BGA Solder Joint Fracture as a Function of Strain Rate and PCB Rigidity
Bibliographic record
Abstract
ABSTRACT Package-on-board systems utilize printed circuit boards (PCBs) with different rigidities depending on the application of the product. This study investigated the effect of PCB stiffness on the fracture loads of ball grid array (BGA) solder joints over a range of strain rates. Fracture experiments under bending loads were performed using specimens with 1, 2 or 3 laminated PCBs, each 1 mm thick. Intermediate strain rates (0.2-0.6 s -1 ) were achieved using a servo-electric machine, while a drop tester was used for high strain rate (30-50 s -1 ) experiments. A strain-rate dependent cohesive zone model was calibrated using the measured fracture load of one specimen with 1 or 2 laminated PCB(s) in each of these strain rate regimes. This model was then used to predict the fracture loads of the specimens with 2 or 3 laminated PCBs. The predicted fracture loads agreed reasonably well with the measured values, being within 12% and 15% of the measured forces for intermediate and high strain rates, respectively. The cause of the residual error was believed to be the inability of the model to account for changes in adherend rigidity which would affect the solder joint constraint and hence the extent of its plastic deformation.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".