Carbon ink is a conductive material used in printed circuit board (PCB) manufacturing. It is typically applied through screen printing to create conductive traces, switches, or contacts on the PCB surface, often as an alternative to traditional copper for specific applications like membrane switches or keyboard contacts.
Carbon ink offers several distinct properties that make it suitable for certain PCB designs.
While less conductive than copper, carbon ink provides sufficient conductivity for low-current applications. It is ideal for creating resistive elements or non-critical signal paths.
The cured ink layer is resistant to abrasion and oxidation, making it durable for contacts that experience frequent physical interaction, such as in keypads.
For simple conductive patterns, the screen printing process can be more economical than etching copper, especially for large panel quantities.
Carbon ink is utilized in various electronic products and PCB features.
When ordering PCBs with carbon ink, specific parameters must be considered and communicated.
Specify the required properties, such as sheet resistance (measured in ohms per square), and any necessary curing parameters.
Define the alignment accuracy required for the carbon ink layer relative to other PCB layers, like solder mask or copper pads.
Clearly indicate on your fabrication drawings which layers require carbon ink and the precise areas to be printed.
Understanding the trade-offs is essential for design.
Follow these guidelines when designing for carbon ink.
Design traces wider than typical copper traces to compensate for higher resistivity and printing tolerances.
Ensure a reliable electrical and mechanical connection where carbon ink traces meet copper pads. Overlap design is critical.
Specify any electrical testing requirements for the carbon ink layers, such as continuity or resistance checks.
Carbon ink PCB technology provides a reliable and cost-effective solution for specific conductive applications where traditional copper etching is not ideal. Proper specification during the ordering process ensures the final product meets the intended electrical and mechanical performance.
