TC1262 - Thermal Resistance and Copper Surface Area
The SOT-223 package of TC1262 has a thermal resistance junction to ambient versus copper area (one layer and one ounce is attached). A second layer lowers the ΘJA roughly 20% to 40% depending on the package size and style, the number of vias, etc. In JEDEC conditions JESD51-7 (four layers board):
ΘJA = 62°C/W.