Comparison of thermal enhancements to a commercial quad flatpack

The thermal characteristics of three 160 pin commercial quad flatpacks were examined. The packages were modeled and tested in accordance with MIL STD 883C-Method 1012.1 and SEMI Standards G38-87, G42-88, G43-87. The purpose of the comparison was to find the coolest commercial class package currently available for high-power RISC devices. The author addresses the relation of theta jc as a poor predictor of theta ja for the thermal enhancements presented and introduces a possible heuristic for modeling semiconductor component packaging. Use of the heuristic is shown to be generally accurate within 5% of the measured values using the data presented. The all-aluminum quad flatpack appears to have the best thermal characteristics of the packages compared. Although it has a theta jc comparable to that of the thermally enhanced plastic quad flatpack, it has better theta ja numbers from still air to high-speed air flow. For low-power applications the normal plastic quad flatpack seems to be an acceptable package, but when the power dissipation exceeds 2 W or more, the thermally enhanced packages must be used