With the arrival of flip-chip packaging and multi-level metallization on dies, present tools and techniques are having increasing difficulty in meeting failure analysis needs. Recently a magnetic field imaging system has been demonstrated to localize shorts in buried layers of both packages and dies. This system uses a SQUID (Superconducting Quantum Interference Device), which is a very sensitive magnetic sensor that can image magnetic fields generated by magnetic materials or currents (such as those in an integrated circuit or package). These currents (as low as microamperes) can be detected even when they are buried deep within a package or assembly. Since magnetic fields are not affected by most materials used in circuit technology, magnetic field imaging can be applied to several vertical layers enabling problem detection in a multi-layer stack involving the die, solder bumps, package, BGA and board. The current density distribution in the sample can then be calculated from the magnetic field image providing a map of current flow in the assembled device. This can be helpful for design verification and short localization, including determining which layer of the structure contains the defect. To image these devices, the SQUID must be cooled to temperatures around 77K while the sample is at room temperature. In order to image these parts non-invasively, the system has been designed to keep the SQUID cold and in vacuum while the sample is at room temperature in air. The design of this system as well as the application to failure analysis will be presented. Peak localization of defects to ± 5 microns has been demonstrated in the best case with sub-10 microns being typical.