Reliability & Quality glossary

Reliability and quality terms cover how long a chip lasts and how a supplier proves it: failure rates and their units, stress tests and acceleration models, qualification plans, failure analysis, and the quality systems behind every shipment.

Reliability and quality engineers use them to plan qualification, answer a customer return, and show that a process change has not made parts weaker. Buyers use them to compare suppliers on more than price.

103 terms in 11 groups, 49 with a full explanation and examples. Each term has its own page.

Compliance testing

Electromagnetic compatibilityIn depth: Electromagnetic compatibility: the ability of a device to work as intended in its electromagnetic environment without disturbing other equipment.

ESD and latch-up

Charged Device ModelIn depth: The ESD stress model for a device that has itself become charged and then discharges rapidly to ground through a single pin.
EOS: Electrical OverstressIn depth: Damage from applying voltage, current or power beyond absolute maximum ratings for longer than an ESD event.
ESD: Electrostatic DischargeIn depth: A rapid transfer of static charge into or out of a device, delivering nanosecond to microsecond current pulses that can rupture gate dielectrics, melt junctions or fuse metal.
Human Body Model: The ESD stress model representing a charged person touching a pin, simulated by discharging a 100 pF capacitor through 1500 ohms into the device.
Latch-upIn depth: Triggering of the parasitic PNPN thyristor formed by the well and substrate of a CMOS structure, creating a low impedance path from supply to ground that persists until power is cycled and can dest...
Machine Model: A legacy ESD stress model representing discharge from a charged metallic tool or machine, using a 200 pF capacitor with essentially no series resistance.

Failure analysis

C-SAM: C-mode Scanning Acoustic MicroscopyIn depth: Non-destructive imaging that couples ultrasound into a package through water and maps reflections from internal interfaces, showing delamination, voids and cracks as phase inverted echoes at disbon...
Curve trace: Measuring the current versus voltage characteristic of each pin against ground or supply to check for opens, shorts, leaky junctions and damaged protection devices.
DecapsulationIn depth: Removing the mould compound or lid from a package to expose the die while leaving bond wires and die surface intact, done with hot acid jet etching, laser ablation or mechanical milling depending o...
EBIC: Electron Beam Induced Current: A technique in which the electron beam of a scanning electron microscope generates carriers in the sample and the resulting current is measured, mapping junctions, depletion regions and recombinati...
EDX: Energy-Dispersive X-ray SpectroscopyIn depth: Energy-dispersive X-ray spectroscopy (EDX): a technique, usually run in an electron microscope, that identifies the elements present at a point or across an area from the X-rays the beam excites.
EFA: Electrical Failure Analysis: The first phase of failure analysis, using curve tracing, functional test, scan diagnosis and fault isolation techniques to characterise the electrical signature and narrow the defect down to a net...
Failure analysisIn depth: The disciplined investigation of a failed device, moving from non-destructive checks and electrical characterisation through fault localisation to physical inspection, in order to identify the fail...
FIB: Focused Ion BeamIn depth: A tool that uses a focused gallium or xenon ion beam to mill precise cross-sections, thin TEM lamellae, expose buried structures and, with gas injection, deposit metal to cut or add connections for...
Lock-in thermography: A hot spot localisation method that modulates the device bias and uses an infrared camera with lock-in averaging synchronised to that modulation, extracting temperature signals of a fraction of a m...
Nano-probing: Contacting individual transistor terminals on a delayered die with piezo-driven tungsten or AFM tips inside a scanning electron microscope, so that a suspect device can be characterised electricall...
OBIRCH: Optical Beam Induced Resistance ChangeIn depth: A fault localisation technique that scans a laser over a biased die and maps the change in supply current caused by local heating, highlighting high resistance vias, voids and short paths as bright...
PFA: Physical Failure AnalysisIn depth: The destructive phase of failure analysis, in which the located site is exposed by decapsulation, delayering or cross-sectioning and then imaged and analysed with optical, electron and ion beam tec...
SEM: Scanning Electron MicroscopeIn depth: An imaging instrument that rasters a focused electron beam over a sample and detects secondary or backscattered electrons, giving nanometre scale topographic and compositional images of exposed die...
TEM: Transmission Electron MicroscopeIn depth: An instrument that passes electrons through an ultra-thin specimen, resolving atomic scale detail of gate stacks, interfaces, grain structure and crystal defects that scanning electron imaging cann...
X-ray inspectionIn depth: Non-destructive imaging of internal package features using transmitted X-rays, revealing solder voiding, wire sweep, broken bonds, die attach coverage and misalignment.

