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Current density and copper width evidence

ZapTrace emits a machine-readable current-density report for high-current nets and power rails. The report compares routed trace widths against explicit net constraints or IPC-2221 trace-width estimates.

Inputs

The report consumes:

Net.type == power
Net.constraints.is_high_current
Net.constraints.min_trace_width_mm
rail-current-budget total load current
Design.routing.traces[].width

Report

build_current_density_report(design) returns:

schema_version
high_current_net_count
trace_count
violation_count
missing_route_count
blocked
human_review_required
traces[]
missing_route_nets[]
assumptions[]

Each trace entry records net id/name, layer, actual width, current, required width, margin, status, and message.

Policy

  • Trace width below the required current-carrying width blocks autonomous sign-off.
  • High-current nets without routed trace evidence require human review.
  • Rail currents come from rail-current-budget evidence when available.
  • High-current non-rail nets without richer current metadata use a conservative 1A default and record that assumption.

Proof-pack sign-off

Proof manifests can attach current_density evidence:

blocked=true                    -> current-density blocks autonomous-pass
human_review_required=true      -> current-density requires human review
passed=true with complete data  -> current-density passes