The technology of PCB Fabrication has become more advanced since manufacturers have started offering printing. Printed Circuit Boards are used to support and connect electrical components mechanically. They are inexpensive and are also used for the high-volume production. Before fabricating a PCB, manufacturers define its design vaguely. Here, a PCB prototype plays the key role in the creation of its design and facilitates the manufacturer to foresee if anything needs to be resolved in the PCB’s design. In case of any failure in the prototype, a fresh prototype is created and is kept under custody till it performs well.
The process of PCB Fabrication goes under extreme conditions and a lot of steps are involved, like etching, engraving photos, multi-layer processing, drilling, masking, finishing, and finally electrical testing. PCB Test is done to check its efficiency and see if it delivers what it is supposed to do. Some manufacturers use different kinds of PCB specifications to make it perform, as required, such as using polyimide for flexibility, Arlon for longer life in high temperatures, and Isola range for PCB prototype. However, if the PCB Test comes out to be negative, then the entire circuit board is to be replaced or rectified accordingly.
On the other hand, talking about PCB Assembly, it is when electronic components are connected to a circuit board, we call it PCB Assembly. To connect these electronic components to the PCB, several techniques are used and two main techniques are, surface mount technique and through-the-hole technique. But, in most of the circuit boards, both these techniques are combined, to achieve maximum efficiency in the design and performance of the Printed circuit board. However, in some cases manufacturers employ highly skilled technicians to solder minute or small parts using microscope. They also use other equipments like tweezers, soldering tip, etc.
For a printed circuit board to be complete, not only equipments are important, but also PCB Fabrication, PCB Assembly and PCB Test. Hence, everything needs proper care. So, while choosing your manufacturer, do a thorough research about the company, its background, so that you get genuine and high-quality services in return.
After the material has been selected, the first process is to apply a coating of copper to the entire board. The circuit layout will then be printed on the board by a photosensitive process. Then, a photo engraving process will be used so that all the copper that is not part of the circuit layout will be etched out or removed from the board. The resulting copper creates the traces or tracks of the PCB circuit. To connect the circuit traces, two processes are used. A mechanical milling process will use CNC machines to remove the unnecessary copper from the board. Then, an etch-resistant, silk-screen, printing process is applied to cover the regions where traces must exist.
At this point in the PCB fabrication process, the PCB board contains copper traces without any circuit components. To mount the components, holes must be drilled at the points where the electrical and electronics parts are placed on the board. The holes are drilled with either lasers or a special kind of drill bit made of Tungsten Carbide. Once the holes are drilled, hollow rivets are inserted into them or they are coated by an electroplating process, which creates the electrical connection between the layers of the board.
A masking material is then applied to coat the entire PCB with the exception of the pads and the holes. There are many types of masking material such as, lead solder, lead free solder, OSP (Entek), deep/hard gold (electrolytic nickel gold), immersion gold (electroless nickel gold – ENIG), wire bondable gold (99.99% pure gold), immersion silver, flash gold, immersion tin (white tin), carbon ink, and SN 100CL, an alloy of tin, copper, and nickel. The final step in the low cost PCB fabrication process is to screen print the board so labels and the legend appear at their proper locations.