Thermal fatigue behaviors of SiC power module by Ag sinter joining under harsh thermal shock test

The excellent properties of SiC bring new challenges for the device packaging.In this study,the bonding strength,fracture behaviors and microstructural evolution of micron-porous Ag joint were elevated during thermal cycling(–50 ℃–250 ℃) in SiC/DBC(direct bonding copper) die attachment structure for different time.During harsh thermal shock test,the strength of sintered joint deceased gradually with the increase of cycling number,and the value just was half of the value of as-sintered after 1 000 cycles.Coarsening of Ag grains was observed in micron-porous joint with the structure inhomogeneity and defects increasing,which were the reasons of the strength decease.In addition,it was also found that the fracture behavior of sintered joints was changed from ductile deformation of Ag grain to brittle fracture of crack propagation after 1 000 cycles.This study will add the understanding in the mechanical properties of Ag sinter joining and its applications at high temperature.

Accelerated Degradation Reliability Modeling and Test Data Statistical Analysis of Aerospace Electrical Connector

As few or no failures occur during accelerated life test,it is difficult to assess reliability for long-life products with traditional life tests.Reliability assessment using degradation data of product performance over time becomes a significant approach.Aerospace electrical connector is researched in this paper.Through the analysis of failure mechanism,the performance degradation law is obtained and the statistical model for degradation failure is set up; according to the research on statistical analysis methods for degradation data,accelerated life test theory and method for aerospace electrical connector based on performance degradation is proposed by improving time series analysis method,and the storage reliability is assessed for Y11X series of aerospace electrical connector with degradation data from accelerated degradation test.The result obtained is basically consistent with that obtained from accelerated life test based on failure data,and the two estimates of product＇s characteristic life only have a difference of 8.7%,but the test time shortens about a half.As a result,a systemic approach is proposed for reliability assessment of highly reliable and long-life aerospace product.

Mechanical Integrity and Failure Analysis of Photovoltaic Modules under Simulated Snow Loads Using Pneumatic Airbag Setup

Photovoltaic (PV) modules have emerged as an ideal technology of choice for harvesting vastly available renewable energy resources. However, the efficiency of PV modules remains significantly lower than that of other renewable energy sources such as wind and hydro. One of the critical elements affecting a photovoltaic module’s efficiency is the variety of external climatic conditions under which it is installed. In this work, the effect of simulated snow loads was evaluated on the performance of PV modules with different types of cells and numbers of busbars. According to ASTM-1830 and IEC-1215 standards, a load of 5400 Pa was applied to the surface of PV modules for 3 hours. An indigenously developed pneumatic airbag test setup was used for the uniform application of this load throughout the test, which was validated by load cell and pressure gauge. Electroluminescence (EL) imaging and solar flash tests were performed before and after the application of load to characterize the performance and effect of load on PV modules. Based on these tests, the maximum power output, efficiency, fill factor and series resistance were determined. The results show that polycrystalline modules are the most likely to withstand the snow loads as compared to monocrystalline PV modules. A maximum drop of 32.13% in the power output and a 17.6% increase in series resistance were observed in the modules having more cracks. These findings demonstrated the efficacy of the newly established test setup and the potential of snow loads for reducing the overall performance of PV module.

PV Capacity Evaluation Using ASTM E2848: Techniques for Accuracy and Reliability in Bifacial Systems

A variety of test methodologies are commonly used to assess if a photovoltaic system can perform in line with expectations generated by a computer simulation. One of the commonly used methodologies across the PV industry is an ASTM E2848. ASTM E2848-13, 2023 test method provides measurement and analysis procedures for determining the capacity of a specific photovoltaic system built in a particular place and in operation under natural sunlight. This test method is mainly used for acceptance testing of newly installed photovoltaic systems, reporting of DC or AC system performance, and monitoring of photovoltaic system performance. The purpose of the PV Capacity Test and modeled energy test is to verify that the integrated system formed from all components of the PV Project has a production capacity that achieves the Guaranteed Capacity and the Guaranteed modeled AEP under measured weather conditions that occur when each PV Capacity Test is conducted. In this paper, we will be discussing ASTM E2848 PV Capacity test plan purpose and scope, methodology, Selection of reporting conditions (RC), data requirements, calculation of results, reporting, challenges, acceptance criteria on pass/fail test results, Cure period, and Sole remedy for EPC contractors for bifacial irradiance.

