Evaluating Thermal Cycling Fatigue Resistance for LED Chip-on-Board Applications

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 000706-000737
Author(s):  
Ravi M. Bhatkal ◽  
Ranjit Pandher ◽  
Anna Lifton ◽  
Paul Koep ◽  
Hafez Raeisi Fard
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Cycle ◽  
Metal Core ◽  
Creep Fatigue ◽  
Cte Mismatch ◽  
Thermal Cycling Fatigue ◽  
Transient Thermal ◽  
The Impact

LED chip-on-board applications typically involve assembling an LED die stack directly on to a high thermal conductivity substrate such as a Metal Core PCB. If solder is used for die-substrate attach for such chip-on-board applications, one needs to consider the CTE mismatch between the die stack and the MCPCB and its impact on thermal cycle-induced creep fatigue of the solder material. This paper presents a methodology to compare relative performance of different solder materials with varying thermo-mechanical properties, and compare the impact of CTE mismatch and temperature swings on transient thermal properties and relative reliability of the solder attach materials. Implications for LED chip-on-board applications are discussed.

scholarly journals Thermal Behavior of Worsted Fabrics Produced from Different Yarn Spinning Systems

2013 ◽  
Vol 8 (3) ◽  
pp. 155892501300800 ◽  
Author(s):  
Abolfazl Mirdehghan ◽  
Siamak Saharkhiz ◽  
Hooshang Nosraty
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Behavior ◽  
Thermal Insulation ◽  
Weft Yarn ◽  
Spun Yarn ◽  
Finishing Process ◽  
Yarn Structure ◽  
Fabric Structures ◽  
The Impact

This paper describes an experimental study of the impact of yarn structure on the thermal properties of worsted fabric. In this study, four different spun yarn structures (Solo, Siro, and single ply and two ply Ring) were woven into four fabric structures (Plain, Twill2/1, Twill2/2 and Basket2/2) and their thermal properties were studied. In addition, the thermal behavior of finished and unfinished samples was also evaluated. Results showed that the finishing process causes an increase in thermal conductivity and warmth to weight factor and a decrease in thermal insulation. Different spinning systems, also affect the thermal properties of the worsted fabrics. Samples with Siro yarns in the weft were found to have the highest thermal conductivity and those made from single ply weft yarn the lowest thermal conductivity. A relation between fabric thermal insulation and air permeability and thickness was also found.

Effect of extrusion treatment on mechanical, thermal conductivity and corrosion resistance of magnesium alloys

2019 ◽  
Vol 9 (5) ◽  
pp. 405-412
Author(s):  
Bo Zhang ◽  
Huichao Jia ◽  
Quanyong Lian ◽  
Lianyu Jiang ◽  
Guangxin Wu
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Thermal Properties ◽  
Magnesium Alloys ◽  
Driving Force ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Extrusion Temperature ◽  
Zr Alloys

The effect of extrusion treatment on the mechanical, thermal and corrosion resistance of Mg–La–Zn–Zr alloys were presented. It is suggested that the amount of recrystallized grains played a major role in both mechanical properties and thermal properties. It should be noted the as-cast alloy shows the best thermal conductivity reached the value about 137.507 W/(m · K), however, the mechanical performance of magnesium alloys does not reach the expected results. The thermal properties of extruded alloys have slightly decreased and then increased with the increase of extrusion temperature. Then the tensile properties of Mg–La–Zn–Zr were significantly improved after extrusion treatment. Furthermore, with the increase of extrusion temperature, the elongation-to-fracture increased substantially. After extrusion treatment, the corrosion driving force of the alloy decreases, which reduces the corrosion tendency of the magnesium alloy. The alloy presented in this paper is expected to be applied in industry.

