A visual reliability demo that explains why edge regions often experience elevated exposure earlier than interior regions.
This interactive version uses a simplified diffusion-inspired model so you can change key assumptions and immediately see how
probe curves and a near-edge risk index respond.
Moisture ingress begins at the exposed boundary, then competes with barrier protection and transport distance before it reaches the regions we care about.
The central idea is geometric: near-edge regions usually respond earlier because the exposure source enters from the boundary and propagates inward over time.
Why do edge regions usually fail earlier than deeper interior regions?
The exposure source begins at the edge. Distance delays transport, barriers slow it, and fast paths accelerate it. The reliability story is therefore not just about material sensitivity, but about where the source enters and how easily it can propagate.
Core intuition:
edge source → inward transport → local exposure → degradation risk
How to read this lab
Read the figures first, then use the interactive controls. The probe curves tell you when different physical locations begin to feel the ingress. The risk index tells you how severe the near-edge exposure becomes for the chosen region-of-interest.
This figure establishes the basic geometry. Moisture ingress begins at the exposed boundary, then competes with barrier protection and transport distance before it reaches the regions we care about.
Figure 2. Time progression
static explainer
The simulator curves are just another way to read this story. Earlier times mainly reflect edge behavior; later times reveal whether the front has propagated far enough to influence deeper regions.
Figure 3. Strong barrier vs weak barrier
tradeoff view
Increasing barrier strength in the model is a compact way to represent better sealing, slower permeation, or a more protective path from the edge to the active region.
Figure 4. Bulk path vs fast path
failure acceleration view
The fast-path factor does not mean all material suddenly diffuses faster. It means some route, interface, crack, seam, or under-protected region becomes disproportionately important.
🎛️ Interactive Lab
The original simulator structure is preserved below. Move the transport and geometry knobs to see how the near-edge and interior probe curves separate, and how the edge-weighted risk index shifts in time.
Probe curves
The near-edge probe should generally rise earlier than the interior probe. The spacing between them is a compact measure of edge dominance.
Risk index
The risk index summarizes exposure in a near-edge region-of-interest. It moves earlier when fast paths dominate and later when barriers are strong.
How the simulator works
The model computes simplified normalized exposure curves C(t) using a diffusion-inspired delay term.
It is not a full PDE solver, but it preserves the main physical ideas:
Open boundary behaves like a persistent source at the edge
Distance delays the response deeper into the structure
Barrier strength slows effective transport
Fast paths increase effective transport and accelerate exposure
🔗 From Environment to Failure Risk
Figure 5. From environment to failure risk
concept chain
The current lab only models the left half of this chain: exposure formation and edge-weighted risk. That is enough for intuition-building, even before adding chemistry-specific degradation kinetics.
Figure 6. Parameter-to-meaning map
reading guide
Control
Main meaning
Typical visual effect
distanceNear
how close the ROI is to the exposed edge
smaller value shifts near-edge response earlier
distanceFar
how far the interior probe sits from the edge
larger value delays the interior curve
diffusionRate
overall transport speed
higher value moves both curves leftward in time
barrierStrength
protective slowing effect
higher value delays response and softens early rise
fastPathFactor
dominance of preferred ingress routes
higher value sharpens and advances edge-sensitive behavior
roiWeight
how strongly the risk metric emphasizes near-edge behavior
higher value makes the risk index more edge dominated
timeMax
visible observation window
changes how much of the story is shown on screen
Assumptions and scope
important note
This lab deliberately compresses several physical effects into a few intuitive knobs. That makes it useful for teaching and for early framing discussions.
normalized exposure rather than absolute moisture concentration
effective barrier behavior instead of a multilayer calibrated stack
effective fast-path behavior instead of explicit crack/interface geometry
risk index as an intuition metric, not a qualified lifetime model
How to read the two plots together
The probe curves answer: when do different physical locations begin to feel the ingress?
The risk index answers: how serious is the edge-focused exposure for the chosen region-of-interest?
When both shift earlier, the system is becoming more vulnerable. When the near-edge curve moves much earlier than the interior curve, the device is becoming more edge-dominated.
Real-world interpretations
Depending on the application, this same intuition can be reused for package-edge moisture ingress, sidewall exposure, passivation weakness, adhesive seam leakage, or other edge-initiated reliability problems. The specific chemistry may change, but the geometric story often stays similar.