A printed circuit board (PCB) is the central unit of an electronic device. It establishes the functionality of an electronic device. It controls the flow of electricity to an electronic device. Before it becomes functional, it undergoes many stages of fabrication. PCB fabrication consists of five stages, the prototyping, manufacturing of the board, assembly process, testing for electrical connections and packaging of the PCB.
Before bulk production of the PCB starts, manufacturers create a prototype. The design-engineering department produces a design according to the specifications of the client who orders for the PCB. In some instances, the client provides the design. The PCB manufacturer creates a prototype, and determines if the design is feasible.
This prototype becomes the sample PCB where manufacturers test and rectify any defects on the designed circuitry of the board. In this stage, manufacturers perform all of the stages, except for the packaging stage, on a single PCB. Usually, manufacturers use the through-the-hole technology in making prototypes. When the prototype becomes functional and free of any electrical defects, the actual fabrication begins.
The Manufacturing of the Board
The manufacturing department chooses the right materials for the fabrication. Choosing of the materials is based on the bill of materials forwarded to the department. Careful planning of the substrates, electrical components, type of assembly technology used that are applicable to the design of the PCB is important. This planning stage begins in the prototyping stage. Thus, when the board is forwarded for PCB fabrication, the design and circuitry should have minimal electrical defects, if not 100% free of any defects.
The manufacturing stage consists of processes before the PCB is forwarded to the assembly house. These processes include producing the substrates, printing of the circuitry and testing for the circuitry. The substrates production involves the use of a compressing machine. This machine compresses layers of dielectric materials and copper foils to form the board. The dielectric materials act as insulators for the electrical components and the copper layers. Thus, choosing the right dielectric materials is important. The most common is the FR-4.These materials should be resistant to heat, chemicals, electricity and mechanical stresses.
After the forming of the board, the next process is the printing of the circuitry. In this stage, manufacturers use a high quality-printing machine and an etching process. In the etching process, chemicals are used to remove the portion of the printed circuitry that is not needed. That is why substrates or the board should be chemically resistant. In some PCB manufacturing company, printing of the circuitry includes a machine that directly prints the circuitry on the board, which requires the substrates to be resistant to mechanical stresses.
After etching the circuitry, an initial testing is performed before the PCB is forwarded to the assembly team.
The Assembly process
In this PCB Fabrication stage, manufacturers place electrical components on the board. A separate bill of materials (BOM) is accomplished. This BOM may contain the part number, the component type, serial number and instructions in cases the specific materials are not available.
In this process, the assembly team uses either through-the-hole or surface mount technology, depending on the instructions indicated in the BOM.
The Testing Stage
This stage is essential in determining whether the mounted electrical components are working correctly. Manufacturers sample a PCB in the batch and test it. When defects are found, the PCB (the whole batch) is forwarded to the repair department. If no defect are found, the assembly team forwards the batch to the packaging area. In bulk manufacturing, batch testing is more appropriate. When a certain batch is defective after it goes to the market, manufacturers recall it or provide technical support to rectify the mistakes.
The Packaging Stage
This stage is a minor one but it is still essential in making the service life of PCB longer. The materials for the packaging should be dielectric and resistant to moisture, electrical static and other environmental stresses that may render the board useless.
Extra measures are required to make sure that the PCB reaches the client in good condition. These measures include using bubble packaging, good stacking practices and careful transporting of the PCB from the packaging department to the dispatching area.
PCB fabrication involves various processes. Here pcbnet.com, you get more different PCB fabrication processes. This includes careful planning for the circuitry, and materials used, creating the substrates and assembling the components. It also entails testing to ensure that the PCB is functioning. Printed circuit boards are very sensitive. Thus, manufacturers should employ good practices from manufacturing the board up to the time it goes out for delivery – and that’s what we do.