CALCULATORS / PCB INTERCONNECT AND PACKAGING

Via-array current sharing screening calculator

Identical vias share DC current equally; mutual thermal effects omitted.

pcb-via-array.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

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

Scenario	perViaA	equivalentohm	lossW
	1.25	0.00025	0.00625
	1	0.00025	0.004

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.

per via current budget example1.25 A✓ passes

BASELINE INPUTS

current5 Acount4 singleResistance0.001 ohm

CALCULATED

perVia1.25 A

equivalent0.00025 ohm

loss0.00625 W

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Via-array current sharing screening
# Scope: Identical vias share DC current equally; mutual thermal effects omitted.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

current = 5 A
count = 4
singleResistance = 0.001 ohm

perVia := current/count [A]
equivalent := singleResistance/count [ohm]
loss := current^2*equivalent [W]

check per via current budget example: perVia <= 1.5 A

scenario alternative: current = 4 A

Calculated from your source · not saved

Baseline · Baseline

per via current budget example1.25 A ✓ passes

alternative · alternative

per via current budget example1.00 A ✓ 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.

per via: perVia = current/count [A]
equivalent: equivalent = singleResistance/count [ohm]
loss: loss = current^2*equivalent [W]

Original worked example

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

Given

current: 5 A
count: 4
single resistance: 0.001 ohm

Calculated

per via: 1.25 A
equivalent: 0.00025 ohm
loss: 0.00625 W

Assumptions and limits

Identical vias share DC current equally; mutual thermal effects 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-array current sharing screening. Inputs: via geometry/count; connection symmetry; current. Outputs: idealized sharing; aggregate resistance. 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: via geometry/count, connection symmetry, current
Outputs: idealized sharing, aggregate resistance
Modes: calculate, compare, sweep
Drawing: Layer viewer and cross section

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