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- 摘要
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Bonding of Large Substrates by Silver Sintering and Characterization of the Interface Thermal Resistance
摘要： Low-temperature silver sintering technology, which has been proven to be a promising die-attach solution, was extended to bonding large substrates. Strong bonding strengths for substrates greater than 25 mm × 50 mm were achieved by sintering a nanosilver paste at temperatures below 270oC with less than 5 MPa pressure. To characterize the thermal performance of the substrate-attach interface, we applied a transient thermal technique with cumulative structure function analysis. Using self-heating and temperature-sensitive threshold voltage of a power device, we measured the transient thermal responses of the device placed at various locations on the bonded structures. Each transient thermal response was used to determine cumulative structure function, which represents the relationship between cumulative thermal capacitance and cumulative thermal resistance from the device junction to the ambient environment. Two-dimensional maps corresponding to interface thermal resistance were obtained from structure function plots. We found that for well-bonded substrates, the average specific thermal resistance contributed by the sintered silver interface was between 5.20 mm2K/W and 5.78 mm2K/W with a variation of 4.7% to 6.0%.
关键词： silver sintering,Substrate-attach,two-dimensional map of interface thermal resistance,transient thermal characterization
更新于2025-09-23 15:23:52
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Thermal Analysis on the Degradation of GaN HEMTs
摘要： High temperature operation(HTO) experiments were performed on industrial GaN HEMTs devices. Several degradation failure modes of DC parameters such as transconductance reduction, threshold voltage shift, and gate leakage current increase were identified. The vertical failure localization and analysis of the devices were carried out by electrical method. The results show that the increase of the degradation of the die attach layer is the main reason for the increase of the junction temperature and thermal resistance of the devices. Furthermore, the results are analyzed by three-dimensional X-ray imaging confirming the degradation of the die attach layer. The voids in the die attach layer expanded during the high temperature operation stress experiments, led to a worse heat dissipation performance, which resulting in increased junction temperature, and further accelerate the performance degradation of the devices.
关键词： junction temperature,thermal resistance,reliability,GaN
更新于2025-09-23 15:22:29
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LTspice Electro-Thermal Model of Joule Heating in High Density Polyethylene Optical Fiber Microducts
摘要： At present, optical fiber microducts are joined together by mechanical type joints. Mechanical joints are bulky, require more space in multiple duct installations, and have poor water sealing capability. Optical fiber microducts are made of high-density polyethylene which is considered best for welding by remelting. Mechanical joints can be replaced with welded joints if the outer surface layer of the optical fiber microduct is remelted within one second and without thermal damage to the inner surface of the optical fiber duct. To fulfill these requirements, an electro-thermal model of Joule heat generation using a copper coil and heat propagation inside different layers of optical fiber microducts was developed and validated. The electro-thermal model is based on electro-thermal analogy that uses the electrical equivalent to thermal parameters. Depending upon the geometric shape and material properties of the high-density polyethylene, low-density polyethylene, and copper coil, the thermal resistance and thermal capacitance values were calculated and connected to the Cauer RC-ladder configuration. The power input to Joule heating coil and thermal convection resistance to surrounding air were also calculated and modelled. The calculated thermal model was then simulated in LTspice, and real measurements with 50 μm K-type thermocouples were conducted to check the validity of the model. Due to the non-linear transient thermal behavior of polyethylene and variations in the convection resistance values, the calculated thermal model was then optimized for best curve fitting. Optimizations were conducted for convection resistance and the power input model only. The calculated thermal parameters of the polyethylene layers were kept intact to preserve the thermal model to physical structure relationship. Simulation of the optimized electro-thermal model and actual measurements showed to be in good agreement.
