The maximum thickness of solder mask depends on the thickness of the underlying copper.
Solder Mask Thickness Explained
Solder mask is a protective layer applied to printed circuit boards (PCBs). It prevents solder from bridging between conductors during the soldering process. The required thickness of the solder mask is influenced by the copper thickness.
Maximum Solder Mask Thickness Based on Copper Thickness:
Here's a breakdown of the maximum solder mask thickness based on copper thickness:
| Copper Thickness | Maximum Solder Mask Thickness |
|---|---|
| Up to 35 µm | 40 µm |
| Greater than 35 µm | 80 µm |
- Copper Thickness Up to 35 Micrometers: For copper layers that are 35 micrometers thick or less, the maximum solder mask thickness is 40 micrometers. The reference states, "The maximum thickness for solder masks on finished copper parts of up to 35 micrometers is 40 micrometers."
- Copper Thickness Greater than 35 Micrometers: If the copper layer is thicker than 35 micrometers, the solder mask can have a maximum thickness of 80 micrometers. The reference mentioned that, "If the copper is thicker, the solder mask can be as thick as 80 micrometers."
- It is also mentioned that, "On the side edges and top of the conductor, you'll want a thickness greater than 7 micron."
Practical Insights:
- Ensuring Adequate Coverage: A proper solder mask thickness is essential to ensure complete coverage of copper traces and pads, preventing unwanted solder bridging.
- Process Control: Solder mask thickness should be consistently controlled during PCB fabrication to maintain high-quality production.
- Thicker Layers for Robustness: The increased maximum thickness of solder mask on thicker copper layers provides a more robust protective layer.
In summary, the maximum thickness of the solder mask ranges from 40 to 80 micrometers depending on the copper thickness on the PCB.
