Development and application of ferrite materials for low temperature co-fired ceramic （LTCC） technology are dis- cussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZ...Development and application of ferrite materials for low temperature co-fired ceramic （LTCC） technology are dis- cussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 ℃. These ferrite materials are research focuses and are applied in many ways in electronics.展开更多
Modern electronic circuit requires compact,multifunctional technology in communication systems.However,it is very difficult due to the limitations in passive component miniaturization and the complication of fabricati...Modern electronic circuit requires compact,multifunctional technology in communication systems.However,it is very difficult due to the limitations in passive component miniaturization and the complication of fabrication process.The bandpass filter is one of the most important passive components in millimeter（mm）-wave communication system,attracting significant interest in three-dimension（3D） miniaturized design,which is few reported.In this paper,a bandpass filter structure using low-temperature co-fired ceramic（LTCC） technology,which is fully integrated in a system-in package（SIP） communication module,is presented for miniaturized and high reliable mm-wave application.The bandpass filter with 3D end-coupled microstrip resonators is implemented in order to achieve a high performance bandwidth characteristic.Specifically,all of the resonators are embedded into different ceramic layers to decrease the insertion loss and enhance the out-of-band rejection performance by optimizing the coupling coefficient and the coupling strength.A fence structure,which is formed by metal-filled via array with the gap less than quarter wavelength,is placed around the embedded bandpass filter to avoid electromagnetic（EM） interference problem in multilayer structure.This structural model is validated through actual LTCC process.The bandpass filter is successfully manufactured by modifying the co-fireablity characteristics,adjusting the sintering profile,releasing the interfacial stress,and reducing the shrinkage mismatch with different materials.Measured results show good performance and agree well with the high frequency EM full wave simulation.The influence of layer thickness and dielectric constant on the frequency response in fabricated process is analyzed,where thicker ceramic sheets let the filter response shift to higher frequency.Moreover,measured S-parameters denote the center frequency is also strongly influenced by the variation of ceramic material＇s dielectric constants.By analyzing the relationship between the characteristics of the ceramic tape and the center frequency of the filter,both theoretical and experimental data are accumulated for broadening application filed.With the coupling resonators embedded into the ceramic layers,the bandpass filter exhibits advantages of small size and high reliability compared to conventional planar filter structure,which makes the bandpass filter suitable for SIP communicational application.展开更多
The quality of a via hole on a multilayer stack of Low Temperature Co-fired Ceramic (LTCC) tape is of utmost importance to its functionality. This paper investigates a substitute for the commonly used circular shape h...The quality of a via hole on a multilayer stack of Low Temperature Co-fired Ceramic (LTCC) tape is of utmost importance to its functionality. This paper investigates a substitute for the commonly used circular shape hole to a more complex one and its implications when different parameters such as sheet thickness, punch speed, travel distance and tool clearance are?changed. Fabrication of the punch tools and the punching process is carried out at the same machine, ensuring alignment. Two types of non-circular shape are chosen to carry out the experiment. Pre-sintered complex shape hole measurements show that while punch conditions such as speed and tool gap have?little effect on the size, sheet thickness and travel depth play a vital role in the overall dimension. Albeit having only a slight effect on the size, those parameters are significant in other aspects of hole quality. Post-sintering investigation is also observed and discussed.展开更多
The study of swirling jet combustor for biomass coal co-firing is of great interest for energy industry. The biomass co-firing can serve as a NOx reduction method as well as the better use of renewable energy source. ...The study of swirling jet combustor for biomass coal co-firing is of great interest for energy industry. The biomass co-firing can serve as a NOx reduction method as well as the better use of renewable energy source. Large eddy simulation (LES) and RANS modelling have been performed with two different burner designs. Usually pulverized coal-biomass mixture enters the furnace along with primary air through primary pipe, and the secondary pipe provides necessary air and mixing for combustion. The improved model has three passages including primary, secondary and middle passage for swirling. The simulations on two geometries have been compared, and the aim is to design a better and improved burner model for better pre-combustion mixing in the biomass co- fired furnace. The results from two-way and three-way geometry have been compared with each other as well as with the results from the furnace model used by Apte and Mahesh [8].展开更多
High temperature co-fired ceramics(HTCCs) have wide applications with stable mechanical properties,but they have not yet been used to fabricate sensors.By introducing the wireless telemetric sensor system and ceramic ...High temperature co-fired ceramics(HTCCs) have wide applications with stable mechanical properties,but they have not yet been used to fabricate sensors.By introducing the wireless telemetric sensor system and ceramic structure embedding a pressure-deformable cavity,the designed sensors made from HTCC materials(zirconia and 96% alumina) are fabricated,and their capacities for the pressure measurement are tested using a wireless interrogation method.Using the fabricated sensor,a study is conducted to measure the atmospheric pressure in a sealed vessel.The experimental sensitivity of the device is 2 Hz/Pa of zirconia and 1.08 Hz/Pa of alumina below 0.5 MPa with a readout distance of 2.5 cm.The described sensor technology can be applied for monitoring of atmospheric pressure to evaluate important component parameters in harsh environments.展开更多
