Evaluation of alternative cooling techniques for TAB packages

Abstract

Cooling chip on board (COB) using TAB technology is sometimes tricky. Thermal vias with cooling copper planes are often used. This design may not be adequate when cooling high powered chips, therefore alternative designs will need to be investigated. In doing so it is necessary that performances be properly predicted especially when operating conditions are expected to be close to design limits. This study evaluates three cooling designs and three analytical methods of predicting the thermal performances of each design. The three designs are: 1. thermal vias connected to a cooling ground plane; 2. thermal vias connected to a cooling ground plane and a heatsink attached to the back side of the vias; and 3. a copper slug with a heatsink attached to the back side. The three methods of prediction are: 1. a one dimensional analysis; 2. a numerical analysis using FLOTHERM thermal and fluid analysis software; and 3. experimental analysis.<>