In 1936, the very 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 Printed circuit boards in their bomb detonator systems that printed circuit boards found wide application. PCBs are utilized in almost all manufactured products like, automobiles, cellular telephones, personal computers, and others.
A Summary in the PCB Fabrication Processes – PCBs are initially fabricated by using 2 kinds of software. Computer Aided Design (CAD) software is utilized to design the electronic schematic in the circuit to be produced. Right after the schematic was created, Computer Aided Manufacturing (CAM) software program is used by engineers to generate the PCB prototype.
Once the PCB prototype was created, the initial step in the PCB production is to pick the material from the printed circuit board. There are numerous types of PCB materials available, but the popular ones, based on the application along with a customer’s requirements, include: Alumina, Arlon, Bakelite, CEM1, CEM5, Ceramic, FR1, FR4, FR4 High Temperature, GeTek, Nelco, Polyimide and Rogers.The style requirement dictates the dimensions of the PCB (I.e., length, width and thickness).
After the material continues to be selected, the very first process is to apply a coating of copper towards the entire board. The circuit layout will then be printed on the board by way of a photosensitive process. Then, a picture engraving process will likely be used so that all the copper which is not area of the circuit layout will be etched out or removed from the board. The resulting copper produces the traces or tracks of the PCB circuit. To get in touch the circuit traces, two processes are used. A mechanical milling process will make use of CNC machines to remove the unnecessary copper from the board. Then, an etch-resistant, silk-screen, printing process is used to cover the regions where traces must exist.
At this stage inside the flexible pcb, the PCB board contains copper traces without any circuit components. To mount the components, holes must be drilled on the points where the electrical and electronics parts are placed on the board. The holes are drilled with either lasers or a special sort of drill bit made from Tungsten Carbide. After 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 from the board. A masking material will then be put on coat the entire PCB with the exception of the pads and also 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 ultimate 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 – Prior to placing the electrical and electronic components on the PCB, the board should be tested to verify its functionality. In general, there are 2 types of malfunctions that can ysfurn a faulty PCB: a short or perhaps an open. A “short” is really a connection between two or more circuit points that will not exist. An “open” is a point when a connection should exist but will not. These faults has to be corrected prior to the PCB is assembled. Unfortunately, some rigid flex circuit boards do not test their boards before they may be shipped, which can cause problems at the customer’s location. So, quality testing is a crucial process of the PCB fabrication process. Testing ensures the PCB boards are in proper working condition just before component placement.