This category includes backplane connectors designed for high-density interconnections between circuit boards in data centers, servers, and industrial applications. It includes connectors like PC/104, PC/104 Plus, and similar high-pin-count, through-hole connectors. Excludes photovoltaic (solar panel) connectors, circular, rectangular, card edge, terminal blocks, board-to-board, crimp and solder terminals, flexible flat cable (FFC) and flexible printed circuit (FPC) connectors, D-sub, coaxial (RF), and other types of connectors.