Spatially Resolved, Non-Destructive in-situ Detection of Interface Degradation by Remote Electrical Readout of an on-chip Thermal Pixel (Thixel) Matrix

We have developed a novel, rapid, robust and non- destructive experimental technique for in-situ monitoring of delamination of interfaces for electronic packages. The method is based on a simple thermal transducer matrix of so-called THIXELS (thermal pixels) which allows a spatially resolved real- time image of the current status of delamination as from a proximity camera. The transducers are small metal wire meanders which are electrically driven and read out using the well-known 3-omega method. This method has special advantages over other thermal contrast methods with respect to robustness, sensitivity and signal-to-noise ratio. Notable is the absence of cross-effects. The proof of concept has been furnished on an industry-grade flip-chip package with underfill on an organic substrate with in-situ and real-time remote readout capability, showing CCD look & feel in delamination testing. The technique is especially powerful for buried interfaces, where time-honoured methods like scanning acoustic microscopy (SAM) cannot be applied.