SiP器件回流焊时湿热应力的分析

应用有限元方法分析了QFN形式的SiP封装器件在回流焊中的热应力与湿热合成应力。结果表明,在回流焊过程中,由于其结构特点与湿气的扩散不均引起湿热应力变化梯度加大,在其材料交界处应力集中现象明显。最大湿热应力是单纯考虑热应力的情况1.66倍左右。通过比较得知湿热环境对这种SiP器件的影响比一般的封装器件要大,更可能导致器件失效。     

长期湿热环境下塑封电路Au-Al键合退化研究

为评估塑封电路Au-Al键合点在长期湿热环境下的可靠性,对Au-Al键合界面抵抗长期湿热应力的能力进行了试验研究.选择2款Au-Al键合塑封电路,分别设置2组湿热应力试验条件加速Au-Al键合退化.采用扫描电子显微镜(SEM)和能谱仪(EDS)对键合界面形貌、成分进行观测,分析长期湿热应力作用下Au-Al键合界面微观结...     

超声电机湿热环境试验研究

为研究超声电机对湿热环境的耐受性,采用人工模拟加速法对其进行湿热环境试验,测试并比较超声电机湿热环境与常态环境下的电机机械性能、定子性能及摩擦材料吸湿性能.试验结果表明,经过湿热环境加速试验后,超声电机仍可正常工作;电机机械性能与定子性能试验前后较稳定;以聚四氟乙烯作为摩擦材料基体对超声电机在湿热环境下工作或储藏较适合...     

湿热环境与电子产品可靠性

阐述了湿热环境对电子产品质量寿命的影响，并重点介绍了目前湿热试验的热门话题：离子迁移失效的机理和试验方法。     

潮湿扩散及湿热应力对叠层封装件可靠性影响

利用MARC软件,通过模拟实验分析了潮湿扩散及湿热应力对叠层封装器件可靠性的影响,对30℃,RH 60%,192 h条件下预置吸潮到后面的无铅回流焊解吸潮过程进行了有限元仿真;对85℃,RH 85%,168 h条件下元件内不同界面的潮湿扩散进行分析,得出潮湿扩散对界面的影响规律。使用一种湿热耦合方法计算湿热合成应力并与单纯热应力进行了对比。结果表明:最大湿热应力和热应力一样总是出现在顶部芯片与隔离片相交的区域,其数值是单纯热应力数值的1.3~1.5倍。     

电子产品的湿热试验

对湿热空气的定义及特征参数、湿热的环境影响及物理现象、试验方法的选择等作简要概述,并对GB4937-85半导体分立器件机械和气候试验方法等标准中有关加速湿热试验提出几点看法。     

湿热对电子设备的影响及其防护

本文仅阐述作为气候环境之一的湿热条件及其气候特征,分析了湿热因素对电子设备产生的劣化效应,并提出电子设备的防潮措施和考核方法,供工程设计时参考.     

湿热环境对PbS光导探测器可靠性影响

叙述了PbS薄膜的化学水浴制备方法及PbS薄膜形貌、性能测试及湿热环境（相对湿度95%）试验的过程,阐述了PbS探测器芯片经湿热环境试验后暗阻等性能参数的变化情况,分析了其原因和相关机理。短时间（1 h）内湿热环境下,其性能参数变化在5%以内,在持续24 h的潮湿环境后,PbS的暗阻增大50%以上。在之后的2×24 h、3×24 h、4×24 h、5×24 h湿热环境下,暗阻值增量随时间递增呈正比例关系。当潮湿试验进行到7×24 h后,部分试验样件无法测试出响应信号,样件失效。     

集成湿热及蒸汽压力对塑封器件可靠性的影响

分析了湿热及蒸汽压力对塑封器件可靠性影响的研究现状;结合已有的研究方法,提出一种有限元直接集成湿热及蒸汽压力的分析方法,并以裸露焊盘塑封器件DR-QFN为例进行应用研究。结果表明,该方法能有效分析裸露焊盘塑封器件在湿热、蒸汽压力因素综合影响下的可靠性问题。在无铅回流焊过程中,蒸汽压力为2.5~4.5MPa,对器件可靠性影响很大。     

芯片堆叠封装耐湿热可靠性

采用Abaqus软件模拟了CPU和DDR双层芯片堆叠封装组件在85℃/RH85%湿热环境下分别吸湿5,17,55和168 h的相对湿气扩散分布和吸湿168 h后回流焊过程中湿应力、热应力和湿热应力分布,并通过吸湿和回流焊实验分析了该组件在湿热环境下的失效机理。模拟结果表明,在湿热环境下,分别位于基板和CPU、CPU和DDR之间的粘结层1和2不易吸湿,造成粘结层的相对湿度比塑封材料低得多,但粘结层1的相对湿度比粘结层2要高。吸湿168 h后,在回流焊载荷下湿应力主要集中在芯片DDR远离中心的长边上,而最大湿热应力和热应力一样位于底层芯片CPU的底角处,其数值是单纯热应力的1.3倍。实验结果表明,界面裂纹及分层集中在底层CPU芯片的边角处和芯片、粘结层和塑封材料的交界处,与模拟结果相一致。     

浅谈JJF1101—2003和GB／T5170．x-2008的区别

文章简述了JJF1101—2003的六个计量特性与GB／T5170．x-2008中相应的检验项目的差异,以及两个标准在温、湿度试验设备的校准,检验上的区别,以使大家了解在验收和管理温、湿度试验设备时应怎样正确使用这两个标准。     

