Printed circuit boards are connected directly to a motherboard (mainboard) using PC / PCI slot connectors. There exist the PC-AT Standard (also called “ISA”) with a grid spacing of 2.54mm (0.1 inch) and the PCI Standard with a grid spacing of 1.27mm (0.05 inch) for the gold fingers.
- The entire plug area including the gold fingers must not be covered by solder-stop (see diagram)
- Plated-through holes within the contact area are not allowed
- The circuit board surface may be freely selected
- The gold fingers are manufactured using “hard gold” (electroplated gold), Au thickness 0.1 - 2µm