Field use environment for a FCBGA in a laptop computer application

A laptop computer was disassembled, and several thermocouples were attached to the die, heat sink, substrate, and motherboard. The laptop was then re-assembled and run under various conditions to measure the effects on temperature distribution. The assembly was then deconstructed and samples were extracted for material property measurements. Elastic modulus and thermal expansivity were measured for the heat sink, substrate, motherboard, thermal interface pad, and underfill materials. Typical temperature rise of the IGP die above ambient was 40 C. Video use increased the temperature by 5 C to 10 C. Wrapping the laptop to constrict airflow increased the temperature by 15 C. Hence, the operating temperature range is approximately 55 C to 80 C. The substrate and motherboard are hotter on the side facing the CPU. There are gradients of up to 20 C in the structure (difference between hottest and coolest regions). The initial temperature change rate during a power cycle is 5 C/sec for the IGP die.