Reworkable underfill investigation on flip chip packages
Bibliographic record
Abstract
This paper investigates the feasibility of reworkable underfill in flip chip packages. Conventional underfills are not reworkable after post cure. As a result, faulty packages are often disposed of if failure occurs. Reworkable underfill on the other hand, enables packages to be reworked. In this paper, information covering the equipment and setup, die removal and substrates cleaning methods, process issues, as well as reliability results are discussed. Two reworkable underfill materials were evaluated. The materials were compatible with eutectic-type solder systems whereby the rework temperature was specified around 220/spl deg/C. A rework system was used to remove both underfill materials. Two site-cleaning techniques, namely hot gas cum vacuum method, and abrasive rotary brush method were used. Die shear after rework, temperature cycling at -55/spl deg/C/125/spl deg/C for 2000 cycles, and high temperature storage at 150/spl deg/C for 1000 hours, were conducted to evaluate the performance of the reworkable underfill.
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 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".