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Suitable coatings on electronic packaging substrates are generally preferred to surround the internal components, protect them from adverse conditions, and improve heat-dissipating performance. Such coatings are developed using different deposition techniques to attain a cosmetic appearance on a single sheet, preferably aluminium alloys. These coatings have to overcome certain challenges, including heat dissipation and mechanical robustness. In this study, a nickel–boron (NiB) binary alloy was sealed and deposited on an already developed nanoporous anodic aluminium oxide (AAO) pattern using an electroless deposition method. The performance is studied with respect to different deposition times. The resulting NiB layer has a nano nodular-like morphology with a 0.95-μm layer thickness. The structural analysis shows a mixture of amorphous and crystalline nature with sharp Ni peaks (111), (220), including the crystallite size of 377 nm. Compared with the bare Al substrate, the 1-hr NiB sealing on AAO has a significant reduction in thermal resistance (Rth) to 29.65%, a rise in junction temperature (Tj) to 27.36%, and improved bulk thermal conductivity (k) to 50.1%. In addition, this binary NiB exhibits a roughness of 0.89 μm, an indentation hardness of 2560 MPa, and a scratch hardness of 8764 MPa. Results show enhanced properties of the AAO sealed binary NiB coating as a feasible option for packaging substrates.

In a solid-state lighting, the thermal performance of light emitting diode (LED) is one of the crucial aspects in determining the quality of the LED. To improve the thermal performance of LED, thermal interface material (TIM) was employed and proven to help the transfer of heat in solid state lighting. In this study, zinc oxide thin films were deposited on aluminum (Al) substrates using chemical vapor deposition method and the effect of annealing temperature was discussed. The thermal and optical performances of OSRAM golden dragon white LED attached on bare and ZnO thin film coated Al substrate were measured by Thermal Transient T3ster (T3ster) and Spectrometer respectively. Noticeable improvement in the reduction of junction temperature (ΔTj = 13.79 ℃) was observed for ZnO thin film annealed at 400 ℃ compared with the bare Al (without ZnO) boundary condition and hence improvement in optical output was achieved with the same boundary condition. Overall, rise in junction temperature, Tj of ZnO thin film demonstrated positive result in reducing the temperature of the LED package. The total thermal resistance (Rth-tot) was low for the sample coated with ZnO thin film compared with the bare Al substrate at high driving currents with the lowest reported value of 7.37 K/W for ZnO thin film annealed at 400 ℃. Correlated color temperature (CCT) and illuminance (LUX) value showed that the ZnO thin film sample displayed better performance than bare Al sample. From the result, it can be suggested that ZnO thin film would be an effective and suitable thermal interface material (TIM) for the solid-state lighting application.

To ensure the highest quality & long-term reliability of LED components it is necessary to examine LED dice that have sustained mechanical damage during the manufacturing process. This paper has demonstrated that detection of die crack in mass manufactured LEDs can be achieved by measuring Temperature Sensitive Parameters (TSPs) during final testing. A newly-designed apparatus and microcontroller was used for this investigation in order to achieve the millisecond switching time needed for detecting thermal transient effects and at the same time meet the expected speed for mass manufacturing. Evaluations conducted at lab scale shows that thermal transient behaviour of cracked die is significantly different than that of an undamaged die. Having an established test limits to differentiate cracked dice, large volume tests in a production environment were used to confirm the effectiveness of this test method. Failure Bin Analysis (FBA) of this high volume experiment confirmed that all the cracked die LEDs were detected and the undamaged LEDs passed this test without over-rejection. The work verifies that tests based on TSP are effective in identifying die cracks and it is believed that the method could be extended to other types of rejects that have thermal transient signatures such as die delamination. Keywords: Cracked die, Germanium substrate, Thermal resistant, Crack detection

