By Norman Quesnel, Senior Member of Marketing Staff Advanced Thermal Solutions, Inc. (ATS)
Liquid cooling systems transfer heat up to four times better than an equal mass of air. This allows higher performance cooling to be provided with a smaller system. A liquid cooled cold plate can replace spaceconsuming heat sinks and fans and, while a liquid cold plate requires a pump, heat exchanger, tubing and plates, there are more placement choices for cold plates because they can be outside the airflow. [1]
One-time concerns over costs and leaking cold plates have greatly subsided with improved manufacturing capabilities. Today’s question isn’t “Should we use liquid cooling?” The question is “What kind of liquid should we use to help optimize performance?”
Figure 1. A Liquid Cooling System for a Desktop PC with Two Cold Plates. [2]
For liquid cold plates, the choice of working fluid is as important as choosing the hardware pieces. The wrong liquid can lead to poor heat transfer, clogging, and even system failure. A proper heat transfer fluid should provide compatibility with system’s metals, high thermal conductivity and specific heat, low viscosity, low freezing point, high flash point, low corrosivity, low toxicity, and thermal stability. [3]
Today, despite many refinements in liquid cold plate designs, coolant options have stayed relatively limited. In many cases, regular water will do, but water-with-additives and other types of fluids are available and more appropriate for certain applications. Here is a look at these coolant choices and where they are best suited.
Basic Cooling Choices
While water provides superior cooling performance in a cold plate, it is not always practical to use because of its low freezing temperature. Additives such as glycol are often needed to change a coolant’s characteristics to better suit a cold plate’s operating environment.
In fact, temperature range requirements are the main consideration for a cold plate fluid. Some fluids freeze at lower temperatures than water, but have lower heat transfer capability. The selected fluid also must be compatible with the cold plate’s internal metals to limit any potential for corrosion.
Table 1 below shows how the most common cold plate fluids match up to the metals in different cold plate designs.
Table 1: Compatibility Match-ups of Common Cold Plate Metals and Cooling Fluids [1]
The choices of cold plate coolants will obviously have varied properties. Some of the differences between fluids are less relevant to optimizing cold plate performance, but many properties should be compared. Tables 2 and 3 show the properties of some common coolants.
Tables 2 and 3. Comparisons of Properties of Typical Electronic Coolants. [4]
An excellent review of common cold plate fluids is provided by Lytron, an OEM of cold plates and other cooling devices. The following condenses fluid descriptions taken from Lytron’s literature. [5]
The most commonly used coolants for liquid cooling applications today are:
Water
Deionized Water
Inhibited Glycol and Water Solutions
Dielectric Fluids
Water – Water has high heat capacity and thermal conductivity. It is compatible with copper, which is one of the best heat transfer materials to use for your fluid path. Facility water or tap water is likely to contain impurities that can cause corrosion in the liquid cooling loop and/or clog fluid channels. Therefore, using good quality water is recommended in order to minimize corrosion and optimize thermal performance. If you determine that your facility water or tap water contains a larger percentage of minerals, salts, or other impurities, you can either filter the water or you can opt to purchase filtered or deionized water. [5,6]
Deionized Water – The deionization process removes harmful minerals, salts, and other impurities that can cause corrosion or scale formation. Compared to tap water and most fluids, deionized water has a high resistivity. Deionized water is an excellent insulator, and is used in the manufacturing of electrical components where parts must be electrically isolated. However, as water’s resistivity increases, its corrosivity increases as well. When using deionized water in cold plates or heat exchangers, stainless steel tubing is recommended. [5, 7]
Inhibited Glycol and Water Solutions – The two types of glycol most commonly used for liquid cooling applications are ethylene glycol and water (EGW) and propylene glycol and water (PGW) solutions. Ethylene glycol has desirable thermal properties, including a high boiling point, low freezing point, stability over a wide range of temperatures, and high specific heat and thermal conductivity. It also has a low viscosity and, therefore, reduced pumping requirements. Although EGW has more desirable physical properties than PGW, PGW is used in applications where toxicity might be a concern. PGW is generally recognized as safe for use in food or food processing applications, and can also be used in enclosed spaces. [5, 8]
Dielectric Fluid – A dielectric fluid is non-conductive and therefore preferred over water when working with sensitive electronics. Perfluorinated carbons, such as 3M’s dielectric fluid Fluorinert™, are non-flammable, non-explosive, and thermally stable over a wide range of operating temperatures. Although deionized water is also non-conductive, Fluorinert™ is less corrosive than deionized water. However, it has a much lower thermal conductivity and much higher price. PAO is a synthetic hydrocarbon used for its dielectric properties and wide range of operating temperatures. For example, the fire control radars on today’s jet fighters are liquid-cooled using PAO. For testing cold plates and heat exchangers that will use PAO as the heat transfer fluid, PAO-compatible recirculating chillers are available. Like perfluorinated carbons, PAO has much lower thermal conductivity than water. [5, 9]
Conclusion
Water, deionized water, glycol/water solutions, and dielectric fluids such as fluorocarbons and PAO are the heat transfer fluids most commonly used in high performance liquid cooling applications.
