September 2010

Nanowick at Heart of New System to Cool Power Electronics 
Researchers have shown that an advanced new cooling technology being developed for high-power electronics in military and automotive systems is capable of handling roughly 10 times the heat generated by conventional computer chips.

The miniature, lightweight device uses tiny copper spheres and carbon nanotubes to passively wick a coolant toward hot electronics, said Suresh Garimella, a R. Eugene and Susie E. Goodson Distinguished Professor of Mechanical Engineering at Purdue University. This wicking technology represents the heart of a new ultrathin thermal ground plane, a flat, hollow plate containing water.

New findings indicate the wicking system that makes the technology possible absorbs more than 550 watts per square centimeter, or about 10 times the heat generated by conventional chips. This is more than enough cooling capacity for the power-electronics applications.

The new type of cooling system can be used to prevent overheating of devices called insulated gate bipolar transistors, high-power switching transistors used in hybrid and electric vehicles. The chips are required to drive electric motors, switching large amounts of power from the battery pack to electrical coils needed to accelerate a vehicle from zero to 60 mph in 10 seconds or less.

Inside the cooling system, water circulates as it is heated, boils and turns into a vapor in a component called the evaporator. The water then turns back to a liquid in another part of the heat pipe called the condenser. The wick eliminates the need for a pump because it draws away fluid from the condenser side and transports it to the evaporator side of the flat device.

Allowing a liquid to boil dramatically increases how much heat can be removed compared to simply heating a liquid to temperatures below its boiling point. Understanding precisely how fluid boils in tiny pores and channels is helping the engineers improve such cooling systems.

The wicking part of the heat pipe is created by sintering, or fusing together tiny copper spheres with heat. Liquid is drawn sponge-like through spaces, or pores, between the copper particles by a phenomenon called capillary wicking. The smaller the pores, the greater the drawing power of the material, Garimella said. Such sintered materials are used in commercial heat pipes, but the researchers are improving them by creating smaller pores and also by adding the carbon nanotubes.

The researchers are creating smaller pores by ‘nanostructuring’ the material with carbon nanotubes, which have a diameter of about 50 nanometers, or billionths of a meter. However, carbon nanotubes are naturally hydrophobic, hindering their wicking ability, so they were coated with copper using a device called an electron beam evaporator.

 Tactilus Sensor System Ensures Optimal Heat Sink Efficiency
The new Tactilus heat-sink analysis system by Sensor Products, Inc. enables research and design engineers to precisely test and correct the surface contact and pressure distribution between the heat sink and its source. Even a slight warping of the heat exchange structure or reduction in surface contact area can have an effect on cooling efficacy. If the pressure distribution is not uniform, heat conduction will be low, and the electronics may overheat.

With Tactilus, engineers can visualize actual contact forces and pressure distribution data on the circuit board components. As the mounting screws between the CPU and the heat sink are torqued, Tactilus maps and measures the changing pressure distribution between the mating surfaces and displays it through its software. The heat sink interface can be tested, manipulated and repositioned in real-time, speeding the trial and error process and eliminating the need for additional assembly. Tactilus also provides the pressure data needed for FEA simulation predictions.

Unlike conventional transducers, the Tactilus sensor is flexible and only 0.015-in. thick (0.38 mm), allowing it to be placed between the CPU and heat sink without affecting the assembly. The sensor pad has 625 resistive sensing points arrayed on a 25 by 25 grid. The total sensing area is 2 inches by 2 inches. The scan speed is up to 1,000 Hz, and the operating pressure range is 0 to 100 psi (0 to 7 kg/cm2).

The Tactilus sensor system will endure hundreds of diagnostic uses on different heat sinks with consistent repeatability. It is highly resistant to electromagnetic noise, temperature, and humidity fluctuations. Accuracy is ± 10 percent, repeatability is ± 2 percent, hysteresis is ± 5 percent and non-linearity is ± 1.5 percent.

FLIR Lowers Infrared Camera Prices Under $1,600
FLIR Systems jas announced new lower prices for its FLIR i5 and FLIR i7 thermal imaging cameras. The entry level FLIR i5 will retail for $1,595. The FLIR i7 will retail for $1,995, making it the first infrared camera to meet the proposed RESNET thermal imaging inspection requirements for under $2,000.

The FLIR i5 and FLIR i7 permit home inspectors, building inspectors, energy audit professionals, plant maintenance technicians, and water damage restoration specialists to upgrade from a single-spot IR thermometer to the big picture of a FLIR infrared camera.

