UTILIZATION OF THE IPC B52 TEST BOARD FOR PLATFORM RELEASE IN THE AUTOMOTIVE INDUSTRY

摘要

Miniaturization and increasing voltage for e-mobility solutions both are a big challenge for the design of robust electronic devices in the automotive industry considering the harsh environmental conditions that they work in. The operation of electronic control units (ECU) in humid environments can lead to electrochemical migration (ECM) that can cause unpredictable electrical failures in cases where unsuitable materials, processes, or housing concepts are used. Due to the variety of components, materials, and assembly steps, following the common no-clean approach in the automotive industry, a complex mixture of materials with a specific ionic load and hygroscopic behavior is combined on a printed circuit board assembly (PCBA) in a way that the electrochemical reliability is not easily predictable. The simple measurement of ionic contaminants on PCBAs, as widely assumed, does not predict the reliability of the unit in the end-use-environment. Therefore, reliability testing by measurement of the surface insulation resistance (SIR) of the combination of materials that are used and processed on high volume electronic assembly lines is a fundamental task for the automotive industry. Robert Bosch GmbH has established the B52 test board (IPC-9202) and developed it further in a way that it can be used as a base for material and process release on an ECU-platform level. SIR-results from long-term testing (constant climate conditions) and from damp heat testing (environmental testing following IEC60068-3-4) with B52 test boards are presented. The results show that even under high humidity load reliable electronic devices can be achieved with the benefit of no-clean fluxes, if suitable materials and processes are chosen and controlled. The approach and results confirm that the B52 test board and content of the IPC-9202 can be successfully transferred and applied to the requirements of the automotive industry if improvements are considered. These should become part of further international standardization.