Application of phase-change materials in Pentium® III and Pentium® III Xeon™ processor cartridges

Thermal interface materials (TIM's) were widely used to reduce thermal resistance between the electronic device and the cooling solution. One typical TIM is the phase-change material (PCM) which melts after the electronic device starts to power up. The PCM has the advantage over the common thermal grease and paste. The PCM after melting will flow, wet out the contact surfaces, and conform to the irregular surface shapes. The PCM will then reduce its thickness due to the clamping force between the electronic device and the cooling solution, resulting in optimal thermal interface thickness. In addition, the PCM does not require the complicated and expensive dispensing process as thermal grease and paste. A survey of the commercially available PCM was performed. Thermal characterization of these PCM's was conducted by using the guarded heater based on ASTM D5470. The characterization results are compared to the suppliers' data sheets. In addition, the thermal test vehicle with the single edge contact (S.E.C.) cartridge form factor is also used as a screening tool to evaluate the PCM's through the power cycles. A BrN-filled PCM was finally selected as the S.E.C. cartridge TIM. The impact of the fiber mesh carrier and the tilting of interface layer on the PCM thermal performance is discussed.