The ongoing reliability test (ORT) is a hardware test process usually used in manufacturing to ensure that quality of the products is still of the same specifications as the day it first went to production or general availability.
Manufacturing is the production of products for use or sale using labour and machines, tools, chemical and biological processing, or formulation. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial design, in which raw materials are transformed into finished goods on a large scale. Such finished goods may be sold to other manufacturers for the production of other, more complex products, such as aircraft, household appliances, furniture, sports equipment or automobiles, or sold to wholesalers, who in turn sell them to retailers, who then sell them to end users and consumers.
The products currently in the manufacturing line are randomly picked every day with a predefined percentage or numbers and then put in an environmental chamber that provides the stress profile of thermal cycling, elevated temperature, or combined environmental stresses to induce fatigue damage. The profile should stimulate the precipitation of latent defects that may be introduced from the manufacturing process but not remove significant life from the product or introduce flaws to risk failure during its intended mission. highly accelerated stress test is a Ongoing Reliability Test that uses the empirical operational limits as the reference for the combined vibration, thermal cycling, and other stress applied to find latent defects.
Quality of the products is then measured with the results of this test. If a unit fails, it goes under investigation to see what caused the failure and then remove the cause whether it came from an assembly process or from a component being incorrectly manufactured, or any other cause. If it is proven that a real failure occurs, the batch of units that were produced along with the failed unit, is then tagged for re-test or repair to either verify or fix the problem.
Wire bonding is the method of making interconnections (ATJ) between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC to other electronics or to connect from one printed circuit board (PCB) to another. Wire bonding is generally considered the most cost-effective and flexible interconnect technology and is used to assemble the vast majority of semiconductor packages. Wire bonding can be used at frequencies above 100 GHz.
Failure mode and effects analysis (FMEA)—also "failure modes", plural, in many publications—was one of the first highly structured, systematic techniques for failure analysis. It was developed by reliability engineers in the late 1950s to study problems that might arise from malfunctions of military systems. An FMEA is often the first step of a system reliability study. It involves reviewing as many components, assemblies, and subsystems as possible to identify failure modes, and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets. An FMEA can be a qualitative analysis, but may be put on a quantitative basis when mathematical failure rate models are combined with a statistical failure mode ratio database.
Burn-in is the process by which components of a system are exercised prior to being placed in service. This testing process will force certain failures to occur under supervised conditions so an understanding of load capacity of the product can be established.
Rework is the term for the refinishing operation or repair of an electronic printed circuit board (PCB) assembly, usually involving desoldering and re-soldering of surface-mounted electronic components (SMD). Mass processing techniques are not applicable to single device repair or replacement, and specialized manual techniques by expert personnel using appropriate equipment are required to replace defective components; area array packages such as ball grid array (BGA) devices particularly require expertise and appropriate tools. A hot air gun or hot air station is used to heat devices and melt solder, and specialised tools are used to pick up and position often tiny components.
Reliability engineering is a sub-discipline of systems engineering that emphasizes dependability in the lifecycle management of a product. Dependability, or reliability, describes the ability of a system or component to function under stated conditions for a specified period of time. Reliability is closely related to availability, which is typically described as the ability of a component or system to function at a specified moment or interval of time.
Environmental stress screening (ESS) refers to the process of exposing a newly manufactured or repaired product or component to stresses such as thermal cycling and vibration in order to force latent defects to manifest themselves by permanent or catastrophic failure during the screening process. The surviving population, upon completion of screening, can be assumed to have a higher reliability than a similar unscreened population.
Annealing of glass is a process of slowly cooling hot glass objects after they have been formed, to relieve residual internal stresses introduced during manufacture. Especially for smaller, simpler objects, annealing may be incidental to the process of manufacture, but in larger or more complex products it commonly demands a special process of annealing in a temperature-controlled kiln known as a lehr. Annealing of glass is critical to its durability. Glass that has not been properly annealed retains thermal stresses caused by quenching, which indefinitely decrease the strength and reliability of the product. Inadequately annealed glass is likely to crack or shatter when subjected to relatively small temperature changes or to mechanical shock or stress. It even may fail spontaneously.
A test engineer is a professional who determines how to create a process that would best test a particular product in manufacturing and related disciplines in order to assure that the product meets applicable specifications. Test engineers are also responsible for determining the best way a test can be performed in order to achieve adequate test coverage. Often test engineers also serve as a liaison between manufacturing, design engineering, sales engineering and marketing communities as well.
