Temperature Forcing Systems Information

Figure 1: Temperature forcing systems provide tight temperature controls across a large span of possible temperatures. Source: Karel De Vlieger 007/CC BY-SA 4.0 DEED

The effects of temperature can have wide-ranging outcomes on many systems, often leading to unexpected behavior or failure. Temperature forcing systems provide tight temperature controls across a large span of possible temperatures, creating an environment to test devices or systems in specific conditions. With a temperature forcing system, devices can be tested in many different conditions to ensure their performance is as expected before devices are deployed in the field.

Theory of Operation

Temperature forcing systems are vital tools in environmental and semiconductor device testing, ensuring that products can withstand the conditions in which they'll be employed. At the core of these systems is the temperature control unit (TCU), which meticulously adjusts the temperature of a medium, commonly air or a fluid.

Air-based systems utilize blowers, circulating air that's been either heated or cooled around the test sample. Alternatively, liquid systems might immerse the sample in a temperature-controlled bath or circulate fluid through a mechanism to achieve the desired temperature range. Integral to the process are heating and cooling elements. While heating components, like resistive heaters, increase the temperature, cooling elements — such as refrigeration compressors or liquid nitrogen —  it down.

Figure 2: The temperature control unit (TCU) meticulously adjusts the temperature of a medium, commonly air or a fluid. Source: Cjp24/CC BY-SA 3.0 DEED

A critical aspect of the system's accuracy is the feedback mechanism. Thermocouples or other temperature sensors relay real-time temperature data to the TCU, ensuring the environment remains at the set temperature and making necessary adjustments.

The test sample itself is positioned within a chamber or enclosure, which can vary in size from accommodating a singular device to being as large as a walk-in chamber for more extensive items. One of the advanced features of these systems is ramp rate control, which ensures the temperature changes at a specified pace. This precise control is vital for tests that require specific temperature change rates.

Safety is paramount, especially considering the extreme temperatures these systems can achieve. Thus, they are typically equipped with over-temperature cut-offs and alarms. Moreover, for more complex testing scenarios, users can often program a sequence of temperatures and durations, creating a custom temperature "profile" for the sample. This is complemented by data logging capabilities, allowing analysts and researchers to track temperature changes over time, providing insights into how the sample responded to different conditions. Temperature forcing systems offer a controlled setting for assessing product durability, reliability, and operational limits, ensuring that they meet quality and safety standards.

Specifications

Temperature forcing systems come with a variety of specifications that determine their performance, capability, and suitability for specific applications. Here are some common specifications you'll find associated with these systems:

Temperature Range

Arguably the most important specification, temperature range specifies the minimum and maximum temperatures the system can achieve, such as -80° C to 225° C. Some systems have an even wider range.

Temperature Stability

Not all systems are as good at maintaining a given temperature. The temperature stability indicates how consistently the system can maintain a set temperature over a given period.

Ramp Rate

The ramp rate defines how quickly the system can change from one temperature to another, often given in degrees per minute (°C/min).

Cooling and Heating Capacity

Every system will have a given amount of capacity to heat or cool. When this capacity is exceeded, the system will no longer be able to maintain the temperature of the environment. The cooling and heating capacity specifies the power of the cooling and heating elements, often measured in watts.

Chamber/Workspace Volume

Regardless of capacity, the chamber must be big enough to fit the device or sample being tested. The workspace volume describes the size of the testing area or chamber, indicating the maximum size of the sample or device that can be tested.

Temperature Uniformity

A homogeneous temperature profile can be difficult to achieve throughout the chamber volume. The temperature uniformity specification determines how evenly the temperature is distributed throughout the chamber or testing area.

Control Accuracy

Every system will deviate from the temperature set point by some amount. Control accuracy indicates how closely the system can maintain the temperature to the set point.

Interface and Programming

The type of user interface (e.g., touchscreen, digital display) and any programmability features, such as the ability to set temperature profiles is specified as interface and programming capabilities.

Data Logging Capabilities

For test chambers that need to record data, data logging capabilities specify how the system records temperature and other relevant data, as well as the format and storage capabilities.

