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PCB fabrication may look easy but in a larger scale, it is broader than what you think. PCB manufacturing requires larger equipment and much more technical skills since the fabricated circuit board that one needs to make is shipped to different companies to be used as electronic components for various gadgets.
Here are the steps in doing a PCB fabrication on a larger scale.
1. Preparation of data.
A manufacturer has its own board designer that produces the circuit layout using Computer Aided Design or CAD software. All are checked automatically to ensure accuracy.
2. Preparation of photo tools.
Photo tools such as photo plotters are used to transfer the image into the PCB. The photo plotter takes the board data from the CAD system and then converts it into a pixel image. It is then printed onto a film using laser. The film is printed out and is now ready to be used for PCB fabrication processes.
3. Printing of inner layers.
For multilayer PCBs, laminates are used to make the inner layers. Laminates are epoxy resins and glass-fiber core with copper foil that are pre-bonded on both surfaces. The panels are processed in a clean room to make sure that there will be no dust as it may cause short circuits to finished boards
4. The etching process.
The excess copper plating in the board is removed using an etching solution. This step should be done with extra caution as the process produces an exothermic reaction. In addition, the process is controlled carefully to ensure that the finished board is in exact dimensions just like in the design layout. After the etching process, the covering of copper image is removed to finally expose the exact board design.
5. Inspection of printed circuit boards.
An Automatic Optical Inspection or AOI system is used to scan the board and compare it with the digital image of the circuit. Any mistakes or errors detected by the system are displayed on a screen to determine the actions needed to be done.
6. Drilling the holes.
Drilling the holes for PCBs is a slow process as each drilling is done individually. Each hole is drilled carefully as this will serve as the connecting points for the electronic components of the board.
7. Electroless copper deposition process.
Electrocopper is deposited onto the hole walls that will serve as a conductor for the electricity to flow once the board is completely fabricated.
8. Imaging the outer layers.
For multilayered PCBs, the outer or exposed layers are imaged with the use of a photosensitive film on which the circuit is designed. The image is then transferred onto the board using ultraviolet light.
The board is then subjected to copper plating. Once done, a thin layer of tin is added. When the application of layers is done, the PCBs are checked to ensure that each layer is of right thickness.
10. Etching of outer layers.
The thin layer of tin is used as etch resistant. This will protect the copper linings that are necessary for the board. To etch, a powerful alkaline solution is used to remove the excess copper on the circuit.
11. Application of solder mask.
This step is done to prevent short circuits once the PCBs are used.
12. Surface finish.
A surface finish is important for PCB fabrication since it will protect the electrical components mounted into the circuit. One common surface finish is by depositing nickel and a thin layer of gold over nickel.
13. Electrical testing.
The finished boards are tested by using a probe tester to ensure that they are working well and ready to be used for commercial purposes.
14. Final inspection.
This is necessary to make sure that the manufactured PCBs are safe and ready for release.
PCB fabrication is indeed very important in the industry so that people will be able to use machines and gadgets that make life much easier.