Ergonomically lightweight by design, the rugged FLIR i5 and i7 infrared cameras are heavyweight performers. Both thermal imagers offer infrared image quality with 2 percent accuracy, a large 2.8 inch color display and 80 by 80 pixel resolution on the FLIR i5 or a RESNET-compliant 120 by 120 pixel resolution on the FLIR i7. The FLIR i5 offers a center-spot measurement mode and, for extensive analysis of job sites, the FLIR i7 adds two measurement modes: area (minimum/maximum), and isotherm (above/below).

Orion Fans Develops Low Profile, Stackable DC Fans for Telecom, Appliance Applications
Orion Fans has developed a series of low profile, stackable DC fans. Designated the OD172SAPL series, the stackable, low profile, aluminum DC fans feature two flat sides and measure 172 by 150 by 38 mm.

The OD172SAPL series stackable fans are constructed with a die-cast aluminum frame and a PBT, UL94V-0 plastic impeller. The fans feature a dual ball bearing system and a polarity protected, auto restart, brushless DC motor. The DC fans are also available with tachometer (5 V/TTL) output, locked rotor alarm (5 V/TTL), as well as thermistor, PWM and constant speed controls.

Available in 12, 24 and 48 VDC versions, the OD172SAPL fans feature voltage ranges from 8 to 14, 15 to 28, and 28 to 63, respectively. Airflow ranges from 120 to 225 CFM, with speeds from 2,000 to 4,000 RPM and maximum static pressure from 0.35 to 0.73 H2O. Operating temperature ranges from -20°C to 80°C, and life expectancy is to 60,000 hours.

Marlow Industries Awarded $3.9 Million DARPA Contract for Advanced Thermoelectric Materials and Device Construction
Marlow Industries has been awarded a $3.9 million contract by the Defense Advanced Research Projects Agency (DARPA) for the development of new thermoelectric materials and active cooling modules. The advancements in thermoelectric materials and devices will enable Department of Defense (DOD) thermal management systems to operate at lower temperatures with higher performance and longer lifetime.

The materials in development by Marlow Industries will extend the present state of the art by utilizing a Colloidal Nanocrystal (ICN) synthesis to produce high performance nanocomposite thermoelectric materials. When combined with Marlow Industries’ thermoelectric modeling and device assembly capabilities, the advancement will revolutionize thermoelectric cooling and impact a vast array of commercial and military applications.

The Active Cooling Module program will extend over 24 months culminating in a design to meet or exceed the DARPA program goals. Follow-on contracts are anticipated to apply this technology to specific military applications.  Marlow Industries will lead a team of academic and commercial partners to fulfill the program goals, including: Evident Technologies, the University of Texas at Dallas and the University of Colorado at Boulder.

Oak Ridge National Lab Achieves Unique Design for New Cooling Jacket
The Oak Ridge National Laboratory’s (ORNL) new accelerator-based Spallation Neutron Source (SNS) is a facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development.  When ORNL sought to improve the cooling jacket for the aluminum nitride plasma chamber that produces ions for the SNS, it chose Ensinge,r Inc. extruded TECAPEEK made with Victrex Peek polymer in place of polycarbonate.

The plasma chamber containing the RF-driven multicusp ion source measures about 76 mm in diameter and 178 mm in length. The ions produced are formed into a pulsed beam and accelerated to very high temperatures.

“The plasma puts a nominal 3 kW heat load on the plasma chamber which must be cooled,” said Robert Welton, Ph.D., of SNS.  “The function of the cooling jacket is to cool the plasma chamber by channeling water around it.”

The original cooling jacket was a 2-part design made with a polycarbonate material.  It failed because of cracking and poor tolerances; the application was exceeding what the material could handle. Another contributing factor was the high amount of machining that went into creating the two parts added internal stress. Ensinger, in consultation with their distributor AIN Plastics, a division of ThyssenKrupp, offered ORNL a 1-part design solution using Victrex Peek polymer for the cooling jacket. 

Given the critical nature of the application, Victrex Peek polymer offered a number of essential properties including: low thermal conductivity to prevent the ions from reaching high temperatures, radiation resistance because x-rays are present, chemical resistance to prevent reduction by hydrogen, and electrical properties because of low RF losses.

