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52 I-CONNECT007 I REAL TIME WITH... IPC APEX EXPO 2023 SHOW & TELL MAGAZINE 52 I-CONNECT007 I REAL TIME WITH... IPC APEX EXPO 2023 SHOW & TELL MAGAZINE N olan Johnson speaks with Lothar Henneken, PhD, of Robert Bosch GmbH, whose paper, "Risk Predic- tion of Electrochemical Migration on Electronic Control Units—A Practical Approach," was of one of three papers that won the prestigious Best Technical Paper award in the Best of Conference category at IPC APEX EXPO 2023. [Dr. Henneken's] paper, which was presented during Technical Con- ference Session S25: QRTI-Assembly Risk Pre- diction and Failure Analysis, on Wednesday, Jan. 25, sought to mathematically model the risk of electronic failures in relation to cli- mate-related factors, such as local humidity, as well as a device's physical properties and the voltage applied. Dr. Henneken, you received an award for one of the best technical papers at IPC APEX EXPO this year. Tell me about it. What was your topic? My paper is about the reliability of electron- ics depending on the situation they are in. In a harsh or humid environment, the surface of electronic boards can get a little bit wet, which can cause undesirable parasitic cur- rents or shorts; but determining the likeli- hood of such failures occurring is highly complex. It depends on the local humidity and the microclimate inside the device and the distances, so fine pitch components are more critical than larger components. It's also driven by the voltage that is applied. It's very important for the world because com- plexity is just going up and up, meaning that we have a higher risk of such failures. What were your findings and conclusions? One problem is that there is not really a good lifetime risk prediction model. What we nor- mally do is apply a specific test, such as a sur- face insulation resistance test, for example, and this is always for a short time, based on some clearly defined climate distances on a constructure. That's not really realistic to what's happening on what level. The most critical point is that there is not really a tool available to give a prognosis if there is a prob- lem or not. If there is a change in material, or if there's a change to an assembly process, service, or shift in some components—or maybe copper distance is a little bit smaller— then a manager's typical question is, "What does it mean? Can I deliver it to you? I need the answer right now—I don't want to wait for a test that takes six months." Lothar Henneken, PhD Shedding Light on Reliability Risks Interview by Nolan Johnson

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