Simultaneous Characterization of Theta-JC and Theta-JB Using Through-Package 1-D Heat Flow

摘要

A new technique is proposed for simultaneous, in-situ characterization of in-package thermal resistances (junction-to-case andjunction-to-board) in a single test. A thin resistive heater is patterned on package top surface to establish one-dimensional heatconduction along the package vertical direction. Accompanying temperature rise at the heater is measured using a thermocoupleand analyzed to estimate equivalent thermal R-C network model of the package. Due to the one-dimensionality of the probingthermal wave, the derived R-C network model represents physical package thermal structure, enabling simultaneous estimation ofboth thermal resistances (theta-JC and theta-JB). The proposed technique is validated by measuring theta-JC and JB of anovermolded flip-chip ball grid array package. The proposed method eliminates need for a separate test setup for thecharacterization of each thermal resistance, enhancing the accuracy and efficiency of the package thermal characterization. Inaddition, use of the external heater and sensing element, instead of on-chip heater and temperature sensor, enables in-situ thermalcharacterization of a real package mounted on the set board.