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How Printed Circuit Boards Work

By February 26, 2020 No Comments

The Substrate

Every printed circuit board needs a substrate for all of its electronics to be printed on. These substrates or boards are built in layers, almost like a layered cake or lasagna for durability to ensure the quality of the finished product. These layers usually consist of the main substrate, usually fiberglass, to give the board the rigidness that it needs. Sandwiched on top of the fiberglass is a layer of copper, solder mask and silkscreen to allow the printed board to have the versatility to be built with any function in mind. 

 

The copper portion of the board is heated and laminated onto the main substrate. There are usually one or two layers of copper laminated onto the board but often there can be as many as 32 layers of copper. Each one of these layers has its own circuitry to add to the board. 

 

On top of the copper is the layer of the solder mask. This is what gives printed circuit boards their traditional green color and helps insulate the copper from accidental metal conductions in the circuit board. To label the solder mask, a silks screen is used. This allows manufacturers to know what each part of the board is used for. 

 

At this point, the printed circuit board is essentially completed. It is after this point that the accessories are added, computer chips, capacitors, resistors,  and interconnectors that connect the different layers of the board are all put on. PCI slots, heat sinkers, and CPU sockets are added to this as well, depending on what the circuit board needs to accomplish. 

 

Essentially these boards are made to simplify and have a more efficient process of wiring different parts of a computer or other electronics in a way so that you do not need thousands and thousands of wires interlaced all in your machine. The copper substrates end up being printed with an acid-resistant coating so that they can be washed away leaving only the copper circuits that are needed afterward.  This saves a lot of time and while the circuit boards themselves are complicated, it ends up making it simpler for electronics manufacturers to make computers and other electronics. 

 

There are other components to making the printed circuit board. Annular Rings are used on the surrounding the through-holes on PCB’s. Fingers are exposed to metal along the PCB edge that allows the different layers to be connected. Pad’s are exposed portions of metal on the board where components can be installed.

A panel is multiple circuit boards combined to make an installation process faster and easier. A paste stencil is a thin metal stencil that lies over the board during assembly to allow soldering paste to be used in certain areas. Pick and place is the manufacturing process for building the circuit boards. Plated through-hole are insulated holes in the board through which acts as a connecting point for a through-hole component. Slots are any hole that is not round that are drilled through the board. 

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