Decapsulation is also known as Decapping or Delidding. A FA step performed to open a plastic package to facilitate the inspection, chemical analysis, or electrical examination of the die and the internal features of the package. There are several methods available:
Manual Chemical Etching : by using acid to remove the plastic material covering the die. A cavity is first milled on the top surface of the package. Either nitric acid (85°C) or sulfuric acid (140°C) is then repeatedly dropped into the cavity until the die exposed adequately. The unit is then rinsed with acetone followed by D/I water, before being blow-dried.
this method is employed mainly to avoid the corrosive nature of chemical and when foreign material within the package is of interest of analysis. This technique involves heating the package followed by grinding, breaking, and cutting to separate the top part of the package from its bottom part. This technique destroys the bond wires but preserves the die if used properly.
This method removes plastic by making it react with a gas which will then be vented out of the chamber. It is very clean and selective to the exact point of decap.