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为了保证陶瓷栅格阵列(CLGA)封装器件装联可靠性,本文以CLGA封装器件为研究对象,采用Pb90Sn10焊球、Pb90Sn10与Pb80Sn20焊柱、Be-Cu/Sn60Pb40微弹簧圈(MCS)和Sn63Pb37共晶焊料,实现了对CLGA封装器件的二次工艺设计,并采用回流焊工艺方法将器件装联在印制电路板上。通过有限元分析及试验相结合的方法,探索了适用于此类器件的高可靠性装联工艺。对3种元器件建立有限元仿真模型来模拟应力应变情况,同时对印制板组件进行了力学、热学实验分析。仿真发现:弹簧所受的应力和应变最小,焊柱其次,焊球最大;试验验证与仿真结果相符:植弹簧的器件可靠性最高,植焊柱的其次,植焊球的最差;500个温度循环与振动试验表明:植弹簧器件无裂纹,植焊柱、植焊球的器件出现裂纹,焊点金相剖切与SEM能谱显微组织分析均符合航天标准要求。植焊球、植焊柱的器件焊点断裂失效位置均出现在焊球、焊柱与钎料印制板接触的位置,且裂纹处金属间化合物(IMC)层厚度与能谱成分未见异常。 相似文献
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焊膏喷印技术是一种不需要钢网工装,直接将焊料按照设定的形状和厚度喷到印制板对应焊盘上的
工艺方法。焊膏喷印的位置及喷印量可灵活编程控制,适用于多品种、小批量的研发生产。在航空电子产品组
装过程中,片式贴装元器件在回流焊后出现较多锡珠的问题影响了焊膏喷印工艺的推广应用,经过工艺分析和
DOE 试验,在不降低锡量,甚至增加锡量的情况下,将锡珠产生率降低85%,满足IPC-A-610 的3 级高性能
电子产品要求。 相似文献
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本文研制了急冷及普通Al基中间层材料,并对其性能及其在对Si_3N_4陶瓷进行扩散焊时用作中间层进行了研究。结果表明:Al基中间层经急冷凝固处理后组织细小,成分均匀,硬度高,熔点低。接头的剪切强度试验结果表明:在同一扩散焊工艺条件下,急冷中间层接头的剪切强度明显高于普通中间层接头的剪切强度。其中急冷Al-Si-In-Ti-Zn-Mg中间层接头在扩散焊温度为475℃时(保温时间30min,压力为15MPa),强度最高(50MPa)。随着扩散焊温度的提高,接头剪切强度明显下降。断口分析表明:接头均断在界面附近。界面附近的富In相是接头强度的薄弱环节。随着扩散焊温度的提高,富In相尺寸增大,接头强度下降。急冷Al基中间层扩散焊连接Si_3N_4陶瓷的机制是:活性元素Ti向界面扩散富集并与Si_3N_4发生化学反应,生成界面相TiN,同时中间层中的Al也向界面富集并与Si_3N_4发生化学反应,生成AIN界面相。 相似文献
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用快速凝固合金薄膜作插入金属在大气中低温液相过渡连接A12O3陶瓷与低合金钢。接头的剪切强度及开焊温度试验结果表明:用快速凝固合金薄膜作插入金属时能明显地提高接头的剪切强度及开焊温度。其中用非晶态Cu50Ti50合金薄膜作插入金属时接头的改性效果最佳,最高剪切强度达74MPa,开焊温度为780℃。保温时间对接头的强度及开焊温度影响很大,接头的开焊温度随保温时间的延长而明显提高,但对强度而言,保温时间却存在一个最佳范围。 相似文献
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开展了6 mm 2A14-T6铝合金对接接头的单面焊双面成形焊接工艺研究,详细分析了交流频率和装配精度对焊缝成形及接头力学性能的影响规律。结果表明:随着交流频率从60 Hz逐渐增加至80 Hz,2A14铝合金对接接头的平均抗拉强度从356 MPa降低至310 MPa,但接头延伸率没有显著变化。装配精度对焊缝质量的影响分析结果显示:随着装配间隙增大,焊缝背部成形效果变差。当间隙超过20%板厚时,焊缝易直接熔穿或单面切割,无法形成焊漏。随着装配错边增大,焊缝背部成形逐渐变差,出现咬边现象;接头力学性能测试显示,随着装配错边的增加,接头抗拉强度和延伸率均呈逐渐下降的趋势。在实际工程应用中,局部错边应控制在25%板厚范围内。 相似文献
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在武器应急投放过程中,应急投放按钮接通和断开的瞬间都会产生冲击电流,该冲击电流过大就会导致按钮发生粘连。本文详细阐述了瞬时冲击电流对武器系统造成的影响,通过多次武器系统地面通电检查试验,分析验证了武器通电过程中产生过大冲击电流的原因,并针对该类故障进行解决方法探究,提出了此类故障的有效解决方法。 相似文献
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为了探索纳米银浆在大功率器件组装中的应用可靠性,亟待获得纳米银浆的烧结特性和热力学性能。本文对不同烧结温度、烧结时间、升温速率、烧结方式的纳米银浆样件烧结强度,结合烧结形貌进行了系统研究,并与航天电子产品中常规的互连材料Au80Sn20焊料、Sn90.5Ag3Cu0.5焊料以及H20E导电胶的散热性进行了对比分析。研究结果表明:采用可控升温速率空气氛围的烧结方式,在200 ℃下保温90 min,银浆样件的剪切强度最高可达40 MPa。纳米银浆导热性能与Au80Sn20相当,明显高于H20E和SAC305。在经历严酷的热应力和机械应力试验后,其剪切强度保持稳定,因此纳米银浆作为高导热连接材料在宇航大功率器件组装中具有良好的应用前景。 相似文献
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NING Guo-dong ZHANG Shu-guang FANG Zhen-ping 《中国航空学报》2007,20(1):1-8
