Manufacturing a printed circuit board involves many steps. For one, you’ll have to choose the pattern you want and the software you will use to design your own circuit board. Remember that you must design in reverse or have a 360-degree movement for easier view of all parts. Leave a distance of at least 1.0 mm between electrical paths. Make sure that you choose perfect locations for drilling holes in the actual board.
Once the circuit design is laid out, try to find errors and correct them immediately. When you’re completely satisfied, print a copy. Check the printout. Then print a mask or negative image using clear plastic sheet. Using this kind of sheet results to a clearer image of the circuit pattern as unused areas are shown in black color.
Steps in manufacturing a printed circuit board (PCB):
• The first vital step is generating the circuit fabrication data with the use of CAD. Circuit board follows 22 fabrication steps which require data modules and digitally-controlled operation. Once the data is loaded and read by a Computer Aided Manufacturing (CAM) software application, production tools will be generated.
• Penalization groups the circuit boards to the panel for manufacturing process. The main purpose of penalization is to secure the boards as they pass the assembly, manufacturing, and shipping processes. It aims to make the separation free from any damage through routing perforations, drilling, or cutting grooves along the circuit boundaries. Another way is laser penalization.
• Copper patterning is the step to replicate the circuit design using CAM fabricator’s system on the copper foil. The underlying insulating layer of silicon oxide is patterned with trenches and filled with a thick layer of copper coating.
Removing the excess copper can be done through additive, semi-additive, and subtractive methods.
1.Additive method – The circuit pattern in the mask or processed photosensitive film is laminated to the surface of the bare substrate with copper through electroplating. When the mask is peeled off, the printed circuit board is ready for the next step. Using additive method does not require many materials so it reduces waste production.
2.Semi-additive method – In this method, the substrate contains a thin layer of copper. A reverse mask, which exposes the tracing path, is placed on top of the board. With the use of additional copper, the film is plated.
3.Subtractive method removes excess copper from the platform, leaving the desired coated pattern.
• Chemical etching uses ferric chloride or ammonium per sulfate. It is commonly used in small-scale production. There are different kinds of chemical etching:
1.Immersion etching – The board is immersed in the solution.
2.Splash etching – The board is etched with a motor-operated paddle.
3.Bubble etching – Air is applied through an etchant bath to stir the solution, thus hastening etching.
4.Spray etching – The most popular etching method where the solution is sprayed over the substrate.
• Automatic optical inspection – The inside layers pass through a machine to compare the physical form against the original design generated by computer.
• Lamination – It is done by applying heat and pressure for a certain period to press stacks of copper-clad laminated boards with circuit patterns.
• Drilling – The operation is done by automated drilling machines with sharp-coated tungsten carbide drill bits.
• Plating and Coating – The printed circuit board is usually etched then rinsed with water before coating application. The choices vary from solder mask, tin, nickel, or gold coating.
• Application of solder-resist or solder mask – It protects the circuit board from harsh factors in the environment which can affect performance.
• Protection – After the electronic components are soldered into place, the printed circuit board will undergo conformal coating through spraying or dipping. The purpose is to fully protect the finished product against environmental factors that can damage it.
There’s no denying that manufacturing PCBs is far from simple, and so, you need to properly plan before engaging in such an endeavor.