Novel Method for High Reliability Assembly of Microwave QFN Packages for Extreme Thermal Cycling Applications

This paper presents a Quad-Flat no Leads (QFN) package assembly method which has successfully passed the strict assembly process verification flow requested by the European Space Agency (ESA) standards. Getting QFNs approved for space missions is crucial as some devices are only available in this execution, but their history of failures when submitted to continuous thermal cycling makes its approval a tough task. These problems take special relevance in Low Earth Orbit (LEO) satellites because of the short orbital periods transiting from shade to direct sunlight. Design concepts, manufacturing techniques and test results are presented here to validate the proposed QFN package assembly method.