The lead‐free solder joint reliability of several printed circuit board mounted high‐density packages, when subjected to temperature cycling was investigated by finite element modelling. The packages were a 256‐pin plastic ball grid array (PBGA), a 388‐pin PBGA, and a 1657‐pin ceramic column grid array. Emphasis was placed on the determination of the creep responses (e.g. stress, strain, and strain energy density) of the lead‐free solder joints of these packages.
Failure analyses of the lead‐free and SnPb solder joints of high‐density packages such as the plastic ball grid array and the ceramic column grid array soldered on SnCu hot‐air solder levelling electroless nickel‐immersion gold or NiAu, and organic solderability preservative Entek printed circuit boards are presented. Emphasis is placed on determining the failure locations, failure modes, and intermetallic compound composition for these high‐density packages' solder joints after they have been through 7,500 cycles of temperature cycling. The present results will be compared with those obtained from temperature cycling and finite element analysis.
Purpose -This paper aims to describe and document the application of commonly utilized solder joint failure analysis techniques to lead-free solder joints. Design/methodology/approach -Traditional failure analysis techniques, including visual inspection, X-ray radiography, mechanical strength testing, dye and pry, metallography, microscopy and photomicrography, are reviewed. These techniques are demonstrated as applied to lead-free and tin lead solder joints. Common failure modes observed in lead-free and tin lead solder joints are described and compared. Findings -It is shown that the traditional failure analysis techniques previously utilized for tin lead solder joints are widely applicable to the analysis of lead-free solder joints. The changes required to effectively apply these techniques to the analysis of lead-free solder joints are described. Originality/value -This paper will be instrumental to the process, quality, reliability and failure analysis engineering disciplines in furthering understanding of the application of failure analysis techniques of both tin lead and lead-free solder joints.
The mechanical properties of Sn/Ag/Cu solder joints in combination with different component lead coating materials (Ni/Pd/Au, Sn/15 per cent Pb, Sn/2 per cent Bi, and Sn) are studied in this work using a lead pull test and free fall drop test. The results of this study show that the Sn/2 per cent Bi coated components provide the best performance under the drop impact loading followed by the Sn/15 per cent Pb, Sn and Ni/Pd/Au coated components. Failure modes and the structure of the coating surfaces were examined from cross‐sectioned samples using a scanning electron microscope. Furthermore, the wetting of the leads by the solder and thickness of the IMC layers were studied.
Printed circuit board assembly with lead free solder is now a reality for most global electronics manufacturers. Extensive research and development has been conducted to bring lead free assembly processes to a demonstrated proficiency. Failure analysis has been an integral part of this effort and will continue to be needed to solve problems in volume production. Many failure analysis techniques can be directly applied to study lead free solder interconnects, while others may require some modification in order to provide adequate analysis results. In this paper, several of the most commonly applied techniques for solder joint failure analysis will be reviewed, including visual inspection, x-ray radiography, mechanical strength testing, dye & pry, metallography, and microscopy/photomicrography, comparing their application to lead bearing and lead free solder interconnects. Common failure modes and mechanisms will be described with examples specific to lead free solders, following PCB assembly as well as after accelerated reliability tests.
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