I have performed a reliability calculation with FIDES 2009 (tool Ram COmmander v8.2) for an hybrid. The same calculation has been made with a PCB configuration. The result is that the PCB version is more reliable than the Hybrid version. The most difference reason between the two version is the Physical lamda. In the hybrid version, physical lamda are greater than PCB version physical lamda (e.g :10 times for die of integrated circuit in comparison with an IC)
Somebody could explain me the reason?