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Background
The association of a broad spectrum of infectious diseases with cardiovascular outcomes remains unclear.
Objectives
We aim to provide the cardiovascular risk profiles associated with a wide range of infectious diseases and explore the extent to which infections reduce life expectancy.
Methods
We ascertained exposure to 900+ infectious diseases before cardiovascular disease (CVD) onset...
3D packaging using through silicon via (TSV) technology is becoming important in IC packaging industry. The polymer material as insulation material was fabricated by the spin-coating or spray-coating process. And the polymer insulation can relax some of the stress induced and makes the process more convenient compared with CVD. Therefore, it is the most cost effective technology for the wafer level...
The root causes of pad cratering may be divided into two categories, namely, overloading induced pad cratering and fatigue induced pad cratering. The former occurs when the interfacial stresses between the epoxy resin and the pad exceed the failure criterion based on the monotonic loading test. The latter happens under cyclic loading conditions, typically with interfacial stresses much lower than...
Post-reflow residual strain is a typical thermo-mechanical phenomenon of printed circuit board assemblies (PCBA) with a large ball grid array (BGA) component after the surface mount process. In general, the post-reflow residual strain may not directly lead to the failure of solder joints, but it may result in a potential risk for another reliability concern, namely, pad cratering. Without sufficient...
Focused ultraviolet (UV) emission is an ideal configuration to achieve in-situ curing. Conventional UV light-emitting diode (LED) packages, such as ceramic substrate packages, cannot achieve focused UV emission because they possess no reflector and lens, which are required to converge light. Plastic reflectors may be used, but common LED packaging plastics suffer from low UV reflectance and UV degradation...
The non-uniform junction temperature may exist in the high-power light-emitting diode (LED) of flip-chip architecture. Detecting the local hot area on the chip is of great importance to the LED thermal management. Most of the common LEDs exhibit a lower forward voltage when its junction temperature is elevated. The local forward voltage deviation will lead to non-uniform current distribution and consequently...
In this study, the influence of the surface curvature of the phosphor layer on the optical performance of white light-emitting diodes (WLEDs) was investigated. Based on the lead frame of a standard 3528 component, WLEDs with various phosphor layer structures were fabricated for investigation. The curvature of the phosphor layer was adjusted by the volume of phosphor slurry. The consumption of phosphor...
In this study, the influence of phosphor particle size gradient on the optical performance of white light-emitting diodes (WLEDs) was investigated. Three multi-size phosphor layer structures with different size gradients were proposed. The YAG:Ce phosphor particles of 3 μm and 13 μm were configured at three different locations to form the size gradient. Both simulation and experimental investigations...
In this study, in order to resolve the low light extraction issue of chip-on-board light-emitting diodes (COB LED), the phosphor layers in COBs were molded into a pattern of cavity arrays to minimize the trapped radiant power by total internal reflection (TIR). Monte-Carlo ray-tracing simulation was performed for extraction efficiency optimization with the same color coordinates (x, y). It was found...
In recent years, LEDs are widely adopted as a new light source in various applications. Among the many advantages of LEDs over traditional light sources, one key advantage is its long lifespan which substantially reduces the overall maintenance cost. Nevertheless, such characteristic causes various difficulties in the prediction of lifespan and reliability assessment. The lifespan of LEDs can be predicted...
Due to the advantages of joint level tests, such as low cost and flexibility, it is always desirable to predict the board level pad cratering strength by a joint level test. In order to achieve this objective, the correlation between the joint level and the board level tests must be fully understood. Nevertheless, a precise correlation between the two types of tests for pad cratering evaluation is...
The bonding layer in the light emitting diode (LED) device of flip-chip or vertical structure is the most critical part to the device performance since it supports the electrical and thermal interconnection between the chip and its carrier. Therefore, the chip bonding process has become one of the major issues in the practical manufacturing. In this study, we developed a novel bonding technique using...
A novel method for the evaluation of thermal conductivity of paste materials is proposed in this paper. The principle is based on the measurement of the thermal conductivity of composite materials together with finite element modeling (FEM). In the present study, the FEM based on the structure and working principle of an apparatus (THISYS) used for measuring the thermal conductivity of thin and solid...
A low-dielectric-constant organosilica was developed for interlayer dielectric, introducing adamantane which possesses low polarity and unique rigid structure. Novel organosilane precursor, adamantane-bridged organosilane precursor, was synthesized and characterized. Precursor was mixed with porogen P123, acid and ethanol to prepare coating solution, and the novel periodic mesoporous organosilica...
Through silicon via (TSV) is an enabling technology for 3D interconnection. The insulation layer at the bottom of the via usually needs to be removed in order to expose the pad so that the electrical interconnection from the front side to the back side can be realized. This removal may be implemented by plasma etching, laser drilling, or photolithography. Compared with the other two methods, photolithography...
Material characterization is a crucial part of BGA thermal warpage evaluation. In principle, the warpage behavior of BGA under temperature change is affected by the elastic modulus and the coefficient of thermal expansion (CTE) of the packaging materials. Therefore, the accuracy of material properties is critical for predicting the warpage trend and quantity. However, due to the rather thin BT substrate,...
Conventional phosphor converted white light LEDs utilize yellow phosphor to convert the blue light emitted from the chip to yellow light. Although this can generate white light with various correlated color temperatures (CCT), the color rendering properties are generally poor as the spectrum of the LEDs, as compared with the reference light source, is not broad enough. The red light output is low...
Thermal management is a critical issue for the packaging of light-emitting diodes (LED). With poor thermal management, the elevated junction temperature of the LED chip will result in shorter life, lower efficiency, and color shifting. As a common practice, people typically used the thermal resistance concept for thermal management. However, this highly simplified model is 1-D in nature. The heat...
Conventional packaging materials for light-emitting diodes (LED) are susceptible to UV radiation and high temperature. Therefore, for developing UV LED packages, new materials with better UV and high temperature resistance are required. There are two candidates, namely, epoxy molding compound (EMC) and silicone molding compound (SMC), being considered by the industry. This paper focuses on the change...
A novel organosilane precursor, (hexfluoropropane-2, 2-diyl)dibenzyl-bridged organosilane (HFPDBO) precursor, was prepared by a simple and facile synthesis. There are some superiorities designed in HFPDBO precursor, for instance, hexfluoro-substitutions and dibenzene can contribute to higher porosity and lower dielectric constant, rigid carbon bridged construction and tetrafunctional organosilane...
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