A calculator tool used to assist designing rigid PCB traces. Implements both the IPC2221 and IPC2152 standards and has the ability to choose between the two, with the latter having three methods available. Each method used for the standards was derived from one of the various websites that claim to implement an trace width calculator. More information regarding certain formulas used are under docs/.
- Four total methods for calculating trace widths in rigid PCBs, listed in the next section.
- Default units are metric. Choose to change units for any input and change the output units from imperial to metric.
- Convert any value used in the tool with the conversion functions (use
--helpto list them or see below). - Optionally output the results to a file for saving.
I always found confusing how an open-source tool for this type of electronics design use didn't exist, therefore I decided to make one! Through the project I wanted to allow the study of how trace widths are calculated, since I found the complexities behind that interesting. Also I wanted to collect most of the available online trace width calculator implementations, and try to improve on them, while implementing them on an open-source offline command-line tool. The completely different implementations of the IPC2152 standard does put in question the validity of these calculators and their implementations. Thankfully, due to the open-source nature of the project, the differences between the implementations are clearly viewable, and the user can freely choose the one that seems best. Future development is definitely to encourage the creation of a TWC implementation of the IPC2152 method.
One method is implemented for IPC2221 and three methods for IPC2152. The tool defaults to the IPC2152 standard, Method A.
- Method: The ubiquitous way of calculating trace widths. Derived from The CircuitCalculator.com Blog and Omni Calculator. This is the only available method with this standard.
- Method A: Derived from NinjaCalc. Default method for the TWC.
- Method B: Derived from SMPS.us which was also posted on the Altium Resources.
- Method C: Derived from Sierra Circuits.
Currently an automatic installation exists only for Windows, and binaries are built only for Windows. For other Operating Systems you need to build from source.
To install automatically, use the install script located in install/ by executing the command below in a PowerShell terminal with Admin rights,
irm "https://raw.githubusercontent.com/ymich9963/twc/refs/heads/main/install/twc-windows-install.ps1" | iex
The script downloads the executable, moves it to C:\Program Files\twc\, and adds that path to the system environment variable. If you do not want the automated script feel free to download the executable or build from source. In case your organisation doesn't allow you to install from the script due to protected paths, download the script and change the $TWC_install_path variable to a location that suits you.
Please the Building section. Use make to build from source.
Mandatory inputs to get any kind of output are Copper Weight and Current specified with -w and -c respectively. TWC defaults to metric units for input and output, as well as the IPC2152 standard using Method A. TWC accepts SI prefixes on all SI units used in the software (Amps, metres, etc.) from Terrra (T) down to pico (p).
See the --help output below for the available options, as well as some example uses below,
Help for the Trace Width Calculator (TWC). Specify units with the long options, listed below the short options.
--standard <Standard> = Choose the standard to use to calculate trace widths. Options are 'IPC2221' and `IPC2152`.
--method <Method> = Choose the method for the desired standard. Currently only used by the IPC2152 procedure with method options 'A', 'B', and 'C'.
-n, --note "<Text>" = Add a note to the start of the output. Make sure to put the note between quotes.
-c, --current <Current [A]> = Input the trace current in Amps.
-w, --copper-weight <Copper Weight [m]> = Input the copper weight in meters. Use the other options below for imperial units.
-w-mil, --copper-weight-mil
-w-oz, --copper-weight-oz
-r[-C], --temperature-rise <Temp. Rise [C]> = Input the maximum allowed temperature rise in C.
-r-F, --temperature-rise-F
-a[-C], --temperature-ambient <Temp. Ambient [C]> = Input the ambient temperature of the trace in C.
-r-F, --temperature-ambient-F
-l, --trace--length <Trace Length [m]> = Input the trace length in centimeters. Use the other options below for imperial units.
-l, --trace--length-mm
-l-mil, --trace--length-mil
-l-in, --trace--length-inches
-t, --pcb-thickness <Thickness [m]> = Input the PCB thickness in meters. Use the other options below for imperial units.
-t-mil, --pcb-thickness-mil
-t-in, --pcb-thickness-in
-e, --pcb-thermal-conductivity <Therm. Con. [W/mK]> = Input the PCB thermal conductivity in Watts per meter Kelvin.
-p, --plane-area <Plane Area [m^2]> = Input the plane cross sectional area in meters squared. Use the other options below for imperial units.
-p-in2, --plane-area-in2
-p-mil2,--plane-area-mil2
-d, --plane-distance <Plane Distance [m]> = Input the plane distance in meters. Use the other options below for imperial units.
