A PCB is typically made by attaching a copper sheet to a substrate board, sometimes on both sides. The PCB 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.

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.