Source: https://guthlabs.ai/docs/instruments/pcb-trace-resistance-voltage-drop/implementation/

instrument implementation / implementation-contract

# PCB Trace Resistance & Voltage Drop implementation

A source-bound implementation contract for PCB Trace Resistance & Voltage Drop; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-210

**Effect**: Computation or source lookup only

## Input and validation requirements

The zero-width vector produces an undefined division and must be rejected. The specification also leaves signed-versus-magnitude voltage drop and the mil thickness convention vulnerable to interpretation errors; a permissive implementation could return NaN, Infinity, or a result differing by about 39.37 times.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "length": {
      "value": 0.1,
      "unit": "m"
    },
    "width": {
      "value": 1,
      "unit": "mm"
    },
    "copper_weight": {
      "value": 1,
      "unit": "oz/ft^2"
    },
    "current": {
      "value": 2,
      "unit": "A"
    }
  },
  "expected_outputs": {
    "R": {
      "value": 0.0495431,
      "unit": "ohm"
    },
    "Vdrop": {
      "value": 0.0990862,
      "unit": "V"
    },
    "power_dissipated": {
      "value": 0.198172,
      "unit": "W"
    }
  },
  "working": "t=1×34.798×10^-6=3.4798×10^-5 m; w=1 mm=1.0×10^-3 m; numerator=ρL=(1.724×10^-8)(0.1)=1.724×10^-9; denominator=t·w=(3.4798×10^-5)(1.0×10^-3)=3.4798×10^-8; R=1.724×10^-9/(3.4798×10^-8)=0.0495431 Ω; Vdrop=I·R=2×0.0495431=0.0990862 V; P=I²R=2²×0.0495431=4×0.0495431=0.198172 W."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/pcb-trace-resistance-voltage-drop/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/pcb-trace-resistance-voltage-drop/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/pcb-trace-resistance-voltage-drop/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`