Nextreme Expands Engineering Consulting Services to Solve Thermal and Power Management Issues
Nextreme Thermal Solutions has announced the expansion of its services offerings to include materials evaluation and characterization services. Equipped with a full range of thermal modeling, design and engineering consulting services, Nextreme's team of engineers can accelerate the development of new applications that are currently thermally constrained.

With recent advances in materials sciences and nanotechnology, new materials are being developed that exhibit thermoelectric properties. The assessment of thermoelectric materials is a challenge, particularly when investigating them over significant temperature ranges. Nextreme has capabilities to conduct measurements across a range of temperatures ranging below 200K to above 700K. Properties that can be measured include Seebeck coefficient, electrical resistivity and thermal conductivity.

In addition to the evaluation of materials, Nextreme offers thermal modeling, design and engineering services to deliver fully optimized thermal management solutions. Nextreme routinely conducts analytical and numerical thermal modeling at all design levels from component to module to subsystem.  Design services range from rudimentary analysis such as 1 dimensional and 3-D modeling to more complex analyses that may involve the use of passive heat rejection systems, such as heat sinks and exchangers, or the use of active devices such as thermoelectric coolers to solve the overall thermal problem. Advanced analysis of complex systems, components or packages often require more detailed modeling to understand heat flow and thermal gradients.

Coolcentric Teams with SynapSense to Provide Data Center Thermal Management and Monitoring
Coolcentric is teaming with SynapSense Corp. to deliver energy monitoring and management to data centers through its Professional Services organization. Coolcentric Professional Services (CPS) provides expertise in the integration, deployment and support of energy efficient thermal solutions for data centers of any size.

Coolcentric’s Environmental Monitoring System (EMS) will feature the SynapSense Data Center Monitoring and Energy Management Solution. EMS provides immediate visibility to critical locations, processes and equipment within the data center or datacom facility. Comprised of sensor nodes, gateways and server platforms, the EMS Solution is based on a broad range of innovative technologies that provide unique advantages to users. Using EMS, data center operators are able to assess current operating conditions in real-time. With enhanced monitoring and alerts, users can identify opportunities for efficiency improvements and mitigate the risk of potential issues.

“SynapSense is the perfect complement to Coolcentric’s LiquiCool solutions, creating a comprehensive solution portfolio to drive energy efficiency and thermal management throughout the data center,” said Joe Capes, Coolcentric general manager. “Coolcentric’s Environmental Monitoring System provides data center managers with a window into the efficiency and increased performance derived from using passive liquid cooling.”

Learn to Push the Limits of Your Designs at Advancements in Thermal Management 2010

Designing consumer and commercial electronics is often a balancing act between high power/output designs and the ability to cool these advanced systems. To help you push the capabilities of your designs, the Advancements in Thermal Management 2010 Conference (Oct. 19th, 2010 • Dallas, Texas) has brought together a group of industry leaders to educate you on the latest thermal management technology. In a relaxed, informative setting you’ll learn about the latest technology to mitigate thermal management design issues and have an opportunity to walk our co-located, multi-conference exhibit hall.

If you are looking to learn more about managing thermal related issues in your power electronics design, this is your must attend event of the year.

Click Here To Learn More About The Conference

October
19-20 Advancements in Thermal Management Symposium 2010, Dallas, Texas
18-20 Electrical Manufacturing & Coil Winding Expo, Grapevine, Texas
19-20 Battery Power 2010, Dallas, Texas
19-20 Remote 2010 Conference & Expo, Dallas, Texas
20-21 Manufacturing Innovations – Aerospace/Defense, Orlando, Fla.

IMAPS 43rd International Symposium on Microelectronics
Raleigh Convention Center, NC
Oct. 31-Nov. 4th, 2010

The 43rd International Symposium on Microelectronics will be held at the Raleigh Convention Center, Research Triangle, North Carolina, , and is sponsored by the International Microelectronics And Packaging Society. IMAPS 2010 will feature technical tracks on 3D Packaging/Interconnect, Design, Reliability, Advanced Packaging and Material. 25 technical this year including sessions on: 3D IC at RTP, 3D Packaging, 3D Systems Integration, 3D TSV Processes, Materials, Ceramics/LTCC, Flip Chip, WL/CSP, LED, MEMS, Modeling & Design, Pb-Free Solder, Printed/3D Structural Electronics, Thermal, Wire Bonding and more. This year's symposium will also offer you 18 professional development courses, a GBC Marketing Forum on Photovoltaics and 3D, and keynote presentations from Dr. John Edmond, co-founder CREE Research, and Dr. Rao Tummala, Georgia Tech.

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