Lubrication for Micro Forming of Ultra Thin Metal Foil

The objective of the present investigation is to establish lubrication technique in micro forming operation. Conventional lubricant, in general, cannot be applied directly to micro forming process, since the lubricant thickness is similar to the dimensions of feature size in micro forming operations. In present investigation, the Octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) was chosen as a potential lubricant because it sticks to Si wafer die and can be applied to surface with uniform thickness of several nanometer thick. Friction coefficient and adhesion force were measured for OTS SAM coated wafer. It is shown that OTS SAM coated Si wafer offers substantially lower friction and lower adhesion than bare Si wafer. Micro channel wafer die was coated with OTS SAM and channel forming operation with 1μm thick copper foil was carried out. Experimental results show that OTS SAM coated wafer die improves forming characteristic of ultra thin copper foil substantially. These results show that SAM coating can be used as a lubricant in micro forming successfully.