Issue link: https://iconnect007.uberflip.com/i/1357726
44 SMT007 MAGAZINE I APRIL 2021 3. Known good devices. Comparing incoming parts with a golden sample is a good way of searching for coun- terfeits. Figure 2 illustrates how different two devices from a single batch look. To compare accurately, check the lot code, the date code, the part numbers, the place of manufacturer, any external markings, and the construction of the device. 4. Pinout mismatch. e layout of the lead-frame and the wire bond diagram tells you plenty about the compo- nent. Check whether they differ when the wire bond diagram is overlaid on the X-ray image. In Figure 3, you can see the discrepancy in the VPP and VDD pins. 5. Missing wire bonds. An X-ray image can show missing wire bonds, indicating potential for counterfeit and the need for further analysis. However, beware that alumi- num wire bonds do not show in X-ray images, so this could produce a false fail (Figure 4). 6. Internal defects raise red flags. A full inspection of a part can validate mechani- cal integrity. For example, in Figure 5 a wire bond ball and a loop can be seen inside that package. is doesn't confirm the component is a fake, but it should sound alarm bells. 7. External defects. External defects are a pointer to improper handling of a component. Figure 6 shows a ball grid array (BGA) component with dam- Figure 2: Illustration of how different two devices might look from a single batch. Figure 3: Example of a discrepancy in the VPP and VDD pins. Figure 4: Example of missing wire bonds. Figure 5: A wire bond ball and loop inside a package should sound alarm bells. Figure 6: Example of a BGA component with damaged solder balls.