Electrochemical migration properties of fine pitch chip-on-flex (COF) for displays were investigated by a water drop test and scanning electron microscope with energy dispersive spectroscopy. While the time to failure due to ECM is less than 1 s at a direct current (DC) bias of 10 V, it is approximately 330 s at an alternating current (AC) bias of 10 V 10 Hz and approximately 3,940 s at 240 Hz. The ECM failure mode due to AC bias appears to be caused by limitations on the degree of ion diffusion and relatively small changes of the pH, unlike the DC bias case.

The present study investigates the degradation mechanism of a methanesulfonic acid (MSA) based electroplating bath used for the electrodeposition of Sn-Ag alloy solder bumps, and its effects on the microstructure of the solder and on the collapse failure of flip-chip solder bumps. To examine the degradation behavior of the electroplating bath, a degraded electrolyte is prepared by accelerated aging treatment. In the presence of dissolved oxygen and Ag + ions in the electrolyte, the chemical oxidation of