Low-Temperature Slurry-Cast Copper Structures for Multiple Power Electronics 3D Packaging Applications

To meet the increasing demand for higher power density in compact spaces, significant advancements are being made in power electronics, including the development of three-dimensional (3D) integrated packages. However, the 3D integration of power electronics presents several challenges, including effective in-plane and through-plane heat transfer and removal, plus reliable high-temperature layer-to-layer stack bonding technologies. Addressing these challenges requires innovative package assembly solutions, ensuring robust performance and scalability. This study presents a cost-effective and scalable copper (Cu) metal coating process for electronics packaging with adjustable properties, ranging from microporous to dense Cu, achieved by varying the metal particle size. This coating is produced using a “slurry cast” method, where a copper particle slurry is applied to the target surface/feature and reduced at 160 °C, forming a porous or dense copper layer and/or structure. The coating’s thickness, particle size, and porosity can be easily controlled to meet the specific requirements of a vertically integrated 3D power package. To demonstrate the versatility of the slurry-cast structures, we explored their use in three different integration applications: a low-temperature processable planar bonding layer, a large diameter through via to demonstrate it’s prospective to use for making Through Silicon Via (TSV) for efficient cross-plane heat conduction, electrical connectivity and a novel phase change cooling structure for heat removal. The results show that the slurry-cast process has the potential to be applied in a range of future 3D power electronics packaging applications.