Failures in electronics systems
The one sentence summary of electronics failure causes is Murphy's law, "anything that can go wrong, will go wrong." 

The failure types are categorized as:

M: Can be caused by manufacturing

U: Can occur when unused

N: Can occur by normal use of component

A: Can occur by abuse of component

Packaging Failures

The purpose of packaging is to protect electronics from the many hazards of its environment. When packaging fails, the electronics can be exposed to such hazards, leading to unwanted behavior and possibly damage. 


Material fatigue from the thermal expansion caused by heating cycles (U, N, A)
Mechanical stress and shock can crack or fracture packaging (A)
Humidity and chemicals can cause corrosion (U, N, A)
Material defects introduced during manufacturing and processing (M)
Electrical faults introduced during encapsulation (bonding wire short and open circuits) (M)
Migration of contaminants through the packaging onto the semiconductor die (U, N, A)


Contact Failures

PCB Failures

Relay Failures

Semiconductor Failures

Passive Element Failures

MEMS Failures

Sources

Failure modes of electronics