Evaluation of surface heat transfer coefficients for electronic module packages

The Colburn j-factor has been used to correlate characteristic surface heat transfer coefficients from electronic module packages. Experiments were performed using several size modules with and without extended surface thermal enhancements at velocities of 0.5 to 3.8 m/sec. A dimensionless plot of the j-factor versus Reynolds number, defined for the three-dimensionality of the body, results in a simple correlation for all test data within plus or minus 15% bounds. Observations from the plot show that maximum scatter occurs at low Reynolds number coincident with lower velocity values. Correlation at higher Reynolds numbers was good. A simple algebraic expression is presented to apply this work to hardware evaluation at extended altitude or ambient temperature conditions.