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July 2017 • SMT Magazine 27 COUNTERFEIT ELECTRONIC COMPONENTS IDENTIFICATION: A CASE STUDY the mold compound in order to make a visible marking. The groove or depth can vary depending upon the speed, power, and pulse rate of the laser marker. To measure this, special depth measuring equipment is required due to the small dimension of the groove 8 . As indicated by Figure 6, a clear difference is noticed by the texture of the marking. Since the depth of the etching or removing of mold compound can be detrimental to the function of the semiconductor device, it is important to control the depth. The marking from the dis- tributor part is smooth, whereas the marking from the broker is course and the presence of glass beads in the marking area indicate im- proper marking. FTIR Fourier transform infrared spectroscopy (FTIR) 9 is a technique used to obtain an infra- red spectrum of absorption or emission of a sol- id, liquid or gas. A FTIR spectrometer simultane- ously collects high spectral resolution data over a wide spectral range. This confers a significant advantage over a dispersive spectrometer, which measures intensity over a narrow range of wave- lengths at a time 10 . For this evaluation FTIR was used to evaluate the integrity of organic mold compound. When a blacktopping process is used to re-mark previously used parts, FTIR pro- vides the ability to distinguish between two dif- ferent materials. The materials that comprise the component body and any blacktopping ma- terial used to hide the evidence of counterfeit- ing are all organic polymers. As indicated by the spectroscopy measurement in Figure 7, there is a clear difference in response between parts. Us- ing the distributor part as the baseline, the re- sponse from the broker parts suggests a differ- ent material is present. Blacktopping material is added to the baseline material and therefore would create a different response from the base- line. This measurement is one more indication of inconsistency between two different suppli- er parts. Figure 5: Mold compound surface with different texture, color and consistency. Figure 6: Laser marking on mold compound, with smooth surface versus rough.