Magnetically aligned Z-axis anisotropic conductive adhesive and its applications
Abstract
A novel magnetically aligned, Z-axis anisotropic conductive adhesive (ACA) for high frequency interconnects is introduced. The Z-axis ACA is composed of randomly dispersed ferromagnetic particles suspended in a thermally curable epoxy. The particles can be forced to align in the presence of an externally applied field to create one directional current paths through the epoxy while maintaining high isolation in the other directions. It is demonstrated that the magnetically aligned Z-axis ACA can be utilized at microwave frequencies up to 90 GHz. The characteristics of the Z-axis interconnects are analyzed for small pad sizes less than 100 × 100 μm2. In addition, a novel failure estimation approach, using image-processing, is demonstrated to be effective for characterizing the magnetically aligned anisotropic conductive adhesives. This material is verified to be applicable for wide-range of applications such as biomedical devices, highly integrated 3-dimensional packaging, and thermal enhanced packaging thanks to its good electrical and thermal conductivity. Furthermore, an enhanced packaging approach using a self-assembly process, which can intensify selectively column density by depositing ferromagnetic materials on I/O pads, is introduced. By analyzing void regions created by the ferromagnetic particles attraction of the magnetized I/O pads, the performance of the created interconnects can be estimated. Experimentally, the potential of the interconnects created by the self-assembly process is verified through both high-power handling and thermal-cycling. Therefore, this approach is expected to be particularly useful in high power, reliable applications requiring more enhanced interconnects.
Degree
Ph.D.
Advisors
Chappell, Purdue University.
Subject Area
Electrical engineering
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