Wafer Level Integration of 3-D Heat Sinks in Power ICs

13th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, 2012

High power packages require a low junction-to-case thermal resistance (Theta jc) to achieve target junction temperatures. Theta jc is a metric used to compare package-to-package relative thermal performance. It is also used in two-resistor models to predict thermal performance under system level conditions. This study shows that the commonly used Theta jc definition does not correctly track package junction temperatures in actual end-use applications nor does it serve as a reliable metric for comparing package-to-package performance. When spreading resistance in the lid is taken into account, the modified Theta jc definition overcomes some of the shortfalls found with the standard Theta jc calculation. Lastly, a simplified thermal interface resistance model is presented as a more accurate alternative to the one resistor Theta jc and the multi-resistor Delphi models.

Microelectronics Reliability, 2012

Chip scale package (CSP) technology offers promising solutions to package power device due to its relatively good thermal performance among other factors. Solder thermal interface materials (STIMs) are often employed at the die bond layer of a chip-scale packaged power device to enhance heat transfer from the chip to the heat spreader. Nonetheless, the presence of voids in the solder die-attach layer impedes heat flow and could lead to an increase in the peak temperature of the chip. Such voids which form easily in the solder joint during reflow soldering process at manufacturing stage are primarily occasioned by out-gassing phenomenon and defective metallisation. Apparently, the thermal consequences of voids have been extensively studied, but not much information exist on precise effects of different patterns of solder die-attach voids on the thermal performance of chip-level packaged power device. In this study, three-dimensional finite element analysis (FEA) is employed to investigate such effects. Numerical studies were carried out to characterise the thermal impacts of various voids configurations, voids depth and voids location on package thermal resistance and chip junction temperature. The results show that for equivalent voiding percentage, thermal resistance increases more for large coalesced void type in comparison to the small distributed voids configuration. In addition, the study suggests that void extending through the entire thickness of solder layer and voids formed very close to the heat generating area of the chip can significantly increase package thermal resistance and chip junction temperature. The findings of this study indicate that void configurations, void depth and void location are vital parameters in evaluating the thermal effects of voids.

International Journal of Engineering & Technology

This paper presents the simulation of heat sink by using Workbench 18.0 Software to simulate the temperature distribution at different chip power input. 3D model of heat sink is generated using Design Modeler using the same dimension with experimental setup. The study was made for a heat sink mounted on the power source (Chip) under different types of chip powers. The results are presented in terms of temperature distribution when chip powers have been increased from 1 W to 10 W. The temperature distribution is been observed and it was found that the temperature distribution of the heat sink has lower temperature when power source at 1 W and increase significantly when the power source rise up to 10 W. The increase the temperature of heat sink is from 30.8ºC up to 96.2ºC estimated to be 212% the increase of temperature. The simulation also been verify by using different time step use during the simulation and using grid independency test to ensure the simulation result is accurate.

Thermal management materials used for heat sink in laptop computers is reviewed in this paper. In laptop computers, heat sink plays a vital role of dissipating heat from the system. Heat sink is a vital component in a laptop computer because it dissipates the heat generated by the system. The overall efficiency, cost, and size of the system could be influenced by the heat sink device. Four selection criteria; thermal conductivity, coefficient of thermal expansion, density, and cost were abducted for selecting a laptop computer heat sink material in this paper. An ideal heat sink material exhibits high thermal conductivity, low coefficient of thermal expansion, low density, and low cost. Aluminium and copper are mainly used for laptop computer heat sinks. Aluminium is used where weight reduction is needed while copper is used when weight is not considered as a major factor. However, the high demand for materials with low coefficient of thermal expansion and high thermal conductivity is due to the use of ceramic materials for substrates. Aluminium and copper fall short of the required coefficient of thermal expansion hence the need for advance composite materials. Based on the four selection criteria for a laptop computer heat sink material, AI/SiC has superior property potentials and is recommended as a near optimum material for this purpose.

InterSociety Conference on Thermal Phenomena in Electronic Systems

This paper investigates analytical and experimental methodologies for studying silicon device degradation under electro-thermal stress. The experimental data supports the assumption that the thermally induced stress due to power cycling and.power surges is a major cause of device degradation. The analytical models point out the large impact that low thermal diffusivity layers (solder or epoxy), located near the heat source (the thermal junction), have in the acceleration of fatigue phenomena. Crack initiation and propagation in die attach layers due to stress/ strain cycles is shown to be one of the leading factors in degradation of power cycled devices. HOT VOIDS (DIE-ATTACH) THERMAL RESISTANCE RISE WlRE BONDCORROSlON WIRE BOND FATIGUE The study concludes that correct design or selection of the silicon device interconnect can increase device reliability and allow the device to operate at temperatures up to 125 deg C, without increasing the field failure rate. The data in this study was accumulated during the investigation of failure mechanisms of solid state protection devices. The nature of the degradation mechanism we found lead us to believe our conclusions can be extrapolated to the degradation mechanism of common logic devices (Bipolar or MOS). More studies are planed in order to quantify the extent of these phenomena for different types of device packaging.

