In 1936, the very first printed circuit board (PCB) was made by Paul Eisle. However it was not until the 1950s when the U.S. Defense industry began integrating PCBs in their bomb detonator systems that printed circuit boards found wide application. PCBs are now found in almost all manufactured products like, automobiles, cellular telephones, personal computers, among others.
A Summary of the PCB Fabrication Processes – PCBs are initially fabricated by using two types of software. Computer Aided Design (CAD) application is employed to design the electronic schematic from the circuit to be produced. Right after the schematic is made, Computer Aided Manufacturing (CAM) application is utilized by engineers to generate the PCB prototype.
After the PCB prototype is designed, the initial step within the PCB production is always to pick the material of the printed circuit board. There are numerous kinds of PCB materials available, nevertheless the popular ones, based on the application and a customer’s requirements, include: Alumina, Arlon, Bakelite, CEM1, CEM5, Ceramic, FR1, FR4, FR4 High Temperature, GeTek, Nelco, Polyimide and Rogers.The design and style requirement dictates the proportions of the PCB (I.e., length, width and thickness).
Right after the material continues to be selected, the very first process is to use a coating of copper for the entire board. The circuit layout will be printed on the board by a photosensitive process. Then, a photo engraving process will likely be used in order that each of the copper that is not part of the circuit layout will likely be etched out or removed from the board. The resulting copper creates the traces or tracks from the PCB circuit. To connect the circuit traces, two processes are used. A mechanical milling process will make use of CNC machines to eliminate the unnecessary copper through the board. Then, an etch-resistant, silk-screen, printing process is applied to pay for the regions where traces must exist.
At this stage in the flexible pcb, the PCB board contains copper traces without any circuit components. To mount the constituents, holes must be drilled on the points where electrical and electronics parts are positioned on the board. The holes are drilled with either lasers or a special kind of drill bit manufactured from Tungsten Carbide. Once the holes are drilled, hollow rivets are inserted into them or these are coated by an electroplating process, which produces the electrical connection between the layers in the board. A masking material will be placed on coat the entire PCB with the exception of the pads as well as the holes. There are lots of types of masking material including, 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 last step in the PCB fabrication process would be to screen print the board so labels and the legend appear at their proper locations.
Testing the Quality of the PCB Board – Just before placing the electrical and electronic components on the PCB, the board needs to be tested to ensure its functionality. In general, the two main varieties of malfunctions that can ysfurn a faulty PCB: a brief or perhaps an open. A “short” is a link between 2 or more circuit points that will not exist. An “open” is actually a point in which a connection should exist but fails to. These faults should be corrected before the PCB is assembled. Unfortunately, some rigid flex printed circuit boards usually do not test their boards before these are shipped, which can lead to problems in the customer’s location. So, quality testing is a crucial procedure of the PCB fabrication process. Testing ensures the PCB boards are in proper working condition before component placement.