PCB or the printed circuit boards are made with different methods constrained by user budget. The large scale production methods need precision, maximum yield, low cost and lowest manufacturing time for product launch and hence for PCB making. The less costly methods are adapted for in-house prototyping, small production volume and not much cost sensitive items. The later method suites to the students, hobbyists and small scale (workshop level) producers.
A PCB can be fabricated by an automatic CNC milling machine or etching method. A CNC milling method is a good technique for rapid prototyping that works with CAD software generated gerber files. The machine requires a reference point over the PCB and starting from that reference point removes the unnecessary copper from the laminated PCB sheet. This is suitable for single and double sided prototype PCBs making. Because it is milling machine so it is equally suitable for through hole and SMD components. In figure 1, a CNC milling machine is shown for PCBs making. Generally, the pads and/ or vias are not plated through holes and are required to insert ad make connection with a wire. There is no solder masking and overlay printing for component designators.
Figure 1: A CNC PCB milling machine
The etching method most widely used for students, hobbyists and production houses. This method is used for single, double and multilayer PCBs manufacturing. The exact replica map of PCB is reproduced over the lamination sheet suing ultraviolet light. The next step is etching or removing the unnecessary copper from the laminated side. The vias and pads are fabricated with electrolysis method. This is a mature production method so precise and micro-drilling is possible such as by LASER drilling techniques. The complex multilayer rigid PCBs, flexible and rigid-flex PCBs are also manufactured by this technique. The PCBs are solder-masked to avoid solder bridging and to minimize environmental effects such as moisture absorption. The overlays are printed for components marking that helps during assembly and troubleshooting. In figure 2, a multilayer finished PCB making by etching process.
Figure 2: Multilayer finished PCB by etching method
A home based method for PCB making exist that is most widely used only by students and seasonal hobbyists. This is same as replicating the PCB design over lamination sheet by using a toner transfer method or similar one and then etching using in-home-available instruments. In figure 3, a homemade PCB is shown.
Figure 3: Homemade PCB for student project