Decap, also called de-capping or lid removal, means locally etching a fully packaged IC so that the chip is exposed while its function remains intact, preparing it for the next step of chip failure analysis and making it easier to observe or carry out other tests.

Purpose of decapsulation testing

After decapsulation, the surface condition of the die can be clearly seen: whether there is chipping or cracking in the scribe lines, whether there are abnormalities on the chip surface, the chip logo information, the chip dimensions and bonding wire diameter, the bonding wire material, the integrity of the passivation layer and other internal information about the chip.

Decapsulation methods

1. Laser decapsulation

Laser decapsulation mainly uses a laser beam to remove the moulding compound from the surface of the IC sample. Its advantages are speed, little damage to the bonding wires and chip, and no danger.

2. Chemical decapsulation

Chemical reagents that efficiently decompose plastic materials are used, such as fuming nitric acid and concentrated sulfuric acid. The main procedure: drip the chemical reagent onto the surface of the IC package, wait until the polymer resin is etched into low-molecular-weight compounds, then hold the sample with tweezers, clean off the low-molecular-weight compounds in a glass dish with acetone in an ultrasonic cleaner, and dry with a hot air blower to expose the chip surface.

Results after decapsulation

Packages that can be decapsulated

COB, BGA, QFP, QFN, SOT, TO, DIP, BGA, COB ceramic, metal and other special packages.