In 1936, the first printed circuit board (PCB) was made by Paul Eisle. But it wasn’t until the 1950s when the U.S. Defense industry began integrating PCBs in their bomb detonator systems that printed circuit boards found wide application. Printed circuit boards are found in nearly all manufactured products like, automobiles, cellular telephones, computers, among others.
An Overview of the PCB Fabrication Processes – PCBs are initially fabricated by using two kinds of software. Computer Aided Design (CAD) software is employed to design the electronic schematic from the circuit to get produced. Following the schematic is made, Computer Aided Manufacturing (CAM) software program is employed by engineers to create the PCB prototype.
When the PCB prototype was created, step one inside the pcb fabrication and assembly is to pick the material in the printed circuit board. There are many different varieties 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 size of the PCB (I.e., length, width and thickness).
After the material has been selected, the initial process is to use a coating of copper towards the entire board. The circuit layout will likely then be printed on the board by way of a photosensitive process. Then, a photo engraving process will be used so that all the copper which is not part of the circuit layout is going to be etched out or taken off the board. The resulting copper produces the traces or tracks of 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 from the board. Then, an etch-resistant, silk-screen, printing process is used to protect the regions where traces must exist.
At this stage inside the flexible pcb manufacturing process, the PCB board contains copper traces with no circuit components. To mount the constituents, holes has to be drilled in the points where the electrical and electronics parts are placed on the board. The holes are drilled with either lasers or even a special kind of drill bit manufactured from Tungsten Carbide. When 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 whole PCB with the exception of the pads and also the holes. There are numerous varieties 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 ultimate step in the PCB fabrication process is always to screen print the board so labels and also the legend appear at their proper locations.
Testing the Quality of the PCB Board – Before placing the electrical and electronic components on the PCB, the board ought to be tested to ensure its functionality. In general, there are two varieties of malfunctions that can ysfurn a faulty PCB: a quick or even an open. A “short” is a connection between two or more circuit points that should not exist. An “open” is actually a point when a connection should exist but fails to. These faults must be corrected ahead of the PCB is assembled. Unfortunately, some rigid flex circuit boards tend not to test their boards before these are shipped, which can lead to problems on the customer’s location. So, quality tests are a critical procedure for the PCB fabrication process. Testing ensures the PCB boards have been in proper working condition prior to component placement.