Nonequilibrium plasmas have been extensively investigated for polymer surface treatments in industrial applications. Plasma treatments can change the properties, such as electrical, chemical, tribological, biological, optical, and mechanical, which are easy to scale up to industrial applications. These can be extended to electronic industry. Consequently, light-emitting diode (LED) package was processed using Ar plasma at various flow rates and times. Thermal transient analysis showed reduced total thermal resistance ($R_{{\text {th}}}$) and reduced rise in junction temperature ($T_{J}$) for Ar plasma processed LED compared to the bare LED package data. Among the process parameters considered, 20-sccm flow of Ar gas exhibited better performance with respect to processing times. A noticeable reduction in $T_{J}$ value was recorded ($\Delta T_{J} = 49.2\,\,^{\circ }\text{C}$) for Ar plasma processed LED from that of bare LED. Surface modification through cross linking was assumed by the Ar plasma process and supported to enhance the heat transfer through the modified surface of silicone encapsulation of the LED. In addition, the surface smoothness of silicone was induced by Ar plasma and helped to exhibit efficient heat transfer via convection. Based on the observed results, the Ar plasma process would be an effective postprocessing method for LED package to improve the performance as well as lifetime. [ABSTRACT FROM AUTHOR]

Thin film based gas sensor is an advanced application of thin film especially Ga2O3 (GO) thin film gas sensor is useful for high temperature gas sensor. The effect of moisture or environment on thin film properties has more influence on gas sensing properties. Radio Frequency sputtered Ga2O3 thin film was synthesized and processed in ultra-high pure hot water at 95 °C for different time durations. The structural properties were verified by the Xray Diffraction technique and the observed spectra revealed the formation of hydroxyl compound of Gallium (Gallium Oxide Dueterate - GOD) on the surface of the thin film and evidenced for structural defects as an effect of moisture. Decreased crystallite size and increased dislocation density was showed the crystal defects of prepared film. From the Ultra Violet - Visible spectra, decreased optical transmittance was noticed for various processing time. The formation of needle like GOD was confirmed using Field Emission Secondary Electron Microscope (FESEM) images. [ABSTRACT FROM AUTHOR]

This paper proposes a low-cost SU-8 pressure sensor fabricated using a piezoresistive material, SU-8/silver composite (SU-8/Ag), and a substrate material, overhead projector (OHP) transparency. SU-8/Ag has higher gauge factor (26.3) but shows a lower stiffness (2 GPa) compared with doped silicon. The OHP transparency substrate is cheap, easily forms the desired shape, is transparent to light (allows backside exposure), and allows for the dry release method through OHP transparency. Fabrication and characterization in this study were carried out using a typical semiconductor lab setup. The fabricated sensor showed high sensitivity (21.5μV/Pa), low linearity error (Pearson's correlation coefficient = 0.994937), and no apparent hysteresis response. The fabricated sensor with SU-8/Ag as the piezoresistive material exhibited 41 times higher sensitivity compared to that found in a previous study based on SU-8 and doped polysilicon. [ABSTRACT FROM AUTHOR]

In high-power electronic devices, thermal interface material (TIM) helps to conduct heat effectively from the chip to ambient by connect the discrete points of the two mating solid surfaces. This paper demonstrates the use of zinc oxide (ZnO) thin film as TIM prepared on Al substrate using RF sputtering. The total thermal resistance (Rth-tot) measured by dual interface method is lower for ZnO coated than for bare and thermal paste applied Al substrates. The thickness of ZnO thin film also influences the thermal resistance as Rth\-tot decreases with increased thickness at high driving current. Junction temperature (T\bf J) is also reduced noticeably for ZnO coated substrates and \Delta T\bf J between bare and 800-nm ZnO thin film coated substrate is 3.33^\circC as high for other combinations. The thermal resistance of ZnO interface (Rth\-b\-hs) is also calculated from the transient curve and observed low resistance with 800-nm ZnO thin film measured at 700 mA. The observed correlated color temperature values are low for ZnO thin film coated Al substrates measured at >350~mA. ZnO thin film is supported to enhance the luminosity of the given light emitting diode and suggested for the replacement of thermal paste based interface material. [ABSTRACT FROM AUTHOR]

