In 1936, when, Paul Eisle create the world's first printed circuit board (PCB). But until the 1950s, the US defense industry began in their bomb systems integration PCB, printed circuit board and then began to be widely used. PCBs are now almost used to make products such as cars, cellular phones, personal computers, etc. computer products.
A Summary of the PCB Fabrication Processes
Printed circuit board production are initially fabricated with the use of two types of software. Computer Aided Design (CAD) software is used to design the electronic schematic of the circuit to be produced. After the schematic is designed, Computer Aided Manufacturing (CAM) software is used by engineers to produce the PCB prototype.
Once the PCB prototype is designed, the first step in the fabrication process is to select the material of the printed circuit board. There are many different types 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 requirement dictates the dimensions of the PCB (I.e., length, width and thickness).
After the material has been selected, the 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 photo engraving process will be used so that all the copper that is not part of the circuit layout will be etched out or removed from the board. The resulting copper creates the traces or tracks of the PCB circuit. To connect the circuit traces, two processes are used. A mechanical milling process will use CNC machines to remove 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 point in the PCB fabrication process, the PCB board contains copper traces without any circuit components. To mount the components, holes must be drilled at the points where 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 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 of the board. A masking material is then applied to coat the entire PCB with the exception of the pads and 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 step in the PCB fabrication process is to screen print the board so labels and the legend appear at their proper locations.
Testing the Quality of the PCB Board
A qualified High-Quality Printed Circuit Board is arranged before the wire and electronic components, will be tested to ensure that its functions can be used normally. There are two common types of failures typically: short and open circuit. "Short" refers should not exist between two or more nodes connected to a circuit was connected. "Open" means that this should be a connection between two circuit nodes, but not connected. These errors before the PCB assembly must be corrected, otherwise it would invalidate the entire board. Unfortunately, some of the printed circuit board manufacturers before they transfer out of the product and does not test, thus leading to some customers get the products in question. So quality testing printed circuit board production process crucial step. Quality testing must ensure that prior to placing the electronic components on the circuit board is in normal working condition.
Related readings: Electronic Circuit Boards, Printed Circuit Boards Manufacturers,Normal Double Sided PCB