ANSI IPC-2221A PCB Trace Width Calculator

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ANSI PCB Trace Width Calculator

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This is the NEW version of my calculator. The original version
is HERE.

New features in this version include:

use of metric or imperial units for all major fields

the ability to change units for any applicable field on the fly

minor enhancements to some of the calculations - IPC-2221(A) changes
the curve fit

saving of all parameters in a cookie to keep your preferences
between visits

This page calculates approximations to the ANSI / IPC-2221/IPC-2221A
design standards for PCB trace width - this is the replacement for
IPC-D-275.

The approximations and rationale are described in Temperature
Rise in PCB Traces, equations 13 & 15. by Douglas Brooks,
UltraCAD Design, Inc. The original idea for this approach was from
Brad Suppanz.

The figures returned by this calculator are to be taken as a guide
only. I will not be held responsible for any mishap or loss, either
direct or consequential, that may occur as a result of relying on the
figures herein.

The trace width formulas are:

Internal traces : I = 0.024 x
dT0.44 x A0.725
External traces: I
= 0.048 x dT0.44 x A0.725

where:

I = maximum current in Amps
dT =
temperature rise above ambient in °C
A = cross-sectional area in
mils²

Please note that IPC-2221(A) equations are subtly different from
those in IPC-D-275 in that they are typically slightly more
conservative and are impicitly derated to compensate for manufacturing
effects, i.e. they should be more reliable in practice.

The values calculated here compare very closely with those derived by
the UltraCAD PCBTEMP utility, and like the diagrams in the standards
documents, are valid up to 35A for external traces and 17.5A for
internal, 400mil widths and a maximum temperature rise of 100°C.

I've added a recommended track clearance value based on the UL
rule:

clearance in inches = 0.023" + (0.0002" x
V)

The formulae as it stands is simplistic, but is reasonable for V >
50. Note that there are many international standard for this sort of
thing, e.g. EN60065:1994, which for European mains of 230V, allows for
about 120mil for Class I (protected by earthing) and 240mil for Class
II (double isolated). Note that if there is no conformal coating and
the environment is dirty/humid/condensing then all bets are off.
Please read the standards documents yourself.

Ideally, keep
"hot" and "cold" areas of your board well apart.

Change a value in an input field, then press TAB to move to the next
field. The results tables will be updated automatically.

ANSI PCB Trace Width
Calculator

Input Data

Results Data

Internal Traces

External Traces

Field

Value

Units

Trace Data

Value

Units

Value

Units

Current (max. 35A)

Amps
mA

Required Trace Width

mil
mm μm

mil
mm μm

Temperature Rise (max. 100°C)

°C
°F

Cross-section Area

mil²
mm²

mil²
mm²

Cu thickness

oz/ft²
mil mm μm

Resistance

Ω Ohms

Ω Ohms

Ambient Temperature

°C
°F

Voltage Drop

Volts

Volts

Conductor Length

inches
cm mm

Loss

Watts

Watts

Peak Voltage

Volts

Required Track Clearance

mil
mm μm

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Last edited: 13th July 2010, Site powered by Notepad!