Evaluation of Dendrite Growth between Electrodes with Different Shapes and Voltage Polarity

Electrochemical migration (ECM) is an ongoing reliability issue in the microelectronics industry. ECM is characterized by the presence of dendrites, which form between two electrodes with a nonzero electric potential difference and can lead to short circuits. This work is focused on the evaluation of the influence of electrode shapes and voltage polarity on dendrite growth. Several combinations of straight, oval, and angular shapes were tested, along with the changing polarity of the applied electric field. Water drop test (WDT) with 1.5 wt.% and 0.01 wt.% NaCl solution was used to examine ECM. The results show a difference in the dendrite growth depending on the electrode’s shapes and the voltage polarity. The longest time to failure (TTF) and the most remarkable differences between the different voltage polarities occurred when the combinations with the angular electrodes were tested.

I. Introduction

Electrochemical migration is a reliability problem in the electronics industry, which is nowadays very relevant mainly due to the trend of miniaturization of electronic components and the spacing between them. If the components are exposed to a harsh environment, the probability of failure caused by ECM increases [1, 2]. To improve the lifetime of the products and their reliability, which is important, especially in medical, automotive, or aerospace fields, it is necessary to consider all the factors influencing ECM [3]. The most critical factors include electrode material, temperature, relative humidity, contamination, substrate type, and voltage magnitude. Other factors affecting ECM are electrode solubility, metal ion migration rate, PCB absorbency, flux residue, evaporation, or electrode spacing [4].