关键词： thermal capacitance,RC-ladder,electro-thermal model,thermal resistance,Cauer network,high-density polyethylene,Foster network
更新于2025-09-23 15:21:01
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Contents: (Adv. Funct. Mater. 44/2018)
摘要： Silica nanofibrous membranes produced by direct electrospinning of a sol-gel solution without a sacrificing polymer allow high-end separation and purification due to a high thermal and chemical resistance. The water repellent or absorbing nature can be tuned by applying a humidity or thermal treatment. It is showcased that fast gravity driven membrane separation of heterogeneous azeotropes can be achieved.
关键词： thermal resistance,chemical resistance,sol-gel,electrospinning,azeotrope separation,silica nanofibrous membranes
更新于2025-09-23 15:21:01
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Continuous-wave operation of a 1.3 <i>??</i> m wavelength npn AlGaInAs/InP transistor laser up to 90 ?°C
摘要： A transistor laser (TL) is a device that operates at a high-speed with multiple functions such as output control with low wavelength shift and signal mixing. By adopting a high heat dissipation structure with a high-speed compatible wide electrode pad and thick Au plating in TLs, improvement of temperature performance in 1.3 μm wavelength npn AlGaInAs/InP TL was demonstrated. As a result, continuous-wave operation of a 1.3 μm TL up to 90 °C was achieved. The thermal resistance was estimated to be 25 K W?1, based on the spectrum behavior, which is at least four times lower than the previously observed value.
关键词： transistor laser,AlGaInAs/InP,continuous-wave operation,thermal resistance,high heat dissipation structure
更新于2025-09-23 15:21:01
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Discrete-Pulsed Current Time Method to Estimate Channel Thermal Resistance of GaN-Based Power Devices
摘要： A simple electrical method to extract device channel thermal resistance in transistors is presented here. The method compares the dc to discrete-pulsed characteristics and estimates the effective increase in channel temperature under dc biasing conditions. Using the discrete-pulsed I versus t method, the self-heating of the device is effectively eliminated, which helps avoiding the underestimation of the device channel thermal resistance, therefore, making it possible to perform thermal measurements at the high power operation. This technique was applied to lateral GaN HEMTs with three different substrates as well as vertical GaN current aperture vertical electron transistor (CAVET) on sapphire, which proved its sensitivity and validity for different device structures and geometries.
关键词： high-electron mobility transistors (HEMTs),self-heating,current aperture vertical electron transistor (CAVET),Channel thermal resistance
更新于2025-09-23 15:21:01
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Research on Thermal Analysis of Iris Recognition Module Package Structure
摘要： The existing iris recognition module is realized by assembly, which has large volume, high power consumption. The iris recognition module does not conform to the light and thin development trend of integrated circuits. Therefore, the industry is considering building a new iris recognition module from the bare chip and micro interconnect technology. The new module integrates a number of bare chips and passive devices in a limited space, and its thermal performance becomes more complex. It performance systematically. In this paper, thermal performance of the iris recognition module is systematically studied by the finite element method, and the influence of the thermal power of the chip, the thermal conductivity of the material and the area of PCB on the temperature and thermal resistance of the package are discussed. The results show that the thermal conductivity of chip material, the thermal power consumption of chip and the area of PCB have significant influence on packaging junction and thermal resistance of package. Package junction temperature and thermal resistance first decrease rapidly with the heat transfer coefficient of the package material, and then gradually tends to be horizontal, The effect of PCB area on the thermal performance of packaging is similar to that of the loading material, and the thermal dissipation power of the package is linearly increasing with the junction temperature of the package, and it has a horizontal linear relationship with the thermal resistance of the package.
