SMTA International Conference Proceedings


Authors: Pradeep Lall, Dhananjay Panchagade, Deepti Iyengar
Company: Auburn University - Department of Mechanical Engin
Date Published: 9/24/2006   Conference: SMTA International

Abstract: There is a fundamental need for development of predictive techniques for electronic failure mechanisms in shock and drop-impact. Presently, one of the primary methodologies for assessment of shock and vibration survivability of electronic packaging is the JEDEC drop test method, JESD22-B111 which tests board-level reliability of packaging. However, packages in electronic products may be subjected to a widearray of boundary conditions beyond those targeted in the test method. Development of damage-equivalency methodologies will be invaluable in correlating standard test conditions to widely varying design-use conditions.

In this paper, the development of a solder-joint stress based relative damage index has been investigated to establish a method for damage equivalency. Modal Analysis, Wavelet Decomposition, and Explicit Finite Element analysis has been used to assess reliability performance of the electronic boards. Deformation kinematics have been measured with the help of ultra high-speed data acquisition and video systems. Experimental data has been correlated to the finite element models. Failure predictions along with their modes and mechanisms have been discussed. Damage proxies for failure mechanisms in first-level interconnects have been developed. The approach is scalable to a wide variety of electronic applications.

Component types examined include, plastic ball-grid arrays, flex ball-grid arrays for various pitch sizes between 0.5 mm to 1mm in both 63Sn37Pb and 95.5Sn4.0Ag0.5Cu solder alloy compositions. Dynamic measurements like acceleration, strain and resistance are measured and analyzed using highspeed data acquisition system capable of capturing in-situ strain, continuity and acceleration data in excess of 5 million samples per second. Ultra high-speed video upto 50,000 fps has been used to capture the deformation kinematics. Experimental results are correlated with finite element models which include reduced integration element formulations.

Keywords: Shock, Vibration, Drop-Impact, Ball-Grid Arrays, Life-Prediction, Reliability

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