Counterfeit Detection Using X-Ray Image as a Fingerprint
Taggants have been widely adopted in the fight against counterfeit components. The process of applying taggants to components consists of first determining the authenticity of the part. This step can be achieved by either knowing that the component is authentic (by a well-documented chain of custody from the original component manufacturer), or by running a batch of tests to sufficiently determine the conformity of the component to its original specifications. Taggants are often chemical compounds with a unique mix of elements that are embedded into the surface of the component. This unique mix effectively introduces a fingerprint to the component, and the combination of component identification and fingerprint is carefully uploaded to a database. Later in the supply chain, the taggant can be read back by special sensors to verify that the component and the attached fingerprint match as in the database. Some of the shortcomings of this method include the need to prepare this unique compound, the need to correctly apply it to the surface of the component, and the need to use expensive sensors to read back the fingerprint of the component at the point of use. There is also the risk that the taggant might end up in the wrong hands, which would allow such individuals to criminally authenticate counterfeit components. The other major shortcoming of taggants relate to the authenticity protection of printed circuit board assemblies (PCBA). PCBAs can be considered electronic systems, each with hundreds or thousands of electronic components. Thus, the application of a unique taggant to each component is not feasible. In this work, we introduce the use of the x-ray image as the unique fingerprint for an electronic component or PCBA. Unique features of the x-ray image such as solder voids, cracks, part alignment, die attach porosity and voiding, die placement and alignment, and wire bonding diagram. These are just a few of the many features in the x-ray image that can be used in tandem to create a unique fingerprint for a single component or an entire PCBA. This technique can also be expanded to mechanical objects by utilizing other idiosyncratic features of the part – such as voids and porosity – to generate the x-ray image fingerprint.
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Counterfeit Detection Using X-Ray Image as a Fingerprint
- 1. www.creativeelectron.com Dr. Glen ThomasSMTA International October 12-15, 2018 1 X-Ray Fingerprinting
- 2. www.creativeelectron.com Summary • Introduction to X-ray inspection • X-ray inspection – Detection of counterfeited parts – Validation of certified parts 2
- 3. www.creativeelectron.com “Authentication” vs “validation” • Authentication: the process or action of proving or showing something to be true or genuine. • Validation: the action of making or declaring something legally or officially acceptable. 3
- 4. www.creativeelectron.com Detection & authentication process Part to be validated Set of tests to rule out the part as counterfeited X-ray fingerprint validation Good Bad Discard/quarantine Detection Validation
- 5. www.creativeelectron.com 2D x-ray imaging Slide 5 Imaging Analysis 1. X-ray Tube Produces high resolution x-ray beam cone 2. Flat Panel 3. Computer Analyzes Image PCB
- 6. www.creativeelectron.com Penetration Density and Thickness Slide 6 PCB’s & Solder Joint materials block x-rays based on: ◆ Material Density (Lead, Copper, Plastics, Heat Sinks, etc.) ◆ Material Thickness t Lightest - Darkest
- 7. www.creativeelectron.com Field of View (FOV) FOV Influences: • Test Throughput • Resolution / Detection • Clearance .25 in 6.4 mm 1.0 in 25.4mm .5 in 12.7 mm Low Resolution Higher Resolution Larger FOV Smaller FOV 7
- 8. www.creativeelectron.com Resolution • Resolution is measured as Line Pairs – X-ray Tube spot size – Detector resolution – Field ofView • Resolution Influences – Clarity of image – Measurement repeatability – Detection capabilities – False calls Slide 8 .5in (12.5mm) FOV 1in (25mm) FOV
- 9. www.creativeelectron.com • Even though they look identical in the outside, sometimes components are just empty in the inside.These images are 3D renderings of the internal structures of 2 components in the same lot. 1Ÿ Empty package Good Component Counterfeited Component
- 10. www.creativeelectron.com • It is critical to inspect 100% of the parts – so you don’t get fooled by criminals who mix bad parts with the good ones. Can you tell which one doesn’t belong? 2Ÿ Lot anomalies
- 11. www.creativeelectron.com • Finding a counterfeit component becomes easy if you have a known good sample to use as a reference part. Check how different these two parts – found in the same lot – look from each other. 3Ÿ Different from known good sample Good Component Counterfeited Component ¡ When comparing components, make sure the following is identical between the parts: § Lot code § Date code § Part number § Place of manufacturing § External markings § Construction ¡ 100% visual inspection is highly recommended
