Microstructural Evaluation of Low and No-Ag, Bi-Containing Pb-Free Solders
Bibliographic record
Abstract
ABSTRACT This paper describes the solidification characteristics of solder joints formed using three different Low (or no) Ag, Bi-contaioning Pb-free alloys. It considers the effects of Cu dissolution, undercooling and IMC formation on the bulk solder. The formation of interfacial IMCs is also evaluated with both Cu-Sn and Cu-Ni-Sn systems being considered. This work also investigates the impact of Bi on both the bulk solder and the interfacial IMC. Of the three solders being evaluated, two have a near-eutectic composition in a quaternary system, while a third has a composition along the eutectic valley of a ternary compound. The properties and microstructures of each are compared to SAC305. This study includes the evaluation of solder joints formed on QFPs, and therefore primarily made up of the alloy under study as well as solder joints formed using BGAs having a solder ball composition of SAC305; therefore the combined solder joint is made up of the alloy under study mixed with SAC305. This work considers the solidification which occurs in a typical assembly reflow process and is therefore representative of “as manufactured” product.
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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".