Environmental Test Chambers

About Environmental Test Chambers and Environmental Test Chamber Manufacturers Including: AGREE Chambers, Altitude Chambers, Benchtop Test Chambers, Environmental Chambers, Humidity Test Chambers, Salt Spray Chambers, Temperature Chambers, Thermal Shock Chambers, Vacuum Test Chambers & Walk-In Test Chambers.

Environmental test chambers replicate environmental conditions such as high temperature or humidity, allowing engineers to evaluate the effects that environmental changes have on products placed within the chamber. An environmental test chamber evaluates product quality and identifies flaws and weaknesses in products before they go to market. Environmental testing falls under two categories: climatic and mechanical. Climatic testing evaluates the effects of natural environmental conditions such as temperature, humidity and precipitation upon an object, although test chambers accelerated the rate of effect these conditions have in order to test products within a reasonable time frame. Mechanical testing evaluates the effects of causal environmental conditions such as vibration, shock, dust or salt spray upon an object. How products respond and function after these tests determines whether they are ready for the market or need further development. Several specific types of environmental test chambers includes altitude chambers, humidity test chambers, salt spray chambers, temperature chambers, thermal shock chambers, vacuum test chambers and military/defense regulation AGREE chambers. Sizes of test chambers vary, ranging from benchtop test chambers to walk-in test chambers.
 
Environmental test chambers are utilized in all industries, from automotive and engineering to construction and medical, pharmaceutical, food processing and packaging. Manufacturers test consumer items such as cars, cigarettes, makeup, medicine and medical instruments. Electronics and home appliance manufacturers use rigorously test their products under harsh environmental conditions to reveal flaws and malfunction susceptibilities before the product goes to market. There is a growing demand by customers to have extended warranties and maintenance on products. Manufacturers would be at high risk in offering these long-term warranties and service contracts without test data to back up product performance guarantees. Some manufacturers in industries where there is no pressure to prove long-term reliability consider forgoing the thousands of hours of costly product testing, but testing products in test chambers is recognized across the manufacturing industry as good practice, and product manufacturers that refuse to rest products before release risk product malfunction in the market and, consequently, future business loss.
 
Environmental test chambers test products in a variety of ways, depending on the product application. THB (Temperature/Humidity/Bias) testing is one of the most common tests used for integrated circuit chips, because the test chambers can hold 1851/4F/851/4C and 85% relative humidity condition while bias loads are applied to the samples. The HAST (Highly Accelerated Stress Test) uses high temperature (over 2121/4F/1001/4C), high relative humidity (about 85%) and high atmospheric pressure conditions (up to 4 atms) to test products such as integrated circuits. HASTs greatly decrease the time needed to achieve useful test results, especially in evaluating non-hermetic packaging of solid state equipment in humid conditions. High temperature chambers are used to assess potential product failure such as damage, junction thermal resistance increase and depolymerization. Products are subjected to temperatures of about 3021/4F/1501/4C for more than 1,000 hours, after which electrical measurements are taken. Mixed flowing gas chambers subject products to a mixture of pollutant gases in a controlled temperature and humidity environment in order to assess the damage to a product after long-term use in office and light to heavy industrial settings.
 
Terms regarding thermal shock testing are often used incorrectly. Liquid-to-liquid thermal shock is a process in which a product is alternately dipped in non-toxic, noncombustible, chemically inert and low viscosity fluids maintained at a specific temperature. Air-to-air, or two-zone, thermal shock is the transferring of a product from a hot chamber to a cold chamber or some other sudden change in air temperature, and vice versa. Sometimes, in a transfer, there is an intermediate step in which the product is exposed to room temperature conditions, which is called three-zone thermal shock. Simply changing the air as quickly as possible in a single chamber is more accurately referred to as thermal cycling or stress screening.

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Environmental Test Chamber Types

• AGREE chambers can produce fast temperature changes of 41-104˜F (5-40°C) per minute, even with large loads. Vibration test systems can be integrated within agree chambers, as they have removable floors.
  
• Altitude chambers test the effects of low pressure on an object and are capable of replicating low-pressure environments found at altitudes of up to 200,000 feet above sea level.
  
• Bench top test chambers reduce test time when testing small items.
  
• Drive-in chambers accommodate large items, such as vehicles, and are useful when performing batch testing.
  
• Engineering Stress Screening (ESS) chambers change the temperature of a product at a highly accelerated rate through high air velocity conditioning.
  
• Environmental chambers replicate environmental conditions for engineering tests.
• High Altitude Simulation (HAS) chambers replicate environmental extremes that an airplane typically endures when in operation.
  
• Humidity Chambers are able to simulate a variety of humidity conditions in order to test the effects of humidity on an object. Used for specific testing in industrial and biotechnology applications.
  
• Mixed Flowing Gas (MFG) chambers are used to expose electronic equipment to a mixture of pollutant gases in an environment in which the temperature and humidity are controlled.
  
• Reach-in chambers often contain shelves and other amenities for easy storage and user convenience.
  
• Salt spray or fog chambers test the corrosion resistance of an object. The object usually hangs from a rod while the chamber introduces a salty residue, which creates a foggy atmosphere, although the object remains visible throughout the process.
  
• Temperature chambers test the effects of temperature on an object. Temperature cycling is performed alone or in conjunction with other tests, such as altitude and vibration tests.
  
