The thermal resistance of the boards varies with thickness. These are given below in Square Mts x k / W where k/W denotes Kelvins per Watt
6mm -- 0.0231
8mm -- 0.0308
10mm -- 0.0385
12mm -- 0.0461
16mm -- 0.0615
20mm -- 0.0769
40mm -- 0.1538