Printed Circuit Boards: From The Cradle To The Grave
It is common knowledge by now that circuit boards are an integral part of electronics. Their importance cannot be undermined by the size. Whether or not an electronic works the way it should depends on how well their PCBs (printed circuit boards) are made. There are various steps that happen before a finished circuit board is finally produced. These steps include procurement of materials, design, manufacture, testing, finishing and finally, rollout. It sounds quite simple, but a lot of hard work goes into the process.
The first step in material procurement. There are many materials that go into making circuit boards. The most widely used material is the FR-4 glass epoxy. This works as the insulator. To serve the purpose of conductor in a circuit, copper laminates are used. Depending on which kind of circuits are to be produced, a layer of copper laminate is stuck to this insulating substrate. This process determines whether the circuit is going to be one-sided or two-sided. Multiple layers can also be given to the board using this technique. Other materials may be used if there are special purposes for which a custom-fit or retrofitted PCB is to be made.
The next step is printed circuit board design. Earlier on, the process of design was a completely manual task. There was no use of computers or other designing software. Design used to be done by creating photomasks on a sheet made of mylar. This photomask was not the same size as the original circuit. For the purpose of ease of design and visibility, this photomask used to be magnified by two or four times. The designer would make a schematic layout of the circuit on the mylar sheet, and then lay out the component pin pads on it. The component footprints would then be transferred on it through dry transfer technique. Tracing out connections between components using self-adhesive tape was the next step. This completed design was then photolithographically transferred onto the blank copper-clad boards. Today, this method has become obsolete. There are printed circuit board design software that care of everything.
When the design has been confirmed, the next step is constituted in manufacturing the boards. This is a process that begins with Computer Aided Drafting – CAD. This software generates a Gerber Excellon file, which contains fabrication data. However, it is never directly fed into the manufacturing equipment. This file is first sent into the Computer Aided Manufacturing (CAM) software. This software then starts the following process. It reads the input file and verifies the data. If there are some deviations to be accounted for in the manufacturing process, it compensates for them. Panelization is the next step, wherein many PCBs are grouped together to be printed on the same large panel, which is later broken up into several units of manufactured PCBs. The next step CAM performs is the digital tool outputs, where it takes care of things like drill files, copper patterns, etc.
Once the board is manufactured, it is tested. Successfully tested boards are then sent for distribution.
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About The Author
James Whitehall is an expert when it comes to printed circuit board manufacturing and design. He loves writing interesting articles and blogs about the topic and recommends PCBCart.com as the name to trust if you are looking printed circuit board fabrication services and support.