The Effect of Thermal Cycling Dwell Time on Reliability and Failure Mode of 3rd Generation High-Performance Pb-Free Solder Alloys
Bibliographic record
Abstract
ABSTRACT The past decade has seen the development and introduction of commercial, third-generation, high-performance Pb-free solder alloys designed to meet the requirements of higher temperature use environments. Most of these offerings are based on the Sn-Ag-Cu (SAC) system, with major alloying additions of bismuth (Bi), antimony (Sb), or indium (In). These elements, individually or in combination, promote additional precipitate, solid solution, or dispersion strengthening that can enhance resistance to degradation at elevated temperature or during aggressive thermal cycling. Results from the literature show that an increase in thermal cycling dwell time can decrease the thermal cycling reliability of SAC solders. Because high-performance alloys are designed for extended operation at higher temperatures, it is important to understand their behavior and characterize their reliability at extended thermal cycling dwell times. This paper presents the initial results from an experimental program designed to compare thermal cycling results for high-performance solder alloys using an extended dwell of 60 minutes to a typical short dwell time of 10 minutes. The 10-minute dwell data were generated in the initial phase of testing and published previously. The data reported here are from a thermal cycling profile of -55/125 °C (TC7 in IPC9701B) and the test vehicle is a 192-pin chip array ball grid array (192CABGA). Contrary to the results for SAC solders, the 60 minute dwell time did not reduce the reliability consistently for all the high-performance alloys in the test matrix. Based on evaluation criteria of characteristic lifetime and 1% cumulative failure rate from a 2-parameter Weibull plot, the high-performance alloys had comparable reliability performance with 60-minute and 10-minute dwell times. Although all the alloys exhibited fatigue failures in the bulk solder, many of the alloys also exhibited interfacial and mixed mode failures, which complicates interpretation of the data. Multiple failure modes for these solder alloys also were reported for the 10-minute dwell testing.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".