Session: 08-02 Mini-Symposium for Professor Dasgupta II

Paper Number: 92306

92306 - Electro-Chemical Migration in Aerosol-Jet Printed Electronics Using Temperature-Humidity and Water Droplet Testing Methods 

Additive manufacturing (AM) technologies nowadays are used not only to fabricate parts that meet specific structural requirements but also to build functional products, such as printing hybrid electronic (PHE) circuits. Aerosol-jet printing (AJP), with its extraordinary resolution, is one of the most important AM methods used in PHEs. Accordingly, it is important to understand the reliability of AJP printed electronics to ensure the high quality and robustness of printed products.

Electrochemical migration (ECM), resulting in ionic transport and conductive path formation between neighboring conductors, is one of the major degradation/failure mechanisms for electronic assemblies subjected to humid environments. In conventionally manufactured multilayer circuit boards, ECM may cause leakage currents through the formation of dendrites or sub-surface conductive filaments that bridge between features that are at different potentials; e.g., (i) neighboring traces; (ii) neighboring plated through holes (PTHs); or (iii) internal conductive layers.  In multi-layer ceramic capacitors (MLCCs), ECM may form dendrites between electrode layers along the surface of cracks in the intervening dielectric material. Although these kinds of phenomena have been widely studied in conventional circuit boards, the understanding of ECM in additively manufactured electronics is still not mature.

In this study, temperature-humidity-bias (THB) testing and water droplet (WD) testing have been conducted to study ECM across features in AJP printed patterns. Test specimen design has been guided by the IPC-9201 standard, and the testing conditions were guided by IPC-TM-650 2.6.14.1 standard and related research studies. Time-to-failure (TTF) for AJP printed silver patterns is found to be much smaller than that for conventional copper patterns in THB testing, under a similar voltage gradient between neighboring traces. However, the dendrite growth times are found to be identical between printed silver and copper patterns in water droplet (WD) testing. Furthermore, TTF for dendrite growth between neighboring biased conductors at constant temperature and humidity conditions was found to have a non-monotonic dependence on the electric potential gradient. The dendrite density was found to vary significantly with different applied voltage gradients. Those observations can help to guide future investigation and life-prediction modeling of AJP printed electronics subjected to combined temperature, humidity, and voltage stresses.

Presenting Author: Abhijit Dasgupta University of Maryland, College Park