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Do you know about the true origin of this diagram?

If you want to know, please send an email to info@adam-research.deDo you know about the true origin of this diagram?

If you want to know, please send an email to

Thermo-Electric Circuit Board Simulation with


Components and currents heat the PCB (assembly) - but how hot will it get? Are the temperature limits complied with? No data sheet or guideline will tell you.

With TRM (Thermal Risk Management) you are able to calculate the thermal performance of your circuit board before the laboratory test

… and with new TRM 3.7 it's even easier to generate a better temperature forecast. Made easier than with add-ons of the big EDA vendors.

• Import your Gerber, placement, drill files or netlist or set the necessary    data manually (see FAQ)

• 3D circuit board model with up to 50 layers

Update: Easy export and import for ALTIUM users

NEW:       Easy export and import for EAGLE users

• Clearly arranged operation

• Templates and file formats for parameter input

• Can also be used without CAD data - for technologists

• No FEM knowledge required


• Accuracy through physics and geometry

• Heating by components and/or currents

• Environmental conditions. Air cooling, heat sinks and heat sinks, radiation into a vacuum, and much more

• Virtual thermograms of all layers and prepregs in high resolution

• DC potential distribution and current density in nets

• Steady-state or transient

• Temperature-dependent material data

• Self and mutual inductance (inductance matrix)

• Automatically generated result tables


• Licensing by your server

• Short to moderate computing time on laptop and PC

Request a free Trial installation ar a webdemo .


Good news for board designers using Autodesk's EAGLE or Fusion 360!

Transfer board data in 2 clicks and start a thermal simulation with TRM. The first action starts a special export, the second one an import wizard in TRM. Layer stackup, holes, netlist and components are automatically merged into an assembly model. Then just assign the most relevant Watts and/or Amps - done.
Request a test installation or an online demo by email to

Printed circuit boards with many layers, fine x-y resolution or large "pie trays" pose a numerical challenge. Up to now it was like this: the more temperature nodes to solve, the more iterations were required and it was not unlikely that unstable convergence would occur (has been got under control by internal repair mechanisms).

With Release TRM3.6, a new "Turbo" algorithm has been added, which solves the 3D temperature field about 10x faster than before. By activating multi-threading, you can possibly get even more out of it. Really demanding projects are now completed in tens of minutes instead of one or more hours.

Ask for a test installation here

My friend and colleague Doug Brooks has decided to take retirement. Therefore he has summarized his best articles and parts of his books in a new work "UltraCAD's Best".
Doug Brooks: UltraCAD's Best

Also, his calculation tools are now available for FREE instead of $250:
FREE: UltraCAD tools and calculators

Let's wish Doug lots of good times with his (big) family!

TRM3.5.7 was released on 10.11.2021. At first glance, the differences seem to be small. But TRM has become much more performant for very large or high resolution boards (> 10 megapixels per layer, many layers or tens of thousands of laser vias). Also, once again some dialects in the input files are better interpreted.
You may request a test installation here

Doug Brooks has revised his previously self-distributed book on Amazon and it is now available from Artech House.

PCB Design Guide to Via and Trace Currents and Temperatures

Explores how hot traces and vias will be and what board, circuit, design, and environmental parameters are the most important;
● Covers PCB materials (copper and dielectrics) and the role they play in the heating and cooling of traces;
● Details the IPC curves found in IPC 2152, the equations that fit those curves and computer simulations that fit those curves and equations;
● Presents sensitivity analyses that show what happens when environments are varied, including adjacent traces and planes, changing trace lengths, and thermal gradients;
● Explores via temperatures and what determines them, along with fusing issues and whether we can predict the fusing time of traces;
● Readers learn how to measure the thermal conductivity of dielectrics and how to measure the resistivity of copper traces and why many prior attempts to do so have been doomed to failure.

He also uses TRM and outlines the process of model building.

You may also be interested in other titles from the Artech range.

The thermal resistance "Junction-Ambient" ΘJA or RΘJA links a temperature node inside the silicon die (Junction) with the surrounding air (Ambient). "Ambient" includes everything around the component, from the pad to the air - i.e. especially the special topology of the PCB. Therefore RΘJA cannot be used to predict the temperature for a specific board. Here are some screenshots from Don't believe the data sheets. Design007 Magazine (September 2020).They show that the heat spreading on a real PCB is not perfect and that it was certainly different on the test PCB of the data sheet.

  • This Arduino board is 2-layer. The parallel running tracks can improve and impede the heat spreading.
Simulated thermal image of top Layer of Arduino Board
Top Layer of an Arduino Board calculated with TRM3


  • Even with multilayer boards with solid inner layers, the layout can dominate the heat spreading. In this evaluation board we see that the thermal vias are in fact useless, because they are just as warm as the component, so no heat    is removed.
PCB Simulation of Microchip Eval Board EVB-USB580X
Bottom Layer of MicroChip Eval Board EVB-USB580X calculated with TRM3

A TRM release is available: assign a resistor attribute (mOhm) to SMD parts to connect nets or copper geometries. Can be applied it with or without net list. The current goes through it and the voltage drop is adapted to the input value. I^2*R can be used for the heat and add to the Joule heat in traces. Also works in temperature-dependet mode.

  • Simple example with resistors. Total resistance is 1 Ohm in each circuit.
  • 3 half-bridges (Rdson=3 mOhm each, yellow)  with shunt resistors (5 mOhm each, green) share the current.