- 12. www.creativeelectron.com • The layout of the lead frame and the wire bond diagram tell a lot about the component. On the left, you can tell whereVDD, GND, and no connect (NC) are located. Check how they differ when overlaid with the part’s real pinout (on the right). 4Ÿ Pinout mismatch Pin location analysis Overlay of real pinout with analysis to show discrepancies
- 13. www.creativeelectron.com • If the x-ray image of a component does not show the presence of wire bonds, further analysis is needed. Either it is a counterfeited part with no wire bonds, or it is a component with aluminum wire bonds.Aluminum is a light material that does not show in x-ray images. 5Ÿ Missing wire bonds
- 14. www.creativeelectron.com • A complete inspection of the part is needed to validate its mechanical integrity. In this example we can see the wire bond ball (right) and the loop (left) laying around the package.Although this information is insufficient to assess it is a counterfeit, it should raise many red flags. 6Ÿ Internal defects
- 15. www.creativeelectron.com • The rotation and tilt of the sample can reveal defects imperceptible otherwise.The defects on these balls are very difficult to observe from a straight x-ray picture. 7Ÿ External defects Image of BGA part inside sealed tray
- 16. www.creativeelectron.com • Counterfeiters like to pull components out of old boards to resell them as new. • However, when they pull BGAs, counterfeiters need to have the parts re-balled. • In that process voids inside the balls are created. So excessive voiding may indicated a counterfeited component. 8Ÿ Excessive BGA voids BGA Inspector identified excessive voiding in this part
- 17. www.creativeelectron.com • Components inside trays, tubes, and tape have to be perfect. Suspect components with bent pins – that usually means they have been handled outside the original package. 9Ÿ Bent pins
- 18. www.creativeelectron.com • Electronic component manufacturers heavily invest the consistency of the products they ship. If you find a few of the components in a lot with anomalous die attach voiding, like the one in this example, suspect the overall quality of the part and the lot. It may have been stored in inappropriate thermal conditions. In other words – it was likely stored in very hot and/or humid environments. 10Ÿ Excess die attach voiding
- 19. www.creativeelectron.com Now that we’re done testing the component, how to validate it? 19
- 20. www.creativeelectron.com X-ray fingerprint vs chemical tagging X-ray fingerprint • Utilizes sample features to uniquely identify part • Works in all samples with radiopaque features • Utilizes installed x-ray machines to encrypt/decrypt code • No special training or certifications required • Can show changes to sample, specially temp cycles • Nothing to secure but sample 20 Chemical tagging • Inserts foreign material to uniquely identify part • Limited to surface preparation • Requires new systems to make and prepare taggants. Special systems to read back • Extensive training and certification required • Not impacted by physical changes applied to sample • Need to secure taggant in safe and temp controlled storage
- 21. www.creativeelectron.com How to use the x-ray image as a fingerprint? • What we usually consider ”defects” in an assembly can be used as unique identifiers • Identifiers are unique to each component and each PCB assembly • Features change if component is reworked from PCB • Fast and easy way to set authenticity timeline to PCB assembly and components • Doesn’t work for all components – works for all PCB assemblies 21
- 22. www.creativeelectron.com X-Ray fingerprint features • Wire bonds • Die attach voids • Component solder voids • Pin alignment • Solder distribution • Fillets on pads • Through-hole via fills • Other features 22
- 25. www.creativeelectron.com Encryption algorithm on image 25
- 28. www.creativeelectron.com Component level: Cu wire bonds 28
- 32. www.creativeelectron.com Mechanical devices: injection molded respirator 32
- 34. www.creativeelectron.com Conclusion • X-ray image used as the unique identifier to recognize sample – fingerprint • Utilizes installed x-ray machines – no need to acquire new equipment • No extra material needs to be inserted in sample • No need to store, maintain, and prepare taggant • Robust inspection technique • No extra training required • Image acquisition is part of the detection stage, thus little overhead required 34
- 35. www.creativeelectron.com Thanks for your time! +1 760.752.1192 info@creativeelectron.com www.creativeelectron.com 35