-d-mil, --plane-distance-mil
-d-in, --plane-distance-inches
--resistivity <Resistivity [Ohm m]> = Input the resistivity in Ohm meters.
--temperature-coefficient <Temp. Coef. [1/C]> = Input the temperature coefficient.
-o, --output <File Name> = Write the name of the outputted file. Use '.txt' to create a text file. Use a single '.' to auto-generate
the name based on date/time. Can also write the full path to the file, e.g. 'C:/Users/user/output.txt'
or stop at 'C:/Users/user/' to use the auto-generated file name.
-m, --metric = Make the output units be metric.
-i, --imperial = Make the output units be imperial. Default behaviour, therefore just implemented for completion.
CONVERSIONS
Usage example 'twc --conversion-m-to-ozft2 <Value>'. Can use an SI prefix in the input when converting from meters.
--convert-m-to-ozft2 = From meters to oz per foot sq.
--convert-m-to-mil = From meters to mil.
--convert-m2-to-in2 = From meters sq. to inches sq.
--convert-m2-to-mil2 = From meters sq. to mil sq.
--convert-mil-to-mm = From mils to milimeters.
--convert-mil-to-ozft2 = From mils to ounce per foot sq.
--convert-mil2-to-cm2 = From mils sq. to centimeters sq.
--convert-mil2-to-mm2 = From mils sq. to milimeters sq.
--convert-ozft2-to-mil = From ounce per foot sq. to mils.
--convert-ozft2-to-mm = From ounce per foot sq. to milimeters.
--convert-ozft2-to-um = From ounce per foot sq. to micrometers.
--convert-F-to-C = From Fahrenheit to Celsius.
--convert-C-to-F = From Celsius to Fahrenheit.
--convert-WmK-to-BTUhftF = From Watts per mili Kelvin to BTU/h*ft*F.
--convert-BTUhftF-to-WmK = From BTU/h*ft*F to Watts per mili Kelvin.
Most basic type of output where the current is 1 A and the copper weight is the 35 um standard,
twc -c 1 -w 35u
Changing standards can be done with the --standard and --method flags. For example to use the IPC2221 standard,
twc -c 1 -w 35u --standard IPC2221
Can instead use imperial inputs like oz/ft^2 to specify the copper weight. This can be done for all the options listed in the --help,
twc -c 1 -w-oz 1 --standard IPC2221
Feel free to add more options for use with the desired method. Some options won't have any effect on other methods, and that's easy to figure out from the output or the details in the --help option. Example below shows how to use trace length and plane distance in IPC2152, Method A,
twc -c 1 -w-oz 1 -l 2c -d 1c
Choose to place a small note at the top of your output to remind yourself what this output is for,
twc -c 1 -w-oz 1 -l 2c -d 1c --note "Example note!"
Output from that command is shown below,
Note:
Example note!
Current: 1.000000 [A]
Copper Weight: 1.000000 [oz/ft^2]
Temperature, Rise: 10.000000 [C]
Trace Length: 2.000000 [cm]
PCB Thickness: 1.600000 [mm]
Plane Distance: 1.000000 [cm]
PCB Thermal Cond.: 0.200000 [W/mK]
Area: 0.009919 [mm^2]
Corrected Area: 0.016523 [mm^2]
- Constants used for the P/I/V calculations were,
a = 0.0039300 [1/C] (Temperature Coefficient)
rho = 0.000000017200 [Ohm m] (Resistivity)
- Constants and method used were derived from https://ninjacalc.mbedded.ninja/calculators
/electronics/pcb-design/track-current-ipc2152.
- TWC used the IPC2152 standard, Method A.
Design assistance by the TWC tool is provided with no liability whatsover. For final deci
sions on electronics designs, please consult an actual qualified person.
Choose to output this to a text file by using the -o option and by either inputting a name or a '.' to use the autogenerated output.
twc -c 1 -w-oz 1 -l 2c -d 1c --note "Example note!" -o .
The internal conversion functions are also available for quick and easy conversion for some of the inputs to the TWC, for example convert um to oz/ft^2.
twc --convert-m-to-ozft2 35u
Clone the repository and got to this directory. Using make simply run in a command line,
make
And twc should be build in a new build/ directory.
Running the tests or coverage can be done by running,
make test
make coverage
Testing suite used is Unity and LLVM-COV for coverage.
Some sources for creating the tool are listed below,
- Trace Width Calculators,
- Conversion calculators,
- Convert-me for area conversion
- UnitConverters
- Convert-measurement-units
- Metric Conversions C to F conversion
- Other Resources