Do you agree that the question can be improved?
False conclusions, missing data, is this real problem or a simulation
The skin depth of 0.5MHz on a printed copper trace is 100%.
After examining your plot
- the current spikes are from the capacitance ESR || RdsOn for all (I=V/R)
- the slope on square wave rising is the load inductance. nH/V = 500 approx from V = L * dI/dt
I don't know how they fit a 15A Cu fuse in a tiny SMD package but it is spec'd to rise 100'C at 75% of 15A ~ 11A which results in 39% rise in resistance for Cu.
I verified for my own satisfaction on Saturn PCB.exe and I agree that nobody else thinks there is any skin effect and ESL. Yet the FET also has a PTC effect like the fuse which Rs rises +39% for a 100'C rise which can lead to thermal runaway and fusing and maybe faster than the SMD fuse. It depends on a thermodynamics heatsink analysis for which you need to get specs and verify.
Protection & Power Delivery Network Design.
Unless you have specs. in mind for OTP or OCP, (protection from over-temp. or over-current) hypothetical questions like this should have some specs, assumptions & analysis. this includes I2t, packaging and environmental factors.
Although it is a creative idea to use a fast blow SMD fuse to protect a switching FET, unless you regulate the FET by some time limiter (e.g. PWM or disable), what's the point when there is no purpose, design specs or even logic diagram offered?
It would be more thoughtful in future to include all the details of your problem with assumptions and simulation and/or photo-layout of the realization.
This is how I would structure a question (more or less) in some logical sequence.
0. Problem statement or Executive Summary
1. Purpose of sub-system
2. Assumptions (what we need to know)
3. Design Specs (relevant subset)
4. Troubleshooting data
5. Analysis
Whereas for design the sequence is slightly different with Design for Testability DFT included with Design Specs and "unknowns" tested beforehand and Design Review and Verification Testing (DVT) as part of the design process.
A less useful question to assume you need to use some part and have a hypothetical issue with no purpose.
This is for others in a similar learning modes, to take this as constructive advice.
We all make
misteaks, and the more you self-correct, gives you self-confidence and experience.
Solving problems early is a good thing, and there are better ways to save time for all of us.
Most errors are from wrong assumptions, simple over-sights and
Murphy's Law.
How many watts does it take to blow a fuse? Actually it is based on energy or I²t * Rs with PTC effects and thermal mass & insulation causing latency and loop gain of temperature towards melting point.