Soldering the thermal pad of an SMD onto a PCB by heating the bottom with a solder gun
You are probably looking for whats called &quot;thermal vias&quot;.
https://www.pcb-investigator.com/en/blog/thermal-vias-benefits-and-limitations
https://www.electronics-cooling.com/2004/08/thermal-vias-a-packaging-engineers-best-friend/