Post cure behaviour of encapsulants for QFN packages processed by an open-ended single mode resonant microwave applicator

An open-ended single mode resonant microwave applicator has been developed for the curing of encapsulants materials used for microelectronic packaging. Post cure behaviour of HenkelTM E01080 encapsulant material has been studied by Differential Scanning Calorimetry (DSC), Attenuated Total Reflectance Fourier-Transform Infrared (ATR-FTIR) analysis and Dynamic Mechanical Analysis (DMA). DSC based measurement of the microwave cured samples indicates a ~ 99.2% degree of cure and a glass transition temperature, Tg, of 113°C for a sample cured at 150°C for 90 seconds. For the corresponding convection oven cured sample the degree of cure was found to be approximately 70% for the same duration of cure. The ATR-FTIR analysis showed no significant difference between the conventionally and microwave cured samples. Thermal ageing analysis performed on fully conventional and microwave cured samples showed similar ageing behaviour for both samples at a given temperature under Tg.