TY - GEN
T1 - A reliability evaluation of lead-free ball grid array (EGA) solder joints through mechanical fatigue testing
AU - Ryan, Claire
AU - Punch, Jeff
AU - Rodgers, Bryan
PY - 2005
Y1 - 2005
N2 - Lead is a hazardous substance which, when ingested can be toxic to humans; therefore it has been banned by a European Union directive in an aim to reduce its harmful effects on health and the environment. The ban, which comes into force on July 1st 2006, means that electronic manufacturers must transfer from a tin-lead soldering process to a lead-free process. In this paper a reliability evaluation of a tin-silver-copper (SnAgCu) solder is presented with a baseline of tin-lead (SnPb). An experiment was carried out to optimise the surface mount reflow process and the reliability of the resulting solder joints was investigated using a torsional mechanical fatigue test method. The test vehicle comprised of an 8-layer FR4 printed circuit board (PCB) mounted with four ball grid array (BGA) components - each package comprising four daisy-chains. The basic principle of the torsion test was to stress the BGA solder joints repetitively in order to determine the number of cycles to failure. Graphs of the cycle number versus resistance were created and the numbers of cycles to failure were determined. The failure mechanisms were examined using cross-section and scanning electron microscope (SEM) techniques which showed cracking that initiated at the upper comer of the solder joint and propagated in the solder along the upper copper pad. This failure mechanism was observed for both SnAgCu and Snb solder joints. From a comparison of number of cycles to failure, the reliability of SnAgCu BGA solder joints was found to be superior to that of SnPb joints in torsion tests.
AB - Lead is a hazardous substance which, when ingested can be toxic to humans; therefore it has been banned by a European Union directive in an aim to reduce its harmful effects on health and the environment. The ban, which comes into force on July 1st 2006, means that electronic manufacturers must transfer from a tin-lead soldering process to a lead-free process. In this paper a reliability evaluation of a tin-silver-copper (SnAgCu) solder is presented with a baseline of tin-lead (SnPb). An experiment was carried out to optimise the surface mount reflow process and the reliability of the resulting solder joints was investigated using a torsional mechanical fatigue test method. The test vehicle comprised of an 8-layer FR4 printed circuit board (PCB) mounted with four ball grid array (BGA) components - each package comprising four daisy-chains. The basic principle of the torsion test was to stress the BGA solder joints repetitively in order to determine the number of cycles to failure. Graphs of the cycle number versus resistance were created and the numbers of cycles to failure were determined. The failure mechanisms were examined using cross-section and scanning electron microscope (SEM) techniques which showed cracking that initiated at the upper comer of the solder joint and propagated in the solder along the upper copper pad. This failure mechanism was observed for both SnAgCu and Snb solder joints. From a comparison of number of cycles to failure, the reliability of SnAgCu BGA solder joints was found to be superior to that of SnPb joints in torsion tests.
UR - http://www.scopus.com/inward/record.url?scp=33745726126&partnerID=8YFLogxK
U2 - 10.1109/ESIME.2005.1502845
DO - 10.1109/ESIME.2005.1502845
M3 - Conference contribution
AN - SCOPUS:33745726126
SN - 0780390628
SN - 9780780390621
T3 - Proceedings of the 6th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Micro-Electronics and Micro-Systems - EuroSimE 2005
SP - 436
EP - 440
BT - Proceedings of the 6th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Micro-Electronics and Micro-Systems - EuroSimE 2005
T2 - 6th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Micro-Electronics and Micro-Systems - EuroSimE 2005
Y2 - 18 April 2005 through 20 April 2005
ER -