Fluid or Air Delivery Rate

For systems that use air or fluid as a transfer medium, this indicates the flow rate, often given in liters per minute (L/min) or cubic feet per minute (CFM).

Safety Features

This specification lists safety mechanisms such as over-temperature protection, alarms, safety cut-offs, and emergency shut-down features.

Power Requirements

The power requirements specify the electrical requirements for the system, such as voltage, current, and frequency.

Physical Dimensions and Weight

Provides the size and weight of the system, which can be important for installation and space planning.

Noise Level

For some applications, especially in labs or cleanroom environments, the noise generated by the system can be a concern. This specification indicates how loud the system operates, usually in decibels (dB).

Refrigerants Used

To achieve cooling capacity, some systems rely on refrigerants. This specification details the type of refrigerants used for cooling, which can be important for environmental and safety considerations.

When selecting a temperature forcing system, it's crucial to match these specifications to the needs of the application. For example, semiconductor testing might require rapid ramp rates, while long-term environmental testing could prioritize stability and temperature range. Always consult with manufacturers or experts to ensure a suitable match for your needs.

Figure 3: Temperature forcing systems can be categorized based on several criteria. TEHb K0CM0CA/CC BY-SA 4.0 DEED

Types

Temperature forcing systems can be categorized based on several criteria, including the mechanism of heat transfer, the size and type of the chamber, and the specific applications they serve. Here are some common types of temperature forcing systems:

Air-Based Systems

The two main types of air-based systems are direct injection and air chambers. Direct injections systems directly inject temperature-controlled air onto the device under test (DUT). They're often used in semiconductor testing where a precise temperature needs to be delivered rapidly to a localized area. Air chambers are enclosed spaces where products or samples are placed, and temperature-controlled air is circulated around them.

Liquid-based Systems

Liquid-based temperature forcing systems also come in two main types: liquid baths and fluid circulation systems. Liquid baths immerse samples in a bath of temperature-controlled fluid, often used for calibration or testing smaller components. Fluid circulation systems use fluids that are circulated through a system to provide temperature control, often used for larger systems or when higher precision is needed.

Environmental Chambers

Environmental chambers are often classified by size and come in many different varieties such as:

  • Benchtop chambers
  • Walk-in chambers
  • Climatic chambers

Benchtop chambers are smaller chambers designed to sit on a laboratory bench, suitable for testing small devices or samples. Walk-in chambers are large chambers that can accommodate bigger items, batches of products, or even allow personnel to walk in during setup. Climatic chambers can simulate a range of environmental conditions including temperature, humidity, and sometimes even other factors like altitude or vibration.

Ovens and Furnaces

These are primarily designed for heating and are used in applications like material curing, aging, and thermal treatment. Ovens and furnaces are typically capable of achieving very high temperatures.

Freezers and Cryogenic Systems

Designed specifically for very low-temperature testing, they utilize refrigerants or liquid nitrogen to achieve extremely cold temperatures.

Thermal Shock Chambers

Thermal shock chambers are designed to rapidly change temperatures, exposing the sample to extreme cold and hot conditions in quick succession. They're used to evaluate the robustness of materials or products against sudden thermal changes.

Each type of temperature forcing system serves unique applications and offers different advantages. For instance, direct injection systems provide rapid temperature changes for semiconductor devices, while environmental chambers can simulate a variety of conditions for holistic product testing. When choosing a system, it's essential to consider the specific requirements of the testing application, the size of the samples, and the desired temperature range and precision.

Figure 4: In systems that operate at very low temperatures, this feature helps maintain performance by periodically defrosting the system. Source: Public domain

Features

Temperature forcing systems come with a range of features designed to enhance their functionality, precision, versatility, and user-friendliness. Here are some common features found in these systems:

Programmable Profiles

Many tests require different temperatures and ramp rates. Programmable profiles allow users to set sequences of temperature changes, durations, and ramp rates, automating the testing process.

Touchscreen Interface

Modern systems often include touchscreen controls for easier programming, monitoring, and data retrieval.

Remote Control and Monitoring

Some systems can be controlled remotely via computer interfaces, enabling automated testing sequences and integration with other equipment.

Data Logging

Records temperature data, test durations, and other relevant parameters, which can be exported for analysis.