A highly accelerated life test (HALT), is a stress testing methodology for enhancing product reliability. HALT testing is currently in use by major manufacturing and research & development organizations to improve product reliability in a variety of industries, including electronics, computer, medical, and military.
Worst-case circuit analysis is a cost-effective means of screening a design to ensure with a high degree of confidence that potential defects and deficiencies are identified and eliminated prior to and during test, production, and delivery.
Time-dependent gate oxide breakdown is a failure mechanism in MOSFETs, when the gate oxide breaks down as a result of long-time application of relatively low electric field. The breakdown is caused by formation of a conducting path through the gate oxide to substrate due to electron tunneling current, when MOSFETs are operated close to or beyond their specified operating voltages.
Microvias are used as the interconnects between layers in high density interconnect (HDI) substrates and printed circuit boards (PCBs) to accommodate the high input/output (I/O) density of advanced packages. Driven by portability and wireless communications, the electronics industry strives to produce affordable, light, and reliable products with increased functionality. At the electronic component level, this translates to components with increased I/Os with smaller footprint areas, and on the printed circuit board and package substrate level, to the use of high density interconnects (HDIs).
Reliability of semiconductor devices can be summarized as follows:
- Semiconductor devices are very sensitive to impurities and particles. Therefore, to manufacture these devices it is necessary to manage many processes while accurately controlling the level of impurities and particles. The finished product quality depends upon the many layered relationship of each interacting substance in the semiconductor, including metallization, chip material and package.
- The problems of micro-processes, and thin films and must be fully understood as they apply to metallization and wire bonding. It is also necessary to analyze surface phenomena from the aspect of thin films.
- Due to the rapid advances in technology, many new devices are developed using new materials and processes, and design calendar time is limited due to non-recurring engineering constraints, plus time to market concerns. Consequently, it is not possible to base new designs on the reliability of existing devices.
- To achieve economy of scale, semiconductor products are manufactured in high volume. Furthermore, repair of finished semiconductor products is impractical. Therefore, incorporation of reliability at the design stage and reduction of variation in the production stage have become essential.
- Reliability of semiconductor devices may depend on assembly, use, and environmental conditions. Stress factors affecting device reliability include gas, dust, contamination, voltage, current density, temperature, humidity, mechanical stress, vibration, shock, radiation, pressure, and intensity of magnetic and electrical fields.
Temperature cycling is the process of cycling through two temperature extremes, typically at relatively high rates of change. It is an environmental stress test used in evaluating product reliability as well as in manufacturing to catch early-term, latent defects by inducing failure through thermal fatigue.
An environmental chamber, also called a climatic chamber or climate chamber, is an enclosure used to test the effects of specified environmental conditions on biological items, industrial products, materials, and electronic devices and components.
Accelerated life testing is the process of testing a product by subjecting it to conditions in excess of its normal service parameters in an effort to uncover faults and potential modes of failure in a short amount of time. By analyzing the product's response to such tests, engineers can make predictions about the service life and maintenance intervals of a product.
Electronic components have a wide range of failure modes. These can be classified in various ways, such as by time or cause. Failures can be caused by excess temperature, excess current or voltage, ionizing radiation, mechanical shock, stress or impact, and many other causes. In semiconductor devices, problems in the device package may cause failures due to contamination, mechanical stress of the device, or open or short circuits.
HASA is a proven test method developed to find manufacturing/production process induced defects in electronics and electro-mechanical assemblies before those products are released to market. HASA is a form of HASS – a powerful testing tool for improving product reliability, reducing warranty costs and increasing customer satisfaction.
Software reliability testing is a field of software testing that relates to testing a software's ability to function, given environmental conditions, for a particular amount of time. Software reliability testing helps discover many problems in the software design and functionality.
Welding is a manufacturing method used to join various materials in order to form an assembly. During welding, joints are formed between two or more separate pieces of material. A welded joint subjected to cyclic loading could fail due to fatigue. Fatigue results from this cyclic loading, as well as strains, in the material. Throughout a welded assembly's life, cracks, which reduce the fatigue life of a joint, could initiate, propagate, and grow causing the assembly to fail even if these cyclic stresses are low and smaller than the base material and weld filler material yield stress. Hence, the fatigue strength of a welded joint does not correlate to the fatigue strength of the base material. Incorporating design considerations in the development phase can reduce failures due to fatigue in welded joints.