Optimization of Synthetic Jet Fluidic Structures in Printed Wiring Boards

2006 ◽  
Vol 128 (4) ◽  
pp. 353-359 ◽  
Author(s):  
Yong Wang ◽  
Guang Yuan ◽  
Yong-Kyu Yoon ◽  
Mark G. Allen ◽  
Sue Ann Bidstrup
Keyword(s):  
Fluid Mechanics ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Fluidic Channel ◽  
Electromagnetic Actuators ◽  
Wiring Board ◽  
Silicon Based ◽  
Surrounding Fluid

The active cooling substrate in this study is a microelectromechanical system device that implements the synthetic jet concept into a printed wiring board (PWB) to enhance thermal management. Synthetic jets are oscillatory jets synthesized from the surrounding fluid using electromagnetic actuators. The jet fluid mechanics and heat transfer applications have been investigated by a variety of on-board (PWB) fluidic structures. A testbed comprising six different fluidic channels has been fabricated and characterized with a standard silicon based platinum heater. Based on the fluid mechanics measurements and cooling performance tests, an empirical correlation of synthetic jet Nusselt number with its Reynolds number, fluidic channel dimensions, and jet locations has been derived. Through a magnitude analysis, jet actuator diaphragm, fluidic channel dimension, and cooling location optimizations have been investigated.

Design and Thermal Characteristics of a Synthetic Jet Ejector Heat Sink

2004 ◽  
Vol 127 (2) ◽  
pp. 172-177 ◽  
Author(s):  
Raghav Mahalingam ◽  
Ari Glezer
Keyword(s):  
Thermal Resistance ◽  
Steady Flow ◽  
Heat Sink ◽  
Power Dissipation ◽  
Ambient Air ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Transfer Coefficients ◽  
Electromagnetic Actuators ◽  
Air Jet

The design and thermal performance of a synthetic-air-jet-based heat sink for high-power dissipation electronics is discussed. Each fin of a plate-fin heat sink is straddled by a pair of two-dimensional synthetic jets, thereby creating a jet ejector system that entrains cool ambient air upstream of the heat sink and discharges it into the channels between the fins. The jets are created by periodic pressure variations induced in a plenum by electromagnetic actuators. The performance of the heat sink is assessed using a thermal test die encased in a heat spreader that is instrumented with a thermocouple. The case-to-ambient thermal resistance under natural convection with the heat sink is 3.15°C∕W. Forced convection with the synthetic jets enables a power dissipation of 59.2W at a case temperature of 70°C, resulting in a case-to-ambient thermal resistance of 0.76°C∕W. The synthetic-jet heat sink dissipates ∼40% more heat compared to steady flow from a ducted fan blowing air through the heat sink. The synthetic jets generate a flow rate of 4.48 CFM through the heat sink, resulting in 27.8 W/CFM and thermal effectiveness of 0.62. The effect of fin length on the thermal resistance of the heat sink is discussed. Detailed measurements on an instrumented heat sink estimate that the average heat transfer coefficients in the channel flow between the fins is 2.5 times that of a steady flow in the ducts at the same Reynolds Number.

A Heat Transfer Comparison Between a Synthetic Jet and a Steady Jet at Low Reynolds Numbers

2008 ◽  
Author(s):  
Rayhaan Farrelly ◽  
Alan McGuinn ◽  
Tim Persoons ◽  
Darina B. Murray
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Stroke Length ◽  
Low Reynolds Numbers ◽  
Nusselt Numbers ◽  
Significant Difference ◽  
Low Reynolds ◽  
Surrounding Fluid

A study has been carried out to compare steady jet and synthetic jet heat transfer distributions at low Reynolds numbers. Both jets issued from a 5mm diameter orifice plate with air for the steady jet being supplied by a compressor via a plenum chamber. Tests were conducted for Reynolds numbers ranging from 1000 to 4000, and for non-dimensional surface to jet exit spacings (H/D) from 1 to 6. Dimensionless stroke length (Lo/D) for the synthetic jet was held constant at 8. A significant difference was observed between the steady and synthetic jet Nusselt numbers at low Reynolds numbers and low H/D. In comparison to steady jets, the stronger entrainment of surrounding fluid and the vigorous mixing near the impingement surface are characteristics of synthetic jets that are beneficial to heat transfer. Nonetheless, the steady jet yields higher Nusselt numbers for all test conditions.

An Efficient Numerical Technique for Thermal Characterization of Printed Wiring Boards

1993 ◽  
Vol 115 (4) ◽  
pp. 366-372 ◽  
Author(s):  
G. G. Stefani ◽  
N. S. Goel ◽  
D. B. Jenks
Keyword(s):  
Numerical Technique ◽  
Thermal Characterization ◽  
Computer Time ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Equivalent Parameter ◽  
Finite Element Package ◽  
Multiple Materials ◽  
Wiring Board

Thermal modeling of Surface Mount Technology (SMT) microelectronics packages is difficult due to the complexity of the printed wiring board (PWB) plates through hole (PTH) structure. A simple, yet powerful finite difference based approach, called EPIC (Equivalent Parameter for Interfacial Cells), for modelling complex 2-D and 3-D geometries with multiple materials is used to model the PTH structure. A technique for computing an effective thermal conductivity for the PWB is presented. The results compare favorably with those from a commercially available finite element package but require far less computer time.

