| 1. |
- Anton Remirez, Raul, et al.
(författare)
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Compact CFD modeling of EMC screen for radio base stations : A porous media approach and a correlation for the directional loss coefficients
- 2007
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Ingår i: IEEE transactions on components and packaging technologies (Print). - : IEEE Press. - 1521-3331 .- 1557-9972. ; 30:4, s. 875-885
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Tidskriftsartikel (refereegranskat)abstract
- A methodology to obtain the directional pressure loss coefficients in a porous media model of an electromagnetically compatible screen of a radio base station model is presented. The directional loss coefficients of this compact model are validated against a detailed computational fluid dynamics model not only by comparing the total pressure drop, but also by evaluating the flow pattern after the screen. The detailed model was validated in an earlier article by the authors. A parametric study is conducted for 174 cases. Seven parameters were investigated: velocity, inlet height, screen porosity, printed circuit board (PCB) thickness, inlet-screen gap, distance between two PCBs and screen thickness. Based on the compact model parametric study, two correlations for the directional loss coefficients are developed as a function of the Reynolds number and the above geometrical parameters. The average disagreement between the compact model that uses the directional loss coefficients from the correlations and the detailed model was of 3% for the prediction of the total pressure drop and less than 6.5% and 9.5% for two coefficients that accurately characterize the flow pattern. © 2007 IEEE.
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| 2. |
- Anton Remirez, Raul, et al.
(författare)
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Detailed CFD modelling of EMC screen for radio base stations : a parametric study
- 2009
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 32:1, s. 145-155
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to make a parametric study of the hydraulic resistance and flow pattern of the flow after an electromagnetic compatibility screen and between two printed circuit boards (PCBs) in a model of a 90° subrack cooling architecture. The parametric study is carried out using a detailed 3-D model of a PCB slot. The detailed model was experimentally validated in a previous paper by the authors. Seven parameters were investigated: velocity, inlet height, screen porosity, PCB thickness, distance between two PCBs, inlet-screen gap and screen thickness. A correlation for the static anddynamic pressure drop, the percentage of dimensionless wetted area, Aw*, and the RMS* factor (a function of the flow uniformity along the PCB) after the screen is reported as a function of six geometrical dimensionless parameters and the Reynolds number. The correlations, that are based on 174 three dimensional simulations, yield good results for the total pressure drop, in which the values are predicted within the interval of ±15%. For the, Aw* all the predicted values are within the interval of ±22% of the observed values. Finally, for the RMS* factor, the majority of the values also have a disagreement of less than 20% of the observed values. These last two parameters are believed to provide a correct insight about the flow pattern after the screen.
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| 3. |
- Anton Remirez, Raul, et al.
(författare)
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Detailed CFD modelling of EMC screen for radio base stations : a benchmark study
- 2007
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 30:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to investigate the performance of five well-known turbulence models, in order to find a model that predicts the details of the flow patterns through an electromagnetic compatibility (EMC) screen. The turbulence models investigated in the present study are five different eddy-viscosity models; the standard k-ε model, the renormalization group (RNG) k-ε model, the realizable k-ε model, the standard k-ω model, as well as the shear stress transport k-ω model. A steady-state 3-D detailed model, which serves as the most accurate representation of the model, was used in order to evaluate the details of the airflow paths and pressure field. The flow was assumed to be isothermal, turbulent and incompressible. A general model that covers a considerable range of velocities and geometries was validated experimentally by wind tunnel measurements. The result shows that for most of the k-ε models used with correct y+ and mesh strategy, the pressure drop and the velocity field deviation is small compared to experimental data. The k-ω models overpredict the overall pressure drop. When using the RNG k-ε model, the total static pressure drop predicted differs around 5%-10% and the average velocity deviation at several locations before and after the screen is around 5%.
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| 4. |
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| 5. |
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| 6. |
- Dejanovic, Slavko, et al.
