In 1936, the 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 virtually all manufactured products including, automobiles, cellular telephones, pcs, among others.
A Summary of the PCB Fabrication Processes – PCBs are initially fabricated with the aid of two types of software. Computer Aided Design (CAD) application is used 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 is made, the first step in the pcb fabrication specifications is to choose the material from the printed circuit board. There are numerous kinds of PCB materials available, but the popular ones, based on the application and 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).
Right after the material continues to be selected, the very first process is to use a coating of copper for the entire board. The circuit layout will be printed on the board by way of a photosensitive process. Then, a photograph engraving process will be used in order that each of the copper that is certainly not portion of the circuit layout will likely be etched out or taken off the board. The resulting copper creates the traces or tracks of the PCB circuit. For connecting the circuit traces, two processes are employed. A mechanical milling process uses CNC machines to get rid of the unnecessary copper through the board. Then, an etch-resistant, silk-screen, printing process is used to protect the regions where traces must exist.
At this time inside the flexible pcb, the PCB board contains copper traces with no circuit components. To mount the ingredients, holes must be drilled in the points where the electrical and electronics parts are positioned on the board. The holes are drilled with either lasers or even a special type of drill bit made from Tungsten Carbide. After 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 whole PCB with the exception of the pads and the holes. There are many kinds 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 step in the PCB fabrication process is always to screen print the board so labels and also the legend appear at their proper locations.
Testing the Quality 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 two types of malfunctions that may ysfurn a faulty PCB: a brief or perhaps an open. A “short” is really a connection between two or more circuit points that should not exist. An “open” is a point in which a connection should exist but fails to. These faults should be corrected before the PCB is assembled. Unfortunately, some rigid flex circuits do not test their boards before these are shipped, which can cause problems at the customer’s location. So, quality tests are a critical procedure for the PCB fabrication process. Testing ensures the PCB boards have been in proper working condition before component placement.