Mechanical Properties and Thermal Conductivity of Coal Ash-Recycled High-Density Polyethylene Composite

2018 ◽  
Vol 06 (01n02) ◽  
pp. 1850002
Author(s):  
Ban M. Alshabander ◽  
Awattif A. Mohammed ◽  
Asmaa Sh. Khalil
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
High Density Polyethylene ◽  
Waste Product ◽  
Construction Materials ◽  
Coal Ash ◽  
High Density ◽  
Plastic Composite ◽  
The Impact ◽  
Recycled Hdpe

In this study, coal ash/recycled plastic composite material was fabricated with post-consumer high-density polyethylene (HDPE) and coal ash particles. The main idea of using coal ash, since it is also a waste product, as reinforcing filler in recycled HDPE is to reduce the cost, develop lightweight and produce environmental-friendly materials. Coal ash/recycled plastic composite have been used in significant applications as construction materials including flooring, landscaping, fencing, railing window framing and roof tiles. Effect of coal ash loading on the mechanical properties and thermal conductivity of coal ash/recycled HDPE composite were determined. It is expected to use waste materials in new field by getting novel composite materials with developed mechanical properties. It was found that coal ash filler indicated significant improvement on the mechanical properties of composites. The results show that the impact decreased tremendously from 57.32 to 15.8[Formula: see text]kJ/m2 with only 30[Formula: see text]wt.% loading of coal ash. The filler increases the elasticity of the material and reduces its ability to absorb deformation energy.

scholarly journals Thermal, mechanical and morphological properties of polyurethane–zirconia loading

2020 ◽  
Author(s):  
Ali J Salman ◽  
Ali Assim Al-Obaidi ◽  
Dalya H Al-Mamoori ◽  
Lina M Shaker ◽  
Ahmed A Al-Amiery
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Thermal Properties ◽  
Material Science ◽  
Morphological Properties ◽  
Flexural Stress ◽  
Renewable Materials ◽  
Sem Images ◽  
The Impact ◽  
Scanning Electron

Abstract The polyurethane (PU) has been showing a dramatic increase in applications related to material science and technology. However, the mechanical, physical and thermal properties could be further improved by loading PU with zirconia (Zr) to create renewable materials known as polyurethane–zirconia (PUZ) composites. In this study, PU matrix was treated with wt.% Zr at 0.5, 1.0, 1.5 and 2.0. In this study, the thermo-mechanical properties and the morphology were investigated of PU and PUZ nano-samples. The images of the scanning electron microscope (SEM) were the prime tool in investigating PU and PUZ surfaces and fractured surfaces showing vanishing the cracks and formation of agglomeration on the sample PUZ-1.5%. In addition, the tensile strength, Young’s modulus and maximum loading were improved by 36.7, 31.8 and 39.1%, respectively, at Zr loading of 1.5 wt.%. The flexural stress and the load were improved by 94.3% and 93.6%, respectively, when Zr loading was 1.5 wt.%. The impact without and with a notch was improved by 110.7% and 62.6%, respectively, at Zr loading of 1.5 wt.%. The the morphologies of the PU surface and Zr surface supported by SEM images. Regarding the storage modulus ability of PU and PUZ composites, Zr loading has negatively influenced E. The E functioning temperature was observed to move from 142 to 183°C. Another effect was determined by adding a small amount of Zr. This small amount was enough to shift the crystallization temperature (${T}_c$) and the melting temperature (${T}_m$) of PU from 125 to 129°C and from 150 to 144°C, respectively.

Preparation and Characterization of GNP/Nylon Composites

2014 ◽  
Vol 556-562 ◽  
pp. 339-342 ◽  
Author(s):  
Bao Feng Xu ◽  
Zhi Dan Lin ◽  
Jiang Ming Chen ◽  
Jun Lin
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Graphene Nanoplatelets ◽  
Melt Blending ◽  
Blending Method

