How Is A Printed Circuit Board Manufactured?
To make a customized PCB, first the electronic diagram from the required circuit is ready using Computer Aided Style (CAD) software. After that the PCB prototype is developed using Computer Assisted Manufacturing Software technology.
The common materials employed for manufacturing PCBs are: FR4, FR4 High Temperature, Polyimide, GeTek, Rogers, Arlon, Nelco, Alumina, Ceramic, Bakelite, FR1, CEM1, and CEM5. The size and thickness from the board depends upon what’s needed of the circuit. The substrate is coated having a layer of copper. Then, using photosensitive coating, the circuit diagram is printed about the board. The undesired copper is etched out from the board to form copper “tracks”, called traces. This process is referred to as Photoengraving. There are two other common methods used for developing connecting traces. PCB milling is a mechanical system where undesired copper is removed along with CNC machines. Another process is Silk-Screen publishing, where special ink that’s etch-resistant is used to pay for the areas where the copper traces have to be made.
Once the board is ready with copper traces, holes are drilled to the board to assemble leaded electric and electronic components. For drilling, special Tungsten Carbide exercise bits or laser is used. The holes made are full of hollow rivets or coated through utilizing an electroplating process, thus forming an electrical connection one of the various layers. The next step is coating from the entire board, except holes and patches, with masking material. Materials commonly used for this function are: 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 (whitened tin), carbon ink, and SN 100CL, an alloy of container, copper, and nickel. The last step is screen-printing, where the legend as well as text are printed on the PCB.
Testing Of PCB
Before assembly of elements or delivery of Printed Circuit Boards, the board should be tested to find any possible “shorts” and “opens” that can lead to a non-functioning board. A “short” indicates the existence of an undesired connection and a good “open” indicates that two points which should have been connected tend to be unconnected. All such errors should be fixed before PCB set up. It is important to note that not all PCB Production shops test the boards before shipping, it is sometimes considered an added cost but a vital one to provide a fully functioning board before adding elements.
PCB Assembly
Once the board is actually ready, components are assembled and added to the surface as per the circuit diagram. Some of the common assembly techniques used tend to be surface-mount construction and through-hole building. Sometimes, a combination of these two techniques is also used for assembly.
Types of Printed Circuit Boards
Single Sided Board
This is the least complex from the Printed Circuit Boards, since there is merely a single layer of substrate. All electrical parts and components are fixed on one side and copper traces are on the other side.
Double Sided Board
This is the most typical type of board, where parts and components are mounted on both sides of the actual substrate. In such cases, double-sided PCBs that possess connecting traces on both sides are used. Double-sided Printed Circuit Boards usually make use of through-hole construction for set up of components.
Multi Layered Board
Multi layered PCB includes several layers of substrate separated by insulation. Most common multilayer planks are: four layers, six layers, eight layers, and 10 layers. However, the total number of layers that may be manufactured can exceed more than 42 layers. These types of boards are utilized in extremely complex digital circuits.
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