(författare)
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Metal Covered Elastic Micro-Bump Contacts as an Alternative to Commercial Elastic Interconnection Techniques
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this work, a novel chip-to-board interconnection structure have been manufactured, and some of its characteristics have been investigated. This chip connection technique can for instance serve as a FCOB (Flip Chip on Board) technique, for connecting test equipments during testing bare chip on wafer, and with some more development, in three dimensional multi chip modules. A setup of elastic micro-bumps was cast, metal covered, patterned, and electro-mechanically characterized. The metal-covered silicon elastomer contact-structures were manufactured on FR-4 carrier-plates. Visual inspection of the micro-bumps was conducted in a SEM (Scanning Electron Microscope). The electro-mechanical properties were measured by simultaneous use of a DMA (Dynamic Mechanical Analyzer) and a Kelvin Bridge structure for resistance measurement. The measurements gave the micro-bump to chip resistance behavior as a function of the micro-bump deflection distance and applied mechanical force when direct current was applied. The results obtained from the measurements have revealed that such a technique requires less than one tenth of the mechanical contact force for achieving the contact resistance of the same magnitude as for commercial elastic interconnection techniques. This would be of significant advantage because the amount of electrical contacts per unit of area has tendency of continued growth.
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| 7. |
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| 8. |
- Eriksson, P., et al.
(författare)
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Design of accelerated corrosion tests for electronic components in automotive applications
- 2001
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Ingår i: IEEE transactions on components and packaging technologies (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1521-3331 .- 1557-9972. ; 24:1, s. 99-107
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Tidskriftsartikel (refereegranskat)abstract
- Two new accelerated laboratory corrosion tests for electronic components in automotive applications have been developed, based on the use of metallic copper as a meter for corrosivity. The accelerated tests are designed so that they reproduce the same kind of corrosion effects as observed with exposure of copper in real vehicle environments. The test cycle that best simulates the corrosion characteristics of an engine compartment is composed of the following steps: a) exposure to neutral salt spray for 2 h; b) drying at 23 degreesC and 50% RH for 22 h; c) exposure to a test atmosphere of 1.5 ppm NO2 and 0.5 ppm SO2 at 25 degreesC and 95% RH for five days; d) drying at 23 degreesC and 50% RH for one day. The predominating corrosion products of copper, formed both during service exposure and in the accelerated test, are Cu2O and Cu2Cl(OH)(3), with a small amount of sulphur-containing corrosion products in the form of sulphates, In terms of corrosivity of copper, a test duration of six weeks corresponds to 7.5 years of exposure in the reference engine compartment selected for this study. The test cycle designed for the passenger compartment contains the steps: a) exposure for five days to a test atmosphere of 10 ppm NO2 and 95% RH at 35 degreesC, followed by b) drying at 23 degreesC and 50% RH for two days. In this case, Cu2O is the predominating corrosion product. Zn terms of corrosivity of copper, a test duration of four weeks corresponds to 7.5 years of exposure in the reference passenger compartment of this study.
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| 9. |
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| 10. |
- Jonsson, Hans, et al.
(författare)
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Modeling of the thermal and hydraulic performance of plate fin, strip fin, and pin fin heat sinks : Influence of flow bypass
- 2001
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Ingår i: IEEE transactions on components and packaging technologies (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1521-3331 .- 1557-9972. ; 24:2, s. 142-149
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Tidskriftsartikel (refereegranskat)abstract
- Tests have been conducted in a wind tunnel with seven types of heat sinks including plate fin, strip fin, and pin fin heat sinks. In the case of strip fin, and pin fin heat sinks, both in-line and staggered arrays have been studied. The pin fin heat sinks had circular and square cross-sections, For each type, tests were run with fin heights (H) of 10, 15, and 20 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. In total, 42 different heat sinks were tested, The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB = 0.84, 0.53, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH = 1, 0.67, and 0.33 while the duct Reynolds number was varied between 2 000 through 16 500. An empirical bypass correlation has been developed for the different fin designs. The correlation predicts the Nusselt number and the dimensionless pressure drop and takes into account the influence of duct height, duct width, fin height, fin thickness, and fin-to-fin distance. The correlation parameters are individual for each fin design. Further, a physical bypass model for plate fin heat sinks has been developed to describe the bypass effect.
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| 11. |
- Jonsson, Hans, et al.
(författare)
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Thermal and hydraulic behavior of plate fin and strip fin heat sinks under varying bypass conditions
- 2000
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Ingår i: IEEE transactions on components and packaging technologies (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1521-3331 .- 1557-9972. ; 23:1, s. 47-54
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Tidskriftsartikel (refereegranskat)abstract
- Tests have been conducted in a wind tunnel with nine heat sinks of three different types including plate fin heat sinks and strip fin heat sinks arranged in both inline and staggered arrays. For each type, tests were run with fin heights (H) of 10, 15, and 20 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB = 0.84, 0.53, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH = 1, 0.67, and 0.33 while the duct Reynolds number was varied between 2000 through 14000. An empirical bypass correlation has been fitted to the experimental data. Generally, the agreement between experimental data and correlation is within +/-10% for the thermal resistance, and within +/-20% for the pressure drop. From the experimental data, the fraction of the total airflow passing through the heat sink have been estimated and are compared to a simple physical bypass model.