It is important to select a heat transfer fluid that is compatible with your fluid path, offers corrosion protection or minimal risk of corrosion, and meets your application’s specific requirements. With the right chemistry, your heat transfer fluid can provide very effective cooling for your liquid cooling loop.
Expanding the Internet of Things (IOT) into time-critical applications such as with autonomous vehicles, means finding ways to reduce data transfer latency. One such way, edge computing, places some computing as close to connected devices as possible. Edge computing pushes intelligence, processing power and communication capabilities from a network core to the network edge, and from an edge gateway or appliance directly into devices. The benefits include improved response times and better user experiences.
While cloud computing relies on data centers and communication bandwidth to process and analyze data, edge computing provides a means to lay some work off from centralized cloud computing by taking less compute intensive tasks to other components of the architecture, near where data is first collected. Edge computing works with IoT data collected from remote sensors, smartphones, tablets, and machines. This data must be analyzed and reported on in real time to be immediately actionable. [1]
FIgure 1: Edge Computing Architecture Scheme with Both the Computing Power and Latency Decreasing Downwards [2]
In the above edge computing scheme, developed by Inovex,
the layers are described as follows:
Cloud: On this layer
compute power and storage are virtually limitless. But, latencies and the cost
of data transport to this layer can be very high. In an edge computing
application, the cloud can provide long-term storage and manage the immediate
lower levels.
Edge
Node: These nodes are
located before the last mile of the network, also known as downstream. Edge nodes
are devices capable of routing network traffic and usually possess high compute
power. The devices range from base stations, routers and switches to
small-scale data centers.
Edge
Gateway: Edge
gateways are like edge nodes but are less powerful. They can speak most common
protocols and manage computations that do not require specialized hardware,
such as GPUs. Devices on this layer are often used to translate for devices on
lower layers. Or, they can provide a platform for lower-level devices such as mobile
phones, cars, and various sensing systems, including cameras and motion
detectors.
Edge
Devices: This
layer is home to small devices with very limited resources. Examples include
single sensors and embedded systems. These devices are usually purpose-built
for a single type of computation and often limited in their communication
capabilities. Devices on this layer can include smart watches, traffic lights and
environmental sensors. [2]
Today, edge computing is becoming essential where time-to-result must be minimized, such as in smart cars. Bandwidth costs and latency make crunching data near its source more efficient, especially in complex systems like smart and autonomous vehicles that generate terabytes of telemetry data. [3]
Figure 2: A Small Scale Edge Computing Device from LeapMind [4]
Besides vehicles, edge computing examples serving the IoT include
smart factories and homes, smartphones, tablets, sensor-generated input,
robotics, automated machines on manufacturing floors, and distributed analytics
servers used for localized computing and analytics.
Major technologies served by edge computing include
wireless sensor networks, cooperative distributed peer-to-peer ad-hoc
networking and processing, also classifiable as local cloud/fog computing,
distributed data storage and retrieval, autonomic self-healing networks, remote
cloud services, augmented reality and virtual reality. [5]
Autonomous Vehicles and Smart Cars
New so-called autonomous vehicles have enough computing
hardware they could be considered mobile data centers. They
generate terabytes of data every day. A single vehicle running for 14 to 16 hours
a day creates 1-5TB of raw data an hour and can produce up to 50TB a day. [6]
A moving self-driving car, sending a live stream continuously to servers, could meet disaster while waiting for central cloud servers to process the data and respond back to it. Edge computing allows basic processing, like when to slow down or stop, to be done in the car itself. Edge computing eliminates the dangerous data latency.
