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This paper describes a systematic experimental and numerical study of the thermal characterization of a flip-chip package. A cold-plate based test method is used for thermal characterization and internal thermal resistance is used as the basis of all comparisons. Experiment results are presented for three flip-chip packages. Test parameters such as thermocouple wire, attachment, thickness of interface...
INTRODUCTION Maintaining the integrity of the heat dissipation path for high end microelectronic devices has become increasingly challenging as the industry migrates from ceramic to organic packaging. Typically, flip chip organic packages undergo significant thermal and mechanical stresses throughout the manufacturing process, including chip join, underfill, encapsulation, BGA attach and card join...
A multi-scale modeling approach is proposed and employed to investigate thermal issues and to enable "thermally aware" design of radio-frequency (RF) integrated circuits (ICs). Thermal analysis from full-chip scale down to the single transistor level was made possible with the development of this approach using the finite volume three-dimensional (3D) numerical technique. We have developed...
The packaging industry has devised various die stacking solutions to meet the electronic industry's growing demand for higher memory and functionality. Multiple devices packaged within the same footprint results in higher temperatures which adversely affect thermal performance and reliability. Thermal management and characterization of stacked die packages thus becomes vital. Thermal evaluation of...
To address the thermal management challenges associated with high power dissipation devices, we describe a novel hybrid thermal management device, which enables significant enhancement of conventional air-cooled heat sinks using on- demand and spatially controlled droplet/jet impingement evaporative cooling. The device architecture modifies an air (gas)-cooled heat sink by adding a multiplexed, planar...
With the relentless trend of increasing power and decreasing dimensions, thermal management of electronic packages is becoming a critical issue. Existing cooling techniques are fast becoming inadequate for the powerful electronic components expected in the near future. Researchers all over the world have been experimenting with advanced cooling techniques such as spray and impingement cooling using...
A pressure atomized evaporative spray cooling nozzle array was used to thermally manage the power electronics of a 3 phase inverter module. The module tested was a COTS module manufactured by Semikron, Inc., and has a maximum DC power input of 180 kW (450 VDC and 400 A) with 25degC coolant. However, the standard heat sink that the module uses is a single phase liquid heat sink and when 100degC coolant...
Digitized heat transfer, or DHT, is a new technique for the thermal management of electronic devices where discrete droplets are used in place of continuous flows. This paper investigates the thermal management potential of a DHT system through the numerical solution of the mass, momentum, and energy equations of a simplified droplet travelling between heated parallel plates. The analysis shows much...
In this paper, we compare thermal performances of two-types of heat sinks commonly used in the electronic equipment industry: plate-fin and pin-fin heat sinks. In particular, heat sinks subject to an impinging flow are considered. For comparison of the heat sinks, we suggest a model based on the averaging method for predicting the pressure drop and the thermal resistance. Experimental investigations...
In natural convection applications, the components used for cooling may represent a significant portion of the overall weight of the system. Consequently, advanced materials are of interest in such applications, as they may substantially reduce the total size and the weight of the system. Many of these advanced materials have anisotropic thermo physical properties, hence the control of thermal conductivity...
In high power electronics applications, the most preferred way of thermal management is the use of a heat sink and a fan for active cooling. Though this thermal solution is fairly adequate for the current heat dissipation needs, it suffers from some serious limitations, which may tend to limit its use with time. In the present study, we quantify the limitations of a conventional fan-cooled heat sink...
Thermal performance of a high-power (>1 kW peak) automotive electronics module was evaluated using ANSYS' ICEPAKtrade Computational Fluid Dynamics (CFD) software. The module exchanges heat with cooling air via a plate-finned aluminum heat sink. To confirm the CFD model, the numerical air exit temperature results are compared to that of using the mass flow heat transfer equation. Additionally, convection...
The performance of high power packages is limited in part by the interfacial resistance between the die and lid or heat sinks. The thermal resistance depends on the shape of mating surfaces, bondline thickness (BLT) of the thermal interface material (TIM), bulk thermal conductivity and contact resistance. This paper focuses on warpage modeling methods to predict the local variation of TIMs and its...
In a typical power electronics package, a grease layer forms the interface between the direct bond copper (DBC) layer or a baseplate and the heat sink. This grease layer has the highest thermal resistance of any layer in the package. Reducing the thermal resistance of this thermal interface material (TIM) can help achieve the FreedomCAR program goals of using a glycol water mixture at 105degC or even...
An innovative in-situ electronic package assembly process is presented using the on-chip power to cure the package thermal interface and seal materials and to verify the thermal performance of the electronic package. The in-situ curing process was thermally modeled to demonstrate that the thermal interface and seal materials would reach their required curing temperatures by controlling the chip power...
Integrating microchannels at the thermal interfaces of heat sinks, spreaders, and microprocessor chips can reduce bond line thickness, assembly pressure, and overall thermal resistance. The channels help control the flow of particle-filled thermal interface materials (TIM) during the assembly squeeze but the relationship between channel geometry, material properties, and interfacial area is not fully...
Thermal interface material (TIM) is a major hurdle in heat flow for typical chip/heat sink assemblies. In many electronic devices, hot spots occur in areas of high activity during the device operation. These hot spots can lead to high thermal gradients, which in turn result in performance and reliability hindrances. The elevated, non-uniform power density confronted with conventional TIMs that contain...
Hot spots on thin wafers of IC packages are becoming an important issue in thermal and electrical engineering. To investigate these hot spots, we developed a diode temperature sensor array (DTSA) that consists of an array of 32 times 32 diodes (1,024 diodes) in an 8 mm x 8 mm surface area. We used chemical-mechanical planarization to make DTSA chips with various thicknesses (21.5 mum, 31 mum, 42 mum,...
Microprocessors continue to grow in capabilities, complexity and performance. Microprocessors typically integrate functional components such as logic and level two (L2) cache memory in their architecture. This functional integration of logic and memory results in improved performance of the microprocessor. However, the integration also introduces a layer of complexity in the thermal design and management...
This paper proposes a new effective thermal material simulation model as well as a non-destructive failure analysis for multi-layer substrates with thermal vias to derive exact failure data to supplement existing lifetime models. An effective thermal material simulation model is derived which is validated in simulation and experiment in transient mode. The modelling is done for a test matrix of representative...
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