The global transition from fossil fuel-based energy sources to renewable energy sources will be most effective,for at least the near future,by utilizing local resources and existing infrastructure.In many areas of the...The global transition from fossil fuel-based energy sources to renewable energy sources will be most effective,for at least the near future,by utilizing local resources and existing infrastructure.In many areas of the eastern United States,forest residue is abundant and can be used in existing facilities to supplement coal in coal-fired power plants.Thus forest residue has potential as a renewable energy source that could be effectively utilized in the near future.This study uses GIS to estimate the potential quantity of forest residue available for use in coal-fired power plants in the eastern United States.Transportation costs limit the distance over which it is feasible to transport forest residue to the power plants and these costs may fluctuate depending on economic conditions.Thus,we consider three scenarios in our analysis assuming the maximum feasible transport distances to be 60,80,and 100 km.In the eastern U.S.,the total annual forest residue available to coal plants is approximately 29.4,40.2,and 48.2 million dry tons,respectively,for maximum transport distances of 60,80,and 100 km.Assuming an 80 km transport distance,forest residue has the potential to reduce coal consumption by 22.3 million tons per year.Under this scenario,greenhouse gas emissions would be reduced by almost 58.1 million tons per year,and NOx and SOx emissions would be reduced by 69.3 and 122.6 thousand tons respectively.This analysis suggests that by offsetting coal use,forest residue has the potential to substantially reduce power plant emissions.展开更多
基于提升低温共烧陶瓷(low temperature co-fired ceramic,LTCC)厚度的检测精度、测量效率和可溯源性的需求,设计一套LTCC激光测厚系统。针对测量精度难以满足需求的问题,对存在误差进行分析,采用厚度测量用调整夹具消除同轴度误差和线...基于提升低温共烧陶瓷(low temperature co-fired ceramic,LTCC)厚度的检测精度、测量效率和可溯源性的需求,设计一套LTCC激光测厚系统。针对测量精度难以满足需求的问题,对存在误差进行分析,采用厚度测量用调整夹具消除同轴度误差和线性度误差,优化设计结构降低倾角误差,循环传感器标定消除重复度误差,通过数据优化和滤波处理降低机械振动误差,提高了系统测量精度。与实际产品厚度数据对比,最终精度误差≤5μm,符合产品的应用要求,具有广阔的应用市场。展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2012CB933100)the National Natural Science Foundation of China(Grant Nos.51132003,61021061,and 61171047)the Second Item of Strongpoint Industry of Guangdong Province,China(Grant No.2012A090100001)
文摘Development and application of ferrite materials for low temperature co-fired ceramic （LTCC） technology are dis- cussed, specifically addressing several typical ferrite materials such as M-type barium ferrite, NiCuZn ferrite, YIG ferrite, and lithium ferrite. In order to permit co-firing with a silver internal electrode in LTCC process, the sintering temperature of ferrite materials should be less than 950 ℃. These ferrite materials are research focuses and are applied in many ways in electronics.
基金supported by Research Fund for the Doctoral Program of Higher Education of China(Grant No.20060614021)Sichuan Provincial Fundamental Research of China(Grant No.2008JY0057),Fundamental Research Funds for the Central Universities of China(Grant No.ZYGX2009J091)
文摘Modern electronic circuit requires compact,multifunctional technology in communication systems.However,it is very difficult due to the limitations in passive component miniaturization and the complication of fabrication process.The bandpass filter is one of the most important passive components in millimeter（mm）-wave communication system,attracting significant interest in three-dimension（3D） miniaturized design,which is few reported.In this paper,a bandpass filter structure using low-temperature co-fired ceramic（LTCC） technology,which is fully integrated in a system-in package（SIP） communication module,is presented for miniaturized and high reliable mm-wave application.The bandpass filter with 3D end-coupled microstrip resonators is implemented in order to achieve a high performance bandwidth characteristic.Specifically,all of the resonators are embedded into different ceramic layers to decrease the insertion loss and enhance the out-of-band rejection performance by optimizing the coupling coefficient and the coupling strength.A fence structure,which is formed by metal-filled via array with the gap less than quarter wavelength,is placed around the embedded bandpass filter to avoid electromagnetic（EM） interference problem in multilayer structure.This structural model is validated through actual LTCC process.The bandpass filter is successfully manufactured by modifying the co-fireablity characteristics,adjusting the sintering profile,releasing the interfacial stress,and reducing the shrinkage mismatch with different materials.Measured results show good performance and agree well with the high frequency EM full wave simulation.The influence of layer thickness and dielectric constant on the frequency response in fabricated process is analyzed,where thicker ceramic sheets let the filter response shift to higher frequency.Moreover,measured S-parameters denote the center frequency is also strongly influenced by the variation of ceramic material＇s dielectric constants.By analyzing the relationship between the characteristics of the ceramic tape and the center frequency of the filter,both theoretical and experimental data are accumulated for broadening application filed.With the coupling resonators embedded into the ceramic layers,the bandpass filter exhibits advantages of small size and high reliability compared to conventional planar filter structure,which makes the bandpass filter suitable for SIP communicational application.
