The effects of sintering parameter to the microstructure and thermal properties of CuSiC composite for electronic packaging application

Microelectronics and nano-electronics play a prominent role in current technologies and will do so to a greater extent in the future. The availability of suitable new materials for the electronic packaging is critical to the continuing advancement (miniaturisation and integration) of electronic components. As matter of fact, a plethora of new products/processes have been brought-in over the last few years. Much of the materials and microstructure research related to packaging has involved investigation toward better thermal management. Miniaturisation of electronic chips which have increasing functionality within the same package size has inducedsignificant increases in requirements for extraction of heat from the integrated circuit (IC). Packaging materials therefore have to be capable to conduct heat efficiently and at the same time have low coefficient of thermal expansion (CTE) to minimize the thermal stress and warping. Since copper (Cu) is a better thermal conductor than aluminium (Al), therefore, copper should be the best candidate as thermal material. With the presence of silicon carbide (SiC) as reinforcement, copper silicon carbide (CuSiC) metal matrix composite (MMC) should be able to perform better as a heat spreader or a heat sink than aluminium silicon carbide (AlSiC) metal matrix composite. In the present study, the focus was toward development of light weight metal matrix composite with high ceramic contents, good thermal dissipation and easy of processability. Copper silicon carbide was chosen as the material basis for focused investigation to solve thermal management problems presented by current IC systems. Powder metallurgy routes were chosen to fabricate the MMC based on this materials system. Copper and silicon carbide powders were mixed together in a planetary ball mill, and the green articles were then compacted and sintered to produce the final product of CuSiC. The effects of sintering parameters were investigated for their effects towards the produced composite density, porosity and specific heat capacity. Sintering parameters investigated included temperature, heating duration and the gaseous environment. Upon sintering, the CuSiC particle bond to one another giving a higher strength and a possibility in attaining desirable density. The higher in density and the lower in porosity of the CuSiC composite, will create a low specific heat capacity characteristic which is closer to the specific heat capacity of pure copper (Cu). Thus to achieve the lower specific heat capacity, the amount of porosity in the CuSiC composite must be minimized through the optimization of the sintering parameters.Finally in a nutshell, in order to boost the specific heat capacity of the CuSiC, the recommended sintering parameter suggests that the CuSiC composite should be sintered at 950oC for seven hours in nitrogen gas

Application of a stochastic weather generator to assess climate change impacts in a semi-arid climate: The Upper Indus Basin

Assessing local climate change impacts requires downscaling from Global Climate Model simulations. Here, a stochastic rainfall model (RainSim) combined with a rainfall conditioned weather generator (CRU WG) have been successfully applied in a semi-arid mountain climate, for part of the Upper Indus Basin (UIB), for point stations at a daily time-step to explore climate change impacts. Validation of the simulated time-series against observations (1961–1990) demonstrated the models’ skill in reproducing climatological means of core variables with monthly RMSE of <2.0 mm for precipitation and ⩽0.4 °C for mean temperature and daily temperature range. This level of performance is impressive given complexity of climate processes operating in this mountainous context at the boundary between monsoonal and mid-latitude (westerly) weather systems. Of equal importance the model captures well the observed interannual variability as quantified by the first and last decile of 30-year climatic periods. Differences between a control (1961–1990) and future (2071–2100) regional climate model (RCM) time-slice experiment were then used to provide change factors which could be applied within the rainfall and weather models to produce perturbed ‘future’ weather time-series. These project year-round increases in precipitation (maximum seasonal mean change:+27%, annual mean change: +18%) with increased intensity in the wettest months (February, March, April) and year-round increases in mean temperature (annual mean +4.8 °C). Climatic constraints on the productivity of natural resource-dependent systems were also assessed using relevant indices from the European Climate Assessment (ECA) and indicate potential future risk to water resources and local agriculture. However, the uniformity of projected temperature increases is in stark contrast to recent seasonally asymmetrical trends in observations, so an alternative scenario of extrapolated trends was also explored. We conclude that interannual variability in climate will continue to have the dominant impact on water resources management whichever trajectory is followed. This demonstrates the need for sophisticated downscaling methods which can evaluate changes in variability and sequencing of events to explore climate change impacts in this region

The outcome of sintering parameters study toward the thermal properties of CuSiC composite