Step-stress Accelerated Degradation Test Modeling and Statistical Analysis Methods

In order to get a rapid assessment on the storage reliability of high-reliable and long-life products within the storage period, accelerated degradation test data with a large amount of reliability information of product is adopted. Conducting a constant-stress accelerated degradation test（CSADT） is generally very costly as it requires a large sample size and long time for test. To overcome this problem, it is necessary to carry out research on modeling and statistical analysis methods of step-stress accelerated degradation test （SSADT）. Taking electrical connectors as the object, a research is conducted on statistical model and assessment method for SSADT. On the basis of mixed-effect degradation path model, the statistical model of SSADT for electrical connectors is presented, the maximum likelihood method for SSADT data based on mixed-effect degradation model is proposed. SSADT accelerated by temperature stress is conducted to Y11X-1419 type of electrical connectors, and the storage reliability is assessed with the SSADT data. Compared with the result obtained from accelerated life test, the reliability estimation of 32-year storage period for electrical connectors obtained from S SADT data only have a difference of 0.869%, which validates the accuracy of the degradation model and the feasibility of the test data statistic analysis method put forward.

A Reliability-Based Strategy for the Analysis of Single Proton Exchange Membrane Fuel Cells

The development of power conversion systems based on fuel cells has been demanding reliability studies since the requirements associated with cost and durability of these technological products have become fundamental to their acceptance by the energy market. The experimental part of the reliability study presented in this work consisted of performing life tests with single proton exchange membrane fuel cells (PEMFCs). The proposed reliability analysis methodology covered the application of qualitative and quantitative techniques. In the qualitative approach, a Failure Mode and Effect Analysis was developed in order to identify and evaluate all potential failures associated with the operation of fuel cells. In the quantitative approach, a statistical analysis was applied to the sample data generated in long-term steady-state tests of these devices. A two-parameter exponential distribution was fitted to data and the maximum likelihood estimate for the mean time to failure (MTTF) of the fuel cells was calculated. It is important to point out that the tests performed under the scope of this study were the first long-term experiments performed with the fuel cells produced in the laboratories of IPEN-CNEN/SP, Brazil. Although the results indicated that fuel cell performance and durability were still at a level below the targets normally established for similar commercial devices, the improvement of the main components of PEMFCs has been the objective of several projects developed at the institute. Thus, the main benefit brought by this study is the proposed methodology, which can be implemented as part of a reliability growth analysis of the fuel cells and can be integrated into the design process of these devices.

T/R组件过激励试验可靠性与失效机理研究

T/R组件作为通信系统的核心部件,在运行环境下其接收通道经常面临外界大功率强扰动信号。外界大功率强扰动信号是影响T/R组件可靠性的重要因素,鉴于此本文搭建T/R组件过激励测试试验平台,对T/R组件接收通道进行过激励试验,并借助金相显微镜及聚焦离子束等失效分析技术对试验后T/R组件开展失效分析研究。依据试验结果,确定了组件中接收通道在过激励下的失效部位、失效模式及失效机理,检验了典型T/R组件的抗扰动、耐功率、抗烧毁能力,为T/R组件的耐功率、抗烧毁设计提供借鉴和指导。

缓蚀剂对雷达T/R组件腐蚀行为的影响

T/R组件作为雷达系统的重要组成部分,在严酷海洋大气环境的侵蚀作用下,容易发生腐蚀,从而导致雷达系统性能下降,甚至引发故障。基于实测的某型机雷达舱环境数据,编制加速腐蚀试验环境谱,针对喷涂和未喷涂TFHS-20缓蚀剂的T/R组件开展当量加速腐蚀对比试验,并以收发通道芯片的微观腐蚀形貌、铝合金外壳蚀坑深度、T/R组件收发性能和输出功率等为指标参数,表征缓蚀剂对T/R组件腐蚀行为的影响。结果表明,TFHS-20缓蚀剂仅使T/R组件的输出功率降低0.59%~0.78%、接收增益降低0.11 dB~0.21 dB,缓蚀剂对T/R组件收发性能影响非常小。未喷涂缓蚀剂的T/R组件,在加速腐蚀试验的第4周期时,发射通道性能和接收通道功能失效;喷涂缓蚀剂的T/R组件,在加速腐蚀试验的8个周期时,接收通道功能失效。所以,TFHS-20缓蚀剂能够有效地提高T/R组件的使用寿命。

