Solder Joints are considered to be one of the most vulnerable components of electronic packages and their fatigue failure is regarded to be one of the major methods of electronic package failure.  The prediction of solder joint reliability is thus of great importance, and most finite element packages utilize the Anand Viscoplastic Model to model the solder joints.  In this study, the creep response equation of the solder has been derived from the Anand viscoplastic constitutive model.  A procedure for extracting Anand constants from the experimental creep data was also established.  Sandwich samples were fabricated that included 3x3 arrays of SAC305 solder joints of roughly 750 mm in diameter that were reflowed in between two FR-4 printed circuit boards.  These samples were then subjected to creep testing in shear at various temperatures (T = 25, 50, 75, 100 °C) and stress levels (t = 5, 10, and 15 MPa) by using a set of specially designed fixtures to grip these sandwiched joint specimens.  The nine Anand model constants were then extracted from the creep data using the developed procedure.  The Anand model predicted creep response curves were then compared with the experimental creep response curve to determine the accuracy of the model.  In all cases, Anand model predicted creep response matched the observed data very well over a wide range of temperature and stress levels.


Determination of Anand Parameters From Shear Creep Tests of Lead Free Solder Joints

Division / Sponsors: 
Electronic & Photonic Packaging Division (EPPD)

Paper Proceedings: https://asmedigitalcollection.asme.org/InterPACK/InterPACK2020/volume/84041

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