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26 SMT Magazine • July 2017 COUNTERFEIT ELECTRONIC COMPONENTS IDENTIFICATION: A CASE STUDY Figure 3 as a reference, the left leadframe used by the distributor and the broker (in some lots) showed acceptable delamination between the mold compound and the leadframe. Howev- er, there was significant delamination between the interfaces in the right leadframe. Delamina- tion provided a source for trapping moisture in the part, which could lead to electrical issues in- cluding short circuits. Decapsulation Decapsulation of the packaged devices ex- poses the internal components of the package. Opening devices by decapsulation allows in- spection of the die, interconnects and other fea- tures typically examined during failure analysis. Device failure analysis often relies on the selec- tive etching of polymer encapsulants without compromising the integrity of the wire bonds and device layers. This is achieved by using mi- crowave plasma to cleanly remove encapsu- lant material 7 . Figure 4 reveals that through de- capsulation two different die were used for this SRAM. Although revealing, it does not immedi- ately suggest counterfeit, as it allows that there may have been die shrink. The date codes from the packages indicate the die and leadframe came from a part manufactured two years earli- er, with a different revision, and were therefore not for the same part. This is another indicator that using older parts with a new date and lot code suggest counterfeiting. The decapsulation results led to anoth- er evaluation of the mold compound to deter- mine if the package mold was replaced after re- use. Two areas were inspected, the mold com- pound surface and the laser marking. Figure 5 shows the texture of the mold compound sur- face of two packages, one from the distributor, and the other from the broker. It is clear under high magnification that there is a difference, suggesting two different mold compounds were used to encapsulate the die within the package from the two different sources. Evaluating laser marking to identify anom- alies involves close inspection of the surface of the mold compound. According to one OCM: In the process of adding a mark, the laser can cause damage to the underlying die or wires if it gets too deep into the package or compound. Basi- cally, the laser creates a groove by burning away Figure 4: Decapsulation of SRAM parts. Different leadframe, different die.