Standard Magnetic Microscopy provides 2D images of the current path inside electronic devices. This project extends the technique to obtain full 3D current reconstructions, therefore making the localization of defects in three-dimensional assemblies possible. We are currently investigating a number of methods. So far we have already developed two patented approaches, for which we hold exclusive licences. Both produce excellent results:
The Sample Tilt
Until now Magnetic Microscopy only used the measurement of the z component of the magnetic field: currents flowing on the top layer could therefore hide those flowing below. By tilting the sample and acquiring the x and y components of the magnetic field it is possible to identify the currents flowing on different layers.
The Simulation Approach
Magnetic Microscopy generates the current map from measurements of the magnetic field using MCI (Magnetic Current Inversion). However, MCI cannot be used to map currents flowing in three dimensions, because in this case there is no unique solution to the inversion problem. The Simulation Approach works by reducing the number of possible solutions: the magnetic field generated by hypotheses about the currents is evaluated and compared to the measurement of the real magnetic field generated by the device. The hypothesis most similar to the measurement gives the precise 3D current path.
At Intraspec Technologies we are currently developing new ways of obtaining 3D information on the currents to increase the sensitivity and spatial resolution of the technique. These projects are carried out in collaboration with Neocera and the French Space Agency (CNES).