Modified microscale pattern transfer without photolithography of substrates

Micro-dimple arrays have recently become a popular feature in tribology for improving the friction and lubrication performances of various mechanical components. Microscale pattern transfer without photolithography of substrates is a common electrochemical micromachining method to generate these micro-dimple arrays with controlled size, location, and density. It is still a challenge to reduce the ratio of etched micro-dimple diameter and mask hole diameter in microscale pattern transfer without photolithography of substrates. In this paper, a modified microscale pattern transfer without photolithography of substrates, through movable dry-film mask electrochemical micromachining, is proposed to allow a reduction of the ratio. In this method, an electrochemical tool carrying a dry-film mask with the pattern of perforations keeps in close contact with the anodic workpiece surface during electrochemical machining. The proposed technology offers some unique advantages such as re-use of the mask and avoiding removal of photoresist. Simulation results indicate that the presented method might reduce the ratio, and experiments verify that this approach is effective in reducing the ratio. Finally, 22,500 micro-dimples of 109.4 μm in diameter and 15.1 μm in depth were prepared in 4 min, with the ratio of micro-dimple diameter and mask hole diameter being only 1.09 at the etched depth of 15.1 μm.