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 PCBs in their bomb detonator systems that printed circuit boards found wide application. Printed circuit boards are now used in virtually all manufactured products including, automobiles, cellular telephones, personal computers, and others.
An Overview of the PCB Fabrication Processes – PCBs are initially fabricated with the use of 2 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) application is used by engineers to create the PCB prototype.
When the PCB prototype is made, the first step in the PCB production is to select the material from the printed circuit board. There are many different kinds 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 style requirement dictates the dimensions of the PCB (I.e., length, width and thickness).
Right after the material has become selected, the first process is to use 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 be used so that each of the copper which is not part of the circuit layout will be etched out or taken off the board. The resulting copper creates the traces or tracks from the PCB circuit. To connect the circuit traces, two processes are utilized. A mechanical milling process will use CNC machines to remove the unnecessary copper through the board. Then, an etch-resistant, silk-screen, printing process is applied to cover the regions where traces must exist.
At this point inside the flexible pcb manufacturer, the PCB board contains copper traces without the circuit components. To mount the components, holes should 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 perhaps a special type of drill bit manufactured from Tungsten Carbide. Once the holes are drilled, hollow rivets are inserted into them or these are coated by an electroplating process, which produces the electrical link between the layers in the board. A masking material is then placed on coat the whole PCB with the exception of the pads and also the holes. There are many types 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 final element of the PCB fabrication process would be to screen print the board so labels as well as 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 ensure its functionality. Generally, there are 2 varieties of malfunctions that may ysfurn a faulty PCB: a short or an open. A “short” is actually a link between several circuit points that will not exist. An “open” is actually a point when a connection should exist but will not. These faults should be corrected prior to the PCB is assembled. Unfortunately, some rigid flex printed circuit boards usually do not test their boards before they are shipped, which can lead to problems on the customer’s location. So, quality tests are a vital procedure of the PCB fabrication process. Testing ensures the PCB boards are in proper working condition before component placement.