A Printed Circuit Board can have many sizes and characteristics. The Back Panel PCB is similar to a personal computer’s motherboard. It contains connection slots for expansion boards and allows for communications between all connected boards.
They are larger and thicker than standard PCBs because of the number of connections, and they need many layers (up to 30) to be stiff enough to support the insertion force to plug the daughter PCB connector into the motherboard (rear panel). Rigid multilayers are the most common technology used to develop back panels, but flex-rigid can also be developed in the case of requiring a special casing solution.
There are two types of back panel systems: active and passive. Active back panels contain the slots as well as the necessary circuitry to manage and control all the communication between the slots. In contrast, passive back panels contain almost no computing circuitry.
Interconnection means communication between the PCBs of a high-speed signal, such that signal integrity is a major requirement. Signal integrity (SI) ensures that a signal is transmitted from one point to another with sufficient quality or integrity to allow effective communication.
There is a wide range of raw materials available for constructing Back Panel PCB's, including standard FR4, which is a composite material, medium and high TG for Glass Transition Temperature, high-speed materials, polyimide materials, high-frequency materials, or mixed materials. For the finishing lead-free HAL, Electroless Nickel, Immersion Gold, or Immersion Tin can be used.