Matthew D. Romig

A quick PCB thermal calculator to aid system design of exposed pad packages

Thermal design of PCBs (Printed Circuit Boards) is important for electronic packages which are intended to be primarily cooled by heat flow into the PCB. Designing the required PCB coverage area through detailed numerical simulations can be computationally expensive. This article presents a quick approach to predict Junction-to-Air thermal resistance of exposed pad packages based on pre-generated detailed thermal simulations and interpolation methodology. The modeling methodology is derived from validated measurements on Quad and Inline packages with different PCB copper coverage areas. Thermal data is pre-generated through parametric simulations conducted with varying package sizes, pad sizes, and PCB copper coverage areas. The interpolation methodology quickly provides a thermal resistance versus copper coverage area curve. The interpolation approach is validated through detailed simulations on cases not included in the pre-generated thermal data. Such a quick prediction capability of temperature rise of exposed pad packages for different PCB copper coverage areas can be a valuable tool for thermal design of PCB layout.