基于往复弯曲的焊点可靠性测试装置设计

针对因机械外力造成微电子器件焊点连接缺陷导致整个焊点失效,进而影响电子产品正常工作的现象,文中设计了一款基于往复弯曲的焊点可靠性测试装置,用于元器件焊点机械性能的可靠性测试。首先,根据测试装置功能设计了装置机械结构,并采用Solid Works软件建立三维模型,验证了设计方案的可行性;其次,通过分析装置传动结构的运动学方程,从运动学上验证了传动机构设计结构的合理性;最后,采用ADAMS软件建立传动结构动力学模型进行仿真,从动力学上验证了传动机构的合理性,采用ANSYS软件建立夹持、施压机构模型对印制线路板进行静弯曲仿真,验证了弧形夹持机构和弧形施压机构的合理性。

基于不同胶膜封装的n型双玻TOPCon光伏组件的可靠性研究

胶膜是光伏组件封装时的关键材料,其性能的优劣将直接影响光伏组件输出功率的大小和使用寿命。采用两种不同的胶膜封装n型TOPCon光伏组件,并通过湿热、热循环、电势诱导衰减(PID)测试,研究两种胶膜封装的光伏组件的电性能和可靠性。实验结果表明:正、背面均采用聚烯烃弹性体(POE)胶膜的光伏组件较正面POE胶膜+背面聚乙烯-聚醋酸乙烯酯共聚物(EVA)胶膜的光伏组件最大功率高2.2 W,光电转换效率高0.08%;正、背面均采用POE胶膜的光伏组件在经过湿热、PID测试后输出功率衰减也低于正面POE胶膜+背面EVA胶膜的光伏组件。POE胶膜可在一定程度上降低出现PID现象的风险,在很大程度上延长光伏组件的使用寿命,因此越来越多的双玻光伏组件开始使用POE胶膜。

刀库系统可靠性快速试验方法

针对刀库系统现有可靠性试验方法试验周期长的问题,对其可靠性快速试验方法进行了研究。首先,根据刀库系统结构和整个周期的换刀动作特征,将其分解为相互独立的结构模组单元,且各结构模组单元能完成特定换刀动作,并在此基础上提出了模组化的并行循环试验方法;其次,依据串联系统可靠性分析方法,计算建立了刀库系统的MTBF评估模型;最后在某型号链式刀库上开展了实际应用验证。结果表明,此方法与传统串行整体式可靠性试验的MTBF评估结果误差率小于7.3%,试验时间缩短了50%左右,验证了所研究方法的有效性和快速性,为解决可靠性试验周期长的问题提供了参考方法。

核磁共振系统用电子监控单元可靠性热设计及其仿真与试验验证

核磁共振系统用电子监控单元作为系统的重要单机,在全寿命周期内面临着很高的热风险。该文从结构设计、器件降额设计2个维度保证电子模块热设计的高效与可靠。为降低电子模块的热设计风险,全面验证电子模块热设计的有效性,采用仿真与试验相结合的方法开展设计验证。在仿真环节,通过建立电路板级的热仿真模型,数值计算得到核心器件的结壳温度,并将该指标分别与热设计指标值以及测试值进行比对,一方面验证仿真模型的正确性,另一方面验证热设计的有效性;在测试环节,通过搭建产品模块的热测试平台,获取模块在极限电气工况下,核心器件的热特性测试值,并通过相应的折算方法,预测产品在不同海拔下的热性能与热设计裕度。结果表明,产品模块在结构设计、核心器件降额设计等方面,均能满足热设计要求,可以确保电子模块在核磁共振系统全寿命周期内安全、可靠地工作。

舰载超短波电台编码调制可靠性测试研究

在复杂的海上环境中,舰载超短波电台面临着多种因素的挑战,因此对编码调制可靠性提出了更高的要求。为此,实施舰载超短波电台编码调制可靠性测试研究。船舶搭载舰载超短波电台在所选择的三个实验区域内进行可靠性测试,测试在电磁干扰环境和多径效应环境下的误码率、信噪比和频谱效率。结果表明:海域2相比海域1和海域3,误码率相对较高。相比海域1和海域2,海域3在多径效应环境下,信噪比相对较低。海域1、海域2在电磁干扰环境下,频谱效率相对较低,其他环境海域下频谱效率相对较高。

