A printed circuit board (PCB) is typically made by attaching a copper sheet to a substrate board, sometimes on both sides. The manufacturer then creates the circuits by removing copper so that only the required copper traces remain. This is called a subtractive method, and there are also additive techniques, usually for multilayer PCBs. There are several types of subtractive methods for creating PCBs, including silk screening, photoengraving and PCB milling.
Instructions
1 Remove metals with silk screen printing. This printing technique uses inks that are resistant to etching to cover the desired copper traces. The copper layer is then immersed in a chemical solution that only dissolves the unprotected copper.
2 Use conductive ink on a non-conductive board to remove the unwanted copper. This silk-screening process uses ink that conducts electricity to protect the copper traces. An electrochemical reaction then removes the unprotected copper.
3 Photoengrave the PCB. Print a photomask with a photoplotter using data from computer-aid manufacturing (CAM) software. Place a photomask over the copper layer and use chemical etching to remove the exposed copper from the substrate.
4 Employ transparencies printed by a laser printer for most PCBs. However, direct laser techniques are beginning to replace transparencies for high-resolution requirements.
5 Implement PCB milling to remove copper from the substrate. This technique uses a mechanical milling system with two or three axes to physically grind the unwanted copper from the substrate. This machine functions in a similar manner to a plotter and receives instructions from the CAM software. The design software outputs files in a specific format which the milling machine uses to create the PCB.
