Bibliographic record
Abstract
ABSTRACT The reliability of solder joints between a ball grid array (BGA) package and a printed circuit board (PCB) is commonly improved by bonding the BGA to the PCB using an underfill epoxy. Experimental fracture measurements were made using specimens prepared from a commercial multi-layer PCB assembled with thin profile fine-pitch ball grid array (TFBGA) packages. Two types of thermally cured capillary underfills were tested: underfill A was an unfilled epoxy, while underfill B contained 38 wt% silica particles. Fracture experiments were performed in a bending configuration under quasistatic loading conditions. In all specimens, the crack initiated within the underfill fillet, indicating the importance of cohesive fracture properties in controlling damage initiation. Finite element modeling showed that this crack initiation occurred under mode I conditions, with subsequent crack growth being mixed-mode in the PCB or at the interface between the PCB and the solder mask. The load corresponding to crack initiation in the underfill fillet for silica-filled underfill was significantly higher than unfilled underfill, indicating the toughening effect of the silica particles on the epoxy.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.002 | 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".