The Necessity of Temperature Humidity Bias Testing with High Voltages = 1000 VAuthors: Erik Biehl, Joachim Hink, Cindy Chak, Noel Jones, Sebastian Maass
Company: Robert Bosch GmbH, Automotive Electronics, Robert Bosch Company Ltd., Robert Bosch Pty. Ltd.
Date Published: 9/17/2017 Conference: SMTA International
Today all temperature humidity bias testing of PCBs e.g. IPC-TM 2.6.25A “Conductive Anodic Filament (CAF) Resistance” are related to voltages of up to 100 V. Voltages greater than 100 V are not fixed in any of the standards as a testing voltage. However, IPC-TM 2.6.25A does also state, that the bias voltage shall be two times higher than the operation voltage of the PCB for a correlation between testing and field. The life time equation from IPC 9691A indicates that isolation distances need to be increased according to voltage that is used. This equation is only valid for the failure mechanism from the formation of conductive anodic filaments (CAF).
This study introduces an approach with increased voltages up to 1000 V and test durations for existing test conditions such as 85º C / 85% RH to accommodate for this increase in demand from the product application and to take into account additional failure mechanisms that could become prevalent from the increased loading conditions.
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