Lidless and lidded Flip Chip Packages for Advanced Applications

Thermal management and reliability are two critical aspects of designing an advanced flip chip package. Lidded and lidless are one of the most important variations depending on specific applications in a view of manufacturing cost, compactness, reliability, and thermal performance. In recent years, lidless packages are widely adopted in high power electronics because its superiorities of better thermal performance, compactness, and cost-effectiveness. In the meantime, various novel designs of lidless package haven been proposed to resolve the potential thermomechanical reliability challenges. This paper reviews the overall thermal resistance and thermal-induced reliability issues of lidless and lidded flip chip packages with different design parameters, such as the properties and thickness of the thermal interface material (TIM), heatsink loading pressure, and the presence of the heat spreader/lid and heatsink. Factors that determine thermal resistance of the TIMs are summarized. They include thickness of the TIM, volume fraction and distribution of the filler particles. Some novel designs and technologies for better thermomechanical reliability of lidless package are reviewed. New designs of the lid and heatsink as well as advanced thermal solutions are also reviewed. Challenges and solutions of lidless package during thermal cycling and power cycling are reviewed.