How do thermal vias work?

[der.ule]

I had the same problems, I solved changing the local clearance from the footprint, take a look at this thread:

Problem with zones and thermal reliefs

Hello, I’m laying a new board and I’m having problem with zones and thermal reliefs. Until now this feature had work great for me however, using the following footprint from the library: Package_DFN_QFN:Texas_S-PWQFN-N24_EP2.7x2.7mm_ThermalVias I get something like this when using a zone to connect the pad of the footprint: [image] As you see, there is no connection between the GND pad and the GND zone and I dont understand why, even with very small clearances and widths: [image] Zoomin…

I hope it helps !