Thermal analysis and characterization of electronic packages with alternative lid coatings

Rigid lids have been integrated in high power electronic packages such as processors or 2.5D/3D packages as protective caps and heat spreaders. The major advantages of the lids lie in the protection of die/package from handling damage, reduced package warpage and stress, and enlarged heat transfer area for thermal management, etc. Currently, the standard copper lid packages suffer from the shortcomings of large weight, limited reliability and high cost. Alternative lids with light-weighted materials such as aluminum or partial aluminum are being considered to develop for possible replacement of copper lids in packages from low to relatively high power dissipations. The use of aluminum lids can reduce the weight by 3 times with additional benefit of cost reduction, which could be used for the medium to high power customer packages. Nonetheless, the lid coatings could have significant effects on the thermal performance and reliability of the packages. In this study, lids with different coatings are examined through both numerical simulation and experimental prototyping tests. Conventional surface treatment of aluminum goes through anodizing process, resulting in a layer of alumina with porous structure and low thermal conductivity. On the other hand, diamond-like coating (DLC) can be developed to minimize thermal resistance with better compatibility with the thermal interface materials and lid attachment. Both numerical simulation and experimental measurements are conducted to investigate the effect of the different coatings. The computational results and experimental measurement support the solution with the DLC coating for new lid development.