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| 12. |
- Kratz, Henrik, 1974-, et al.
(författare)
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Analysis of Thermal Transients in an Asymmetric Silicon-Based Heat Dissipation Stage
- 2007
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Ingår i: IEEE transactions on components and packaging technologies (Print). - : Institute of Electrical and Electronics Engineers (IEEE). - 1521-3331 .- 1557-9972. ; 30:3, s. 444-456
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Tidskriftsartikel (refereegranskat)abstract
- Thermal management is crucial for many microsystems and electronics applications (and that of miniaturized spacecraft is particularly demanding). This paper presents thermal modeling and scaling of a generic multiwafer silicon segment for placement in between two devices, or as a stage for a single one, in need of asymmetric thermal management. The unit is autonomous, i.e., it doesn't require any input signals or power. It comprises paraffin acting both as a heat sink, or thermal storage, and a material activating heat switches. The former mitigates heat bursts and accommodates power initially generated in, e.g., attached electronics, whereas the latter facilitates heat dissipation through heat guides during more intensive operation. Its function and physical properties are described in detail. A lumped thermal model has been constructed and implemented in the Simulink environment to investigate effects from: physical scaling of the unit, and change of its boundary temperature and coupling thereto, power generated, its emission and absorption properties and area fractions dedicated for passive devices, infrared (IR) emission, and heat guides on the unit's exterior, as well as fractional cross sections of paraffin, heat guides and other structural material in its interior. Conclusions, based on simulation results, are made and design rules based on the thermal modeling are presented. It was found that a 68 × 68 mm module could handle more than 10 W for 6 min in its heat sink mode alone. Subjected to 15 W for the same time, the module enters its active dissipation mode by closing its heat switches. A lateral increase and simultaneous vertical decrease of the unit's size resulted in overheating, whereas most scaling did not cause depletion of the heat sink. Changing the area fractions of various constituents also indicated operational stability with exception for excessive enlargement of passive heat guide material, exchanging structural material with paraffin, or severely limiting IR emission (by emitter area reduction or using low emission material), or using high absorbance material. Altering the boundary temperature and interface conductance proved to be means of biasing the system to various operating temperatures.
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| 13. |
- Mbairi, Felix D., et al.
(författare)
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Microwave bandstop filters using novel artificial periodic substrate electromagnetic band gap structures
- 2009
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 32:2, s. 273-282
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Tidskriftsartikel (refereegranskat)abstract
- Novel microwave and millimeterwave (mm-wave) bandstop filters using artificial periodic substrate electromagnetic bandgap (EBG) are investigated in this paper. Three types of microstrip structures using periodically modified trace width, patterned dielectric substrate, and periodically modified ground plane are treated, respectively. By periodically modifying either the width of the conductor trace, the substrate height, or the dielectric constant of a standard microstrip transmission line, it has been possible to design microwave bandstop filter functions with wide stopband characteristics and reduced size, compared to conventional microwave/RF filter structures. Commercial electronic design automation (EDA) and computational electromagnetic tools such as Agilent's advanced design system (ADS) and CST Microwave Studio are used in the design and simulations of these filter structures. The effects of the physical parameters of the structures on the filter characteristic are studied. The design procedure and simulation results are described and possible applications of these filter structures are discussed in this paper. A particularly wide stopband is achieved by the circuits presented in this paper, which use only a few cell elements. A significant performance improvement of microstrip patch antenna has been observed by implementing one of the presented EBG periodic substrate structures.
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| 14. |
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| 15. |
- Mbairi, Felix, et al.