ZnTe thin films were prepared by Stacking of elemental (Zn and Te) layers (SEL) followed by inert gas annealing. The optical parameters were calculated from the transmission spectra. The bandgap of the annealed samples was found between 1.95 eV and 2.06 eV. The change in film thickness after annealing was observed using cross sectional SEM image of the annealed samples. The surface morphology of the annealed Te/Zn stack was also analyzed and observed as very smooth, compact and dense surface. The prepared film was Zn rich evidenced by EDAX. The observed result encourages in pursuing the SEL method for the preparation of compound semiconductor from II-VI group materials. [ABSTRACT FROM AUTHOR]

LiSmxMn2–xO4 samples were synthesized via co-precipitation technique. The structural properties of the synthesized materials were studied using X-ray diffraction analysis and it confirmed the cubic spinel structure for all the compounds. The lattice parameter of LiMn2O4 was observed to be 8.2347 Ǻ and it decreased with Sm3+ concentration, due to the shrinkage in cell volume aided by higher binding energy between Sm-O bond. The SEM micrographs were analyzed using Image processing software (Image-J) to ascertain the pore and grain properties. The microwave synthesis had been observed to control the bulk grain formation and had yielded lesser porous and nanoparticles. The particle size distributions obtained through photocross correlation laser diffraction analysis had shown that LiMn2O4 with 60 nm and Sm-doped compounds with ∼30 nm, respectively. The cyclic voltammetry studies had revealed the decrease in electrocatalytic behavior in the initial cycle for compounds doped with Sm3+ ion. The initial capacities of LiMn2O4, LiSm0.05Mn1.95O4 and LiSm0.10Mn1.90O4 substituted compounds were observed to be 134.87 mAhg−1, 132.22 mAhg−1 and 126.41 mAhg−1, respectively. The cells were simulated using 1D model namely Dualfoil5.1 program. The simulated results coincide well with the measured results. The cycle life studies reveal 93% capacity retention of samarium-0.05-doped samples when compared with 78.4% of the LiMn2O4. [ABSTRACT FROM AUTHOR]

The relationship between the photometric, electric, and thermal parameters of light-emitting diodes (LEDs) is important for optimizing the LED illumination design. Indium gallium aluminium phosphide (InGaAlP)-based thin-film surface-mounted device (SMD) LEDs have attracted wide attention in research and development due to their portability and miniaturization. We report the optical characterization of InGaAlP thin-film SMD LED mounted on FR4, 2 W, and 5 W aluminum (Al) packages. The optical and thermal parameters of LED are determined at different injection currents and ambient temperatures by combining the T3ster (thermal transient tester) and TeraLED (thermal and radiometric characterization of power LEDs) systems. Analysis shows that LED on a 5 W Al substrate package obtains the highest luminous and optical efficiency. [ABSTRACT FROM AUTHOR]

Plasma processing is an approach to modify the surface structure for improved performance of nitride semiconductor using in light emitting diodes. In this work, RF sputtered GaN thin films were synthesized on Si (1 0 0) substrates and processed at two different plasmas (N2 and O2) at various flow rates. The surface nature of plasma processed thin films was characterized using atomic force microscope (AFM) and scanning electron microscope (SEM). Energy dispersive spectrum (EDS) of all samples was recorded to do elemental analysis. Noticeable changes on surface morphology were recorded for the plasma processed GaN thin films at high flow rate (>20 sccm). The roughness and particle size of thin film got decreased as the flow rate of gases increased. Low value in surface roughness (0.26 nm) and particles size (14 nm) was observed at 30 sccm flow rate of O2. SEM images also revealed the surface modification at high gas flow rates during plasma process. Nitrogen deficient GaN thin film was confirmed by EDS spectra and improved N2 concentration was achieved for N2 and O2 plasma processing upto 20 sccm flow rates. I-V characteristics showed the Schottky-contact behavior for all thin films and revealed the improved surface quality to make good ohmic contact for the film processed at high gas flow rate (>30 sccm). [ABSTRACT FROM AUTHOR]