In 1936, the first printed circuit board (PCB) was made by Paul Eisle. But 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. PCBs are now used in almost all manufactured products including, automobiles, cellular telephones, personal computers, among others.
An Overview from the PCB Fabrication Processes – PCBs are initially fabricated by using two types of software. Computer Aided Design (CAD) software is used to design the electronic schematic from the circuit to be produced. Right after the schematic is designed, Computer Aided Manufacturing (CAM) software program is utilized by engineers to produce the PCB prototype.
After the PCB prototype was created, the initial step inside the pcb fabrication specifications is always to choose the material of the printed circuit board. There are numerous kinds of PCB materials available, but 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 size of the PCB (I.e., length, width and thickness).
Following the material has become selected, the very first process is to apply a coating of copper for the entire board. The circuit layout will then be printed on the board by way of a photosensitive process. Then, a photograph engraving process is going to be used so that all of the copper that is certainly 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 use CNC machines to eliminate the unnecessary copper from your board. Then, an etch-resistant, silk-screen, printing process is applied to cover the regions where traces must exist.
At this stage inside the flexible pcb, the PCB board contains copper traces without the circuit components. To mount the constituents, holes must be drilled on the points in which the electrical and electronics parts are put on the board. The holes are drilled with either lasers or perhaps a special sort of drill bit made of Tungsten Carbide. When 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 from the board. A masking material is then placed on coat the entire PCB with the exception of the pads and also the holes. There are lots of types 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 ultimate 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 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 2 varieties of malfunctions that may ysfurn a faulty PCB: a brief or an open. A “short” is really a link between two or more circuit points which should not exist. An “open” is really a point where 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 tend not to test their boards before these are shipped, which can cause problems on the customer’s location. So, quality tests are a critical process of the PCB fabrication process. Testing ensures the PCB boards are in proper working condition just before component placement.