The technique only works on CSP and flip-chip packaged devices. These are chips that are basically bare silicon die that are bonded onto PCBs or substrates. Th

The technique only works on CSP and flip-chip packaged devices. These are chips that are basically bare silicon die that are bonded onto PCBs or substrates. This package type is fairly popular in mobile phones and many types of CPUs. The technique does not see through regular black plastic IC packages.