Failure mechanisms

BTI: Bias Temperature InstabilityIn depth: The umbrella term for threshold voltage drift caused by charge trapping and interface state generation in a gate dielectric under bias at temperature.
ElectromigrationIn depth: Gradual transport of metal atoms along an interconnect caused by momentum transfer from the electron current, producing voids that open the line and hillocks that short to neighbours.
Failure mechanism: The physical, chemical or electrical process that causes a failure, such as electromigration, time-dependent dielectric breakdown, corrosion or solder fatigue.
Failure modeIn depth: The way in which a part or function fails, as seen from outside, such as an open, a short, a stuck output, a drift or a loss of function.
HCI: Hot Carrier InjectionIn depth: Wear-out in which carriers accelerated by the high lateral field near the drain gain enough energy to damage the gate dielectric interface, degrading transconductance and threshold voltage.
NBTI: Negative Bias Temperature Instability: Degradation of a PMOS transistor held at negative gate bias and elevated temperature, which shifts the threshold voltage more negative and cuts drive current.
PBTI: Positive Bias Temperature Instability: The NMOS counterpart of NBTI, in which positive gate bias at temperature traps charge in the gate dielectric and raises the threshold voltage.
Stress migration: Void formation in metal lines and under vias driven by tensile stress gradients from the mismatch in thermal expansion between metal and dielectric, with no current flowing.
TDDB: Time Dependent Dielectric BreakdownIn depth: Progressive generation of defects in a gate or inter-metal dielectric under electric field until a conductive percolation path forms and the insulator fails.

Package reliability

CorrosionIn depth: Chemical or electrochemical attack on bond pads, wires, leads or die metallisation, driven by moisture combined with ionic contaminants such as chloride.
Dendrite growth: Electrochemical migration in which metal ions dissolve at a biased anode, travel through surface moisture or ionic contamination, and plate out as branching structures that grow toward the cathode...
MSL: Moisture Sensitivity Level: A one to six classification of how long a surface mount plastic package may sit exposed to factory humidity before reflow soldering without risking moisture induced cracking or delamination.
Popcorn cracking: Fracture of a plastic package during solder reflow when absorbed moisture flashes to steam and the pressure blows the mould compound apart, often with an audible pop.
Solder fatigue: Progressive cracking of solder joints under repeated thermal cycling, driven by the mismatch in thermal expansion between package and board that forces the joint to absorb cyclic shear strain until...
Tin whiskers: Spontaneous single crystal filaments of tin that grow from pure tin plated surfaces under compressive stress, sometimes millimetres long, and can bridge adjacent conductors to cause intermittent or...
Wire bond lift: Separation of a wire bond from its pad or lead, caused by intermetallic growth, corrosion, contamination, mould compound shear during cycling, or insufficient bond energy at assembly.

Qualification testing

Autoclave: An unbiased moisture resistance test that holds parts in saturated steam at 121 °C and 100 percent relative humidity at two atmospheres, forcing rapid moisture ingress to expose package sealing, co...
Burn-inIn depth: A production screen that operates parts at elevated voltage and temperature for hours so that latent defects fail before shipment, cutting early life failure rate.
Drop test: A board level mechanical shock test in which a populated board is dropped in a fixture to a defined peak acceleration and pulse duration, with joints monitored continuously for resistance events un...
Generic data: Existing reliability results from previously qualified products on the same technology or package, submitted in place of repeating a stress on the new device.
HAST: Highly Accelerated Temperature and Humidity Stress TestIn depth: A biased moisture test run above 100 °C under pressure, typically 130 °C and 85 percent relative humidity, so that 96 to 264 hours reproduces the failure modes that steady state 85/85 testing needs...
HTOL: High Temperature Operating LifeIn depth: The core reliability stress in which parts run with dynamic stimulus at elevated temperature and often elevated voltage, usually 1000 hours at 125 °C, to accelerate intrinsic wear-out and generate...
HTSL: High Temperature Storage Life: An unbiased bake, typically 1000 hours at 150 °C or above, that accelerates diffusion driven degradation such as intermetallic growth at wire bonds, stress induced voiding and data retention loss i...
LTOL: Low Temperature Operating Life: An operating life stress run at low temperature, often minus 40 °C, with dynamic switching and elevated voltage.
ORT: Ongoing Reliability Test: A continuous sampling programme in which units from regular production are pulled each month or quarter and put through life and environmental stress, confirming that reliability has not drifted si...
Product qualificationIn depth: The planned set of stress tests and evaluations showing that a part, built on its production process and package, will be reliable in its intended use.
Qualification family: A group of products sharing process, design rules, package and assembly site closely enough that reliability data from representative members can be claimed for all of them, avoiding a full stress...
Temperature cyclingIn depth: Repeated cycling of a device between hot and cold extremes in air, for example minus 55 to 125 °C, to accelerate fatigue at interfaces caused by thermal expansion mismatch.
THB: Temperature Humidity Bias: A steady state moisture reliability test that biases devices at 85 °C and 85 percent relative humidity for typically 1000 hours, screening for corrosion, electrochemical migration and surface leaka...
Thermal shock: A harsher variant of temperature cycling in which parts are transferred between hot and cold liquid or fast transfer air chambers, giving very short transition times and much higher instantaneous s...
Vibration test: Mechanical qualification in which a device or assembly is subjected to swept sine or random vibration over a defined frequency band and duration, checking for lead fracture, solder joint cracking,...

