Standard PCB Thickness
Despite the large number of PCB manufacturers, PCB types or manufacturing methods, there are some internationally accepted standard PCB thicknesses that are basically 1.57 mm in metric system or 0.063 inches in imperial system of measurement. Behind these conventions, PCB board development has a series of historical events. All this started with the introduction of the first electronic PCB boards which were made of Bakelite sheets.
Bakelite was mass produced as 1.57mm thickness, so it was bought that way and then cut adequately to be used as electronic plates. This is the easiest way of that era. This thickness was of technical significance when multi-layer electronic boards began to take place. In order to connect the circuit boards together, some connecting wires made of copper were needed at the edge of the circuit board.
These connectors between boards had to match the thickness of 1.57 mm and here came the standard PCB thickness into real usage. As PCB boards kept advancing, more appropriate materials were used, for instance, materials like polymide and epoxy substituted the Bakelite. In addition, edge connectors were not used any longer, so the thickness of 1.57 mm was of no use anymore.
Apart of this, PCB boards kept being produced in that thickness until the number of layers went up to ten or more, in that case it was not easy to keep that exact value so another standard PCB thickness came up at 2.35 mm or 0.093 inches. Thicker PCB’s of 3.2 mm or 0.125 inches were later introduced marking the third standard in existence.
The picture below shows some multilayer PCBs with a total thickness of 0.125 inches. We can notice that the thickness of the core and other sheets is very much in line with the layers and has +/- 10% tolerance.