Room-Temperature Bonding with Pd Coated Cu Wire on Al Pads: Ball Bond Optimization with 2-Stage Methodology
Bibliographic record
Abstract
Wirebonding performed at elevated temperatures is the standard interconnect process for integrated circuits, typically with the use of low-cost copper bonding wire. However, for specific applications it is necessary for wire bonds to be reliably joined at room-temperature. This paper details the development of a room-temperature ball bonding process using a 2-stage optimization method. The first stage optimizes ball geometry by applying a 32 design of experiment to bonding parameters impact force (IF) and electric flame-off (EFO) current. In the second stage bond shear strength is optimized by stepwise increase in ultrasonic amplitude. Target ball bond values were attained at optimized parameters: IF of 1331 mN, EFO current of 59.9 mA, and an ultrasonic amplitude of 26.46 US%. Pad lift during bonding was observed at excessive ultrasonic amplitudes above 40 US%, as determined by optical images at the bond interface. Bonding parameters at room-temperature (23°C) were increased when compared to a high temperature process (175°C) to account for reduced thermal energy. For the same geometry at room-temperature a 7 % increase to impact force was required. EFO current levels remained relatively constant between the two bonding temperatures. For the same shear strength at room-temperature a 18 % increase in ultrasound amplitude was required. The confirmed average shear strength achieved via the room-temperature process was 116 MPa. Higher values are possible.
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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 | 0.000 |
| 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".