Metallurgical AuSn Bonding of Piezoelectric Layers
Bibliographic record
Abstract
This study presents a novel and simple approach to form metallurgical bonds between layers of the acoustic stack in an ultrasound transducer using a eutectic AuSn preform, which is a pre-shaped thin sheet of solder. The bonding takes 10 minutes and yields uniform bondlines of 10 μm with a melting temperature of 280 °C. The resulting bonds are electrically conductive, mechanically robust and have a characteristic acoustic impedance of 29 Mrayls. AuSn bonding was demonstrated by successfully bonding two equally thick layers of PZT. The bonded PZT-stacks were polarized and sub-diced into a 2-dimensional array. Characterization was performed by optical microscopy, scanning acoustic microscopy and electrical impedance measurements. Combining scanning acoustic microscopy and electrical impedance measurements proved to be a useful approach to experimentally study inter-element variations induced by varying concentrations of voids in a metallurgical bondline.
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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 | 0.000 | 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".