Thermal Evaluation of High-Current Polyimide Rigid and Rigid-Flex Printed Wiring Board Trace Widths in a Vacuum

2013 ◽  
Vol 2013 (1) ◽  
pp. 000964-000969
Author(s):  
Bennion Cannon ◽  
Frank Friedl ◽  
Gary Gisler
Keyword(s):  
Thermal Imaging ◽  
Hot Spots ◽  
Test Results ◽  
High Current ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Thermal Imaging Camera ◽  
Industry Standards ◽  
Imaging Camera ◽  
Wiring Board

This paper details the thermal evaluation of high-current polyimide rigid and rigid-flex printed wiring boards in a vacuum. Although industry standards, such as IPC-2152 or MIL-STD-275, can be used to determine required trace width for PWB traces that carry current to between 20 or 30 amps for multiple copper plane thicknesses, they typically cannot be used to determine trace width for PWB traces that handle current greater than 15 amps. This paper presents results from testing and analysis of high-current rigid and rigid-flex PWBS that must carry current of up to 60 amps. Testing was performed in vacuum on a controlled-temperature platen, measuring board temperature at specific locations to determine performance of different trace widths using 2 and 4 ounce copper layers. A thermal imaging camera was used to identify PWB hot spots. Test results were compared to IPC-2152 standards, extrapolated to 60 amps current.

Impact of printed wiring board coatings on the reliability of lead-free chip-scale package interconnections

2004 ◽  
Vol 19 (11) ◽  
pp. 3214-3223 ◽  
Author(s):  
T.T. Mattila ◽  
V. Vuorinen ◽  
J.K. Kivilahti
Keyword(s):  
Grain Boundaries ◽  
Lead Free ◽  
Solder Paste ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Snagcu Solder ◽  
Chip Scale Package ◽  
Free Solder ◽  
Wiring Board ◽  
Reliability Performance

When lead-free solder alloys mix with lead-free component and board metallizations during reflow soldering, the solder interconnections become multicomponent alloy systems whose microstructures cannot be predicted on the basis of the SnPb metallurgy. To better understand the influences of these microstructures on the reliability of lead-free electronics assemblies, SnAgCu-bumped components were reflow-soldered with near-eutectic SnAgCu solder pastes on Ni(P)|m.Au- and organic solderability preservative (OSP)-coated printed wiring boards and tested under cyclic thermal shock loading conditions. The reliability performance under thermomechanical loading was found to be controlled by the kinetics of recrystallization. Because ductile fracturing of the as-soldered tin-rich colonies would require a great amount of plastic work, the formation of continuous network of grain boundaries by recrystallization is needed for cracks to nucleate and propagate intergranularly through the solder interconnections. Detailed microstructural observations revealed that cracks nucleate and grow along the grain boundaries especially between the recrystallized part and the non-recrystallized part of the interconnections. The thermal cycling test data were analyzed statistically by combining the Weibull statistics and the analysis of variance. The interconnections on Ni(P)|m.Au were found out to be more reliable than those on Cu|m.OSP. This is due to the extensive dissolution of Cu conductor, in the case of the Cu|m.OSP assemblies, into molten solder that makes the microstructure to differ noticeably from that of the Ni(P)|m.Au interconnections. Because of large primary Cu6Sn5 particles, the Cu-enriched interconnections enhance the onset of recrystallization, and cracking of the interconnections is therefore faster. The solder paste composition had no statistically significant effect on the reliability performance.

Recent Advances in Oxide Glass Fiber Science

2001 ◽  
Vol 702 ◽  
Author(s):  
Ernest L. Lawton ◽  
Frederick T. Wallenberger ◽  
Hong Li
Keyword(s):  
High Speed ◽  
Rapid Development ◽  
Dissipation Factor ◽  
Oxide Glass ◽  
Electronic Systems ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Fiber Glass ◽  
Lower Dielectric Constant ◽  
Wiring Board

ABSTRACTThe predominate substrate for multilayer printed wiring boards is laminate constructed from epoxy resin reinforced with fiber glass fabrics. This combination of materials dominates the segment of the electronics market where dimensional stability of the substrate is critical. The rapid development of high speed digital and analog electronic systems has challenged the predominance of fiber glass as the reinforcement of choice. As systems move to the GHz frequency range, there is a need for lower dielectric constant of the substrate to insure integrity and speed of signals. A lower dissipation factor of the substrate is desired for the wireless communication applications of printed wiring boards. A review is presented of materials competing as substrates for the high speed application of the printed wiring board market.

Ceramic Resistors and Capacitors Embedded in Organic Printed Wiring Boards

2003 ◽  
Author(s):  
William Borland ◽  
John J. Felten ◽  
Lynne E. Dellis ◽  
Saul Ferguson ◽  
Diptarka Majumdar ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Thick Film ◽  
Copper Foil ◽  
Printed Wiring Boards ◽  
Printed Wiring Board ◽  
Ceramic Component ◽  
Board Processes ◽  
Doped Barium Titanate ◽  
Wiring Board ◽  
Lanthanum Boride

Combining thick-film and printed wiring board processes allows thick-film ceramic resistors and capacitors to be embedded in printed wiring boards (PWB). The resistor materials are based on lanthanum boride and cover the range of 10 ohm/square to 10 Kohm/square resistivities. The capacitor material is based on doped barium titanate. Both systems are designed to be “thick-film” printed on copper foil in the locations desired in the circuit and the foil is then fired in nitrogen at 900°C to form the ceramic component on the copper foil. The foil is then laminated, component face down, to FR4 using standard prepreg. The inner layer is then etched to reveal the components in a FR4 matrix. The resistors can be trimmed to tight tolerance at this stage and the components tested. The inner layer can then be laminated into a multilayer PWB. The process is described and the influence of board design, PWB processing and materials are presented and discussed. Examples of circuits using embedded thick-film passives are shown and results of reliability studies are presented.

Sign in / Sign up

Export Citation Format

Share Document