Types of Test Boards
Two test board cross sections are defined in the JESD51 standards.
1s boards (as per JESD51-3): The first cross section is referred to as the low effective thermal conductivity or 1s board. The 1s refers to the one signal layer on the component side of the board, so the board is sometimes referred to as a single layer board. Limited signals are permitted on the opposite side actually, making it a 2s or two-layer board. The key point is that this board does not have power planes (0p). The signal-layer traces (obviously the exposed sides for such a board) are 70 µm (2 oz/ft2) finished copper thickness. Sometimes, this board is referred to as a 2s0p board too.
2s2p boards (as per JESD51-7): The second cross section is referred ...