An effective alternative for marginal thermal improvements of semiconductor devices

The traditional approaches to improving device thermal performance include expensive redesign of the package housing the chip and/or the expensive modification of the thermal environment surrounding the packaged chip. This paper reports the results of using various different methods for improving semiconductor thermal performance of specific surface mount packages. Data is presented for several different thermal environment conditions and package variations. The environmental conditions include still-air, moving-air, heat sink, and tape sink. The package variations studied include die attachment thickness, internal heat spreader, and encapsulant material variations. The tape heat sink, consisting of embossed copper foil with high thermal conductivity adhesive on one side, was applied to the top surface of the test samples. The resultant thermal resistance was improved by 15%-20%, depending on the specific package version and, in some cases, was approximately equivalent in thermal terms to a 500 lfpm (linear feet per min) moving-air environment. The data results indicate that significant marginal thermal performance improvements can be realized with a relatively low-cost tape heat sink approach. The methodology for the thermal measurements is described in sufficient detail so that further data can be taken and compared for alternative packages and/or thermal environment improvements