Quality systems

5 Whys: A simple root cause technique of repeatedly asking why a condition occurred, each answer becoming the next question, until the chain reaches a controllable process cause rather than a symptom or an...
APQP: Advanced Product Quality PlanningIn depth: The structured automotive framework for taking a product from concept to production through defined phases with required deliverables at each gate, including design and process FMEA, control plans...
CAPA: Corrective And Preventive ActionIn depth: The formal system for recording a nonconformance, implementing the change that removes its cause, verifying that the change worked, and extending the lesson to similar processes and products so the...
Change controlIn depth: The managed process for proposing, assessing, approving and recording changes to a design, process, document or product once it has been released.
ContainmentIn depth: The immediate actions taken to stop suspect material reaching or affecting the customer, including sorting stock, quarantining lots, adding temporary inspection and defining the suspect date code w...
Control planIn depth: A living document listing every process step, the characteristic controlled at it, the specification, the measurement method, sample size and frequency, and the reaction plan if the characteristic...
Cpk: Process Capability IndexIn depth: A capability metric comparing the distance from the process mean to the nearer specification limit against three standard deviations of short-term variation.
Document control: The quality system process that makes sure controlled documents, such as specifications, procedures and drawings, are reviewed, approved, versioned, distributed and withdrawn in an orderly way, so...
DPPM: Defective Parts Per MillionIn depth: The count of defective units per million shipped, the standard currency of component quality performance.
Ishikawa diagram: A cause and effect diagram that organises candidate causes of a problem into branches such as machine, method, material, measurement, man and environment, giving a structured way to brainstorm befo...
ISO 9001In depth: The general international standard for quality management systems, specifying requirements for documented processes, customer focus, risk based thinking, internal audit and management review that a...
Measurement system analysisIn depth: Studies that check whether a gauge, metrology tool or tester measures well enough for its purpose, by quantifying bias, linearity, stability, repeatability and reproducibility.
PCN: Product Change NotificationIn depth: The formal notice a supplier issues before changing a product's design, process, materials, assembly site or test flow, giving customers time to assess the impact and requalify.
PPAP: Production Part Approval ProcessIn depth: The automotive submission in which a supplier proves that its production process consistently makes parts to the customer's requirements, packaging up to eighteen elements such as design records, F...
Ppk: Process Performance Index: The long-term counterpart of Cpk, computed from the overall standard deviation of all the data rather than within-subgroup variation, so it reflects the actual shipped distribution including drift...
PPM: Parts Per Million: A general rate unit meaning one in a million, used for defect levels, contamination concentrations and impurity limits.
QA: Quality Assurance: Quality assurance (QA): the planned activities that give confidence a product or process will meet its requirements, such as audits, reviews, process checks and release approvals.
QMS: Quality Management SystemIn depth: Quality management system (QMS): the documented policies, processes and records an organisation uses to deliver products that meet customer and regulatory requirements and to improve over time.
RCA: Root Cause AnalysisIn depth: The investigation that traces a failure back to the underlying process or design cause that must change to prevent recurrence, rather than stopping at the physical failure mode or the immediate sym...
Six SigmaIn depth: A data driven improvement methodology aiming to reduce variation until specification limits sit six standard deviations from the mean, which with the conventional 1.5 sigma shift allowance correspo...
SPC: Statistical Process ControlIn depth: The practice of charting process outputs over time with control limits derived from the process itself, so that special cause variation is detected and acted on before it produces out of specificat...
TraceabilityIn depth: The ability to follow an item through its history.
Zero defect methodology: The automotive quality philosophy that treats any escape as unacceptable and therefore relies on prevention, outlier screening, robust design and rapid containment rather than on an acceptable qual...