关键词： microinterconnection technology,iris identification module,package junction temperature,package thermal resistance
更新于2025-09-23 15:21:01
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Thermal design for the package of high-power single-emitter laser diodes
摘要： An analytical three-dimensional thermal model is employed to perform the thermal design for the package of high-power single-emitter laser diodes. Thermal design curves for the heat sink and submount are presented in detail, for laser diodes subjected to several convective heat transfer conditions on the bottom of the heat sink. An effective heat spreading angle is proposed to characterize thermal design for the heat sink. A differential heat spreading angle is proposed to clearly manifest heat flow in the packages. Full width and length at 90% energy are introduced to reveal the requirement of submount width and length, respectively. The impact of coefficient of thermal expansion (CTE)-matched sandwiched submount on total heat dissipation is studied. Special discussion is presented for a commercial F-Mount laser diode, and it is found that current heat sink design leads to a 27.4% increase in thermal resistance relative to a free lateral diffusion package.
关键词： Thermal resistance,Heat spreading angle,Submount,Heat sink,Thermal design,High-power laser diodes
更新于2025-09-23 15:19:57
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Thermal management of high-power LED based on thermoelectric cooler and nanofluid-cooled microchannel heat sink
摘要： Effective thermal management for light-emitting diodes (LEDs) is critical, as temperature significantly affects their lifetime and performance. In this study, a system combining a thermoelectric cooler (TEC) and a microchannel heat sink (MHS) is investigated experimentally for thermal management of high-power LEDs. Nanofluids and water are used as coolant. The LED substrate temperature (Ts) is measured at various TEC powers, nanofluid concentrations, ambient temperatures of LED (Ta), and ambient temperatures of the fluid radiator (Ta,f). The effective thermal resistance (Rs-fa) of the LED substrate to the ambient of the fluid radiator is analyzed. Correlations of Ts and Rs-fa are obtained. Results show that the Ts is lowest when the TEC works at its rated power, and Ts is lower than Ta at Ta ≥ 55 °C. Using nanofluids instead of water as coolant reduces the Ts by up to 18.5 °C and decreases the thermal resistance by as much as 42.4%. The MHS heat transfer capacity is increased by 38.6%. The Ta,f exhibites greater influence on Ts compared to Ta. Results show that favorable performance of the thermal management of the high-power LED is obtained by the proposed nanofluid-cooled TEC-MHS system, particularly at high ambient temperature of LED.
关键词： Thermal management,Nanofluid,LED,Thermoelectric cooler,Thermal resistance,Microchannel heat sink
更新于2025-09-23 15:19:57
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Microstructure Influence of SACX0307-TiO2 Composite Solder Joints on Thermal Properties of Power LED Assemblies
摘要： The effect of the microstructure of solder joints on the thermal properties of power LEDs is investigated. Solder joints were prepared with different solder pastes, namely 99Sn0.3Ag0.7Cu (as reference solder) and reinforced 99Sn0.3Ag0.7Cu–TiO2 (composite solder). TiO2 ceramic was used at 1 wt.% and with two different primary particle sizes, which were 20 nm (nano) and 200 nm (submicron). The thermal resistance, the electric thermal resistance, and the luminous efficiency of the power LED assemblies were measured. Furthermore, the microstructure of the different solder joints was analyzed on the basis of cross-sections using scanning electron and optical microscopy. It was found that the addition of submicron TiO2 decreased the thermal and electric thermal resistances of the light sources by 20% and 16%, respectively, and it slightly increased the luminous efficiency. Microstructural evaluations showed that the TiO2 particles were incorporated at the Sn grain boundaries and at the interface of the intermetallic layer and the solder bulk. This caused considerable refinement of the Sn grain structure. The precipitated TiO2 particles at the bottom of the solder joint changed the thermodynamics of Cu6Sn5 formation and enhanced the spalling of intermetallic grain to solder bulk, which resulted in a general decrease in the thickness of the intermetallic layer. These phenomena improved the heat paths in the composite solder joints, and resulted in better thermal and electrical properties of power LED assemblies. However, the TiO2 nanoparticles could also cause considerable local IMC (Intermetallic Compounds) growth, which could inhibit thermal and electrical improvements.
关键词： power LED,SAC composite alloy,TiO2 ceramic,luminous efficiency,thermal resistance,microstructure characterization
更新于2025-09-23 15:19:57