Modelling solder extrusion using J-integral method
Bibliographic record
Abstract
Solder extrusion is a phenomenon where molten solder fills a crack in the solder resist during reflow, causing a short failure. FEA was used to first understand this phenomenon, and then investigate the effect of die warpage, presence of stacked via and substrate CTE on solder extrusion risk. A 2D crack propagation model was developed. This model assumes the presence of an initial crack and calculates the propensity of the crack to grow using the J-integral method. The J-integral is equivalent to the energy release rate. Fracture can be predicted by comparing calculated values of J-integral to a critical value for the material being evaluated. This work is important because in the future it can be extended to predict solder extrusion risk before the first packages are built, taking into account factors such as stacked vias, copper plane placements, substrate material properties, size, and warpage. In addition, this model can be used to optimize locations of 3-stack vias and copper planes, in compliance with electrical design.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".