Radiation and soft errors

Alpha particle: A helium nucleus emitted by trace uranium and thorium impurities in package materials, solder and mould compound.
Neutron flux: The rate of atmospheric neutrons, created by cosmic ray showers, passing through a device.
Radiation hardnessIn depth: The ability of a part to keep working within specification when exposed to ionising radiation, measured as tolerance to total ionising dose and to single event effects such as upsets and latch-up.
SEL: Single Event Latch-up: A destructive event in which an ionising particle triggers the parasitic thyristor in a CMOS structure, producing a self-sustaining high current path that persists until power is removed and can pe...
SER: Soft Error RateIn depth: The frequency of radiation induced transient upsets in a device, usually quoted in FIT per megabit for memory or FIT per device for logic, measured by accelerated beam testing or by long unaccelera...
SEU: Single Event Upset: A soft error in which one strike flips the state of a memory cell, flip-flop or latch.

Reliability modelling

Acceleration factor: The ratio of time to failure at use conditions to time to failure at stress conditions, derived from temperature, voltage, humidity or cycling range models.
Activation energy: The energy barrier of a failure mechanism, in electron volts, that sets how strongly its rate depends on temperature in the Arrhenius model.
Arrhenius equation: The temperature acceleration model, in which the reaction rate is proportional to exp of minus activation energy divided by Boltzmann's constant times absolute temperature.
Black's equation: The empirical model for electromigration lifetime, MTTF equal to A times current density to the power minus n times exp(Ea/kT).
Coffin-Manson model: The fatigue life model for cyclic stress, giving cycles to failure as a constant divided by the strain range raised to an exponent.
ELFR: Early Life Failure Rate: The failure rate observed in the first few hundred hours of operation, measured by a dedicated short stress on a large sample, typically 800 units at high temperature and voltage for 48 hours.
FIT: Failures In TimeIn depth: The standard failure rate unit, one failure per billion device hours of operation.
MTBF: Mean Time Between FailuresIn depth: The average operating time between successive failures of a repairable system.
MTTF: Mean Time To Failure: The average time to the first and only failure of a non-repairable item such as a semiconductor die.
RAMS: Reliability, Availability, Maintainability and Safety: Reliability, availability, maintainability and safety (RAMS): the set of properties that railway and other long-life systems are specified for and must be shown to meet, notably under EN 50126.
Useful life: The flat middle of the bathtub curve where infant mortality has been screened out and wear-out has not begun, so failures arrive at a roughly constant random rate.
Weibull distributionIn depth: The two parameter life distribution used for wear-out data, with a shape parameter beta that indicates decreasing, constant or increasing hazard and a scale parameter that sets the characteristic l...

Standards and specifications

AEC-Q101: Automotive Electronics Council Qualification 101In depth: The automotive qualification specification for discrete semiconductors, covering transistors, diodes, thyristors and optocoupled discretes with stresses such as high temperature reverse bias, gate...
AEC-Q102: Automotive Electronics Council Qualification 102: The automotive qualification specification for discrete optoelectronic semiconductors, covering LEDs, photodiodes, laser diodes and optocouplers with added stresses for optical output degradation,...
AEC-Q104: Automotive Electronics Council Qualification 104: The automotive qualification specification for multichip modules, addressing the interactions that arise when several die, passives and interposers share a package, including board level reliabilit...
AEC-Q200: Automotive Electronics Council Qualification 200: The automotive stress test qualification specification for passive components, covering resistors, capacitors, inductors, crystals, fuses and varistors with mechanical, environmental and electrical...
J-STD-046A: The joint industry standard defining how electronic component suppliers must notify customers of product and process changes, covering which change categories require notice, the minimum notice per...
J-STD-048AIn depth: The joint industry standard for product discontinuance notification, specifying the information a supplier must publish when ending production, including affected part numbers, last order and last...
JESD78: The JEDEC standard for IC latch-up testing, defining current injection into I/O pins and supply overvoltage stress at elevated temperature, together with the pass criteria used in qualification.
QML: Qualified Manufacturers List: Qualified manufacturers list (QML): the list of manufacturers whose processes and parts have been qualified to a military or space specification such as MIL-PRF-38535 for integrated circuits.

Test and binning

Speed grade: A performance class in which a programmable device or other part is sold, set from characterisation and sorted by binning tests.

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