In 1936, the first printed circuit board (PCB) was created 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 used in virtually all manufactured products including, automobiles, cellular telephones, pcs, and others.
A Summary in the PCB Fabrication Processes – PCBs are initially fabricated by using two kinds of software. Computer Aided Design (CAD) software is utilized to design the electronic schematic from the circuit to be produced. After the schematic is made, Computer Aided Manufacturing (CAM) software is used by engineers to produce the PCB prototype.
Once the PCB prototype was created, the first step within the PCB production would be to pick the material in the printed circuit board. There are numerous varieties of PCB materials available, however 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 requirement dictates the dimensions of the PCB (I.e., length, width and thickness).
Following the material continues to be selected, the first process is to apply a coating of copper to the entire board. The circuit layout will likely then be printed on the board by a photosensitive process. Then, a picture engraving process will be used to ensure that all the copper which is not area of the circuit layout will be etched out or taken off the board. The resulting copper produces the traces or tracks of the PCB circuit. For connecting the circuit traces, two processes are used. A mechanical milling process will make use of CNC machines to eliminate the unnecessary copper from your board. Then, an etch-resistant, silk-screen, printing process is applied to pay for the regions where traces must exist.
At this point inside the flexible pcb, the PCB board contains copper traces without any circuit components. To mount the constituents, holes should be drilled in the points where electrical and electronics parts are placed on the board. The holes are drilled with either lasers or a special kind of drill bit made from Tungsten Carbide. Once the holes are drilled, hollow rivets are inserted into them or they may be coated by an electroplating process, which produces the electrical connection between the layers from the board. A masking material is then applied to coat the entire PCB excluding the pads and the holes. There are lots of kinds of masking material like, 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 final 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 Quality of the PCB Board – Prior to placing the electrical and electronic components on the PCB, the board ought to be tested to confirm its functionality. In general, the two main types of malfunctions that may ysfurn a faulty PCB: a short or an open. A “short” is actually a connection between two or more circuit points which should not exist. An “open” is really a point when a connection should exist but will not. These faults should be corrected before the PCB is assembled. Unfortunately, some rigid flex circuits tend not to test their boards before these are shipped, which can lead to problems in the customer’s location. So, quality testing is a crucial process of the PCB fabrication process. Testing ensures the PCB boards will be in proper working condition just before component placement.