2026, Vol. 6, Issue 1, Part A
Effect of solder joint quality on long-term reliability of lead-free interconnections
Author(s): Michael Robertson, Sarah Chen-Williams and David Tremblay
Abstract: A 47% increase in field failures prompted automotive electronics manufacturers to investigate solder joint degradation patterns in lead-free assemblies. This research examined the correlation between initial joint quality classifications and long-term reliability performance under accelerated thermal cycling conditions. Test vehicles comprised 1,247 ball grid array packages assembled using SAC305 (Sn96.5Ag3.0Cu0.5) solder paste on organic substrate printed circuit boards. Joint quality was assessed through automated optical inspection, X-ray imaging, and cross-sectional microscopy, enabling classification into five quality tiers based on IPC-A-610 workmanship standards. Accelerated life testing subjected assemblies to thermal cycling between -40°C and +125°C for up to 3,000 cycles with continuous electrical monitoring. Failure analysis revealed intermetallic compound growth as the dominant degradation mechanism, accounting for 34.7% of all failures, followed by void formation at 23.2% and Kirkendall voiding at 18.9%. Statistical correlation between initial quality classification and cycles-to-failure demonstrated strong predictive capability, with Class I joints achieving mean time between failures 4.3 times greater than Class V joints. The research identified a critical threshold where joints initially classified as marginal quality exhibited accelerated degradation rates after 1,500 thermal cycles. Weibull analysis produced shape parameters ranging from 2.8 to 4.6 across quality classifications, indicating wear-out failure modes consistent with cumulative fatigue damage. Regression modeling achieved R-squared values exceeding 0.91 for predicting failure probability based on initial quality metrics combined with intermetallic layer thickness measurements. These findings establish quantitative relationships enabling manufacturers to implement quality-based screening criteria that reduce field failure rates by an estimated 62% compared to pass/fail inspection approaches. The data support recommendations for enhanced incoming inspection protocols targeting specific defect types most strongly correlated with early-life failures.
DOI: 10.22271/27084493.2026.v6.i1a.78
Pages: 07-12 | Views: 36 | Downloads: 17
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How to cite this article:
Michael Robertson, Sarah Chen-Williams, David Tremblay. Effect of solder joint quality on long-term reliability of lead-free interconnections. Int J Electron Microcircuits 2026;6(1):07-12. DOI: 10.22271/27084493.2026.v6.i1a.78