Figure 3: Edge Computing Reduces Data Latency to Optimize Systems in Smart and Autonomous Vehicles [7]
Once an autonomous car is parked, nearby edge computing
systems can provide added data for future trips. Processing this close to the
source reduces the costs and delays associated with uploading to the cloud.
Here, the processing does not occur in the vehicle itself.
Other Edge Computing Applications
Edge computing enables industrial and healthcare providers
to bring visibility, control, and analytic insights to many parts of an
infrastructure and its operations—from factory shop floors to hospital
operating rooms, from offshore oil platforms to electricity production.
Machine learning (ML) benefits greatly from edge computing.
All the heavy-duty training of ML algorithms can be done on the cloud and the
trained model can be deployed on the edge for near real-time or true real-time
predictions.
For manufacturing uses, edge computing devices can translate data from proprietary systems to the cloud. The capability of edge technology to perform analytics and optimization locally, provides faster responses for more dynamic applications, such as adjusting line speeds and product accumulation to balance the line. [8]
Figure 4: EdgeBoard by Baidu is a Computing Solution for Edge-Specific Applications [9]
Edge Computing Hardware
Processing power at the edge needs to be matched to the
application and the available power to drive an edge system operation. If
machine vision, machine learning and other AI technologies are deployed,
significant processing power is necessary. If an application is more modest,
such as with digital signage, the processing power may be somewhat less.
Intel’s Xeon D-2100 processor is made to support edge computing. It is a lower power, system on chip version of a Xeon cloud/data server processor. The D-2100 has a thermal design point (TDP) of 60-110W. It can run the same instruction set as traditional Intel server chips, but takes that instruction set to the edge of the network. Typical edge applications for the Xeon D-2100 include multi-access edge computing (MEC), virtual reality/augmented reality, autonomous driving and wireless base stations. [10]
Figure 5: The D-2100 Processor Dissipates Between 60 -110W. Thermal Management Depends on the Type of Device and Where it is Used [11]
Thermal management of the D-2100 edge focused processor is largely determined by the overall mechanical package the edge application takes. For example, if the application is a traditional 1U server, with sufficient air flow into the package, a commercial off the shelf, copper or aluminum heat sink should provide sufficient cooling. [11]
Figure 6: An Edge Computing Server from ATOS Featuring the Xeon D-2187 from Intel’s D-2100 Family of Processors [12]
An example of a more traditional package for edge computing
is the ATOS system shown in Figure 6. But, for less common packages, where
airflow may be less, more elaborate approaches may be needed. For example, heat
pipes may be needed to transport excess processor heat to another part of the
system for dissipation.
One design uses a vapor chamber integrated with a heat sink. Vapor chambers are effectively flat heat pipes with very high thermal conductance and are especially useful for heat spreading. In edge hardware applications where there is a small hot spot on a processor, a vapor chamber attached to a heat sink can be an effective solution to conduct the heat off the chip.
Figure 7: Coca-Cola’s Freestyle Fountain, a Non-Traditional Edge Computing System, Features an Intel I7 CPU, DRAM, Touchscreen, WiFi and HiDef Display [13]
The Nvidia Jetson AGX Xavier is designed for edge computing applications such as logistics robots, factory systems, large industrial UAVs, and other autonomous machines that need high performance processing in an efficient package.
Figure 8: Nvidia’s Jetson AGX Xavier Produces Little Heat But Could Have Thermal Issues in Edge Computing Applications [14]
Nvidia has modularized the package, proving the needed supporting semiconductors and input/output ports. While it looks like if could generate a lot of heat, the module only produces 30W and has an embedded thermal transfer plate. However, any edge computing deployment of this module, where it is embedded into an application, can face excess heat issues. A lack of system air, solar loading, impact of heat from nearby devices can negatively impact a module in an edge computing application.
Figure 9: Nvidia’s Development Kit for the Jetson AGX Xavier Includes Heat Sink and Heat Pipes [15]
Nvidia considers this in their development kit for this
module. It has an integrated thermal management solution featuring a heat sink
and heat pipes. Heat is transferred from the module’s embedded thermal transfer
plate to the heat pipes then to the heat sink that is part of the solution.
