共查询到20条相似文献,搜索用时 296 毫秒
1.
大功率LED的热阻测量与结构分析 总被引:4,自引:1,他引:3
热阻的精确测量与器件结构分析是设计具有优良散热性能的大功率LED的前提。本文研究了大功率LED的光功率、环境温度和工作电流对热阻的影响规律,论述了积分式结构函数和微分式结构函数的推导过程及其主要性质,提出了大功率LED热阻的精确测量方法,并利用结构函数分析及辨识大功率LED器件的内部结构、尺寸、材料、制造缺陷和装配质量。 相似文献
2.
散热是大功率LED封装的关键技术之一,散热不良将严重影响LED器件的出光效率、亮度和可靠性。影响LED器件散热的因素很多,包括芯片结构、封装材料(热界面材料和散热基板)、封装结构与工艺等。文章具体分析了影响大功率LED热阻的各个因素,指出LED散热是一个系统概念,需要综合考虑各个环节的热阻,单纯降低某一热阻无法有效解决LED的散热难题。文中还对国内外降低LED热阻的最新技术进行了介绍。 相似文献
3.
倒装芯片衬底粘接材料对大功率LED热特性的影响 总被引:6,自引:0,他引:6
针对倒装芯片(Flipchip)大功率发光二极管器件,描述了大功率LED器件的热阻特性,建立了Flipchip衬底粘接材料的厚度和热导系数与粘接材料热阻的关系曲线,以三类典型粘接材料为例计算了不同厚度下的热阻,得出了Flipchip衬底粘接材料选择的不同对大功率LED的热阻存在较大影响的结论. 相似文献
4.
准确测量大功率LED的热阻,关键是准确地确定LED的结温增量.首先利用正向电压法获得LED的结温;通过测量LED的降温曲线,计算获得LED稳定工作时底座的温度,从而得到LED的结温相对底座温度的增量.然后,再与注入电功率相除,即可得到准确的热阻.与常规方法相比,避免了直接测量LED底座温度中界面热阻的影响,使得测量LED的热阻更加准确、方便.该方法还可以用于测量贴片封装LED等常规方法难以测量的LED以及用于分析大功率LED二次封装时引入的热阻,为评价大功率LED的封装质量提供了一种有效的评测手段. 相似文献
5.
为解决大功率LED的散热问题,提出一种应用于大功率LED散热的微型回路热管,研究了充液率和倾斜角度对热管冷却大功率LED的启动性能、结温和热阻等特性的影响.研究结果表明:热管的最佳充液率为60%,系统的总热阻为7.5 K/W,此时对应的热管的热阻为1.6 K/W;热管的启动时间约为6.5 min,LED的结点温度被控制在42℃以下,很好地满足了大功率LED的结温稳定性要求. 相似文献
6.
7.
8.
游志 《现代表面贴装资讯》2011,(1):40-42
本文利用热瞬态分析仪T3ster测试了大功率LED封装阵列中不同阵列点热阻的变化,得到结论:在散热基板中心点处热阻最小,距中心点越远热阻越大,并且热阻与距离呈线性关系。通过分析得到热阻增加的部分为扩散热阻,所以扩散热阻应作为大功率LED封装阵列设计的考虑因素之一。 相似文献
9.
从色度学方面探讨了大功率发光二极管(LED)的可靠性,证实设计问题是影响大功率LED可靠性的主要因素。并分析了热阻的不合理减小会影响产品的可靠性。 相似文献
10.
11.
High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET > PDMAT > TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center. 相似文献
12.
In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal (200) (2d = 0.4027 nm) is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line(w), the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line(x), the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines(y), the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line(z) in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line(q) in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution(λ/△ 2) is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy. 相似文献
13.
This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors. 相似文献
14.
YUXiao-hua XIANGYu-qun 《半导体技术》2005,30(2):30-32,37
An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB. 相似文献
15.
The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO>6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs. 相似文献
16.
We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network. 相似文献
17.
Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources' evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping (266 nm) at power densities of 25-153 kW/cm^2. The full width half maximum (FWHM) of the lasing mode is 0.67 nm 相似文献
18.
TANG Bin JIANG Xing-fang LIU Zhi-min 《光电子快报》2008,4(1):78-80
By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly. 相似文献
19.
Tian-hua Xu Feng Tang Wen-cai Jing Hong-xia Zhang Da-gong Ji Chang-song Yu Ge Zhou Yi-mo Zhang 《光电子快报》2008,4(4):292-294
Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited. 相似文献
20.
《中国通信》2014,(9)
正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its 相似文献