This PCB technology is mainly used for high-power LED chips in order to enhance heat transfer from the LED to the body of the PCB and then through the heat sink or perhaps the body of the fixture. It is very important to manage the heat produced by the LEDs to maintain performance and improve efficacy. Most of the high-power LEDs have separate thermal pads which is relatively small and makes it challenging to transfer the heat across and keep the LEDs running cool.
The regular metal core Aluminum PCBs have a dielectric layer of 50-100uM and their thermal conductivity is about 1-3W/mK.
With Thermoelectric Separation (i.e. called direct touch technology), the thermal pad is directly attached to the Aluminum body with no dielectric layer in between. In this method, the thermal conductivity is about 400W/mK and the LEDs are running cooler by 10-15 degrees.