For a given edge computing application, a thermal solution
might use heat pipes attached to a metal chassis to dissipate heat. Or it could
combine a heat sink with an integrated vapor chamber. Studies by Glover, et al
from Cisco have noted that for vapor chamber heat sinks, the thermal resistance
value varies from 0.19°C/W to 0.23°C/W for 30W of power. [16]
A prominent use case for edge computing is in the smart factory empowered by the Industrial Internet of things (IIoT). As discussed, cloud computing has drawbacks due to latency, reliability through the communication connections, time for data to travel to the cloud, get processed and return. Putting intelligence at the edge can solve many if not all these potential issues. The Texas Instruments (TI) Sitara family of processors was purpose built for these edge computing machine learning applications.
Figure 10: TI’s Sitara Processors are Design for Edge Computing Machine Learning Applications [17]
Smart factories apply machine learning in different ways.
One of these is training, where machine learning algorithms use computation
methods to learn information directly from a set of data. Another is
deployment. Once the algorithm learns, it applies that knowledge to finding
patterns or inferring results from other data sets. The results can be better
decisions about how a process in a factory is running. TI’s Sitara family can execute a trained
algorithm and make inferences from data sets at the network edge.
The TI Sitara AM57x devices were built to perform machine
learning in edge computing applications including industrial robots, computer
vision and optical inspection, predictive maintenance (PdM), sound
classification and recognition of sound patterns, and tracking, identifying,
and counting people and objects. [18,19]
This level of machine learning processing may seem like it would require sophisticated thermal management, but the level of thermal management required is really dictated by the use case. In development of its hardware, TI provides guidance with the implementation of a straight fin heat sink with thermal adhesive tape on its TMDSIDK574 AM574x Industrial Development Kit board.
Figure 11: TI TMDSIDK574 AM574x Industrial Development Kit [20]
While not likely an economical production product, it
provides a solid platform for the development of many of the edge computing
applications that are found in smart factories powered by IIoT. The straight
fin heat sink with thermal tape is a reasonable recommendation for this kind of
application.
Most edge computing applications will not include a lab bench or controlled prototype environment. They might involve hardware for machine vision (an application of computer vision). An example of a core board that might be used for this kind of application is the Phytec phyCORE-AM57x. [21]
Figure 12: The Phytec phyCORE-AM57x Can Be used in Edge Computing Machine Vision Applications [22]
Machine vision being used in a harsh, extreme temperature industrial environment might require not just solid thermal management but physical protection as well. Such a use case could call for thermal management with a chassis. An example is the Arrow SAM Car chassis developed to both cool and protect electronics used for controlling a car.
Figure 13: Chassis for Automotive Application that Protects Components and Provides Thermal Management [23]
Another packaging example from the SAM Car is the chassis shown below, which is used in a harsh IoT environment. This aluminum enclosure has cut outs and pockets connecting to the chips on the internal PCB. The chassis acts as the heat sink and provides significant protection in harsh industrial environments.
Figure 14: Aluminum Chassis with Cut Outs and Pocketts to the Enclosed PCB with Semiconductors [23]
Edge computing cabinetry is small in scale (e.g. less than 10 racks), but powerful in information. It can be placed in nearly any environment and location to provide power, efficiency and reliability without the need for the support structure of a larger white space data center.
Figure 15: The Jetson TX2 Edge Computing Platform from Nvidia [24]
Still, racks used in edge cabinets can use high levels of processing power. The enclosure and/or certain components need a built-in, high-performance cooling system.
Hardware OEMs like Rittal build redundancy into edge systems. This lets other IT assets remain fully functional and operational, even if one device fails. Eliminating downtime of the line, preserving key data and rapid response all contribute to a healthier bottom line.
