Multilayer Printed Circuit Boards

Written by Adam Blau
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Complex circuit systems can be achieved by creating a multilayer circuit board for your electronics project. On multilayer boards there are pathways of current flow that occur at a board layer that is sandwiched between the outer layers. These outer layers contain the main electronics components like capacitors and resistors. As you might imagine, there are several extra steps necessary in order to fabricate multilayer boards.

Making a Multilayer Printed Circuit Board

Different companies will have different ways of creating multilayer circuit boards. The general principle remains the same, however, regardless of the exact methods of fabrication. The one certainty is that it is almost prohibitively complex for an amateur to create a functional multilayer printed circuit board without the assistance of a professional circuit board manufacturing company.

Let's take a four-layer printed circuit board as an example. The middle two layers (numbers 2 and 3) will be created as any two-layer circuit board would be created. First the design is set, then the unneeded copper will be etched off, leaving the conductive pathways for the inner layers.

Then, a layer of non-conductive material (often fiberglass) is added to the outside of this layer. New layers of conductive copper are placed on the outside of these insulated layers, allowing for the sketching and etching processes to be performed again. These outer layers can be labeled, and holes are drilled clear through the entire new structure. For boards with more layers, the process continues in a similar fashion.

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