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Atta Rehman , 03-01-2025, 02:12 AM

#via connect , # EMC/EMI
Hi, @Robert Feranec , @QDrives
please suggest recommended , thermal relief gap and connect track width , for example
1. TI link recommends direct connect via without thermal relief under power IC .
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/940187/tps65130-schematic-configuration-inquiry.
2. Large thermal relief gap creates EMI radiations and noise issues as reference figure 2 blue circled connect style.

3. @Robert Feranec , video recommends to give some thermal relief for better soldering.
https://www.youtube.com/watch?v=4qu4xppIvmM

please suggest ,
> . Recommended thermal relief gap in mils . (plane & polygon connect rule)
> . Via connect track width in mils.
> . Recommended gap in mils between split plane .?
>
> thanks

QDrives , 03-01-2025, 03:03 AM

You (may) need thermal relief for TH (through hole) component pins. The reason is that a lot of heat can be dissipated into inner layers, especially if it is Gnd and multiple layers are/have Gnd.
A via is not soldered. At least, not in a similar way as a TH pin. Therefor no thermal relief is needed.

As for other thermal reliefs: the size of the gap and conductor depends on what you want.
In the attached screenshot you see (a little) different sizes in them. The top is for a 01005 capacitor and the bottom is a 0201. Not shown is the 0402 that has even bigger conductors.
You can play with the rules...

Robert Feranec , 03-01-2025, 07:58 AM

I mostly use thermal relief only on through hole pins connected to GND on multilayer PCBs as these may be hard to solder especially if you have multiple GND planes inside of PCB.

Atta Rehman , 03-01-2025, 08:34 AM

Sir , it means ,
1. is via connect should be direct without thermal relief ?
2. is thermal relief should v be given to components pads only ?
3. is thermal relief gap increase , also increase EMI radiated emission noise ?

QDrives , 03-01-2025, 01:22 PM

1) Yes, see picture for example
2) Yes, see picture too
3) No, EMI does not depend on using thermal relief unless you make the gap very big (>> 1mm)
Besides, you can also be strategic -- place additional traces of a fill on specific layers. Thermal relief is only for polygons.

Atta Rehman , 03-01-2025, 01:28 PM

thanks