Thermal Compression Bonding: Understanding Heat Transfer by in Situ Measurements and Modeling

Thermal compression bonding (TCB) is becoming an increasingly important process step in the assembly of advanced components such as fine pitch flip chip packages, system-in-package products, and 3D IC's. To increase the throughput and robustness of TCB processes, it is crucial to understand and control important process parameters like time, force and temperature. However, for TCB processes it becomes challenging to measure and control the temperature over the bond interface, since typically different temperature profiles are applied to top chip and substrate. This paper proposes and validates a new methodology for temperature measurements and characterization of heat transfer during a TCB process. On-chip thermal sensors measure the temperature in real time during the TCB process, at different locations on both top and bottom chips. Since the proposed methodology does not require the insertion of a thermocouple in between the top chip and substrate, it will enable more reliable measurements, especially for fine pitch micro bump devices.