In 1936, the 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 Printed circuit boards in their bomb detonator systems that printed circuit boards found wide application. PCBs are found in nearly all manufactured products such as, automobiles, cellular telephones, pcs, and others.
A Summary in the PCB Fabrication Processes – PCBs are initially fabricated with the aid of two kinds of software. Computer Aided Design (CAD) application is employed to design the electronic schematic of the circuit to get produced. After the schematic is made, Computer Aided Manufacturing (CAM) software is employed by engineers to generate the PCB prototype.
Once the PCB prototype is made, the initial step within the pcb fabrication and assembly is always to select the material in the printed circuit board. There are numerous varieties of PCB materials available, nevertheless 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 design and style requirement dictates the size of the PCB (I.e., length, width and thickness).
Following the material has been selected, the very first process is to apply a coating of copper to the entire board. The circuit layout will be printed on the board by way of a photosensitive process. Then, a picture engraving process will be used to ensure that each of the copper that is not part of the circuit layout will be etched out or removed from the board. The resulting copper produces the traces or tracks in the PCB circuit. To connect the circuit traces, two processes are employed. A mechanical milling process will make use of CNC machines to get rid of 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 point in the flexible pcb manufacturing process, the PCB board contains copper traces without the circuit components. To mount the constituents, holes has to be drilled in the points in which the electrical and electronics parts are placed on the board. The holes are drilled with either lasers or even 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 creates the electrical link between the layers of the board. A masking material will be put on coat the entire PCB with the exception of the pads and also the holes. There are lots of 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 to screen print the board so labels and also 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 needs to be tested to confirm its functionality. In general, there are 2 kinds of malfunctions that may ysfurn a faulty PCB: a short or even an open. A “short” is a link between several circuit points which should not exist. An “open” is actually a point in which a connection should exist but fails to. These faults has to be corrected prior to the PCB is assembled. Unfortunately, some rigid flex printed circuit boards tend not to test their boards before they may be shipped, which can cause problems on the customer’s location. So, quality testing is a critical procedure for the PCB fabrication process. Testing ensures the PCB boards are in proper working condition just before component placement.