Green solder mask is cost-effective, environmentally friendly, and has mature manufacturing processes. Other colors are typically used for prototype identification or special applications.
ENIG provides a flatter surface for high-density pads, while HASL is more cost-effective but less smooth, making it suitable for standard boards.
Blind vias connect outer to inner layers, while buried vias are entirely within inner layers. Both require HDI technology and enable high-density routing.