A method for the implementation of integrated three-degree-of-freedom constrained entry guidance for reusable launch vehicle is presented. Given any feasible entry conditions, terminal area energy management interface conditions, and the reference trajectory generated onboard then, the method can generate a longitudinal guidance profile rapidly, featuring linear quadratic regular method and a proportional-integral-derivative tracking law with time-varying gains, which satisfies all the entry corridor constraints and meets the requirements with high precision. Afterwards, by utilizing special features of crossrange parameter, establishing bank-reversal corridor, and determining bank-reversals according to dynamically adjusted method, the algorithm enables the lateral entry guidance system to fly a wide range of missions and provides reliable and good performance in the presence of significant aerodynamic modeling uncertainty. Fast trajectory guidance profiles and simulations with a reusable launch vehicle model for various missions and aerodynamic uncertain-ties are presented to demonstrate the capacity and reliability of this method. 相似文献
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基于飞机油箱模型形状特征油量测量切片步长选择方法研究 总被引:1,自引:0,他引:1
在分析飞机数字式油量测量过程中目前广泛使用的切片法油量测量原理的基础上,针对现有的定步长切片法无法得到准确、可靠的燃油质量特性数据库的缺陷,结合对飞机油箱模型形状特征的分析,提出了基于飞机油箱模型形状特征的油量测量切片步长选择方法。此方法包括切片步长整体和局部选择两个过程,整体选择以实现相邻两切片平面所夹油箱模型体积近似相等为目的来确定切片步长,以体现油箱模型截面整体变化规律;局部选择以设计切片平面与截面突变平面重合或尽可能接近的方式,突出油箱截面的局部变化特征。实验结果表明:该切片步长选择方法较定步长方法能够建立更为合理、可靠的燃油质量特性数据库,从而提高了油量测量精度。 相似文献
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The effect of inlet conditions on the flow and heat transfer in multiple rotating cavity with axial throughflow 总被引:1,自引:0,他引:1
This paper discusses experimental results from two different build configurations of a heated multiple rotating cavity test rig.Measurements of heat transfer from the discs and tangential velocities are presented.The test rig is a 70% full scale version of a high pressure compressor stack of an axial gas turbine engine.Of particular interest are the internal cylindrical cavities formed by adjacent discs and the interaction of these with a central axial throughflow of cooling air.Tests were carried out for a range of non-dimensional parameters representative of high pressure compressor internal air system flows(Re up to 5×106 and Rez up to 2×105).Two different builds have been tested.The most significant difference between these two build configurations is the size of the annular gap between the(non-rotating) drive shaft and the bores of the discs.The heat transfer data were obtained from thermocouple measurements of surface temperature and a conduction solution method.The velocity measurements were made using a two component,LDA system.The heat transfer results from the discs show differences between the two builds.This is attributed to the wider annular gap allowing more of the throughflow to penetrate into the cavity.There are also significant differences between the radial distributions of tangential velocity in the two builds of the test rig.For the narrow annular gap,there is an increase of non-dimensional tangential velocity V/Ωr with radial location to solid body rotation V/Ωr=1.For the wider annular gap,the non-dimensional velocities show a decrease with radial location to solid body rotation. 相似文献
