PC/104 is an embedded computer standard defined by its compact footprint and its stacking bus structure. In essence, PC/104 is a modular, ruggedised version of the PC. Instead of using a backplane, PC/104 modules mate together via stackable ISA, PCI, and PCIe bus connectors. The stackable connectors and asymmetric corner mounting holes create a compact and modular rugged system. The design and location of the PC/104 connectors (ISA, PCI, and PCIe) allow PC/104 modules to be connected or stacked like building blocks. A PC/104 stack might include a CPU (single board computer), a power supply module, and peripheral modules such as data collection modules, network modules, or storage devices. Modules within a PC/104 stack are joined by stand-offs. As more powerful components have been developed, the PC/104 systems has been supplemented with the faster PCI bus system, resulting in the PC/104-Plus specification.
While the PC/104 bus comprises two connectors with 40 and 64 pins which can be placed side-by-side and a grid size of 2.54 mm, the PC/104-Plus features 120 pins with a distance of 2.00 mm. By using connectors with long press-fit pins, several boards can be stacked on top of each other. The clearances specified by the PC/104 consortium are ensured by using spacers and shrouds. The additional use of spacing bolts is therefore not required. The superior option for applying a long tail stack-through connector is with compliant pin technology. Adopted by the telecom industry many years ago, ept press fit technology has proven itself to be a cost-effective alternative to soldering connectors to a board. The compliant pins on the connector are designed to deform during the “press-in” process, resulting in an extremely tight and reliable connection to the PCB.