Humidity Control

In addition to temperature, some systems can control humidity levels, offering a more comprehensive environmental testing capability.

Integrated Sensors

Multiple sensors, like thermocouples or resistance temperature detectors (RTDs), provide accurate readings and feedback for control mechanisms.

Self-diagnostics

Modern systems can self-diagnose issues or malfunctions, alerting users to any problems.

Eco-Friendly Refrigerants

Given environmental concerns, many modern systems use refrigerants that have a lower impact on global warming and the ozone layer.

Adaptors and Fixtures

For direct injection systems, specially designed adaptors and fixtures ensure that the temperature-controlled air or fluid is delivered precisely to the device under test (DUT).

Noise Reduction Features

To make them suitable for lab environments, some systems incorporate design elements or materials that minimize operational noise.

Vibration-free Operation

For sensitive testing applications, systems are designed to operate with minimal vibration. Vibration itself can degrade the quality of many tests and must be avoided.

Automatic Defrost

In systems that operate at very low temperatures, this feature helps maintain performance by periodically defrosting the system.

Multi-zone Control

In larger chambers, different zones can be set to different temperatures, allowing for more complex testing scenarios.

Integration with Other Systems

Some temperature forcing systems can be integrated with other testing equipment, like vibration tables or electrical testing apparatuses, for combined tests.

Portability

Compact and mobile designs with wheels or handles make it easier to move the system between testing locations.

When considering a temperature forcing system, it's essential to identify which features are crucial for the intended application. While some tests might require rapid temperature changes, others might prioritize data logging or humidity control. The variety of available features ensures that there's likely a system tailored to any specific testing need.

Figure 5: Manufacturing temperature forcing systems is a complex process that involves multiple stages. Source: Baravara/CC BY 3.0

Manufacture

Manufacturing temperature forcing systems is a complex process that involves multiple stages, from design and engineering to final assembly and testing. Here's a general overview of how these systems are manufactured:

Engineers and designers create detailed specifications based on the intended application of the system. Simulation tools might be used to predict system performance and optimize design. Based on the design, suitable materials are selected. This could include metals, insulating materials, refrigerants, and electronic components.

Suppliers are engaged to provide the necessary raw materials and components. Metal parts, such as the chamber, external casing, and internal components, are fabricated using techniques like cutting, bending, and welding. Insulating materials are cut and shaped to fit the design, ensuring minimal heat transfer and efficient operation.

The main chamber or enclosure is assembled first. Heating and cooling elements, such as resistive heaters and refrigeration components, are installed. Sensors, like thermocouples or RTDs, are placed in appropriate locations. Electronic and control systems, including the user interface and any programmable components, are integrated. Wiring and electrical components are installed and connected.

Once assembled, the system undergoes rigorous testing. The temperature range, ramp rate, stability, and other specifications are verified. Any issues detected are addressed, and the system might undergo further iterations of testing.

Quality assurance teams inspect the system for any defects or deviations from the design. Safety checks are performed to ensure all safety features function correctly. Before shipping, the system's sensors and controls are calibrated to ensure accurate temperature readings and control.

Manufacturing temperature forcing systems requires a blend of mechanical, electrical, and software engineering. The precision and reliability of these systems are paramount, as they play a crucial role in product testing and quality assurance. As such, manufacturers invest heavily in quality control, research, and development to ensure their systems meet the highest standards.

Figure 6: Temperature forcing systems play a crucial role in various industries due to their ability to simulate a wide range of temperature conditions. Source: ishikawa/CC BY-SA 4.0

Applications

Temperature forcing systems play a crucial role in various industries due to their ability to simulate a wide range of temperature conditions. Here are some prominent applications of these systems:

Semiconductor Testing

Integrated circuits, transistors, and other semiconductor devices are tested to ensure they operate correctly across their specified temperature ranges. Burn-in tests subject devices to elevated temperatures to accelerate potential failures.

Aerospace and Defense

Components and systems used in aircraft, satellites, and military equipment are tested to ensure they can withstand the extreme temperatures encountered during flight or in space.

Automotive Testing

Vehicle components, from electronics to materials, are tested to ensure they can withstand the temperature variations experienced in real-world driving conditions.