Although edge computing involves fewer racks, the data needs vital cooling protection. For edge computers located in remote locations, the availability of cooling resources may vary. Rittal provides both water and refrigerant-based options. Refrigerant cooling provides flexible installation, water based cooling brings the advantage of ambient air assist, for free cooling. [25]
Figure 16: LiquidCool Immersion Cooling Technology Eliminates the Need for Air Cooling
LiquidCool’s technology collects server waste heat inside a
fluid system and transports it to an inexpensive remote outside heat
exchanger. Or, the waste heat can be re-purposed. In one IT closet-based edge
system, fluid-transported waste heat is used for heating an adjacent room. [26]
Green Revolution Cooling provides ICEtank turnkey data centers built inside ISO shipping containers for edge installations nearly anywhere. The ICEtank containers feature immersion cooling systems. Their ElectroSafe coolant protects against corrosion, and the system removes any need for chillers, CRACs (computer room ACs) and other powered cooling systems. [27]
A Summary Chart of Suggested Cooling for Edge Computing
The following chart summarizes air cooling options for Edge Computing applications:
Figure 17: Edge Computing Air Cooling Options Summary Chart [click for larger version]
The Leading Edge
The edge computing marketplace is currently
experiencing a period of unprecedented growth. Edge market revenues are
predicted to expand to $6.72 billion by 2022 as it supports a global
IoT market expected to top $724 billion by 2023. The accumulation of IoT data,
and the need to process it at local collection points, will continue to drive
the deployment of edge computing. [28,29]
As more businesses and industries shift from enterprise to
edge computing, they are bringing the IT network closer to speed up data communications.
There are several benefits, including reduced data latency, increased real-time
analysis, and resulting efficiencies in operations and data management. Much critical
data also stays local, reducing security risks.
“Glover,
G., Chen, Y., Luo, A., and Chu, H., “Thin Vapor Chamber Heat Sink and Embedded
Heat Pipe Heat Sink Performance Evaluations”, 25th IEEE Symposium, San Jose, CA
USA 2009.
Heat pipes are commonly used for cooling electronics by
transporting heat from one location to another. They may part of a system that
cools a certain very hot component, but they are used, typically in multiples,
to bring cooling to electronic assemblies. Here are some common attachment
methods used when assembling heat pipe-based cooling applications.
Press Fitting
First, we look at a cooling system where several heat pipes are integrated with a series of cooling metal fins. As shown, the fins may be mechanically press fit over the heat pipes resulting in a structure like that in Figure 1.
Figure 1: Stamped Metal Plates Placed Over the Ends of Some Heat Pipes
At this finned end of the assembly the heat transfers from pipe to fins where it dissipates to the air. These fins are typically stamped from sheet metal and the holes stamped through as well. When they’re properly sized, the fins press fit tightly on the raised heat pipes. The heat transfer is normally very good. To optimize thermal transfer, the fins can be soldered to the pipes, but press fitting into tight holes should provide more than sufficient performance.
Soldering
The other ends of these heat sinks are soldered into grooves in an aluminum plate. (Figure 2) This is an aluminum plate and the heat pipes are copper. In order to solder we need to nickel plate the aluminum. Then we add solder paste into the grooves and then the heat pipes are inserted into the grooves.
Figure 2. Heat Pipes Soldered into Grooves on a Nickel-Plated Aluminum Heat Spreading Plate.
The solder paste is usually a low temperature solder paste,
typically based on tin bismuth alloys with melt temperature of about 138°C.
That’s important because you really can’t bring the heat pipes to more than 250°C
or else the water in the heat pipes will boil and the heat pipes will burst. So,
during the assembly process you would put the solder paste into these grooves,
then insert the heat pipes, and then clamp it with some sort of fixture to
maintain the contact.
Then the whole assembly will go through an oven to reflow the solder paste. The reflow oven will precisely control the temperature of the air inside and will also have some kind of circulating fan so that the part heats evenly and quickly. Temperature control in the oven is critical to avoid exceeding the max temperature of the heat pipes. Other reflow methods for heating up an assembly might include a soldering iron, torch or hot air gun. But these methods can be risky and difficult. It is difficult to heat the part evenly and to control the temperature that the heat pipe is being exposed to.
Thermal Epoxies
In a prototype environment you might turn to an epoxy for attaching heat pipes to assemblies. There are number of thermally conductive epoxies available. Their thermal conductivity ranges from 1 to 6 W/mK. When a heat pipe is epoxied into an assembly, the bond line is so thin that it really doesn’t make too much of a temperature difference, even when compared to solder. There might be a few degrees difference which is usually acceptable in a prototype when you’re in testing mode and are aware that there could be a temperature difference of a few degrees. That’s easily calculated from the specs on the epoxy.
