Intermediate and High Strain-Rate Fracture of Lead-Free Solder Joints as a Function of Mode Ratio
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Bibliographic record
Abstract
ABSTRACT The fracture properties of SAC305 solder joints under intermediate (0.05-1 s -1 ) and high (10-60 s -1 ) strain-rate loading conditions were measured as a function of mode ratio using Cu-solder-Cu double cantilever beam (DCB) specimens of 2 mm long discrete solder joints with a thickness of 150 μm. To perform intermediate strain-rate experiments, a servo-electric testing machine was employed while high strain-rate tests were carried out using a newly-designed drop tester. The failure of the solder joints in the DCB specimen was evident as an abrupt change in the load cell or strain gauge output for intermediate and high strain-rate experiments, respectively. In the latter case, the strain gauge was mounted on the copper bar at the location of the solder joint. This maximum strain was used to find the corresponding failure load. The critical strain energy release rate for crack initiation, J ci , of the solder joint was then calculated using a finite element model. The results showed a substantial effect of strain rate and mode ratio on the fracture of solder joints. There was a significant decrease (about 70%) in mode I J ci when the strain rate was increased from intermediate to high values. At all strain rates, the effect of an increasing mode ratio (more shear loading) was to increase J ci so that when the mode ratio was raised from 8° to 38°, J ci increased by a factor of about 5. These fundamental fracture properties can be used to predict the fracture of this joint system (solder+finish+processing conditions) in arbitrary geometries at strain rates to 60 s -1 .
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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) | 0.000 | 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 it