A micro-electroforming simulation model with dynamic diffusion coefficient for predicting void defects in microstructure

To help reduce or eliminate the void defects, it is critical to accurately predict the size of void defects prior to electroforming experiments. In this study, the limiting current density of nickel ion inside the microchannels of the cathode with a depth of 60
$\boldsymbol{\mu\mathrm{m}}$
and a width from 24 to 120
$\boldsymbol{\mu\mathrm{m}}$
are tested by electrochemical experiments. The diffusion layer thickness is assumed to the microchannel depth, and the measured diffusion coefficient are from
$\boldsymbol{1.27\times 10^{-9}\mathrm{m}^{2}/\mathrm{s}}$
to
$\boldsymbol{4.74\times 10^{-9}\mathrm{m}^{2}/\mathrm{s}}$
, corresponding to the different microchannel with different aspect ratio (2.5:1 to 1:2). The simulation models of dynamic diffusion coefficient and constant diffusion coefficient are established, and the corresponding simulation results are compared with the void defects obtained by micro-electroforming experiments. The results show that when the cathode current densities is 2 A/dm
²
and 4 A/dm
²
, the size of void defects obtained by the dynamic model is closer to the experimental results.