CALCULATORS / PCB INTERCONNECT AND PACKAGING

Via resistance and loss calculator

Thin cylindrical plated barrel DC resistance; pads/contact omitted.

pcb-via-resistance.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	areamm^2	resistanceohm
	0.0235619	0.00114082
	0.0235619	0.000912658

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

via resistance budget0.00 ohm✓ passes

BASELINE INPUTS

resistivity1.68e-8 ohm*mlength1.6 mmdiameter0.3 mmplating25 um

CALCULATED

area0.023562 mm^2

resistance0.0011408 ohm

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Via resistance and loss
# Scope: Thin cylindrical plated barrel DC resistance; pads/contact omitted.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

resistivity = 0.0000000168 ohm*m
length = 1.6 mm
diameter = 0.3 mm
plating = 25 um

area := pi*diameter*plating [mm^2]
resistance := resistivity*length/area [ohm]

check via resistance budget: resistance <= 0.002 ohm

scenario alternative: resistivity = 1.344e-08 ohm*m

Calculated from your source · not saved

Baseline · Baseline

via resistance budget0.00 ohm ✓ passes

alternative · alternative

via resistance budget0.00 ohm ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

area: area = pi*diameter*plating [mm^2]
resistance: resistance = resistivity*length/area [ohm]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

resistivity: 1.68e-8 ohm*m
length: 1.6 mm
diameter: 0.3 mm
plating: 25 um

Calculated

area: 0.0235619 mm^2
resistance: 0.00114082 ohm

Assumptions and limits

Thin cylindrical plated barrel DC resistance; pads/contact omitted.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Via resistance and loss. Inputs: barrel geometry; plating; current; temperature. Outputs: resistance; voltage drop; loss. Model scope: Explicit stackup and trace/via geometry; empirical models identified. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: barrel geometry, plating, current, temperature
Outputs: resistance, voltage drop, loss
Modes: calculate, compare, sweep
Drawing: Layer viewer and cross section

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS