Maybe its time to make Applied Thermal to work for your important company!

iMac – The Rebirth of Cool. Look Ma, no Fan!
Thanks so much for all your help. We couldn’t have done it without you – Bringing Steve Jobs #1 “amazing feature” to market. Thanks again.

Thank you so much for your help on BDxx as well as so many of our other products. We count on you as a critical member of our product design team. You have consistently and rapidly created thermal design solutions that made our products possible and optimal.

Thanks for helping make Xbox a success. You guys are the coolest. Games will never be the same.

Experimental Projects

Chassis and Board level Thermal Design of Backbone Router

Objectives: To develop chassis and board level thermal architecture for a next-generation telecommunication router.
What was done? Original chassis design was not robust enough to provide cooling for next generation high density boards. Applied Thermal Technologies systematically re-design the chassis to maximize total CFM while reducing acoustic noise and respecting NEBS ambient, altitude, and fan failure requirements. Various fan tray positions and thicknesses were explored. Optimum vent pattern, EMI & filter locations were examined to provide not only uniform slot-to-slot airflow but also uniform front-to-back airflow. After completing chassis thermal design, specific boards were modeled and examined inside the chassis slots. Based on simulated airflow and pre-heating over ASIC chips, memories, optical modules and DC-DC power regulators, proper heat sinks were designed to maintain junction/case temperatures to below their spec limits at worst case NEBS required conditions. Following the design via simulation phase, all heat sink plus mounting mechanism were manufactured by AAVID and shipped for thermal testing. Thermal testing of complete chassis with high density boards was conducted inside environmental chamber and passed all the criteria. System has shipped to the end customer and currently serving the internet traffic.
Accomplishments/Recommendations: Complex chassis and board thermal design entirely via simulation, fan tray optimization, fan failure optimization, aluminum zipper fin heat sink with copper base for select components, heat sink design for SFP and XFP.

Experimental Investigation of Effect of Boundary Layer Rougheners for use in Pin Fin Heat Sinks

Objectives: To experimentally compare the performance of two similar pin fin heat sinks, with the principal difference being that the pins on one were screws of the same diameter.
What was done? The heat sinks were mounted to a heat source with a thermal interface material at the heat sink base. The temperature beneath the base and the ambient were measured, as well as the voltage and current supplied to the power source. The thermal resistance for various airflow rates was measured. In addition, system pressure impedance measurements were made, confirming that both heat sinks give similar pressure loss.
Accomplishments/Recommendations: It was found that both heat sinks gave identical system pressure impedance, but the one with the threads gave slightly lower thermal resistance. The threads roughen up the boundary layer. The ease with which these threaded pin fin heat sinks can be manufactured is promising.

Experimental Evaluation of a Solar Cell Heat Sink Radiator

Objectives: Build test bed to measure solar cell radiator effectiveness in natural convection conditions.
What was done? Solar concentrator heat release emulated by the heater embedded in a copper block, heat sink (radiator) temperatures measured at several locations, for various contact pressures, TIM materials, and angles vs. vertical axis. Infrared measurements conducted using IR computer imaging system.
Accomplishments/Recommendations: Estimated upper temperature limits, demonstrated potential Pitfalls of existing approach, demonstrated sub-optimal efficiency of the heat sink, suggested further improvements to heat sink design.

Experimental Evaluation of the Liquid and Evaporation Cooling Heat Sinks for Advanced Computer Chips

Objectives: Use wind tunnel to measure thermal resistance R of next generation liquid cooling and evaporative heat sinks, compare hardware from various suppliers, conduct extensive test matrix, run reliability testing.
What was done? Build test bed that includes heaters embodied into the copper block to simulate computer chip heat release. Enable and maintain liquid cooling pump, and also evaporator pump operation. Vary pump voltage to compare system efficiencies. Connect installation to the wind tunnel, enable data acquisition system. Measure heat sink inlet and outlet temperature at given operating CFM and push/pull flow conditions. Measure junction temperature, estimate thermal resistance.
Accomplishments/Recommendations: Experimental testing allowed pinpointing weak elements in the existing designs, which were subsequently improved by the suppliers. Considerable improvement in thermal resistance was achieved due to several proposed improvements.

Experimental Evaluation of a Data Storage Device

Objectives: Evaluate Airflow Distribution, Airflow temperature, Board and Hard Drive Temperature in the Next Generation Data Storage Devices at various U-Scales.
What was done? Simultaneous air flow measurement was conducted using 20 thermal anemometry probes. Air flows in all critical sections, approach velocities near heat sinks, leakage flows, hard drive cooling flows were characterized. Temperature gain in every key section was established, heat sink temperatures were measured, heat sinks were machined to measure junction temperatures. Hard drives temperatures were measured in 24 locations, board temperatures were measured in 16 locations. System was disassembled, instrumented with sensors, re-assembled and connected to three data acquisition sub-systems for simultaneous measurements.
Accomplishments/Recommendations: Two prototypes of various U-scales were evaluated, existing designs were validated, pointed ways to reduce number of operating fans (reduce electrical consumption, noise), located overheated area, suggested heat sinks to significantly reduce overheating, found optimal composition of various operating parameters to improve flow balance between the power supply, hard drives and main board. Detected hard drive cooling flow non-uniformity, proposed simple ways to alleviate this.

Development of a Compact Wind Tunnel for Heat Sink Thermal Evaluation

Objectives: Build desktop size wind tunnel to major OEM to evaluate various heat sink designs in the lab.
What was done? Prototype was designed by our engineers, metering orifices, pressure sensors, variable flow blower, flow straightners, adjustable experimental test section. All sized to customer requirements, pars were ordered and machined. Documentation package was developed, experimental procedures for system impedance tests and for CFM tests were documented for customer use.
Accomplishments/Recommendations: Installation was assembled, tested in house, disassembled and delivered to the customer site, successfully reassembled at the customer site.

Computer-Assisted Thermal Analyses Projects Thermal Design of a Medical Devices Server using a Combination of Experimental and Computational Methods

Objectives: To develop thermal architecture for a next-generation medical devices server including heat sink selection, baffle design, and power supply unit isolation.
What was done? Preliminary tests indicated that the originally selected heat sinks were not sufficient for the power dissipation. Tests were conducted in the lab to obtain estimates of airflow distribution in the module as well as temperatures so that better heat sinks could be selected. The system CFM was measured with the left and right sides isolated to better understand the flow distribution. The effect of introducing a side vent was investigated. The side vent was found to provide significant cooling and was one of the major design changes. The length of the vent was optimized: if the vent were too short, it did not provide enough exhaust whereas if the vent were too long, there was not enough flow through the back of the boards. In addition, the original bezel upstream of the fans introduced significant pressure impedance and an alternative design was recommended. CFD work indicated that the design would be sufficient to remove the additional heat dissipated in a next-generation design.
Accomplishments/Recommendations: Heat sinks were selected for all components, including a custom heat sink design for the processor dissipating 50 W. A side and bottom vent was included. The power supply units were not isolated from the rest of the system.

Evaluation of Data Center Room Layout – Hot Spot Elimination

Objectives: Provided help in designing data center with the proper flow distribution.
What was done? Applied has conducted 3D CFD simulation to predict airflow and temperature distribution in a modern datacenter, comprising of hundreds of racks. Modeling will take into account all inflow and outflow paths, the type of server mounted on the racks, non-uniform loading of the cabinets across the room, layout of the cabinet and AC units as well as other room details like floor grate opening, floor and ceiling elevation.
Accomplishments/Recommendations: CFD simulation can help in room layout improvement, ducting size for cold air supply, selecting elevations and openings of floor and ceiling and locations of AC units.

Thermal Design of High Definition Digital video receiver (DVR)

Objectives: To provide thermal design for specific HD DVR consumer electronics
What was done? High Definition DVR units are part of entertainment center for most American households. Applied Thermal Technologies has designed cooling mechanism for HD DVR unit with built in DVD player. Due to noise restrictions, main goal was to provide cooling with single exhaust fan running at low rpm while being to cool the unit at worst summer ambient of 40 °C. Several design via simulation iterations were conducted to optimize inlet vents to direct flow underneath the HD, DVD player and over the main board and ASIC. Special heat sinks were designed for HDD and DVD which did not rely on conduction cooling through the chassis itself
Accomplishments/Recommendations: unique vent pattern to optimize flow for HD DVD and board components, unique heat sink designs, low acoustic thermal solution.

Characterization of a DIMM Module

Objectives: 1. Characterize individual components on DIMM module and study board under various conditions using simplified package models.
What was done? A detailed chip-level analysis was performed for various components to determine simplifying resistor network node values. These resistor network models were included in the board-level model and the DIMM was characterized in a variety of environments.
Accomplishments/Recommendations: The customer gained a deeper understanding of the DIMM module operating under various conditions which they could not accurately control in their lab (i.e. power dissipation of the various components). The results showed good agreement with experimental data. The computer simulation results eventually led to the design of a heat spreader for the module.

Thermal Design of High End Internet Router

Objectives: Maximize total airflow and minimize air recirculation, improve flow distribution uniformity; IC junction temperatures below 100 deg. C. What was done: Experimental evaluation of existing design using wind tunnel. System-level computational model was created to investigate air-flow distribution and air temperature. Board level model was developed to investigate package temperature.
Accomplishments/Recommendations: Existing design exceeds thermal specification; air temperature exceeds 80 deg. C. New design changes were recommended, new vents added to increase airflow. New designs were verified to meet thermal specification, no heat sinks were necessary.

Board-level Design of a 1U Network Server

Objectives: To provide a board-level solution for a dense 1U network server.
What was done? Rough calculations indicated the required airflow rate through the system to provide an acceptable average air temperature rise. Commercial heat sinks were selected for most of the components. A side vent was introduced near the daughter cards which were mounted in a dead zone and the fans were operated in pull configuration to draw air through this region. Independent power supply unit baffling was recommended so that the power supply units did not draw air from the system.
Accomplishments/Recommendations: All thermal targets were met with no component junction temperature reaching more than 80% the recommended values (to minimize power leakage losses). No custom heat sinks were required thus significantly lowering the cost below the budget.

Board-level Design of a Free Convection-cooled Flat-screen Monitor Used in Avionics Applications

Objectives: To develop thermal architecture for a flat screen monitor use in avionics applications so that the component case temperatures did not exceed 90 deg. C with a safe touch temperature for the casing (35 deg. C) and the glass (25 deg. C).
What was done? Various designs were considered. Air was entrained into the monitor through a bottom vent and then exhausted through a top vent by natural convection. The total power dissipation was approximately 45 W. A common heat sink was shown to be sufficient but costly. A better solution involved individually heat sinking the components to the back plane of the metal chassis. Thermal grease was placed at the interface of the Aluminum blocks and the back plane and thermal interface materials were selected to satisfy the constraints.
Accomplishments/Recommendations: A design was reached which the client was able to manufacture within tolerance and at low cost. Additional investigations were performed which looked into the behavior of the monitor in various stow positions (arm-rest and seat-back) since the monitors were to be used in airplane environments.

Experimental Characterization of Game Console Heat Sink and Phase-change Thermal Interface Material for System Impedance and Thermal Resistance for Various Loads

Objectives: To experimentally characterize the GPU and CPU heat sinks for the console for system pressure impedance and thermal resistance under typical operating conditions under different loads with two different die sizes.
What was done? Two copper dies were machined and mounted on a heat source controlled with a power supply. Because the die is smaller than the base, the sides are insulated so that all heat leaving the source was passed to the heat sink. Thermocouples were mounted inside the Copper die as well as the base of the heat sink. A phase change thermal interface material was applied at the interface of the die and heat sink base. The load was applied and the system pressure loss and thermal resistance for typical operating conditions (airflow rate and power dissipation) were measured and calculated. The thermal resistance of the phase change material with applied pressure was measured.
Accomplishments/Recommendations: The behavior of the thermal interface material under load was characterized so that a nominal pressure of application could be determined and confirmed with customer’s expectations. The results of the heat sink characterization could be used by customer to build simplified macro models and gave the group a deeper understanding of the thermal performance of their next-generation system.

