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Glossary

Glossary of words that require a description and an explanation.

Burn-In

An elevated temperature test (say +80°C) used to induce early life failures. Most often used at component level. Burn-in can be particularly effective if the devices under test are powered-up and monitored. See Sharetree Tray Systems.

Synonyms: Burn in, Burn In, Burn-in
Cascade Compressors

By connecting two compressors in series, it is possible to achieve temperatures of -70°C with a mechanical cooling plant.

Cryogenic Cooling

Cooling using liquid gases such as Liquid Nitrogen (LN2) or Liquid Carbon Dioxide (LCO2). Very fast cooling rates and low temperatures can be achieved as these liquids change state to become gases.

Dwell

The period in a test cycle during which the conditions in a chamber are kept steady (e.g. ‘dwell’ for 2hours at 50°C).

Environmental Chambers

Chambers that combine temperature and humidity (and/or possibly other effects such as UV, acid rain, etc), usually to simulate real world conditions.

Environmental Test

Product testing that combines temperature and humidity (and/or possibly other effects such as UV, acid rain, etc), usually to simulate real world conditions.

Environmental Testing

Product testing that combines temperature and humidity (and/or possibly other effects such as UV, acid rain, etc), usually to simulate real world conditions.

ESS

Environmental Stress Screening - Testing specifically designed to induce failures in weak products during production. Testing can involve Thermal Cycling, vibration or a combination of the two.

Life-Test

Life-Testing is used to evaluate the long-term performance of a product either during the development phase, production or both (See HALT & HASS).

Synonyms: Life Test, Lifetest
Liquid Nitrogen

Liquid Nitrogen (LN2) is often used for chambers requiring high or very high ramp rates. The state change absorbs heat as the liquid nitrogen changes to a gas at temperatures below -190°C.

Synonyms: LN2
Load Dissipation

The amount of heat energy released by the load under test (often expressed in W or kW). The performance of the chamber will vary with the Load Dissipation.

Load Mass

The mass (often expressed in Kg) of the load under test in a chamber. The performance on the chamber will vary with the Load Mass.

PID Control

Also referred to as ‘Three Term Control’, is a technique used to achieve stable, straight line control at the required setpoint temperature. The three terms are:

P Proportional band
I Integral time
D Derivative time

Product Protection

All Sharetree chambers come with the option of independent Product Protection. This will shutdown the chamber and may also shutoff power to active products under test, in the event that the chamber exceeds customer settable upper and lower temperature limits, either through an error in using the chamber or a fault.

Ramp

The period in a test cycle during which the conditions in a chamber are changing from one condition to another (e.g. ‘ramp’ from 30°C to 150°C).

Ramp Rate

How fast a chamber is able or allowed to change from one condition to another. (ie a ‘ramp rate’ of 10°C/min will translate to 10mins to get from 0°C to 100°C). Maximum Ramp Rates are a key measure of a chamber's performance. Note that Ramp Rates are affected by the temperature range over which they are measured, the load in the chamber at the time and whether they are average or linear.

Relative Humidity

Chambers with Humidity control as an option, are capable of simulating environments from very dry (Desert) to very wet (jungle) conditions. Relative Humidity (RH) is the amount of moisture in the air relative to the maximum it can hold at that temperature (100%RH).

HALT

Highly Accelerated Life Test. A form of Life Test run during the development phase that can identify weaknesses in hours by testing at or beyond a product's design limits. High stress levels (e.g. fast thermal ramp rates) are used to accelerate the failure mechanisms.

HASS

Highly Accelerated Stress Screening. Used in production to quickly uncover latent defects by exposing the products to high stresses (e.g. rapid thermal cycling)

Opto-Electronics

Opto-electronics is a rapidly developing field where many product innovations are being introduced as the technology advances, leading to increased bandwidth, all-optical switching, and lower costs.
Environmental test, Life Test, and Burn-in techniques are used extensively to prove reliability at both the Development and Manufacturing stages. The precise alignment demanded by opto-electronic devices introduces new resources of parameter drift compared to other components, and this responds well to thermal cycling methods.

Single-Stage Compressors

Mechanical cooling plants are used in most test chambers. Single stage plants can achieve temperatures down to -40°C.

Stress Screening

The use of Stress (e.g. elevated temperature, thermal cycling, vibration, etc) to cause latent defects to become failures that can be identified by testing. The failures are then removed from the batch to increase overall reliability.

Synonyms: Stress-Screening
Thermal Cycling

Thermal cycling allows a chamber to automatically change from one temperature to another (through Ramps and Dwells). This requires a cycling controller or chamber control software (such as the Sharetree SIMPLEtouch controller).

Thermal Gradient

The amount of variation in temperature across the useful working space of a chamber. This is often measured 10% from the chamber interior walls at all corners and in the centre of the chamber. The maximum difference is the thermal gradient. Gradient can be specified with our without products.