Lead-Free Assembly and Qualification of a Storage Class PCBA
Bibliographic record
Abstract
ABSTRACT Efforts continue to learn more about the quality and reliability performance of Server and Storage class electronic hardware assemblies using new lead-free assembly processes and materials. In this collaborative qualification trial, a low/medium complexity storage class product vehicle was assembled and tested using next generation lead-free assembly materials. The intent of this work was to continue building a reliability performance database for Storage class hardware and to communicate resultant findings to the industry via case study. This paper will discuss the comprehensive qualification trial results of an IBM low/medium complexity tape storage device using a no-clean lead-free assembly process including primary attach SMT reflow, and hot gas BGA rework processes. Of particular interest in this study was the performance of in-circuit test (ICT) using next generation lead-free solders. Voiding performance, effects of multiple heat cycles, and overall ICT yield improvements were assessed. Various tests were conducted to evaluate resultant time zero quality levels of the product vehicle including 5DX-ray, ICT, bulk solder joint formation via cross sectioning, and metallurgical analysis using SEM. Reliability performance of the product vehicle was tested using accelerated thermal cycling (ATC), high temperature storage (HTS), vibration and shock protocols. The materials / processes were assessed using Surface Insulation Resistance (SIR) electromigration testing on a specially designed test card.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.011 | 0.002 |
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".