| Decapsulation is a chemical
etching technique for opening IC plastic packages in order
to expose their internal components for examination. Although
physically destructive in nature, the process leaves the
die, bond pads, and wire bonds intact. |
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Several methods of decapsulation are available depending
upon the device and the customer’s requirements.
Such methods include jet etching, manual cavity etching,
and total package removal. Fuming nitric acid (HNO3),
sulfuric acid (H2SO4) or a mixture of the two acids are
used. |
Jet etching is an automated version of chemical decapsulation.
The jet etcher dispenses a stream of acid onto the package
creating a cavity and exposing the die. With manual
etching, a depression is first milled into the surface
of the package after which acid is dropped into the
cavity to dissolve the encapsulant over the die.
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Total package removal is performed by dissolving the
entire package in a beaker of sulfuric acid leaving
only the silicon die and some amount of undissolved
metal. This technique is primarily used to inspect for
cracks on the back of the die. |