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Abnormal Shape Mould Winding 总被引:1,自引:0,他引:1
Fu Hongya Wang Xianfeng Han Zhenyu Fu Yunzhong 《中国航空学报》2007,20(6):552-558
为解决网格化芯模的缠绕问题,本文提出了复合材料面片缠绕机理;接着详细分析了面片缠绕过程中的芯模凹曲面上纤维滑线和架空现象,应用微分几何曲面理论和空间几何理论,提出判据及其解决方案;最后,针对飞机发动机进气道的缠绕成型,编制缠绕控制程序并进行相应的实验,验证了面片缠绕方法的可行性。 相似文献
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FU Hong-jun MA Chong-qi KUANG Nai-hang LUAN Shi-lin 《中国航空学报》2007,20(2):124-128
This work was dedicated to performing surface oxidation and coating treatments on carbon fibers (CF) and investigating the changes of fiber surface properties after these treatments, including surface composition, relative volume of functional groups, and sur- face topography with X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) technology. The results show that, after oxidation treatments, interfacial properties between CF and non-polar polyarylacetylene (PAA) resin are remarkably modified by removing weak surface layers and increasing fiber surface roughness. Coating treatment by high char phenolic resin solution after oxida- tion makes interface of CF/PAA composites to be upgraded and the interfacial properties further bettered. 相似文献
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Xu Chenghai Meng Songhe Zhang Mingfu Zuo Hongbo Wang Guigen 《中国航空学报》2007,20(5):475-480
本文利用有限元法对冷心放肩微量提拉法(SAPMAC)生长大尺寸蓝宝石单晶过程中的热应力进行了模拟计算,应用临界缺陷理论解释了裂纹的萌生与扩展机理。研究表明,晶体内的热应力主要与晶体生长速率,环境温度和结晶取向有关;较大热应力多出现在结晶界面,放肩、收尾以及直径急剧变化等位置;最大热应力总是出现在籽晶与新生晶体的界面附近。裂纹将在临界缺陷位置产生,并在应力作用下沿a或m面扩展。计算结果与实验结果基本吻合,通过晶体生长系统和生长工艺的改进,对晶体的开裂问题得到了有效的抑制。 相似文献
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CHENG Wen-yuan CHANG Yan CUI De-gang XIE Xiang-hui 《中国航空学报》2007,20(1):55-59
To solve the topology optimization of complicated multi-objective continuous/discrete design variables in aircmit structure design, a Parallel Pareto Genetic Algorithm (PPGA) is presented based on grid platform in this paper. In the algorithm, the commercial finite element analysis (FEA) software is integrated as the calculating tool for analyzing the objective functions and the filter of Pareto solution set based on weight information is introduced to deal with the relationships among all objectives. Grid technology is utilized in PPGA to realize the distributed computations and the user interface is developed to realize the job submission and job management locally/remotely. Taking the aero-elastic tailoring of a composite wing for optimization as an example, a set of Pareto solutions are obtained for the decision-maker. The numerical results show that the aileron reversal problem can be solved by adding the limited skin weight in this system. The algorithm can be used to solve complicated topology optimization for composite structures in engineering and the computation efficiency can be improved greatly by using the grid platform that aggregates numerous idle resources. 相似文献