Miniaturisation of electronic chips which have increasing functionality within the same package size has induced significant increases in requirements for extraction of heat from the integrated circuit (IC). Packaging materials therefore have to be capable to conduct heat efficiently and at the same time have low coefficient of thermal expansion (CTE) to minimize the thermal stress and warping. In the present study, copper silicon carbide was selected with an aim to solve thermal management problem presented by current IC systems. Powder metallurgy routes were chosen to fabricate the MMC based on this materials system. Copper and silicon carbide powders were mixed together in a planetary ball mill, and the green articles were then compacted and sintered to produce the final product of CuSiC. The sintering parameters were investigated for their effects towards the thermal conductivity of the composite. Sintering parameters investigated included temperature, heating duration and the gaseous environment. Upon sintering, the CuSiC particle bond to one another giving a higher strength and a possibility in attaining desirable density. Thus to achieve good thermal conductivity, the recommended sintering parameter suggests that the CuSiC composite should be sintered at 950oC for 7 hours in nitrogen gas

The effects of sintering parameter to the microstructure and thermal properties of CuSiC composite for electronic packaging application

Microelectronics and nano-electronics play a prominent role in current technologies and will do so to a greater extent in the future. The availability of suitable new materials for the electronic packaging is critical to the continuing advancement (miniaturisation and integration) of electronic components. As matter of fact, a plethora of new products/processes have been brought-in over the last few years. Much of the materials and microstructure research related to packaging has involved investigation toward better thermal management. Miniaturisation of electronic chips which have increasing functionality within the same package size has inducedsignificant increases in requirements for extraction of heat from the integrated circuit (IC). Packaging materials therefore have to be capable to conduct heat efficiently and at the same time have low coefficient of thermal expansion (CTE) to minimize the thermal stress and warping. Since copper (Cu) is a better thermal conductor than aluminium (Al), therefore, copper should be the best candidate as thermal material. With the presence of silicon carbide (SiC) as reinforcement, copper silicon carbide (CuSiC) metal matrix composite (MMC) should be able to perform better as a heat spreader or a heat sink than aluminium silicon carbide (AlSiC) metal matrix composite. In the present study, the focus was toward development of light weight metal matrix composite with high ceramic contents, good thermal dissipation and easy of processability. Copper silicon carbide was chosen as the material basis for focused investigation to solve thermal management problems presented by current IC systems. Powder metallurgy routes were chosen to fabricate the MMC based on this materials system. Copper and silicon carbide powders were mixed together in a planetary ball mill, and the green articles were then compacted and sintered to produce the final product of CuSiC. The effects of sintering parameters were investigated for their effects towards the produced composite density, porosity and specific heat capacity. Sintering parameters investigated included temperature, heating duration and the gaseous environment. Upon sintering, the CuSiC particle bond to one another giving a higher strength and a possibility in attaining desirable density. The higher in density and the lower in porosity of the CuSiC composite, will create a low specific heat capacity characteristic which is closer to the specific heat capacity of pure copper (Cu). Thus to achieve the lower specific heat capacity, the amount of porosity in the CuSiC composite must be minimized through the optimization of the sintering parameters.Finally in a nutshell, in order to boost the specific heat capacity of the CuSiC, the recommended sintering parameter suggests that the CuSiC composite should be sintered at 950oC for seven hours in nitrogen gas

Improving accuracy of downscaling rainfall by combining predictions of different statistical downscale models

A flexible framework of multi-model of three statistical downscaling approaches was established in which predictions from these models were used as inputs to Artificial Neural Network (ANN). Traditional ANN, Simple Average Method (SAM), and combining models (SDSM, Multiple Linear Regressions (MLR), Generalized Linear Model (GLM)) were applied to a studied site in North-western England. Model performance criteria of each of the primary and combining models were evaluated. The obtained results indicate that different downscaling methods can gain diverse usefulness and weakness in simulating various rainfall characteristics under different circumstances. The combining ANN model showed more adaptability by acquiring better overall performance, while GLM, MLR and showed comparable results and the SDSM reveals relatively less accurate results in modelling most of the rainfall amount. Furthermore traditional ANN has been tested and showed poor performance in reproducing the observed rainfall compared with above methods. The results also show that the superiority of the combining approach model over the single models is promising to be implemented to improve downscaling rainfall at a single site

Risk assessment of heavy metals pollution in agricultural soils of siling reservoir watershed in Zhejiang province, China

10.1155/2013/590306BioMed Research International201359030

Charting achievements:a two-year retrospective of the society for environmental geochemistry and health (SEGH) and the evolving strategies

Emerging from the shadow of the COVID-19 pandemic, it is time to ground ourselves and retrospectively assess the recent achievements of SEGH over the past years. This editorial serves as a comprehensive report on the progress made in comparison to the aspirations and goals set by the society's board in 2019 (Watts et al., Environ Geochem Health 42:343–347, 2019) (Fig. 1) and reflects on the state of the SEGH community as it reached its 50th anniversary at the close of 2021 (Watts et al. Environ Geochem Health 45:1165–1171, 2023). The focus lies on how the SEGH community navigated through the extraordinary challenges posed by the COVID-19 pandemic since early 2020, and to what extent the 2023 targets have been met