舰船热力管道保温层受潮对保温性能的影响

舰船热力管道的保温层受潮后会影响管道的保温效果,并会腐蚀管道。建立了保温层受潮模型,采用有限体积法计算了蒸汽管道保温层受潮后的温度场分布以及外表面的温度、传热损失随保温层受潮厚度变化的趋势。结果表明,选定保温材料后,当受潮厚度达到20 mm时温度就会超标。对于相同厚度的受潮区域,离外表面越近,外表面的温度就越高。结果揭示了做好保温层外表面防护的重要性,并为红外热成像诊断提供了依据。     

Evaluation of standard plastic integrated circuits reliability after accelerated sequential testing

We present here in this paper main results obtained during the first phase of a work plan which aim is to allow the use of plastic encapsulated devices (PED’S) in some military equipments. This phase (called feasibility) was conducted in order to evaluate the risk an equip-ment maker takes when using standard PED’S. TO do that a large number OF PED’S (about 1000) were characterized. Main features of performed tests are that they were se-quential file of tests and better suited to assessment of PED’S reliability. Moreover one file included an extremely severe damp heat test, at high temperature and high hu-midity, called HAST. Results we get show a large disparity in PED’S behaviour under rugged environments. Fine fail-ure analysis have shown what are major defect modes and indicated that classical corrosion is not the only failure mechanism which occurs at high temperature and high humidity conditions. Failure rate derived from these results can be compared favourably with those computed following reliability prediction models.     

Accelerated degradation of Al3+ doped ZnO thin films using damp heat test

Two different types of aluminum-doped zinc oxide (AZO) thin films were fabricated using low cost sol–gel technique. By applying damp heat testing, the optical and electrical properties of those films were investigated under the influence of accelerated degradation from moisture or moisture vapor. Complementary measurements of optical transmittance, work function, and conductivity allowed exploring the degradation of AZO thin films and the corresponding OPV devices. We found that optical properties like transmittance, absorption coefficient, and band gap are not influenced by temperature and moisture. However, an increase in the work function, and a decrease in the conductivity of AZO films were observed upon damp heat exposure indicating the formation of a barrier or depletion layer at the metal oxide semiconductor interface.     

Processability and reliability of epoxy adhesive used in microelectronic devices linked to effects of degree of cure and damp heat aging

In an effort to explicate the effects of degree of cure (conversion) and damp heat aging at 85 °C/85% RH on physical properties of the cured epoxy system consisting of diglycidyl ether of bisphenol F (DGBF) and imidazole as a curing agent, an experimental approach was systematically performed using a dynamic mechanical analyzer (DMA) and thermomechanical analyzer (TMA). Of interesting physical properties are the storage modulus, loss modulus, tan δ, glass transition temperature (T_g), and coefficient of thermal expansion (CTE). The die shear test was performed to evaluate changes in adhesion strength of the cured epoxy with and without an epoxy silane before and after the damp heat aging. We have found that the magnitude of storage modulus in a glass transition region and the onset temperature for degradation of storage modulus, DMA T_g, increase as the conversion of cure increases. Even though such benefits observed at ambient are lessened after extended exposure to the damp heat aging, higher conversion has less degradation than lower conversion. It is observed that T_g taken from DMA and TMA decreases approximately from 132 °C to 81 °C after 500 h of damp heat aging. Such large diminution is attributed to high moisture diffusivity of 2.0 × 10⁻⁸/cm²/s at 85 °C/85% RH and can cause large dimensional instability at the critical interface supported by the epoxy adhesive. We have also found that a 3-parameter exponential function is useful to predict the degradation of T_g under the given aging condition. Although the effect of an epoxy silane is negligible at ambient, it provides better adhesion strength after the damp heat aging. Finally, we intend to give process guidelines for the usage of DGBF/imidazole epoxy system to ensure stringent reliability in electronic device applications.     

电子设备的热设计

从热源、失效率入手 ,分析了热产生的机理 ,并提出了电子设备热设计的基本方法。     

Reliability of fluoride fiber module for optical amplifier use

We report reliability test results for a fluoride fiber module. We developed a sealed fluoride fiber module for practical optical fiber amplifier use. Trouble-free damp heat storage and low-temperature storage for 5000 h and trouble-free temperature cycling and temperature-humidity cycling tests revealed that our fluoride fiber module has long-term stability under practical environmental conditions     

探讨环境对LED背光源的影响

文章主要探讨不同的环境条件如低温、恒定湿热、冷热冲击等对LED背光源性能的影响,同时对LED背光源的主要应用领域进行了阐述,并期待LED背光源测试方法的标准尽早发布实施。     

ZnO压敏电阻器在稳态湿热试验中的性能变化与分析

通过对ZnO压敏电阻器试验结果的分析,探讨其在稳态湿热试验中引起性能变化的因素,提出要提高产品的耐湿性能,必须在包封料选择和瓷体制作工艺上加以改进。     

某型模块的热设计及仿真

以某型模块热设计为例,首先按自然散热方式进行理论计算,然后应用FloTHERM软件对导航模块的散热性能进行仿真分析,为电子设备的散热设计提供了设计依据和参考,最后对仿真分析的结果进行了分析总结。