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In this article, silicone rubber (SiR) is filled with industry preferred micro-silica and specialty hexagonal boron nitride (h-BN) nanosheets, by varying the ratio between the two fillers, while keeping the filler to matrix ratio the same in all three composites. The fillers are added to SiR using an electrostatic disperser which aids in homogenizing the filler-polymer mixture by means of shearing force along with elongation. The performance of synthesized silicone composites are evaluated using thermal, erosion resistance, morphological, mechanical, and high-temperature dielectric properties. Addition of as low as 5 wt% h-BN fillers significantly improved the thermal properties; 6%–20% improvement in thermal conductivity and in less than half the weight loss compared to only silica filled composites with laser erosion. The morphological and mechanical analyses showed improved filler dispersion and filler to silicone matrix interaction owing to good filler dispersion achieved through the electrostatic dispersing method. The dielectric properties measured in wide frequency range, between 10−4 and 103 Hz and at elevated temperatures (up to 175 °C) showed a negligible effect of increase in h-BN content. Thus, this article implies that low amounts of h-BN in silica-silicone composites improve thermal conductivity and erosion resistance significantly and not altering the dielectric responses of these hybrid composites even at elevated temperatures. Hence these composites can find applications both in the high voltage industry and as electronic packaging materials. [ABSTRACT FROM AUTHOR]

This article explores the potential of epoxy resin/silicon carbide whisker (EP/SiCw) composites (1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%) as the field-dependent conductivity (FDC) packaging materials for the high-voltage power modules by investigating their thermal and electrical properties at different temperatures. The cross-sectional morphology of the prepared materials is characterized by field emission-scanning electron microscopy (FE-SEM). The thermal analysis consists of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The electrical properties, such as dc conductivity, dielectric spectroscopy, thermally stimulated discharge current (TSDC), space charge distribution, and dc breakdown strength, are measured. The molecular orbital energy levels of the EP and SiCw monomers are calculated by quantum chemical calculation (QCC) to analyze the effect of EP interfacial trap sites on the electrical properties. The effect of the EP/SiCw interfacial charges and electrical field distortion on the electrical properties of the EP/SiCw composites with different filler content is investigated by the finite-element method (FEM) simulation. It is found that the 2 wt% EP/SiCw composite has a better thermal performance. The 1 wt% has lower real permittivity, lower trap density, lower space charge accumulation, and higher breakdown strength. The EP/SiCw composites have a higher trap level than the pure EP. The nonlinearity percolation threshold of the EP/SiCw composites is 3 wt%. As the filler content increases, the nonlinear conductivity coefficient of the EP/SiCw composites becomes higher, whereas the breakdown strength decreases due to the electric field distortion near the electrodes caused by the apparent hetero charge accumulation at high filler content. [ABSTRACT FROM AUTHOR]

Die-bonding materials are essential packaging materials for high-power light-emitting diodes (LEDs), which affects their heat dissipation and reliability. In this work, a die-bonding structure with high strength and low thermal resistance was proposed for high-power LEDs. A Cu-foam/Sn composite preform was prepared as the die-bonding material in this die-bonding structure. The composite preform is composed of high-melting-point Cu skeleton and low-melting-point Sn. The Cu-skeleton structure accelerates the bonding process and forms intermetallic compounds (IMCs) with high remelting point. Consequently, the die-bonding structure displays robust joints from the transient-liquid-phase (TLP) interconnection layer and high thermal conductivity from the Cu skeleton. The effects of bonding temperature on the mechanical and thermal properties of LEDs were investigated. After bonded with the Cu-foam/Sn composite preform, the LED achieves a low thermal resistance of 6.75 K/W, a low junction temperature change of 6.5 °C, and a high shear strength of 37.8 MPa. Moreover, the proposed die-bonding structure has a lower thermal resistance and higher light output power, which are 27.2% lower and 7.2% higher than the traditional die-bonding structure, respectively. [ABSTRACT FROM AUTHOR]

The traditional cup-shaped LED packaged with epoxy molding compound materials (EMC-LED) and chip-scale packaged LED (CSP-LED) were prepared and analyzed in this article. It is found that high temperature can result in the spectrum red shift and the photoelectric performance degradation for these LEDs due to the degradation of chip and packaging materials. Compared with EMC-LED, the CSP-LED device has a lower thermal resistance of 3.31 °C/W due to the shorter thermal dissipation path and has better stability under the different temperature and drive current conditions. All the simulation results agree well with experimental and theoretical results, indicating that the photoelectric and thermal properties of the CSP-LED can be improved by introducing ceramic substrate and optimizing the material of the interconnected surface and the size of the conduction area. These results have guiding significance for the future CSP-LED design and application. [ABSTRACT FROM AUTHOR]

This work investigates the effect of graphene filler in epoxy resin with the purpose of developing an improved thermally conductive epoxy encapsulation material for electronic devices. The findings in this work show that the thermal conductivity increases by a factor of about 1.6 times with 0.1 wt% loading of graphene in epoxy resin. The increase in the rate of surface charge verifies an improved anti-static property. On examining the phase resolved partial discharge patterns, it is observed that the inception voltage and the number of partial discharge pulses is lower for the filled epoxy compared to that of the neat epoxy. The increase in the rate of surface charge decay indicates an improved anti-static property. The findings in this paper provide a reference in the development of materials with improved thermal conductivity and anti-static properties for graphene/epoxy materials for use in the packaging of electronic devices. [ABSTRACT FROM AUTHOR]