Figure 3. Adding Thermal Epoxy to Grooves in a Heat Spreading Plate Prior to Installing Heat Pipes.
To begin the epoxying process, first you either mix your epoxy or use a mixing tube. You apply a thin layer into the groove and then insert the heat pipe. The grooves shown here are for heat pipes that are pre-bent and fit very precisely. Once in place, a flat plate that goes on top and is clamped down during the epoxy curing period.
In the example here, the epoxy has room temperature cure. Once the heat pipes are in and clamped down, the assembly can be conveniently left for a time at room temperature for the epoxy to cure. For a shorter time, the assembly can go into an oven at a high temperature – not a soldering temperature, but still hot enough that it will accelerate the cure time.
Figure 4A. With Deep Enough Grooves, Heat Pipes Are Same Level as the Plate Surface for Better Thermal Contact with a Board.
Figure 4B. With Deep Enough Grooves, Heat Pipes Are Same Level as the Plate Surface for Better Thermal Contact with a Board.
When embedding heat pipes into a surface a good practice is to machine the grooves slightly deeper than the heat pipes are. Then, you can create a fixture that is like a negative of this plate with raised areas where those heat pipes. Such a fixture will press the heat pipes down into those grooves. After they’re epoxied or soldered in the assembly the heat pipes and base will be at the same height for optimum thermal contact.
In this kind of application, flat heat pipes should be used. They
can maximize the surface contact area where there are hot components. And in applications
where the components do not come in direct contact with the pipe it’s often
easier to use round heat pipes. This is because round heat pipes are easier to
bend and have slightly better thermal performance than the flat heat pipes. So
whenever possible we use the round heat pipes, but when they are embedded into
a surface and they have contact with the components then we use the flat heat
pipes.
For More Information
The above article is taken from a descriptive video by Advanced Thermal Solutions, Inc. that you can find on the ATS YouTube page at: https://www.youtube.com/watch?v=I5CQsBWKtOg
In this article, Qpedia will explore some innovative thermal management products that have recently hit the market. These new thermal products encompass a variety of thermal management applications from CPU coolers to thermal interface materials (TIM) to sensors and test instruments to advanced materials and concepts.
Graphene Sheets
Paragraf, a group affiliated with the University of Cambridge is producing graphene at up to eight inches (20cm) in diameter, large enough for commercial electronic devices. Engineers at Paragraf are creating graphene wafers and graphene-based electronic devices that can be used in transistors, where graphene-based chips could deliver speeds more than ten times faster than silicon chips.
They can also be used in chemical and electrical sensors, where graphene could increase sensitivity by a factor of more than 30. Paragraf’s devices will target markets including transistors, chemical and electrical sensors, and new energy generation devices.
QSFP-DD BiPass Thermal Cooling Configuration
Molex, a global electronic solutions provider, highlights its new BiPass thermal management configuration cooling QSFP-DD modules up to 20 W with a 15°C change from the ambient temperature. First shown at DesignCon 2019, the Molex QSFP-DD thermal solution can cool a range of 15W to 20W in different configurations. The BiPass solution allows higher wattage modules to be cooled and will help designers on the path toward 112 Gbps.
As the industry is readying for the launch of next-generation copper and optical QSFP-DD transceivers, thermal management strategies are critical. During the demonstration, Molex showcased a QSFP-DD belly-to-belly BiPass configuration, QSFP-DD belly-to-belly SMT configuration, 2×1 QSFP-DD stacked configuration and 1×2 QFSP-DD BiPass in a vertical orientation with dual heat sinks.
Running at 15W, all configurations were able to cool at less than 25-degree Celsius delta T rise. The BiPass solution routes high-speed signals through Temp-Flextwinax cables enabling greater channel margin compared to PCB alone and allows for a second heat sink on the bottom side of the cage to make contact with the module, providing additional cooling.
The BiPass solution, allows designers to bypass the lossy printed circuit board by utilizing Temp-Flex high-speed twinax. Because of this, they can achieve lower insertion loss when going from an ASIC in a switch or a router to another server within a rack.
