Key Properties for Successful Ultra Thin Die Pickup

The four major key properties for successful, damage-free ultra thin die (<; 50 um) pickup from a wafer foil are described in detail: die bending stress, die strength, edge peel force, and bulk peel force. First, bending stress for different pickup methods (multi stage, multi disc, multi needle) are calculated and compared using a dynamic FEA model. Second, we summarize how the die strength is influenced by die structures and wafer processing steps, especially by thinning and dicing methods. In addition, we present die strength measurements for TSV test dies. Third, the property “wafer foil edge peel force” is introduced, and the dependency on the dicing method is experimentally verified. It clearly shows, that dicing-before-grinding is to be preferred over single cut dicing. Fourth, we give an overview of bulk peel forces of various commercial wafer foils. Values are taken from datasheet specifications, and compared using Kendall's equation.