Moisture ingress into nonhermetic enclosures and packages. A quasi-steady state model for diffusion and attenuation of ambient humidity variations
Bibliographic record
Abstract
In this paper the rate of moisture ingress into enclosures was studied theoretically and experimentally. A simple quasi-steady state (QSS) model was developed enabling one to calculate easily time constants for moisture diffusion through plastic walls, rubber gaskets and openings. The characteristic time constant is /spl tau/=VL/AP+L/sup 2//2D where P is permeability, D diffusion constant, V volume of the enclosure, L wall thickness and A surface area. The model clarifies the relative importance of moisture permeability vs. diffusion constant of wall materials and is applicable to both large enclosures and microelectronic packages. For thin and/or nonabsorbing walls the first term (a function of P) predominates while with thick and/or absorbing walls the second term (which depends on D) prevails. For openings, /spl tau/=VL/AD, it was shown that the QSS model is practically equivalent to but simpler than full transient solutions of the Fick's second law. The attenuation of variations of atmospheric humidity by packaging was also modeled with the QSS model. The inside air humidity changes with the same frequency as the ambient but its amplitude is attenuated by a factor f=cos /spl phi/=1/(1+/spl omega//sup 2//spl tau//sup 2/)/sup 1/2/ and is phase shifted by an angle /spl phi/=arccos [1/(1+/spl omega//sup 2//spl tau//sup 2/)/sup 1/2/] where /spl omega/ is the angular frequency of humidity changes. Therefore the protective value of packaging will be different in different geographical areas.>
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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 | 0.001 |
| 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 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".