Multilayer PCB with Two-step Blind/Burid Vias:
Base material:Fr-4
Copper thickness:1/1x/1oz
Layer count:4
Board thickness:1.6mm
Min hole size:0.35mm
Min line width/spacing:3/3mil
Surface finishing:immersion gold
Gold thickness:10u-inch
Stack-up structure:L1-L2,L2-L3&L3-L4