In 1936, the very first printed circuit board (PCB) was created by Paul Eisle. However it wasn’t 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 found in virtually all manufactured products including, automobiles, cellular telephones, pcs, among others.
An Overview in the PCB Fabrication Processes – PCBs are initially fabricated with the aid of two types of software. Computer Aided Design (CAD) application is employed to design the electronic schematic of the circuit to become produced. Right after the schematic was created, Computer Aided Manufacturing (CAM) application is used by engineers to create the PCB prototype.
When the PCB prototype is designed, the first step inside the pcb fabrication and assembly is to choose the material from the printed circuit board. There are various types 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 style requirement dictates the size of the PCB (I.e., length, width and thickness).
After the material has been selected, the very first process is to apply a coating of copper to the entire board. The circuit layout will then be printed on the board by a photosensitive process. Then, a picture engraving process is going to be used in order that each of the copper which is not area of the circuit layout will likely be etched out or removed from the board. The resulting copper creates the traces or tracks of the PCB circuit. For connecting the circuit traces, two processes are used. A mechanical milling process will use CNC machines to eliminate 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 time in the flexible pcb manufacturing process, the PCB board contains copper traces with no circuit components. To mount the components, holes should be drilled on the points in which the electrical and electronics parts are positioned on the board. The holes are drilled with either lasers or even a special sort of drill bit made of Tungsten Carbide. Once the holes are drilled, hollow rivets are inserted into them or they are coated by an electroplating process, which creates the electrical connection between the layers from the board. A masking material is then applied to coat the complete PCB except for the pads and also the holes. There are many types of masking material including, 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 step in the PCB fabrication process is to screen print the board so labels as well as the legend appear at their proper locations.
Testing the Quality of the PCB Board – Before placing the electrical and electronic components on the PCB, the board ought to be tested to confirm its functionality. Generally speaking, the two main varieties of malfunctions that can ysfurn a faulty PCB: a quick or an open. A “short” is a link between two or more circuit points that should not exist. An “open” is actually a point where a connection should exist but does not. These faults has to be corrected ahead of the PCB is assembled. Unfortunately, some rigid flex printed circuit boards do not test their boards before these are shipped, which can cause problems on the customer’s location. So, quality tests are a crucial procedure of the PCB fabrication process. Testing ensures the PCB boards will be in proper working condition before component placement.