The Manufacturing Process of a Printed Circuit Board

Printed circuit board assembly and processing are executed in a tremendously clean location where both the components and air can be kept contamination free. Majority of the electronic companies have their own catholicon processes but there is a typical standard procedure to make printed circuit boards.

First, fiberglass is fed through a process station where it is sprayed with or dipped in epoxy resin. The imbued glass fiber is then rolled to the desired thickness of the substrate and passed into an oven for semi curing. It is then cut into large panels and stacked in layers. These layers are alternated with adhesive black copper foil which is then pressed and extremely heated for final curing and to bond the copper foil to the substrate.

When the substrates are finished, they are stacked and pinned together and are put into a computer numerical control machine. Holes are then drilled according to the blueprint. Any excess material is them removes from the holes’ edges. Some holes that are used for conduction are coated with copper; the others are just plugged.

The holes that are used to allow thermal and electrical connection of conductors on the opposite end of the printed circuit pattern are called vias. These are often filled with annular rings to make the supposed function possible. Sometimes, smaller versions of these vias are needed: these are called micro vias.

The printed circuit pattern is done via two processes: the additive and the subtractive. When undergoing the additive process, copper is plated onto the substrate surface in the preferred pattern. The rest of the substrate is then left unplated. When undergoing the subtractive process, the entire surface is copper plated and then parts not part of the preferred pattern are etched away. For a better functioning but more costly printed circuit pattern a low loss material is used.

After either process, the contact fingers are attached to the substrate and connected to the printed circuit. These contact fingers are veiled off from the board before being plated. Three layers of plating will be applied to the contact fingers respectively: tin lead, nickel then gold. Other purchased components are then attached if necessary. When dealing with advanced circuits like the IPC-6012 Class 3 or OMAP circuits, several of these purchased components per board are necessary.

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