In 1936, the first printed circuit board (PCB) was developed by Paul Eisle. But 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 found in nearly all manufactured products including, automobiles, cellular telephones, pcs, and others.
A Summary of the PCB Fabrication Processes – PCBs are initially fabricated by using 2 kinds of software. Computer Aided Design (CAD) application is utilized to design the electronic schematic in the circuit to become produced. Right after the schematic is made, Computer Aided Manufacturing (CAM) software program is used by engineers to generate the PCB prototype.
When the PCB prototype was created, step one in the PCB production is to choose the material from the printed circuit board. There are numerous kinds of PCB materials available, however the popular ones, based on the application as well as 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 dimensions of the PCB (I.e., length, width and thickness).
Right after the material has been selected, the initial process is to use a coating of copper for 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 in order that all of the copper that is not area of the circuit layout is going to be etched out or taken from the board. The resulting copper creates the traces or tracks from the PCB circuit. For connecting the circuit traces, two processes are utilized. A mechanical milling process uses CNC machines to get rid of the unnecessary copper through the board. Then, an etch-resistant, silk-screen, printing process is used to cover the regions where traces must exist.
At this time inside the flexible pcb, the PCB board contains copper traces with no circuit components. To mount the constituents, holes has to be drilled in the points where electrical and electronics parts are put on the board. The holes are drilled with either lasers or even a special sort of drill bit made from Tungsten Carbide. When the holes are drilled, hollow rivets are inserted into them or they are coated by an electroplating process, which creates the electrical link between the layers of the board. A masking material will then be applied to coat the entire PCB excluding the pads as well as the holes. There are many varieties 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 part of the PCB fabrication process is always to screen print the board so labels and the legend appear at their proper locations.
Testing the caliber of the PCB Board – Just before placing the electrical and electronic components on the PCB, the board should be tested to ensure its functionality. Generally, the two main kinds of malfunctions that can ysfurn a faulty PCB: a brief or perhaps an open. A “short” is really a connection between two or more circuit points that will not exist. An “open” is really a point where a connection should exist but will not. These faults must be corrected prior to the PCB is assembled. Unfortunately, some rigid flex circuit boards tend not to test their boards before they may be shipped, which can cause problems in the customer’s location. So, quality tests are a vital procedure for the PCB fabrication process. Testing ensures the PCB boards have been in proper working condition prior to component placement.