A Perturbation Analysis of the Electroforming Process

A theoretical model of electroforming, which includes the effects of current efficiency and periodic reversal of polarity, is derived. The model is analysed by a perturbation procedure for a case where a metal layer is formed upon a mandrel-electrode carrying sinusoidal irregularities on its surface. Analytic solutions of the resulting equations are shown to be so complicated that numerical methods offer the best means of solution. The latter methods are therefore used to demonstrate how the achievement of a uniform thickness for the layer is influenced by the time intervals of the polarity-cycle and the current efficiencies for deposition and dissolution. Extensions of the model to cover arbitrarily shaped surfaces on the mandrel are shown to impose limitations on the amplitude of the irregularities that can be so treated.