SMTA International Conference Proceedings


ACCELERATION FACTOR TO RELATE THERMAL CYCLES TO POWER CYCLES FOR CERAMIC AREA ARRAY PACKAGES

Authors: Andrew Perkins and Suresh K. Sitaraman
Company: Georgia Institute of Tech.
Date Published: 9/25/2005   Conference: SMTA International


Abstract: There is a need for a new Acceleration Factor (AF) that can relate Accelerated Thermal Cycle (ATC) fatigue life to Power Cycle (PC) fatigue life quickly and accurately in order to avoid over designing packages. An AF, such as the Norris-Landzberg AF, is only applicable when using it to predict fatigue life within the same environment, i.e. ATC to ATC or PC to PC. In addition, design factors should be taken into account. This work proposes an AF that takes into account the differences between ATC tests and PC tests for ceramic ball grid array (CBGA) packages.

The new AF is based on relevant design parameters such as substrate size, substrate thermal conductivity, CTE mismatch, board thickness, and environmental parameters such as temperature range, frequency of cycles, and peak/junction temperature. Finite Element Models (FEM), experimental data, Design of Simulation (DOS), and regression analysis are used to develop the new AF. The new AF can be used to more accurately assess PC fatigue life from ATC tests so that expensive over designing of electronic packages can be avoided for desktop/server/laptop applications.

Key words: solder joint fatigue, Accelerated Thermal Cycling ATC, Power Cycling PC, Acceleration Factor AF



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