Whisker Growth on Sac Solder Joints: Microstructure Analysis
Bibliographic record
Abstract
ABSTRACT Sn whisker growth on electronics continues to be a widespread industrial concern. In this study, detailed metallurgical analyses were done on whiskers growing from solder joints formed on leaded components. The whiskers appeared after life testing for 10 days at 60°C and 20-30% RH with voltage cycling. Optical and Scanning Electron Microscopy (SEM) with EDX following by cross-sections through whiskers were performed. The analyses revealed that Sn whiskers originated not from the component lead plating as was expected, but from bulk SAC405 or SAC305 solder. A high precision metallographic technique using progressive polishing was developed to examine the details of whisker formation. This paper discusses the microstructural relationship between the whiskers, hillocks, and shell-like protrusions and the following factors: solder microstructure and its modification during oxidation and corrosion, Alloy 42 lead frame material, lead plating quality, component contamination and flux on solder.
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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 | 0.000 | 0.000 |
| 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".