Updated: Oct 25, 2019
Decapsulation is the process of removing the outer material from a semiconductor to reveal the die that is contained within the device. This can be accomplished in various ways depending on the material that the outer body of the semiconductor. PEM semiconductors are covered with a resin and the resin is generally removed by a chemical process. Chemicals such as sulfuric acid and fuming nitric acid will dissolve the resin without damaging the die when heated. Ceramic semiconductors that are hermetically sealed can be decapped by forcing or cutting the top section from the bottom. Metal cans can be decapped by the use of a cutting instrument such as a diamond saw. Decapping the part to reveal the die is only the beginning of the process. Once the die is available for optical examination the die must be viewed under a fairly high magnification for examination of the die layout, and die markings. Since not all die markings clearly identify the part, the die of a known good device for comparison is the best method to determine if the die is authentic. However, if this is not an option there are some items to look for:
1) Is the manufacturer’s name or logo on the die?
2) Is there part marking on the die that is consistent with the part number on the part itself?
3) Are there trademark and or copyright marks? If so is the copyright date consistent with the part itself?
4) Is there any other marking that can be used to identify the part? Some manufacturers use a “code” to identify a part.
5) Is the die layout consistent with the part? If you have a schematic of the die layout is it comparable to the die?
One major drawback in relying on die comparisons is that they do not necessarily designate the speed or temperature grade of the part. Most commercial and industrial temp parts will use the same die for the part. The difference in the temperature or reliability of a part is usually determined by the amount of testing done to the part after it is assembled. Some manufacturers use the same die for multiple part numbers so verification can sometimes be difficult and may lead to the false identification of a part as counterfeit that is not . Some die may be cross licensed or be manufactured by a secondary vendor where the manufacturer indicated by the die may not be the manufacturer that is indicated by the part itself