A fume hood is strongly recommended, | Nitric acid is quite dangerous so proper safety equipment is a must. I wear a lab coat, splash goggles, and neoprene or Norfoil gloves at all times when doing decapping work. A fume hood is strongly recommended, | ||
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| When the chip is hot enough, place a single drop of acid on the center of the package, or inside the well if it was pre-drilled. Take care not to let any spill onto the pins; this is most critical in small QFP/QFN packages where the leads will be very close to the acid. Large packages such as PDIPs, as well as leadless SMD packages (LGA/ | When the chip is hot enough, place a single drop of acid on the center of the package, or inside the well if it was pre-drilled. Take care not to let any spill onto the pins; this is most critical in small QFP/QFN packages where the leads will be very close to the acid. Large packages such as PDIPs, as well as leadless SMD packages (LGA/ | ||
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| The acid will appear colorless at first, then as it heats up bubbles will form, sometimes followed by a yellowish-white foam. As the acid finishes reacting the foam will disappear. If the acid shows no reaction or just releases a few bubbles the chip isn't hot enough. In case of very soft epoxy with a fast etch rate, the foam may turn black from package fragments. | The acid will appear colorless at first, then as it heats up bubbles will form, sometimes followed by a yellowish-white foam. As the acid finishes reacting the foam will disappear. If the acid shows no reaction or just releases a few bubbles the chip isn't hot enough. In case of very soft epoxy with a fast etch rate, the foam may turn black from package fragments. | ||
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| Immediately after the foam begins to subside, remove the chip from the tray with tweezers and rinse it with acetone over a beaker. (Be careful not to boil the chip dry; this will cause the fragments to stick to the die.) Use fairly high pressure to dislodge debris. | Immediately after the foam begins to subside, remove the chip from the tray with tweezers and rinse it with acetone over a beaker. (Be careful not to boil the chip dry; this will cause the fragments to stick to the die.) Use fairly high pressure to dislodge debris. | ||
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| Return the chip to heat and repeat several times. Make sure the solvent has completely baked off before adding more acid. Eventually, bond wires become visible: | Return the chip to heat and repeat several times. Make sure the solvent has completely baked off before adding more acid. Eventually, bond wires become visible: | ||