A new structure & fabrication of a high dissipation 3D package with flexible substrate

In this paper, a novel HT (high thermal) 3D package structure with 5-side heatsinks is designed to enhance, if not resolve, the heat dissipation capability constraints as encountered by current conventional stacked dies 3D package. This new package not only improves on current 3D package thermal constraints, but also can be easily implemented with low cost 2 layer flexible substrate design. So such HT 3D package feasibility study was also discussed in this paper. Through flexible substrate application, it does not involve too much tooling investment, as this HT 3D package can be easily realized via current available processes and equipment with minimal changes. With the ability to dissipate heat through 5 sides of heatsinks for this HT 3D package, higher heat dissipation than that of a conventional stacked 3D package can be achieved. In order to verify the thermal performance, thermal simulations were carried out using a commercially available CFD tool, FloTHERM©. 4 types of 3D packages were modelled. Through comparison made to conventional 5-die stacked package, this 3D package has the capability to handle 23-38% of additional package power.