The product is subjected to conditions of use or to constraints of environment amplified in order to accelerate the occurrence of failures and to reduce the necessary duration to estimate some behavioural characteristics of the product in the normal conditions of employment. Since higher stresses are used, accelerated testing must be approached with caution to avoid introducing failure modes that will not be encountered in normal service use. There are 3 types of accelerated tests :

• Based on acceleration by reducing the number of experiments , based on design of experiments
• Where the acceleration is based on statistical models ,
• Where the acceleration is based on physical models of failure.

Is a screening production procedure, applicable for all kind of products ; the methodology is widely spread in the electronic producer community all around the world and is generally performed on electronic components, printed circuit board assemblies or at equipment level to find defects and systematic failures during pilot production or to provoke early failures in a series production. It consists primarily of temperature cycling and/or vibration stresses, but in some cases mechanical shocks or humidity stress could also be applied successfully."

is the general concept where the cause of failure is isolated, analyzed and fixed. A number of testing procedures can be used in this method. These procedures can be applied in parallel with existing development tests or as dedicated TAAF (test, analyze and fix) or TAAR (test analyze and redesign) procedures. These are closed-loop reliability growth methodologies. The purpose is not to prove that a reliability goal has been met, but rather to deliberately search out and eliminate deficiencies. In TAAF/TAAR, failures are welcome. The TAAF/TAAR concept is necessary because, even with the very best of modern engineering methods and design tools (CAD, CAE,…), initial designs for mechanical or electronic systems that are complex or that involve new technology have reliability deficiencies that are difficult to fully detect and eliminate through design analysis. To summarise , maturation of revolutionary product ( which includes many news in design, technologies and conditions of use) requires experimentation.

Is a tool that examines potential product or process failures, evaluates risk priorities, and helps determine remedial actions to avoid identified problems. It is useful in developing features and goals for both products and processes, in identifying critical product/process factors and designing countermeasures to potential problems, in establishing controls to prevent process errors, and in prioritizing process subunits to ensure reliability. Possible factors are: Mode of Failure, Cause of Failure, Effect of Failure, Frequency of Occurrence, Degree of Severity, Chance of Detection, Risk Priority, Design Action, and Design Validation. FMEA can be used for improvement of design, production processes, in service use,…

FMECA is a similar method and stands for Failure Mode Effect and Criticality Analysis.

The principle of the Highly Accelerated Environmental Stress Screening is to submit equipments coming out of production to levels of constraint far above the specified values while staying below the destructive limits which could have been revealed by a campaign of Highly Accelerated Tests. Its purpose should not be to highlight design problems, but instead to highlight any latent defects in the unit that have arisen during the production process before the unit leaves the production environment. In this way the infant mortality should have all occurred.. It presents the most intense environment of any seen by the product, but it is typically of a very limited duration. HASS is designed to go to “the fundamental limits of the technology.”. Typically, the HASS limits are determined by the HALT results and the type of failures the testing is searching for. Depending on the volume of production and the type of system, anywhere from an AQL (acceptable quality level) sample of each lot to 100% may be HASSed.

Development Test where the applied constraints raise in a progressive way to much higher values in comparison to the qualification specified values. The essential objective is to investigate the limits of functioning and of destruction of the product in order to eliminate them, by suited actions. The limits are defined as the stress levels at which a small increase in stress causes a large increase in the number of failures. Highly Accelerated Test brings robustness or design margins to the product.

• HALT
  Highly Accelerated Life Test is a type of Highly accelerated test, that is withhold by certain equipment suppliers . The stress comes from a combination of temperature, thermal shock (produced by Nitrogen) and multi 3 axis vibration (along and around the 3 axis : also called 6 degree of freedom ) produced by pneumatic hammers. During HALT, the unit under test must be operational.

• HAST
  Stands for Highly Accelerated (Temperature/Humidity/pressure) Stress Test. Its intend is to increase the rate at which corrosion forms in the product. It has also become known as Autoclave or Pressure cookerTest (PCT). It is more a reliability test than HALT.

These activities includes resources and procedures to ensure that all equipment and support items are preserved, packaged, packed, marked, handled, transported, and stored properly for short- and long-term requirements. It includes material-handling equipment and packaging, handling and storage requirements, and pre-positioning of material and parts. It also includes preservation and packaging level requirements and storage requirements (for example, sensitive, proprietary, and controlled items). These activities include planning and programming the details associated with movement of the system/product in its shipping configuration to the ultimate destination via transportation modes and networks available. It further includes the determination of critical engineering design parameters and constraints that must be considered during system development (e.g., width, length, height, component and system rating, and weight).

Reliability growth is the improvement in the reliability of a product (component, subsystem, system) due to a well structured process of finding reliability problems and monitoring the increase of the product's reliability through successive phases in time. A comprehensive reliability growth program is developed based on three important factors:

• Management, where the decisions are made to keep the program moving.
• Testing, where all the weaknesses and failure modes are found in the design and manufacturing process.
• Failure Identification, Analysis and Fix (FIAAF), where the cause of failure is isolated, analysed and then fixed.

Reliability growth can be characterized after a small amount of tests and improvements (e.g. by the model of Duane).

Example of RAMS engineering are the FMEA and FMECA methods.