Printed Circuit Board PCB

The assembly of the various circuits which form part of the units employed in aircraft electronic systems, necessitates the interconnection of many components by means of electrical conductors. Before the introduction of printed wiring, these conductors were formed by wires which connected to the components either by soldering, or by screw and crimped terminal methods.

In the development of circuit technology, micro-miniaturisation, rationalisation of component layout and mounting, weight saving, and the simplification of installation and maintenance become essential factors; and as a result, the technique of printing the required circuits was adopted.


In this technique, a metallic foil is first bonded to a base board made from an insulating material, and a pattern is then printed and etched on the foil to form a series of current conducting paths, the pattern replacing the old method or wiring. Connecting points and mounting pads, for the soldering of components appropriate to the circuit, are also formed on the board, so that, as a single assembly, the board satisfies the structural and electrical requirements of the unit which it forms a part.

If the circuit is a simple one, the wiring may be formed on one side of a board, but, where a more complex circuit is required, wiring is continued on to the reverse side, which also serves as the mounting for components. In addition, complex circuits may be incorporated in multi-layer assemblies.