Flex boards with stiffener are formed by a flexible part of polyamide material to which a rigid material of FR4 is attached.
and often part of the internal layers are used as a ground plane or power plane, to achieve better signal integrity, higher signaling frequencies, and better power supply decoupling. Flexible stiffener board with In multilayer boards, layers of material are laminated together in an alternating sandwich: copper, substrate, copper, substrate, copper, etc.; each layer of copper is etched
copper from stiffener with Flexible board corrosion and reduces the chances of solder shorting between traces or unwanted electrical contact with possible loose wires. For its function of helping to prevent solder shorts, the coating is called a solder mask. Soldermask is generally green in color but can have different colors: green, red, blue, white, black.
When producing the printed circuit with controlled impedance, the impedance will be controlled by acting on the dimensions of the tracks and the stiffener with Flexible board distance between them, i.e. the insulation. For a multilayer printed circuit with a specific stack-up, it must be taken into account that the internal tracks
