A Novel Milling Method in Integrated Heat Spreader Detachment to Preserve Surface Mount Devices in High Performance Product

This paper presents the pre-shear milling in the integrated heat spreader (IHS) detachment process for samples with surface mounted devices (SMD) proximity to the IHS at 0.5mm or less in X and Y linear position on the substrate and with SMD covered with sealants. IHS milling technique is a complementary process to mechanical shearing that provide safe environment for IHS to be sheared without damaging SMD components. Milling is achieved using Computer Numerical Control (CNC) and is applicable for high performance product with solder thermal interface material (STIM) in land grid array (LGA) and ball grid array (BGA) packages. Both shearing and milling mechanisms are discussed including CNC milling methodology supported by IHS surface profile topology data. More discussions touch upon the drawbacks of the conventional approach to shearing and presents an enhanced approach to IHS shearing techniques and important shearing criteria including IHS heating thermal profile required for STIM samples.