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Common Techniques Used By A Custom PCB Manufacturer In Copper Patterning

by Miguel Laroche

PCB production processes are constantly changing. Lately, new innovations have seen to it that the printed circuit board is smaller in size. The small size does not affect its functionality as a PCB manufacturer ensures that the board maintains its reliability and multi-functionality. Furthermore, PCB development requires several processes to take place. Among the several processes is copper patterning. In copper patterning, there are five common techniques used to attain the desired pattern. Therefore, below are the five common techniques used by a custom PCB manufacturer in copper patterning.

common techniques used by a custom PCB manufacturer in copper patterning

1. PCB milling

PCB milling involves the process of milling away a copper foil by the use of a mechanical milling system with two or three-axis from the substrate. It is a subtractive process that removes excess copper from a PCB sheet material, intending to recreate signal traces, structures, and pads.

In addition, the process involves creating ground planes and the electric isolation needed. The PCB prototype or PCB milling machine receives commands from the computer host software. The host software controls the milling head positioning in the x, y, and z-axis. Additionally, the PCB design software generates data that is used to propel the PCB prototype. Furthermore, PCB milling is commonly used when a manufacturer only has a small volume of boards.

Benefits of PCB milling

  • PCB milling can be used in unique PCB designs and prototyping.
  • The process does not require the use of chemicals

2. Silkscreen printing

The silkscreen printing technique involves the usage of etch-resistant inks. The purpose of the etch-resistant inks is to ensure that the copper foil present in the circuit board is protected. Furthermore, in hybrid circuits, the ink may be printed on a non-conductive board. 

3. Photoengraving

The photoengraving technique is used on a substrate to take away the copper foil from it by chemical etching and photomask. A technician uses computer-assisted PCB design software to produce data used by a photoplotter to prepare the photomask. Furthermore, sometimes custom PCB manufacturers use laser-printing (direct imaging) in employing low-resolution photo designs. Additionally, the purpose of photoengraving is to establish a photoresist mask that ensures the copper below is protected. Photoengraving is commonly used in patterning when finer components are needed.

Benefits of photoengraving

  • The photoengraving technique is a swift process of removing the copper foil.
  • Also, the photoengraving process involves constant repetition of the same process, ensuring that more refined features are obtained.
  • The photo engraving method plays a crucial role in developing durable PCB’s
  • Furthermore, the technique is cost-efficient as it can be used for mass production.

4. Laser etching

The laser etching technique involves using a CNC laser to remove excess copper from the circuit board altogether. Laser etching is commonly used during prototyping.

5. Laser resist ablation

The process involves spraying black paint into a copper-dressed laminate. The laser then vaporizes paint in the PCB where no resistance is needed.

Conclusion

The purpose of copper patterning in the PCB manufacturing process is to remove unwanted copper from the unprotected substrate. Therefore, different patterning options exist for PCB copper patterning. The different patterning options are used depending on the required resolution, and the volume needed.

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