(författare)
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High frequency transmission lines crosstalk reduction using spacing rules
- 2008
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Ingår i: IEEE transactions on components and packaging technologies. - : IEEE conference proceedings. - 1521-3331 .- 1557-9972. ; 31:3, s. 601-610
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Tidskriftsartikel (refereegranskat)abstract
- High-frequency transmission lines crosstalk reduction using spacing rules is treated in this paper. Two of the most popular planar transmission line configurations, namely microstrip and stripline, commonly used in printed circuit boards and radio frequency/microwave integrated circuits, are considered in this work. The trace separation between two adjacent transmission lines of each type is stepwise increased as function of the trace width. The single-ended transmission line structures are numerically investigated by a frequency-based 3-D full-wave electromagnetic analysis tool. A particular case using coated microstrip transmission lines has been fabricated, along with some calibration structures, to allow direct measurement and experimental analysis of crosstalk between the single-ended transmission lines. The test structures are characterized at high-frequency (up to 20 GHz) with scattering parameters using a vector network analyzer. The experimental results are compared with the simulation data, and some conclusions and suggestions on the impact and use of spacing rules for high-frequency crosstalk reduction between single-ended transmission lines are presented. These investigations emphasize the necessity of reevaluating classical design rules for their suitability in high-frequency applications.
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| 16. |
- Mbairi, Felix, et al.
(författare)
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On the problem of using guard traces for high frequency differential lines crosstalk reduction
- 2007
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 30:1, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the problem of using guard traces for reducing crosstalk between differential transmission line pairs is investigated, both experimentally and by full-wave electromagnetic (EM) simulations. Different cases of differential lines crosstalk are treated with and without guard trace separation between the differential line pairs. Coated microstrip printed circuit board test structures including thru-reflect-line calibration standards are designed and fabricated on a high frequency laminate material, allowing direct measurement of crosstalk between adjacent differential line pairs in the absence and in the presence of guard traces stitched with vias of regular spacing. The test structures are characterized with mixed-mode scattering parameters using a physical layer test system. Different configurations (of differential line pairs) without guard trace, with floating guard traces (which are terminated and nonterminated) and with a solid guard trace separation are investigated using a High Frequency Structure Simulator (a commercial full-wave 3-D EM simulation tool). The experimental data are compared with the simulation results, and some conclusions and guidelines on the effect of guard traces for alleviating crosstalk between differential transmission lines are presented.
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| 17. |
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| 18. |
- Norberg, Gunnar, et al.
(författare)
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Contact Resistance of Thin Film Metal Contacts
- 2006
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 29:2, s. 371-378
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Tidskriftsartikel (refereegranskat)abstract
- To be able to reduce the size of products having electronic devices, it becomes more and more important to miniaturize the electromechanical parts of the system. The use of micromechanical connectors and contact structures implies the need of methods for estimating the properties of such devices. This work will, by use of finite element modeling, treat the influence of a thin film constituting at least one of the contacting members of an electrical contact. The error introduced by using the traditional Maxwell/Holm contact constriction resistance theory will be investigated. Numerical methods are used to present a way to approximate the total resistance for the thin metal film contact.
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| 19. |
- Siebert, Peter
(författare)
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High Frequency Cable Connector for Twisted Pair Cables
- 2006
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 26:3, s. 642-650
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Tidskriftsartikel (refereegranskat)abstract
- A new cable connector for twisted.,pair cable usable for high frequency applications is presented in this paper. An elastic conductive matrix as an interface between cable and printed wiring board (PWB) is pressed Against the ends of the copper wires of the cable, and a land grid array on the PWB; thereby making the connections. The shielding braid of the cable is lengthened by a tube structure up to,the same plane as the end of the copper wires, where the shielding is connected to an earth plane on the PWB. This not only gives a sound basis for good electromagnetic interfere (EMI) behavior, but can also serve as an adequate structure for a dc barrier of coin lion-mode currents in the shielding of twisted pair cables. A washer-formed capacitor between the earth of the PWB and the shielding tube structure would, probably be the only addition needed.
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| 20. |
- Siebert, Peter
(författare)
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Soldering Connections for High Frequency Applications between Flexible and Rigid Printed Circuit boards
- 2006
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 29:1, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- This article examines the backplane connector technology for high frequency use and presents a novel concept for shielded enclosures without air vents. The experimental soldering of connections between a flexible printed circuit (flex, for short) and a FR4-board as part of a backplane connector is presented. A very high contact density is reached by soldering vias on the flex to pads on the FR4; this soldering was performed both with ordinary Sn/Pb solder material and as well with lead-free solder alloy. The solder joints were examined using a scanning electron microscope (SEM) and the electrical properties of the flex/solder joint structure were measured.
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| 21. |
- Siebert, Peter W.
