SURFACE FINISHES

A PCB's final finish protects the underlying copper from oxidation. It also ensures a sufficiently firm connection to components and logic chips via soldering, glueing, and bonding processes. Most frequently, chemical plating methods such as immersion Sn, ENIG, or ENEPIG/ENEPAG are used. These are characterised by a planar plating structure with a low layer thickness. Galvanic processes such as galvanic NiAu are frequently used if extra robustness is required (e.g. slider and plug contacts) or in the case of stringent corrosion behaviour requirements. These current-regulated processes have a higher Au layer thickness. The PCBs, with required current connections for the pads to be plated, cannot be designed freely.