This standard covers the design of printed circuit boards (PCBs) used in the thermal characterization of Dual-Inline Packages (DIP) and Single-Inline Packages (SIP). It is intended to be used in conjunction with the JESD51 series of standards that cover the test methods and test environments. JESD51-10 was developed to give a figure-of-merit of thermal performance that allows for accurate comparisons of packages from different suppliers. It can be used to give a first order approximation of system performance and, in conjunction with the other JESD51 PCB standards, allows for comparisons of the various package families.