Graphene nanoplatelets (GNP) and nylon (PA) have been often used as thermal filler and matrix and respectively to produce composites. In this work, PA6/PA66/GNP thermal composites were prepared via a melt blending method. Mechanical properties, morphology, and thermal properties of PA6/PA66/GNP composites were investigated. Because the GNP is very expensive, we investigated to use Al2O3 and graphite and examined the characteristics of the prepared composites. Thermal conductivity values of PA6/PA66/GNP composites remarkably increased with increase of GNP contents mainly via layered dispersion in nylon matrix. The thermal conductivity of composite containing 50 wt % of GNP was measured as 5.03 W·m–1·K–1 at 30 °C, indicating an increase of more than 15 times compared with that of the neat PA6. When the Al2O3 was replaced for GNP, the thermal conductivity of composites decreased, but the mechanical properties improved. When graphite was used to replace for GNP, thermal conductivity basically remained unchanged but mechanical properties decreased.

Thermal Properties and Fire Performance of Woven Glass Fibre Reinforced Nylon 6 Nano-Composites with Carbon Nanotubes

2008 ◽  
Vol 32 ◽  
pp. 9-12
Author(s):  
Shirley Zhiqi Shen ◽  
Stuart Bateman ◽  
Qiang Yuan ◽  
Mel Dell'Olio ◽  
Januar Gotama ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Thermal Properties ◽  
Ignition Time ◽  
Nylon 6 ◽  
Nano Composites ◽  
Fire Performance ◽  
Thermal Stabilities ◽  
Glass Fibre Reinforced

This paper presents the effects of incorporating carbon nanotubes (CNT) into nylon 6 on thermal properties and fire performance of woven glass reinforced CNT/nylon 6 nanocomposite laminates. Incorporation of CNT in nylon 6 improved the thermal stabilities, thermal conductivity and fire performance of laminates without compromising their mechanical properties. The thermal conductivity of laminates with 2 wt% CNT increased up to 42% compared to that without CNT. The ignition time and peak HRR time was delayed approx. 31% and 118%, respectively, in laminates with 4 wt% CNT in nylon 6 over that without CNT.

scholarly journals Effect of Amorphisation on the Thermal Properties of Nanostructured Membranes

2017 ◽  
Vol 72 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Konstantinos Termentzidis ◽  
Maxime Verdier ◽  
David Lacroix
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Amorphous Phase ◽  
Nanoporous Membranes ◽  
Phonon Modes ◽  
Amorphous Phases ◽  
Silicon Devices ◽  
Nanostructured Membranes ◽  
Dynamics Simulations ◽  
The Impact

AbstractThe majority of the silicon devices contain amorphous phase and amorphous/crystalline interfaces which both considerably affect the transport of energy carriers as phonons and electrons. In this article, we investigate the impact of amorphous phases (both amorphous silicon and amorphous SiO2) of silicon nanoporous membranes on their thermal properties via molecular dynamics simulations. We show that a small fraction of amorphous phase reduces dramatically the thermal transport. One can even create nanostructured materials with subamorphous thermal conductivity, while keeping an important crystalline fraction. In general, the a-SiO2 shell around the pores reduces the thermal conductivity by a factor of five to ten compared to a-Si shell. The phonon density of states for several systems is also given to give the impact of the amorphisation on the phonon modes.

Damage Study of 22Cr2Ni4MoVA Steel in Artificial Crystal Growing Environment

2012 ◽  
Vol 472-475 ◽  
pp. 302-308
Author(s):  
Jian Ping Huang ◽  
Kang Lin Liu
Keyword(s):  
Mechanical Properties ◽  
Creep Deformation ◽  
Fatigue Tests ◽  
Metallographic Analysis ◽  
Temper Brittleness ◽  
High Concentration ◽  
Co Activation ◽  
Creep Fatigue ◽  
Growing Environment ◽  
The Impact

Through the chemical analysis, mechanical properties tests, metallographic analysis, fracture and fatigue tests on 22Cr2Ni4MoVA steel cut from deactivated crystal kettle which had been used for 9 years, we obtained a variety of mechanical properties data, and confirmed that the yield strength and ultimate strength of 22Cr2Ni4MoVA steel were basically unchanged in crystal growing environment, but the impact energy, sectional shrinkage and fracture toughness that reflect material toughness were significantly descend, and there existed serious embrittlement and creep deformation. The failure mode of 22Cr2Ni4MoVA steel was brittle fracture under the co-activation of creep fatigue and corrosion. The decline of creep deformation and endurance limit at high temperature played a guiding role; fatigue and corrosion played an initiative attacking role; and temper brittleness acted in degenerating, losing immunity and increasing crack sensitivity; while the stress concentration on kettle bottom and alkaline solution with high concentration provided a breeding ground for failure.

