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The high integration density of microelectronic devices leads to local heat accumulation, and effective heat dissipation and signal transmission of packaging materials have become the primary issues to be solved. However, existing polymer materials have difficulty meeting the requirements due to their unsatisfactory thermal conductivity and thermal expansion properties. In this work, we proposed the use of digital light processing (DLP) printing technology to construct a triply periodic minimum surface (TPMS) skeleton, and a continuous and efficient heat conduction path was successfully constructed in epoxy resin by impregnating h-BN on the skeleton surface. When the loading of h-BN was 20 vol%, the thermal conductivity of the TPMS(SiO 2)@BN/EP(BN) composites was 1.86 W/(m·K), which was 786 % higher than that of pure epoxy resin. In addition, the thermal expansion coefficient of the composites decreased by more than 70 %. At the test frequencies of 3∼10 MHz, the composites showed stable dielectric properties, and the dielectric constant was always maintained in a low range, between 3.85 and 4.15. This work has realized the transformation of the method for constructing a heat conduction path from disordered to ordered and from random to repeatable. This provides a new strategy for the selection of microelectronic packaging materials. [ABSTRACT FROM AUTHOR]

A multicolour LED is a miniaturized, long-lasting, and easy-to-achieve colour adjustable emission light source. It is widely used in outdoor displays and room lighting fields. However, the increase in the cost and the decrease in luminous efficiency when adjusting lighting colours have constrained the development of multicolour LEDs. In this study, we initially designed a phosphor conversion pixel array through optical simulation and then prepared the phosphor conversion pixel arrays with different layouts using a semi-cured template method. Finally, we packaged the phosphor conversion pixel array with the blue LED array as a remote phosphor LED. The measurement of the luminous performance indicated that the colour gamut of multicolour LEDs was included in the simulated colour gamut, and the colour of the light was consistent with the design guidelines. Notably, the multicolour LED emission efficiency packaged with a phosphor conversion pixel array could reach 125 lm/W, and the hexagonal phosphor conversion pixel array had better emission performance than the square phosphor conversion pixel array. • Based on the Monte Carlo principle, multicolour LEDs composed of array phosphor-converted film and blue-LED chip are designed. • Phosphor-converted pixel arrays are prepared by semi-cured template method with high moulding quality. • By comparing the experimental and simulation results, colour-tuneable characteristics of the multicolour LEDs is verified. • The luminous efficiency of multicolour LEDs reach up to 125.0 lm/W and changing pixel can reduce the secondary reabsorption of fluorescence. [ABSTRACT FROM AUTHOR]

A Cu-coated Al 2 O 3 substrates which can be used for power modules are prepared via sintering and reduction of CuO–SiO 2 film onto the surface of Al 2 O 3 ceramic without precious metal brazing filler or high-vacuum equipment. This method has a significant cost advantage over the existing technology. Effects of oxygen partial pressure from sintering atmosphere and SiO 2 content on microstructure and mechanical properties of Cu/Al 2 O 3 interface are systematically investigated. Phase compositions and morphologies of sintered Cu 2 O layer, reduced Cu layer and reactive layer are characterized via X-ray diffraction and scanning electron microscopy. In addition, physicochemical changes within CuO–SiO 2 during sintering are characterized by thermogravimetry-differential scanning calorimeter. It is found that oxygen and SiO 2 can promote the generation of Cu 2 O–CuO–SiO 2 eutectic phase with low melting point upon sintering, which increases the thickness of reaction layer and the densification of Cu layer. The shear strength between the Cu layer and the Al 2 O 3 substrate is enhanced with the increase in Cu layer densification degree, while varying in irregular manner with the thickness of reaction layer. In particular, the highest shear strength of 62.70 MPa is obtained at oxygen partial pressure of 0.02 atm and SiO 2 content of 1.5 wt%. [ABSTRACT FROM AUTHOR]