Pharmaceuticals and Biotechnology

Temperature forcing systems are used to simulate storage and transport conditions to ensure the stability of drugs, vaccines, and biological samples.

Material Testing

Materials, such as metals, polymers, and composites, are tested to determine their properties at different temperatures, including their thermal expansion, brittleness, and resistance to thermal shock.

Consumer Electronics

Devices like smartphones, laptops, and wearables are tested to ensure they operate reliably under various environmental conditions.

Food and Agriculture

Temperature forcing systems can simulate conditions for food storage, transportation, and shelf-life testing. Seeds and agricultural products are tested for their viability and longevity under different temperature scenarios.

Environmental Testing

Products and materials are subjected to temperature cycles to simulate years of environmental exposure in a short time, helping predict long-term durability and performance.

Calibration and Metrology

Instruments and measurement devices are calibrated and validated under controlled temperature conditions to ensure accuracy.

Research and Development

In R&D labs, temperature forcing systems are used to study the effects of temperature on new materials, products, or biological samples.

Battery Testing

Batteries for devices, vehicles, and energy storage systems are tested under various temperatures to determine their performance, longevity, and safety.

Climatic Research

Scientists use temperature forcing systems to simulate future climatic conditions on plants, soil samples, or small ecosystems, aiding in studies related to climate change.

Medical Device Testing

Devices like pacemakers, monitors, and diagnostic equipment are tested to ensure they function reliably under the temperature conditions they might encounter in real-world use.

These applications underscore the importance of temperature forcing systems in ensuring product reliability, safety, and performance across a multitude of industries. By simulating various temperature conditions, these systems provide invaluable insights into how products and materials will behave in real-world scenarios.

Figure 7: Temperature forcing systems, being integral to various testing and validation processes, need to adhere to specific standards to ensure accuracy, repeatability, and safety. Source: TEHb K0CM0CA/CC BY-SA 4.0 DEED

Standards

Temperature forcing systems, being integral to various testing and validation processes, need to adhere to specific standards to ensure accuracy, repeatability, and safety. Several standards are relevant, depending on the industry and the specific application of the system. Here are some of the common standards and organizations that pertain to temperature forcing systems:

International Electrotechnical Commission (IEC) Standards

  • IEC 60068: This series of standards relates to environmental testing. Parts of this standard detail temperature and humidity test methods and conditions for electronic and electrical products.
  • IEC 61010: Pertains to safety requirements for electrical equipment for measurement, control, and laboratory use.

International Organization for Standardization (ISO) Standards

ISO 17025 is a standard that is essential for calibration and testing laboratories. It deals with the general requirements for competence, ensuring that labs produce valid and reliable results.

American Society for Testing and Materials (ASTM) International

ASTM has numerous standards for testing materials under specific conditions, some of which detail temperature testing parameters.

  • ASTM D5470: Measures the thermal transmission properties of thermally conductive electrical insulation materials.
  • ASTM E1952: Measures the thermal conductivities of solids using a transient plane source.

Military Standards (MIL-STD)

A U.S. military standard, MIL-STD-810, describes environmental test methods to gauge the durability and lifespan of equipment. It includes various temperature tests, such as high and low temperature, temperature shock, and more.

When procuring or using a temperature forcing system, it's essential to ensure that the equipment complies with relevant standards for the specific industry and application. This ensures not only the reliability and accuracy of the system but also its safety and environmental compliance.

References

Froilabo—The Dragon Temperature Forcing System

MPI Thermal—MPI TA-5000A Temperature Forcing Systems

Wewon Tech—Environmental Chambers

Wewon Tech—Temperature Forcing System for Semiconductor IC Testing from Wewon

Eldrotec—Temperature Forcing Systems

STS Test—Thermal Forcing System

Department of Defense Mil Std 810G

Related Information

GlobalSpec—How do thermal actuators work?


UNLIMITED FREE ACCESS TO THE WORLD'S BEST IDEAS

SUBMIT
Already a GlobalSpec user? Log in.

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

Customize Your GlobalSpec Experience

Category: Temperature Forcing Systems
Finish!
Privacy Policy

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.