Effects of Thickness on Thermal and Mechanical Properties of Air-Plasma Sprayed Thermal Barrier Coatings

2010 ◽  
Vol 658 ◽  
pp. 372-375 ◽  
Author(s):  
Sang Yeop Lee ◽  
Jae Young Kwon ◽  
Tae Woong Kang ◽  
Yeon Gil Jung ◽  
Ung Yu Paik
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Exposure Time ◽  
Gas Turbines ◽  
Microstructural Analysis ◽  
Thermal Exposure ◽  
Thermal Barrier ◽  
Air Plasma

Thermal barrier coating systems (TBCs) prepared by an air-plasma spray (APS) have been used to protect metallic components of gas turbines because of its economic advantage. To enhance the energy efficiency of gas turbine systems, the operating temperature is increased to over 1300 °C, which requires a new material with low thermal conductivity and an increase of TBC thickness. In this study we have focused the microstructure related to the thickness of TBC and their thermal properties, with specific attention to defect species as well as to its morphology with the thermal exposure time. Resintering of TBC happens during thermal exposure in a high temperature, resulting in the less strain tolerance and the higher thermal conductivity. In order to investigate the thermal properties of TBC related to the microstructural evolution, TBCs with different thicknesses of 200 µm, 400 µm, 600 µm, and 2000 µm were deposited on a flat graphite by the APS. The thermal exposure tests were conducted in different dwell time till 800h at 1100 °C. The thermal diffusivity is significantly increased after thermal exposures, depending on the thermal exposure time. Microstructural analysis clearly shows that the variation of thermal diffusivity is ascribed to the coalescence of small cracks and the resintering effect. The hardness values of TBCs are also increased as well. The relationship between mechanical properties and TBC thickness is discussed, including the effect of thickness on thermal properties.

scholarly journals EFFECT OF ALUMINUM DROSS AND RICE HUSK ASH ON THERMAL AND MOULDING PROPERTIES OF SILICA SAND

2017 ◽  
Vol 36 (3) ◽  
pp. 794-800
Author(s):  
EF Ochulor ◽  
HOH Amuda ◽  
SO Adeosun ◽  
SA Balogun
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Thermal Characteristics ◽  
Silica Sand ◽  
Cast Part ◽  
Solidification Kinetics ◽  
Moulding Sand

Moulding properties of foundry sand should be controlled so as to minimize casting defects. Its thermal characteristics are vital in defining the solidification kinetics of a cast part,  evolving microstructure and mechanical properties. Modification of the thermal properties of the moulding sand mix is important in achieving desired structure and mechanical properties in the cast component. This study investigates the incorporation of 2-12 wt. % aluminium dross (AlDr) and 1-6 wt. % rice husk ash (RHA) in silica sand on moulding and thermal properties of the resulting sand mix. Results show that RHA significantly reduced thermal conductivity of the moulding sand from 1.631-1.141 W/m. K (a 30% reduction).However, AlDr increased its thermal conductivity from 1.631-1.787 W/m.K for 1-6 wt. % AlDr, which later dropped progressively from 1.753-1.540 W/m.K for 8-12 wt. %. The moisture content increased abruptly from 4.0-4.2 % for 6-8 wt. % AlDr addition but decreased from 4.0-2.8% for0-6 wt. % RHA addition in the moulding sand mix. http://dx.doi.org/10.4314/njt.v36i3.19

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