PCB Fabrication: Understanding Its Process

PCB fabrication entails the process of printing on the circuit board to create a wiring pattern that connects integrated circuits, diodes, capacitors, resistors and other electronic components. These boards are used to construct electronic devices such as radios, transistors, cellphones, and computers.

The circuit starts by having a conducting material deposit printed on the surface of a substrate which is the insulating board. Different electronic components are placed on this surface and soldered to the conducting lines that connect each.

A printed circuit board may have a circuit that only performs a single function such as sound amplifying or as a power transformer. There are devices that have either two or three boards installed within, with each representing a function. Other printed circuit board has multiple functions included. You can see such boards used on smartphones.

PCB Fabrication Process

The process of fabricating printed circuit boards entails different methods. However, it always starts with a schematic diagram. To do this, the person must first plan his project’s function.

The Design

The schematic diagram is like a blue print that will guide how integrated circuits, diodes, and other electronic components will be connected to perform a function. This is not the actual design to be printed on the circuit board but it is considered the first skeletal plan of the device.

The schematic diagram shows how each part will be connected. There are layouts which show already how one device will be connected to another even if each will be placed on two different PCBs. To help designers understand the schematic, each part has reference designators that match what is in the Bill of Materials.

pcbThe Bill of Material of BOM is a list of parts that are to be mounted on the PCB. Each of these is described in detail and is identified by a reference designator (i.e. A resistor’s reference designator is R while a voltage source’s reference designator can either be an E or a V.). The BOM also includes parts which are not shown in the schematic diagram such as separators.

To understand each part that will be included in the circuit, the designer can look at its data sheet. Manufacturers of each part provide data sheets which provide the physical dimension and other information about the electronic part. After understanding this part, following the schematic and creating the PCB’s layout design is next.

The Board

Selecting the board where the layout will be printed is the next step. There are certain boards which are better for connecting electronic devices for a certain function. There will also be areas that require the board to have a certain dimension. You also need to define outside factors before designing the board.Get more about printed circuit board from pcbnet.com.You need to also consider its thickness and other external features. Such features are as follows:

•The material used – The board can either be fiberglass resin laminate or a phenolic which is a cheaper type.

•Board layers – PCB fabrication also considers the layers. There boards with a single-copper layer, double-copper layer or multi-copper layer. The single layered board can only allow electronic components to mount on one side. The double layered board allows two sides to be mounted with the components. The multi-layered are used for more complicated circuitry.

The PCB layout

The PCB fabrication is now in process with the layout finally drawn. In this case, it is best to draw manually or by ECAD (Electronic Computer Aided Design) software. If you are doing a simple layout, the manual way of drawing will do. However, for more complicated circuitry, it is best to use the CAD software. To help you finish the fabrication, here are some rules to follow.

•Place the parts on the board’s top side and arrange these according to their specific locations. This includes connectors, switches and more. Keep note to lessen the trace length as much as possible.

•Leave spaces between ICs. This will eliminate any complications and will allow you to adjust wiring if necessary.

•Drill holes that will fit the IC’s pin. There are drills you can use for this.

•Layout the power and ground traces. Have solid lines when you are working with ICs.

•Have signal traces. These can be placed manually or automatically.

Checking Your Work

Before fabricating, there are some who prefer to use a bread board where they can check connections of electronic components first. You should also check your PCB fabrication to see if all the components are placed well. While problems may mean you have to repeat the whole process of laying it on the PCB, checking will ensure the device will work properly.