Failure of electronic components
For example, the power-handling ability of a resistor may be greatly derated when applied in high-altitude aircraft to obtain adequate service life.
Dies can crack due to mechanical overstress or thermal shock; defects introduced during processing, like scribing, can develop into fractures.
Ionic contaminants like alkali metals and halogens can migrate from the packaging materials to the semiconductor dies, causing corrosion or parameter deterioration.
Carbon dioxide and hydrogen may form from organic materials, moisture is outgassed by polymers and amine-cured epoxies outgas ammonia.
As some semiconductors like silicon and gallium arsenide are infrared-transparent, infrared microscopy can check the integrity of die bonding and under-die structures.
The silver bridge may be interrupted by thermal expansion of the package; thus, disappearance of the shorting when the chip is heated and its reappearance after cooling is an indication of this problem.
[3] Delamination and thermal expansion may move the chip die relative to the packaging, deforming and possibly shorting or cracking the bonding wires.
Loose particles, like weld flash and tin whiskers, can form in the device cavity and migrate inside the packaging, causing often intermittent and shock-sensitive shorts.
[2] Printed circuit boards (PCBs) are vulnerable to environmental influences; for example, the traces are corrosion-prone and may be improperly etched leaving partial shorts, while the vias may be insufficiently plated through or filled with solder.
For example, polyglycols from the solder flux can enter the board and increase its humidity intake, with corresponding deterioration of dielectric and corrosion properties.
Metal is introduced to a vulnerable surface typically from plating the vias, then migrates in presence of ions, moisture, and electrical potential; drilling damage and poor glass-resin bonding promotes such failures.
[6] The formation of CAFs usually begins by poor glass-resin bonding; a layer of adsorbed moisture then provides a channel through which ions and corrosion products migrate.
In presence of chloride ions, the precipitated material is atacamite; its semiconductive properties lead to increased current leakage, deteriorated dielectric strength, and short circuits between traces.
[5] Delamination may occur to separate the board layers, cracking the vias and conductors to introduce pathways for corrosive contaminants and migration of conductive species.
As their resistivity drops with increasing temperature, degradation of the maximum operating frequency of the chip the other way is an indicator of such a fault.
Mousebites are regions where metallization has a decreased width; such defects usually do not show during electrical testing but present a major reliability risk.
Increased current density in the mousebite can aggravate electromigration problems; a large degree of voiding is needed to create a temperature-sensitive propagation delay.
[9] Overstress-induced damage like ohmic shunts or a reduced transistor output current can increase such delays, leading to erratic behavior.
ESD in real circuits causes a damped wave with rapidly alternating polarity, the junctions stressed in the same manner; it has four basic mechanisms:[15] Catastrophic ESD failure modes include: A parametric failure only shifts the device parameters and may manifest in stress testing; sometimes, the degree of damage can lower over time.
[17] Newer CMOS output buffers using lightly doped silicide drains are more ESD sensitive; the N-channel driver usually suffers damage in the oxide layer or n+/p well junction.
[19] The structure of the junction influences its ESD sensitivity; corners and defects can lead to current crowding, reducing the damage threshold.
Examples of resistor failures include: Potentiometers and trimmers are three-terminal electromechanical parts, containing a resistive path with an adjustable wiper contact.
Structurally, capacitors consist of electrodes separated by a dielectric, connecting leads, and housing; deterioration of any of these may cause parameter shifts or failure.
[citation needed] Some examples of capacitor failures include: In addition to the problems listed above, electrolytic capacitors suffer from these failures: Metal oxide varistors typically have lower resistance as they heat up; if connected directly across a power bus, for protection against voltage spikes, a varistor with a lowered trigger voltage can slide into catastrophic thermal runaway and sometimes a small explosion or fire.
