18 Fault Isolation and Failure Analysis of 3D Packaging
589
Table 18.3
Acoustic Impedance of common materials in microelectronic packages (Adapted from Ref. [23])
Material
Air
Water
Silicon
Tin
Polyimide (Vespel SP-1)
Indium
Copper
Aluminium
Cast iron
Glass
Acoustic impedance
0.389
× 10 −3
1.48
19.65
24.2
3.61
16.21
41.8
17.1
24.2
15.3