Fiber Bragg Grating Sensors for Failure Detection of Flip Chip BGA in Four-Point Bending Test
Bibliographic record
Abstract
Maintaining structural integrity is an important issue for advanced flip chip ball grid array (FC-BFA) packages especially due to the use of Pb-free solder replacing the Pb-contained solders and the large package size induced mechanical vulnerability. For such packages, the mechanical bending causes fracture in the interconnecting plastic PWB. To determine the critical load becomes a challenge to assembly manufacturers since the conventional testing methods based on monitoring electric continuity of the daisy chained solder joints fail to detect the PWB de-bonding near the interconnect. This thesis researches a new method that uses the Fiber Bragg Grating sensor to detect the interconnect fracture failure of 55 mm lead-free FC-BGA under four-point bend test. Experimental setups and procedures are studied, a proper test configuration is determined and a series of testing performed. The validity of the new method in monitoring the solder joint de-bonding is proved through analyzing the test results, which shows that the FBG sensors are sensitive to capture the onset of the fracture in different cases.
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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 | 0.000 | 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 | 0.001 |
| 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".