Why are my PCB traces overheating during testing?

[Kasuo]

Hey folks, I’m new to PCB design and I ran into something odd. I had a small board made for a project, but during testing some of the traces get warm and one even browned slightly. I thought I sized them correctly in KiCad, but maybe I messed up.

Do PCBs have some kind of standard design rules for current handling? And how do you know what thickness or width to use for power vs signal traces? I keep hearing terms like silkscreen, ground plane, etc., but it’s still confusing to me. Any tips? @Member

[Imen.D]

Hello @Kasuo ,

For which type of hardware, board? Maybe you can do a search in ST web page, as there are several guideline documents that can help you.

For example, for STM32 PCB design, you can find documents named by family: "Getting started with STM32xx MCUs hardware development" such as AN5935, AN5307, AN5711, and AN4488, which provide comprehensive rules and layout recommendations for different STM32 families. These documents are the references for PCB design and provide recommendations and PCB layout best practices: from PCB stack-up, trace width to decoupling and high-speed signal routing, ensuring robust and reliable PCB designs.

You can also refer to these resources: 

• AN5036: Guidelines for thermal management on STM32 applications - Application note
• AN576 Application note PCB layout optimisation.
• PCB layout tips to maximize ESD protection efficiency - Application note
• Introduction to USB hardware and PCB guidelines using STM32 MCUs - Application note

[Kasuo]

Thanks everyone for the pointers! I realized I didn’t account for current properly when sizing my traces. While digging around, I found this breakdown that really helped me understand the basics of PCBs and their design rules: PCBs Explained: How Printed Circuit Boards Power Electronics.

Leaving it here in case it helps someone else who’s just getting into PCB design.

[AScha.3]

Hi,

some basic calculation...ask the tools :

https://www.advancedpcb.com/en-us/tools/trace-width-calculator/

https://de.farnell.com/en-DE/pcb-trace-width

+

 many other - just search: track width calculator .