Key parameters / dielectric thicknesses

The most important parameter for microvias is the aspect ratio, the relationship between the hole diameter and the hole depth. Aspect ratio (AR) = Hole diameter (1) / Hole depth/length (2).

Two standard prepreg types are used as the dielectric material (5):
Prepreg type 1080:
60 – 65 µm dielectric layer thickness(5), end of hole diameter(3) = 100 µm 
Prepreg type 2116:
90 – 100 µm dielectric layer thickness(5), end of hole diameter(3) = 120 µm