a ground plane or power plane, to achieve better signal integrity, higher signaling frequencies, and better power supply decoupling. In multilayer boards, circuit cu stackup imprimat layers of material are laminated together in an alternating sandwich: copper, substrate, copper, substrate, copper, etc.; each layer of copper is etched and any internal sleepers (which
surface) that provide electrical connections on that conductive layer. Another manufacturing process adds plated or metallized holes that allow interconnections between layers. PCBs mechanically support electronic components using pads for bonding the component terminals and electrically connect them using traces of one or more cu circuit imprimat stackup layers of copper sheets laminated on and/or between layers of conductive
red, blue, white, black. Only stackup cu circuit imprimat the outer layers need to be covered with solder mask, the inner copper layers are protected by the adjacent substrate layers. The soldering mask soldermask is made of a fluid substance like an ink and is applied in a thin layer similar to varnish