Power electronic modules serve a critical role in today's world which relies on power electronics so heavily. Many aspects of daily life, the economy, and society revolve around reliable electric power delivery and management, so there is good incentive to improve system reliability and performance. In this paper, some of the research of different packaging technologies is reviewed to show improved reliability and performance primarily in terms of thermal management. With the maturing of semiconductor device research for wide bandgap semiconductors like Silicon Carbide (SiC) and Gallium Nitride (GaN) that can operate at higher voltages, currents, switching speed, and temperature, it is apparent that device operating potential is much less a limitation for power electronics as compared to the limits of packaging. Dissipating the high-power outputs of the devices while also maintaining mechanical integrity to continue being able to operate and protect the devices is now the main engineering challenge. The specific technologies reviewed include comparison of die attach options such as wire bonding with solder bumping interconnects and embedded packaging. As well there is review of double-sided cooling advancements along with micro-channel heat sinks. What was found is that wire bondless options reduce thermal resistance, electrical resistance, and parasitic inductance and have improved reliability. Double sided cooling which is available for certain packaging can greatly reduce thermal resistance and use of forced flow water convection through microchannel heat sinks can lead to high heat transfer coefficients for the system, especially if also using double sided cooling.

Volume 10: Micro- and Nano-Systems Engineering and Packaging, 2015

The continual increase of device power and package integration levels has driven the development of advanced power electronics packaging solutions. This study will focus on a numerical modeling approach to design analysis and material selection to improve solder joint reliability in one of these advanced solutions — a thermally integrated power electronics package that aims to dissipate hot-spot heat flux (5 kW/cm2) via mini-contact based thermo-electric (TE) cooling in addition to removing background heat flux (1 kW/cm2) by manifold-microchannel cooling. The methodology used for performing the structural reliability modeling is a non-linear finite element analysis (FEA) approach. Combined thermal and mechanical analyses were run to obtain stresses and strains in the solder joint used to integrate the TE cooler with the mini-contact and the mini-contact with the Silicon Carbide (SiC) chip. To predict the Mean Time to Failure (MTTF) of SAC305 at various levels of integration, a Physi...

IEEE Transactions on Components and Packaging Technologies, 2002

This paper presents a thermal modeling for power management of a new three-dimensional (3-D) thinned dies stacking process. Besides the high concentration of power dissipating sources, which is the direct consequence of the very interesting integration efficiency increase, this new ultra-compact packaging technology can suffer of the poor thermal conductivity (about 700 times smaller than silicon one) of the benzocyclobutene (BCB) used as both adhesive and planarization layers in each level of the stack. Thermal simulation was conducted using three-dimensional (3-D) FEM tool to analyze the specific behaviors in such stacked structure and to optimize the design rules. This study first describes the heat transfer limitation through the vertical path by examining particularly the case of the high dissipating sources under small area. First results of characterization in transient regime by means of dedicated test device mounted in single level structure are presented. For the design optimization, the thermal draining capabilities of a copper grid or full copper plate embedded in the intermediate layer of stacked structure are evaluated as a function of the technological parameters and the physical properties. It is shown an interest for the transverse heat extraction under the buffer devices dissipating most the power and generally localized in the peripheral zone, and for the temperature uniformization, by heat spreading mechanism, in the localized regions where the attachment of the thin die is altered. Finally, all conclusions of this analysis are used for the quantitative projections of the thermal performance of a first demonstrator based on a three-levels stacking structure for space application.

Thermal issues have become a major consideration in the design and development of electronic components. In power electronics, thermal limitations have been identified as a barrier to future developments such as three-dimensional integration. This paper proposes internal embedded cooling of high-density integrated power electronic modules that consist of materials with low thermal conductivity and evaluates it in terms of dimensional, material property, and thermal interfacial resistance ranges. Enhanced component conductivity was identified as a possible economically viable internal cooling option. Thermal performance calculations were performed numerically for conductive cooling of internal component/module regions via parallel-running embedded solids. Thermal advantage per volume usage by the embedded solids was furthermore optimized in terms of a wide range of geometric, material, and thermal parameters. In the dimensional and material property range commonly found in passive power electronic modules, parallel-running cooling layers were identified as an efficient cooling configuration. Numerically based thermal performance models were subsequently developed for parallel-running cooling inserts. A multifunctional experimental setup was constructed to study the cooling of ferrite (operated as a magnetic core) by means of embedded aluminium nitride layers and to verify the thermal model. Results corresponded well with theoretically anticipated performance increases. However, interfacial thermal resistance constituted a major limitation to the cooling performance and future power density increases. With the thermal model developed, functional optimization in terms of magnetic flux density for parallel-running cooling layer configurations was performed for a wide range of material and geometric conditions.

UNICROSS JOURNAL OF SCIENCE AND TECHNOLOGY, UJOST, 2024

Most electronic components whose duties are attracted to maximum power efficiency required of a system to dissipate internal heat out of such components. MOSFETs, CMOS and special Processors, whose applications geared towards high voltages must have a system to effectively dissipate heat for maximum performance. Components with embedded heat sink have advantage and function effectively, the fact remain that the heat sink material is that which can dissipates heat during conduction of heat from the component. This paper considered various heat sink materials for proper heat transfer, radiation and dissipation. Aluminum, Copper, tungsten and Zinc were evaluated having various thermal conductivity and dissipation, and briefly heat-sink materials characteristics: weight, conductivity and quick thermal dissipation of heat from the heatsink materials were discussed. And was observed that Aluminum heat sink material was more preferable during our evaluation and it was observed that the material is best for our modern day's high thermal components. Aluminum heat sink materials have a nomenclature of quick heat transfer, lighter in weight, Aluminum material is stability since thermal condition increases during high performance of the equipment, though some materials from the analysis have high conductivity but their weight and their radiation efficiency can affect the components which is firmly attached to it, considering new innovation in technology is revolving toward miniaturization of component sizes.