San Francisco Circuits, a provider of printed circuit board (PCB) manufacturing services for unmanned systems across all scales, discusses the benefits of hard and soft gold PCB surface finishes.
Selecting an appropriate surface finish is crucial for optimal PCB performance. Gold stands out as an ideal choice due to its superior electrical conductivity, resistance to tarnishing, excellent solderability, extended shelf life, and effectiveness as an etch resist.
San Francisco Circuits offers a range of modern, lead-free surface finishes that comply with RoHS and WEEE directives.
The Electrolytic Ni/Au finish involves depositing a gold plating layer over nickel. A low-stress nickel layer is applied between the copper base and the gold over-plating.
Gold purity varies between hard gold (approximately 99.6% pure) and soft gold (99.9% pure). The thickness of the gold layer is a critical factor that varies depending on the intended application.
Hard gold is an alloy of gold with cobalt, nickel, or iron. This finish is recommended for applications involving frequent use and high potential for wear, such as:
- Interconnected Carrier Boards
- Edge Connector Fingers
- Keypads
- Contacts
In contrast, soft gold finish is primarily used on boards designed for applications requiring wire bonding, high solderability, and weldability.
