Reliability Investigations of Additive Manufactured RF-Structures on Low-Cost PCB Materials Based on Inkjet Technology

In this paper a reliability study of additively manufactured RF structures on printed circuit boards (PCB) based on inkjet technology is presented. First, the main focus is placed on the development of a suitable PCB test layout which contains microstrip lines, RF filters and ball grid array (BGA) structures. In order to ensure a good comparability with the standard subtractive technology, additive and standard manufactured structures are placed side by side. During our analysis both thermal and mechanical reliability tests were conducted. Possible changes in electrical properties were determined by subsequent RF measurements at multiple readouts. To our knowledge, for the first time an equivalent RF performance of additive and subtractive manufactured structures after stress tests up to 40 GHz was observed. Additionally, the compatibility of the additively manufactured structures with standard assembly processes are examined. Therefore, bond and solder tests are performed. Finally, an extensive assessment of all robustness tests is carried out and a recommendation about a future applicability in series products is given.