System-level design of a Holograph Tile

Objectives: To optimize the system-level design of a holograph tile including fan selection, inlet dimensions, and LED cooling.
What was done? The holograph tile was mounted in a plenum through which the air delivered to the system was pulled. The inlet dimensions were optimized so that there was no re-circulation in the upper boards.
Accomplishments/Recommendations: Mid-plane openings were recommended to minimize the pressure drop in the system. The recirculation in the upper boards was eliminated. A base plate was included in the LEDs to provide thermal contact to the bottom of the module since the upper portion of the module was isolated from air flow. The performance of the tile in a matrix array is an ongoing project.

Thermal Design of All-in-one Desktop PC

Objectives: Thermal design using single or no fan. Less than 15 deg. C overall air temperature rise. CPU junction temperature less than 85 deg. C. Requirement to minimize acoustic noise.
What was done? Created system level computational model. Created subsystem level models to investigate CPU and power supply. Experimental verification using a mockup.
Accomplishments/Recommendations: Single fan thermal design, appropriate fan was selected. We developed extensive air baffling to prevent re-circulation and to direct air to all critical areas. All critical components have met specification including CPU and power supply.

Detailed Package Level Thermal Analysis

Objectives: Create detailed package model that can include power map on the die, and multiple die cases.
What was done? Applied has experience in detail package level simulation for any package type, with ICEPAK CFD tool. Client’s .mcm file can be imported to this tool and detail package model can be created, which can include power map on the die, and multiple die cases.
What was done? Thermal study can help in understanding the heat flow path in and out of the package. JEDEC level analyses for the package were conducted for two resistor model as well as junction-to-air impedance variation at different ambient condition. We can also extract Delphi model from the detail package model.
Accomplishments/Recommendations: Apart from predicting impedance for the package, this detail analysis can help in identifying hot spots on the die.

Evaluation of Several Notebook Computer Designs

Objectives: Each notebook computer design can require a different thermal solution. The temperature of the chassis must be managed so that the end user doesn’t get burned. A skin temperature of 45°C is a common design goal. That’s only 5 degrees above the maximum external air temperature of 40°C.
What was done? Icepak models were built using CAD layouts for three proposed configurations. Each notebook component was modeled using information about power dissipation and physical geometry. Once the entire model is created, a simulation is run to determine problem areas that are too hot. Once that’s done, a thermal solution can be designed to solve the problem. By changing the model to incorporate the thermal solution, a new simulation can indicate if the approach works. Several what-if scenarios took into account different periphery placement and thermal management techniques; preliminary testing correlated well with thermal modeling, with accuracy between 80% and 95%.
Accomplishments/Recommendations: The thermal solution was a heat-pipe assembly to remove the heat from the CPU and transfer it to an extruded heat sink located in front of a system fan. Initial thermal plot analysis showed a critical temperature on the hard-disk drive. Even though the CPU is cool, the disk drive is around 120°C—well over the recommended limit. It became apparent that no air reaches the drive. Based on these results, the thermal solution was modified to include a plate that extends over the drive, reducing the temperature. In our second notebook design we had an additional graphics chipset, a PCI chipset, a floppy drive, a PCMCIA controller, and an audio driver.

The critical temperature reached 70°C at the CPU, audio driver, and PCMCIA controller. Since these components are located close to each other, an initial idea was to use a fan heat sink located on the CPU. The vent locations were well suited to permit air to cool the CPU and the adjacent audio driver. In the thermal analysis of the system using the fan heat sink, the area away from heat sink ran 30°C hotter than the side with the fan heat sink. Even though this approach meat the specification, it showed how a fan heat sink only managed a localized area inside this notebook. A heat pipe with a plate attached to the fan heat sink can be used to spread the heat throughout the system.

The third notebook design represented the typical computer with a total system power of 30 W, with 15 W being dissipated from the CPU.

Once system-level power increases above 25 W, the internal temperature rise can be greater than 10°C.

This jeopardizes the ability to cool the system using internal system fans and heat pipes, as recirculation air tends to heat up the entire system. With this much power, a new concept in cooling was needed to manage temperature rise. The approach was to use a separate air duct, fan, and extruded heat sink. Using heat pipes and an aluminum plate, the entire system’s power can be moved to the extruded heat sink. Rejected air is removed from the notebook without heating the rest of the system. Looking at a temperature distribution of the plate the maximum temperature difference was within 5°C