Micro and Macro Channel Liquid Cooling
Rogers now provides curamik CoolPower and CoolPower Plus as well as the curamik CoolPerformance and CoolPerformance Plus. The liquid coolers feature either a micro or macro channel structure made of thin copper foils that are put together into a hermetically tight block using Rogers’ curamik bonding process. The specific channel structure determines the thermal resistance, pressure drop and flow rate. The coolant usually enters and exits through openings connected with O-rings or screw fittings.
Ideal for high power applications, the curamik CoolPerformance coolers are high performance copper coolers for laser diode cooling. curamik CoolPerformance Plus coolers are high performance isolated copper coolers that contain an AlN isolation layer on top and bottom.
Thermal Tape Offers Low Thermal Resistance
DuPont Temprion AT adhesive thermal tapes deliver grease-like wettability at low application pressures, providing the freedom to assemble devices without introducing excess stress to a system’s complex circuitry.
The highly conformable pressure-sensitive adhesive tapes achieve low thermal impedance at only 20 psi of pressure to offer best-in-class thermal performance, easier package assembly, reduced device failure and higher system performance. Thermal conductivity is 0.7 W/m·K.
Use of Temprion AT thermal tapes eliminates the need for mechanical fasteners when assembling electronic packages. Applications include heat sink attachment for CPUs and GPUs, LED bonding, and assembly of flat panel displays.
Peltier Coolers Keep Machine Vision Systems Cool
The HiTemp ET Series Peltier thermoelectric module from Laird Thermal Systems is designed to keep the sensors in machine vision systems cool and operating at peak performance. Solid-state thermoelectric coolers can reduce the sensor’s temperature to meet proper design specifications.
A standard single-stage Peltier cooler can achieve temperature differentials of up to 70°C, while a multi-stage Peltier module can achieve much higher ΔTs. Thermoelectric modules are integrated directly into the sensor assembly and typically require a heat sink or other heat exchanger to dissipate heat into the surrounding environment.
Supporting applications operating in temperatures ranging from 80 to 150°C, the single-stage HiTemp ET Series offers a cooling capacity of more than 300 watts in a compact form factor. The HiTemp ET Series includes over 50 models with a wide variety of heat pumping capacities, form factors and input voltages.
InRow Data Center Cooling Solution
Schneider Electric has expanded its EcoStruxur Ready cooling portfolio with a 30kW InRow DX solution. Available in a 300mm rack format, this data center cooling solution offers industry leading efficiency and addresses the increasing demand for higher density cooling in the data center.
The trend toward modernization and consolidation of data centers is driving the need for a cooling solution that provides more cooling capacity in a smaller footprint and flexible capacity to adapt to the actual data center load. The 30kW InRow DX is ideal for data centers that are being modernized or retrofitted, or anywhere IT space is at a premium.
Due to its powerfully compact size and energy efficient design, the InRow DX is the most versatile and predictable cooling system for next generation small and medium data centers and an optimal choice for edge and enterprise environments. The 30kW InRow system can provide 30% improved efficiency, reducing operating expenses and improving PUE (power usage effectiveness).
In this article, Qpedia will explore some innovative thermal management products that have recently hit the market. These new thermal products encompass a variety of thermal management applications from CPU coolers to thermal interface materials (TIM) to sensors and test instruments to advanced materials and concepts.
Wireless Temperature Sensor for Data Centers
The IoT-enabled EkkoSense Wireless Temperature and Humidity Sensor. (EkkoSense)
The sensor features a local display of the measured temperature and relative humidity values, with additional screens that can be cycled through to show temperature profiles over the last hour, 24 hours and seven days for quick thermal assessment on-site. Wireless EkkoSensors are entirely self-contained and battery-powered for simpler installation.
The sensors provide a direct sensor-to-hub linkage to keep the radio network simple and deliver predictable levels of battery life and performance. All temperature and humidity data is encrypted with 128-bit AES encryption before transmission to an EkkoHub wireless data receiver for forwarding to EkkoSense’s cloud-based EkkoSoft 3D visualization and analysis software.
Non-Silicone TIMs for LED Cooling
Non-silicone TIMs from Electrolube can be used in LED cooling applications. (Electrolube)
Electrolube has introduced non-silicone TIMs for use in LED cooling in response to silicone-related issues with long term reliability, contamination and availability. Heat can substantially impacts the lifetime, cost and performance of an LED luminaire. Without suitable thermal management, a luminaire will be thermally inefficient, have a reduced operating life and high maintenance costs.
