A comprehensive thermal management strategy requires a system-level thermal budget including custom or OEM heat sink solutions based on physical and mechanical constraints. Tailor the heat sink to your design and system constraints. Account for the device's inherent ability to transfer heat to the surface.
By considering the system's physical, mechanical, and environmental constraints, the overall thermal budget is maintained and does not exceed the device’s maximum operating temperature. The heat sink is an integral part of the thermal management solution to maintain a safe operating temperature. As a result, the system-level designer must consider the following issues:
- For lidless packages, the nominal stiffener height can be different from the height of the die. Therefore, the heat sink must have an island to contact the die.
- Especially for lidless packages, run system thermal simulations in worst-case environmental conditions. Use detailed thermal models that accurately represent device thermal performance across all boundary conditions.
- Consider the package's mechanical specifications. Select the thermal interface between the die and the thermal management solution to minimize thermal contact resistance.
- Determine total thermal contact of the thermal interface material using parameters from the thermal interface manufacturer's data sheet.
- Refer to the following applied-pressure recommendation. Lower pressure can cause poor thermal contact. Higher pressure can damage the device. This recommendation requires strict pressure control. Use a smart-torque tool when applying a heat sink to control the rate of short-term transient pressure as the thermal interface material (TIM) relaxes. Always follow the TIM supplier's specifications.
- Account for thermal modeling uncertainties, including tolerances and manufacturing variations. Consider fan airflow, heat pipe or vapor chamber performance, fin-to-heat-sink-base attachment, and surface flatness.