16-layer HDI PCB with ENIG Surface Finish

16 layers
1+N+1 HDI
1.37mm thick
FR4 (Tg180)
HOZ base copper on all layers
Drill bit: 0.25mm
Green solder mask
Immersion gold surface finish with impedance control, plasma cleaning, 
BGA pad size: 0.25mm
Line width/space: 3.0/4.0mil
Blind via holes from L1 to L2, L15 to L16
Medical application