In 1936, the initial printed circuit board (PCB) was created by Paul Eisle. However it wasn’t 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 utilized in nearly all manufactured products like, automobiles, cellular telephones, computers, and others.
An Overview of the PCB Fabrication Processes – PCBs are initially fabricated with the use of two kinds of software. Computer Aided Design (CAD) software is used to design the electronic schematic in the circuit to become produced. Following the schematic is designed, Computer Aided Manufacturing (CAM) software program is employed by engineers to create the PCB prototype.
After the PCB prototype is designed, the first step within the pcb fabrication and assembly is to pick the material from the printed circuit board. There are many different 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 style requirement dictates the proportions of the PCB (I.e., length, width and thickness).
After the material continues to be selected, the very first process is to use a coating of copper to the entire board. The circuit layout will then be printed on the board with a photosensitive process. Then, a photograph engraving process is going to be used in order that all of the copper which is not part of the circuit layout will be etched out or taken from the board. The resulting copper produces the traces or tracks in the PCB circuit. To connect the circuit traces, two processes are utilized. A mechanical milling process will use CNC machines to get rid of the unnecessary copper from the board. Then, an etch-resistant, silk-screen, printing process is applied to cover the regions where traces must exist.
At this stage in the flexible pcb manufacturer, the PCB board contains copper traces without any 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 a special kind of drill bit made from Tungsten Carbide. When the holes are drilled, hollow rivets are inserted into them or they may be coated by an electroplating process, which creates the electrical link between the layers of the board. A masking material will be applied to coat the whole PCB with the exception of the pads and the holes. There are many varieties 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 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 – Prior to placing the electrical and electronic components on the PCB, the board should be tested to confirm its functionality. Generally, there are two types of malfunctions that will ysfurn a faulty PCB: a quick or even an open. A “short” is really a link between two or more circuit points that should not exist. An “open” is a point in which a connection should exist but will not. These faults must be corrected prior to the PCB is assembled. Unfortunately, some rigid flex circuits usually do not test their boards before they are shipped, which can cause problems in the customer’s location. So, quality tests are a critical process of the PCB fabrication process. Testing ensures the PCB boards have been in proper working condition before component placement.