文摘The quality of a via hole on a multilayer stack of Low Temperature Co-fired Ceramic (LTCC) tape is of utmost importance to its functionality. This paper investigates a substitute for the commonly used circular shape hole to a more complex one and its implications when different parameters such as sheet thickness, punch speed, travel distance and tool clearance are?changed. Fabrication of the punch tools and the punching process is carried out at the same machine, ensuring alignment. Two types of non-circular shape are chosen to carry out the experiment. Pre-sintered complex shape hole measurements show that while punch conditions such as speed and tool gap have?little effect on the size, sheet thickness and travel depth play a vital role in the overall dimension. Albeit having only a slight effect on the size, those parameters are significant in other aspects of hole quality. Post-sintering investigation is also observed and discussed.
文摘The study of swirling jet combustor for biomass coal co-firing is of great interest for energy industry. The biomass co-firing can serve as a NOx reduction method as well as the better use of renewable energy source. Large eddy simulation (LES) and RANS modelling have been performed with two different burner designs. Usually pulverized coal-biomass mixture enters the furnace along with primary air through primary pipe, and the secondary pipe provides necessary air and mixing for combustion. The improved model has three passages including primary, secondary and middle passage for swirling. The simulations on two geometries have been compared, and the aim is to design a better and improved burner model for better pre-combustion mixing in the biomass co- fired furnace. The results from two-way and three-way geometry have been compared with each other as well as with the results from the furnace model used by Apte and Mahesh [8].
基金Project supported by the National Basic Research Program (973) of China (No. 2010CB334703)the National Natural Science Foundation of China (No. 51075375)
文摘High temperature co-fired ceramics(HTCCs) have wide applications with stable mechanical properties,but they have not yet been used to fabricate sensors.By introducing the wireless telemetric sensor system and ceramic structure embedding a pressure-deformable cavity,the designed sensors made from HTCC materials(zirconia and 96% alumina) are fabricated,and their capacities for the pressure measurement are tested using a wireless interrogation method.Using the fabricated sensor,a study is conducted to measure the atmospheric pressure in a sealed vessel.The experimental sensitivity of the device is 2 Hz/Pa of zirconia and 1.08 Hz/Pa of alumina below 0.5 MPa with a readout distance of 2.5 cm.The described sensor technology can be applied for monitoring of atmospheric pressure to evaluate important component parameters in harsh environments.
文摘The global transition from fossil fuel-based energy sources to renewable energy sources will be most effective,for at least the near future,by utilizing local resources and existing infrastructure.In many areas of the eastern United States,forest residue is abundant and can be used in existing facilities to supplement coal in coal-fired power plants.Thus forest residue has potential as a renewable energy source that could be effectively utilized in the near future.This study uses GIS to estimate the potential quantity of forest residue available for use in coal-fired power plants in the eastern United States.Transportation costs limit the distance over which it is feasible to transport forest residue to the power plants and these costs may fluctuate depending on economic conditions.Thus,we consider three scenarios in our analysis assuming the maximum feasible transport distances to be 60,80,and 100 km.In the eastern U.S.,the total annual forest residue available to coal plants is approximately 29.4,40.2,and 48.2 million dry tons,respectively,for maximum transport distances of 60,80,and 100 km.Assuming an 80 km transport distance,forest residue has the potential to reduce coal consumption by 22.3 million tons per year.Under this scenario,greenhouse gas emissions would be reduced by almost 58.1 million tons per year,and NOx and SOx emissions would be reduced by 69.3 and 122.6 thousand tons respectively.This analysis suggests that by offsetting coal use,forest residue has the potential to substantially reduce power plant emissions.
文摘基于提升低温共烧陶瓷(low temperature co-fired ceramic,LTCC)厚度的检测精度、测量效率和可溯源性的需求,设计一套LTCC激光测厚系统。针对测量精度难以满足需求的问题,对存在误差进行分析,采用厚度测量用调整夹具消除同轴度误差和线性度误差,优化设计结构降低倾角误差,循环传感器标定消除重复度误差,通过数据优化和滤波处理降低机械振动误差,提高了系统测量精度。与实际产品厚度数据对比,最终精度误差≤5μm,符合产品的应用要求,具有广阔的应用市场。
