Electronic products continue to evolve and be more technologically advanced in the 21st century. The miniaturization of almost all gadgets and electronics has resulted in manufacturing printed circuit boards (PCBs) that are smaller and more densely packed. However, even if these PCBs are smaller, they have increased electronic capabilities. There are four main processes in manufacturing a printed circuit board. These are design, fabrication, assembly and test. These processes are all interrelated to each other. This article shall focus on the PCB fabrication process.
PCB fabrication is part of the process in manufacturing a Printed Circuit Board. The operations that are part of a circuit fabricator’s realm are cleaning, shearing, hole-drilling, pattern-imaging, etching and plating. Plating includes two processes: electro less and electrolytic plating. It should be emphasized that the environment in PCB fabrication should be spotlessly clean in order to avoid defects. In addition, fabricating PCBs should be done in a standardized, efficient and reliable manner.
The first step that should be determined in fabrication is what happens to the PCB designer’s data when it reaches the fabricator? When a PCB fabricator gets a data set, the first thing that must be done is to load it into a system to recreate the same PCB model. Good designers must construct valid PCB data sets. Fabricators receive what is called a fabrication drawing or a schematic diagram, which is the dimensional configuration of the board, size and location of the holes, and material and process specifications. This is the main reference document for the design.
A fabrication set should also have general PCB specifications such as board outline and thickness, material, finishes, compliance, number of orders and even addresses and delivery time. Other important PCB specifications are test, inspection and qualification requirement and change/modification control information.
The fabricator has to remember that fabrication data is not a set of files that run independently. All these data are interrelated, and are ordered sets of layers that are laminated together. The fabricator should also make sure that there is a digital data file for every pattern in the PCB. This means that the fabricator should check digital data files for copper layers, solder masks, and other patterned layers.
The physical layout is derived from the schematic diagram, and it defines the final physical form of the circuit. When it is complete, it is reduced to final size and a positive (electrolytic) or negative (electro less) print is made, depending on the specifications of the client.
The next phase is the transfer of the artwork pattern to the actual copper surface. Next is the etching process, which some consider as the core of the PCB manufacturing process. It is usually done by immersion, bubble, splash or spray method. After that is board drilling, then coating. The base metal conductor used in PCB fabrication is copper. Copper is used because it is an excellent conductor of heat and electricity. Several other coatings are applied to protect the product.
When all these are done, the PCB board will be subject to testing. There are generally two types of tests that are used: bare board test and loaded board tests. On each stage of the manufacturing process, it is of utmost importance to carry out inspections. It should also be noted that many chemicals are used in the PCB fabrication process, so protective measures should be undertaken. All protective devices such as goggles, masks and gloves should be on hand and wearing these should be strictly enforced and monitored. Additionally, all toxic chemicals should be sealed and stored properly. They should also be properly labeled. There should be no smoking and eating inside the facility.
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