theta /sub jc/ characterization of chip packages-justification, limitations, and future

It is noted that there has been increased use of theta /sub jc/ for the thermal characterization of chip packages. The longevity of theta /sub jc/ can be traced to its simplicity, its utility as a figure of merit, and its convenient use in numerical analysis of packaging configurations. To enhance the utility of this parameter, the distinct contribution of various segments of the 'case' area to the junction temperature is recognized, and this dependence is embodied in a modified- theta /sub jc/ relation. The analytical basis and methodology to be used in obtaining this relation are presented and illustrated by the use of detailed chip package temperatures obtained from numerical analysis of a generic PLCC (plastic leaded clip carrier) package.<
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