(författare)
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Cooling Structure for EMC Shielded High Frequency Electronics
- 2006
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 29:1, s. 155-163
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Tidskriftsartikel (refereegranskat)abstract
- Cooling of electronics is normally achieved using air passing through apertures in the enclosure; as a result the shielding effectiveness of the shielded enclosure is reduced. In this paper, the design of a new cooling structure and its evaluation in a wind tunnel is presented.The developed design presented here is a double heat sink in extruded aluminum. Into one side of the heat sink, the printed circuit boards (PCBs) are inserted and enclosed by a complementary shielding surface. The other side of the heat sink is cooled by forced ventilation. The heat transport between these parts is completely inside the same body, without any heat flow interruptions. Tests carried out on a prototype have shown that the performance of the cooling structure is satisfactory for electronic cooling. An additional electromagnetic compatibility (EMC)-test has also elucidated the satisfactory shielding effectiveness of the structure.The cooling structure is scaleable and can accommodate for both future smaller printed circuit boards (PCBs) and those of today. The entire enclosure is furthermore based on near-standard items, which allows it to be inexpensive in high volume production.
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| 22. |
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| 23. |
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| 24. |
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| 25. |
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| 26. |
- Siebert, W Peter
(författare)
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Solder connections for high frequency applications between flexible and rigid printed circuit boards
- 2006
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Ingår i: IEEE transactions on components and packaging technologies (Print). - 1521-3331 .- 1557-9972. ; 29:1, s. 118-126
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Tidskriftsartikel (refereegranskat)abstract
- This article examines the backplane connector technology for high frequency use and presents a novel concept for shielded enclosures without air vents. The experimental soldering of connections between a flexible printed circuit (flex, for short) and a FR4-board as part of a backplane connector is presented. A very high contact density is reached by soldering vias on the flex to pads on the FR4; this soldering was performed both with ordinary Sn/Pb solder material and as well with lead-free solder alloy. The solder joints were examined using a scanning electron microscope (SEM) and the electrical properties of the flex/solder joint structure were measured.
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| 27. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling aging effect on the shear strength, microstructure, IMC and initiation and propagation of surface mounted Sn-3.8Ag-0.7Cu and wave soldered Sn-3.5Ag ceramic chip components
- 2008
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Ingår i: IEEE Transactions on Components and Packaging Technologies. - 1521-3331. ; 31:2, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of electronic components was carried out at two different temperature profiles, the first ranging between -55°C and 100°C (TC1) and the second between 0°C and 100°C (TC2). Totally, 7000 cycles were run at TC1 and 14500 cycles at TC2. The test board’s top-side components were surface mounted using Sn-3.8Ag-0.7Cu solder alloy, and bottom side SMD components were wave soldered with Sn-3.5Ag alloy. The solder joint degradation was investigated as a function of cycle number by means of shear strength measurements and cross-sectioning. The shear strength drop was correlated to both crack initiation time and propagation rate, and Microstructural changes. The effect of manufacturing process (reflow versus wave soldering) and component size (0805 versus 0603 components) on the shear strength were also investigated.For both reflow and wave soldered components, the harsher the test environment the faster and largest the decrease in shear strength. The shear force is higher for the 0805 components compared to the 0603. The effect of component size on the residual shear strength is higher for the testing condition TC1. TC1 also seems to have a higher effect on the residual shear strength compared to TC2. The main difference between wave soldered and reflow soldered components is that the shear strength is in average higher for the wave soldered components compared to the reflow soldered. For the reflow soldered components using SAC, the microstructure coarsens, especially the Ag3Sn intermetallic particles. Furthermore, this alloy shows an increase of the IMC layer (Cu-Ni-Sn) thickness, and the IMC layer growth is controlled by a diffusion mechanism. The IMC growth coefficient is for the SAC system tested at TC1 0.0231 μm/hr1/2 (0.00053μm/hr) and for TC2 0.0054 μm/hr1/2 (2.9*10-5μm/hr). The microstructural changes during thermal cycling are a result of both static and strain-enhanced aging. For the wave soldered components the microstructure also became coarser, however, the IMC layer (Ni3Sn4) thickness did not change.The IMC layer growth does not affect the shear strength for the test conditions applied in this work. The shear strength decrease observed in the present work as a result of thermal cycling is a result of both microstructural coarsening and crack propagation inside the solder joint.
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