Mechanical and temperature resilience of multi-material systems for printed electronics packaging

Abstract

In this work, two AM technologies were utilized to compare the effectiveness of fabricating a simple electronic device with a conductive trace and hollow cylinder representative of 'printed packaging' that would survive harsh environmental conditions. The printed packaging cylinder delineates printed potting for electronics packaging. An nScrypt direct write (DW) system was the primary manufacturing system but a developing technology-coined large area projection sintering (LAPS)-manufactured a subset of samples for comparison. The tests follow Military Standard (MIL STD) 883 K and include resiliency evaluation for die shear strength, temperature cycling, thermal shock, and high G loading by mechanical shock. Results indicate DW Master Bond epoxy devices show resilience to extreme temperatures, thermal shock, and mechanical shocks while also surpassing the die shear strength failure criteria specified by the MIL STD. LAPS sintered Nylon devices also show mechanical resilience to thermal shock and surpass the die shear strength failure criteria. However, there were some open circuits, increases in resistance, and delamination when LAPS Nylon devices were subjected to extreme temperatures and 20 000 G shock loading normal to the substrate. The thermal effects are likely due to the thermal expansion mismatch between Nylon and the conductive paste while the mechanical shock effects may be attributed to the geometry differences of the LAPS Nylon printed packaging. Further studies are required to understand these failure modes in some of the LAPS Nylon samples and refine the process to address them.