Electrolube’s non-silicone thermal pastes include HTC (Heat Transfer Compound) and HTCP (Heat Transfer Compound Plus), which avoid silicone migration onto electrical contacts. Potential issues with silicone migration include high contact resistance, arcing, soldering problems and mechanical wear.
Electrolube’s X range of non-silicone thermal products features the low viscosity HTCX, for ease of use, and HTCPX for gap filling applications. These ‘Xtra’ versions of HTC and HTCP provide increased thermal conductivity, lower oil-bleed and lower evaporation weight loss, making them comparable or better than some silicone-based materials.
Heat Insulating Sheets Have Air-Like Conductivity
Panasonic introduced NABSIS (nano silica balloon insulator sheet) composed of an aerogel and polyester fiber. (Panasonic)
The thermal conductivity of NASBIS is comparable to that of air, making it a very attractive material for heat insulation. NASBIS sheets protect thermally weak products from heat and work to maintain a uniform temperature throughout a device. When combined in a stack with Panasonic’s pyrolytic graphite sheet or PGS, NASBIS insulating sheets enable the control of heat direction.
The proprietary composite material provides greater heat insulating performance. Applications include wearable devices, LED modules and drivers, micro inverters, IGBT modules, radio devices, notebook and tablet PCs, satellites and cameras.
High Performance CPU Cooler for Gaming PCs
The HEX 2.0 CPU Cooler from Phononic pushes a processor up to 140 watts TDP. (Phononic)
The HEX 2.0 CPU cooler from Phononic offers superb performance in a compact design that allows users to push their processor up to 140 watts TDP (thermal design power) and beyond. The cooler’s innovative design combines a small form factor measuring just 125 x 112 x 95 millimeters, unique styling via a swappable 92-millimeter fan, and customizable LED illumination.
Users can select cooling profiles, change LED colors and keep up-to-date with the latest firmware through the HEX 2.0 software application dashboard. The HEX 2.0 offers an alternative for high performance cooling without going to a much larger heat sink/fan or a water-based solution.
The HEX 2.0 has an integrated electronic control board and utilizes an active and passive cooling design to deliver high performance cooling only when necessary, minimizing the power and fan noise. The HEX 2.0 requires zero power consumption when the CPU is under low stress, up to a peak power of 35 Watts when the CPU is under stress or in overclocked mode.
High Performance, Low Compression Gap Filler
Henkel introduced the new GAP PAD HC 5.0 to manage high power density components. (Henkel)
The new GAP PAD HC 5.0 for Henkel is designed to manage the heat generated by today’s reduced form factor, high power density components. A soft and compliant gap filling material, GAP PAD HC 5.0 has a thermal conductivity of 5.0 W/mK and delivers outstanding thermal performance with very low compression stress.
The low modulus and unique filler package is ideal for applications that require minimal component or board stress during assembly, yet demand high heat transfer across the interface with very low thermal resistance. GAP PAD HC 5.0 allows for superb interfacing and wet out, even to rough surfaces and topographies, which ensures uniform material coverage across the component and heat sink for maximum performance.
Compared to previous-generation materials, GAP PAD HC 5.0 offers better handling, an enhanced dielectric constant, improved volume resistivity and better thermal impedance performance. Manufactured with a natural tack on both sides, GAP PAD HC 5.0 contains no thermally-impeding adhesive layers and is available in a range of thickness from 0.508 mm up to 3.175 mm.
Top Mount Enclosure Air Conditioner
Thermal Edge has released a new top mount air conditioner for enclosures. (Thermal Edge)
To accommodate these applications, Thermal Edge has added a series of Top Mount enclosure air conditioners in a variety of capacities and voltages that provides the same unique features as their side mounted models, including an active condensate evaporation system, digital controller, and a thermal expansion valve to maintain cooling capacity over a broad ambient temperature range.
The Top Mount models also offer a unique option that allows engineers to enhance the airflow inside the cabinet by adjusting the distance between the cold air outlet and the warm air intake. The Top Mount models are designed to be filter free (filters optional) and are available with 6,000 and 8,000 BTU/H performance. The air conditioners are available in NEMA Types 12, 4 and 4X.