• Thermal cycling or stress screening chambers involve the subjection of an object to extreme changes in temperature within a single chamber in which the temperature alternates between cold and hot for a given number of cycles.
  
• Thermal shock chambers initiate automatic changes between two compartments, in which one compartment contains an extremely cold environment and one compartment contains an extremely hot environment. The rapid transference of the object between these two compartments of extreme temperatures causes a shock to the object.
  
• Thermotron chambers are used for thermal and dynamic testing and have shock and vibration capacity.
  
• Vacuum chambers are chambers from which almost all matter, especially air, has been removed.
  
• Vibration chambers apply shock vibrations of varying frequencies to an object, including the bumping, shaking and bouncing of an object, and can be administered in conjunction with temperature and humidity testing. Vibration chambers have sensors that perceive and monitor the object's reaction to the vibration.
  
• Walk-in chambers vary in size and can usually accommodate one or more persons. Walk-in chambers are useful when testing large objects and performing batch testing.  

Environmental Test Chamber Terms

Absolute Humidity - The amount of water vapor, or moisture, in a unit of air.
 
Absolute Vibration - The measurement of an object's vibration in comparison to a fixed point in space.
 
Accelerated Life Testing - The subjection of a product to stress during the development phase in order to gauge the quality of the product. The stress applied to the product often exceeds that which the product would sustain during normal use.
 
Accelerated Stress Testing - The subjection of a product to stress after production in order to identify production flaws before the product reaches retailers and consumers.  
 
Aggravated Testing - The process of applying greater stress to an object than that which the object would sustain during normal use, the purpose of which is to identify guidelines by which the product may be used.
 
Air-To-Air Thermal Shock - Also called "two-zone thermal shock," this process is the transferring of a product from a hot chamber to a cold chamber or other sudden changes of the air temperature.
 
Ambient Environment - The given temperature and humidity content of an indoor (internal) or outdoor (external) environment.
 
Atmospheric Pressure - The amount of force the atmosphere exerts upon the earth's surface, measuring 14.7 psi at sea level.
 
Batch Testing - A test procedure in which multiple items are tested at the same time.
 
Burn-In - The hastening of a product's aging process through the continuous operation of the product, usually at higher than moderate temperatures, in order to evaluate product quality.
 
Calibration - The process of comparison between the current operation of an object or a system and the operating standards of that object or system. Calibration determines the efficiency of an object and identifies errors and the manner in which the system can improve.
 
Corrosion - The gradual deterioration of a metal caused by oxidation or chemical reaction.
 
Critical Frequency - The frequency level at which point the destruction of the object subjected to such frequency begins.
 
Damping - Decrease in the vibration of an object.
 
Dew Point - The temperature of a given unit of saturated (containing the maximum amount of water vapor) air.
 
Dry Room - An environmental chamber in which the humidity level remains below a 14° F/-10° C dew point.
 
Environment - The internal and external conditions, regardless of the source, which affect a given object. The environment includes temperature, humidity, electricity, precipitation, etc.
 
Environmental Stress Screening - The determination of the working efficiency of an object or system through the identification of the effects of thermal changes upon the object or system.
 
Frequency - The rate of movement, measured in cycles, of a wave within a set time frame, usually one second. Frequency is often measured in hertz (Hz), which equals one wave cycle per second.
 
Highly Accelerated Life Test (HALT) - A test that assesses the lifetime of a product, reduces its development cycle time and increases confidence in the life-cycle reliability of the product.
 
Highly Accelerated Stress Test (HAST) - Product reliability test in which an object is subjected to high temperature, humidity and pressure. HAST has also come to be called Autoclave or Pressure Cooker Test (PCT).
 
Hermetic - The airtight sealing of an object.
 
Life Cycle Testing - The subjection of a product to stress comparable to that which the product will sustain during use in order to determine product quality.
 
Liquid-To-Liquid Thermal Shock - Alternately immersing an object in hot and cold liquids.
 
Product Recovery Time - The recovery time of a physical product after it has been subjected to testing. Product recovery time is dependent upon the location of the sensor in the load.
 
Psi (Pounds Per Square Inch) - Unit that measures the amount of pressure applied to an object.
 
Relative Humidity - The ratio of the current amount of water vapor in a given unit of air at a given temperature to the greatest amount of water vapor the unit of air could hold at that temperature.
 
Relative Vibration - The measurement of an object's vibration in comparison to a fixed point on the object.
 
Saturation Humidity - The maximum amount of water vapor a given unit of air can hold at a given temperature. Air becomes saturated when relative humidity reaches 100%.
 
Stress - Condition or force applied to an object that may impair the object's quality and performance.
 
Temperature/Humidity/Bias (THB) Test - Product reliability test in which an object is subjected to high humidity under a constant temperature. Test time greatly exceeds that of HAST test time.
 
Thermal Cycling - Subjecting an object to extreme changes in temperature within a single environmental chamber.
 
Thermal Shock - Stress sustained by an object as a result of rapid temperature changes.
 
Three-zone Thermal Shock - Moving the object from a hot to a cold chamber and vice versa, with an intermediate step of exposure to room temperature.
 
Transfer Time - The amount of time it takes for an object to be moved from one chamber to another.
 
Upstream Recovery Time - Also called "downstream recovery time," this is the time required for the air temperature to recover in the new zone. Upstream recovery time can be measured in the air stream prior to or following the test load.
 
Vibration - Motion of an object around a position of equilibrium.