基于TLCP应用系统的性能测试方法

随着国家对网络安全和信息安全的重视,网络安全传输密码协议(TLCP)从密码行业标准上升到独立的国家标准,各种应用系统也积极跟进支持TLCP协议。由于国内基于商用密码算法实现的TLCP协议发展至今不足10年,导致应用系统支持TLCP协议的脚步比较缓慢,而评估基于TLCP协议的应用系统的性能/可靠性测试工具更是极其欠缺。为解决此类应用系统性能及可靠性工具的问题,提出了构造国密客户端和实现TLCP VPN网关2种解决方案,并详细阐述了构造国密客户端的实现方法,以及在多个应用系统中的实践推广情况。

基于t检验的光伏电站中能效异常光伏组件识别研究

由于目前光伏电站能效指标缺乏具体的应用方式,光伏组件发电效率优劣的界限模糊,且光伏电站在正常运行中光伏组件I-V特性曲线难以获取,导致目前识别异常光伏组件的方法难以应用到实际光伏电站中。基于此,利用光伏组件能效比服从正态分布的特点,提出了一种基于t检验的光伏电站中能效异常光伏组件的识别方法,对光伏组件实际能效比与理论能效比之差进行假设检验,并结合实际光伏电站进行实验验证。研究结果表明:该方法可以有效识别异常光伏组件,可为光伏电站的运维提供数据支持。

不同模拟环境下高效HJT光伏组件的可靠性研究

随着光伏发电技术的进步和太阳电池结构的创新,太阳电池的光电转换效率得到了显著提高,光伏组件的输出功率也随之提高。目前,n型光伏组件因具有较高的光电转换效率,已逐渐成为市场主流。对采用乙烯-醋酸乙烯共聚物(EVA)封装胶膜和高透光玻璃封装的异质结(HJT)光伏组件在偏压、湿热、风/雪荷载、紫外线照射、干热环境下的可靠性进行了系统研究。将HJT光伏组件样品放入不同的模拟环境室中,对其分别进行电势诱导衰减(PID)测试、湿热(DH)测试、机械荷载测试、紫外(UV)测试、热循环(TC)测试这一系列可靠性测试,分析了HJT光伏组件正面和背面输出功率的衰减情况及其外观情况。研究结果表明:在分别进行PID测试、DH测试、机械荷载测试、UV测试和TC测试后,HJT光伏组件正面和背面的输出功率损耗均较小,损耗率最高值仅为1.21%,这意味着HJT光伏组件在不同环境中都表现出了优异的可靠性。研究结果可为未来高性能HJT光伏组件的结构设计和新材料开发等方面提供指导。

建筑光伏组件SBI燃烧性能测试与分析

依据国家标准《建筑材料或制品的单体燃烧试验》GB/T 20284[1]中规定的燃烧性能的单体燃烧测试(SBI)试验方法,分别对三种不同类型的建筑光伏组件进行燃烧性能试验,并对试样在试验过程中现象进行描述,进而按国家标准《建筑材料及制品燃烧性能分级》GB 8624[2]对试样的燃烧性能等级进行判定,为编制建筑用光伏组件的防火性能要求等相关规范提供依据,降低建筑应用光伏组件的安全风险。

功率半导体发展与测试技术研究

以GaN、SiC新材料功率半导体为代表的高性能功率器件和功率模块的出现,在太阳能光伏、风能、新能源汽车、高性能电源、储能、家电等领域广泛应用,其电压电流能力的提升,开关速度和功率密度的提升,对功率半导体的性能和可靠性提出了新的要求,对制造过程各阶段的测试要求也提出了新的挑战。通过分析新材料技术特点和生产工艺要求的研究,研究相关参数测试方法和测试流程,提出了降低功率模块制造成本、提高模块可靠性的基本要求和方法。

高压线路电力金具性能优化设计与应用

针对高压线路下的电力金具在恶劣环境下发生性能衰减的问题,建立金具性能评估体系。通过对金具的电气性能、机械性能以及环境适应性进行系统测试与分析,量化评估了金具在抗拉强度、导电性、防腐蚀性等关键指标上的表现。在此基础上,优化了金具的材料选择及结构设计,提出了防腐蚀措施。最后,对优化后的金具展开实际应用,进行现场检测和运行评估。结果表明,优化设计的金具性能优异,满足高压线路长期运行需求,可有效提高线路的可靠性和安全性。

汽车空调压缩机性能试验方法及常见问题解析

基于GB/T 21360—2018《汽车空调用制冷剂压缩机》和GB/T 5773—2016《容积式制冷剂压缩机性能试验方法》,以及笔者的实践经验,介绍汽车空调压缩机性能试验前期准备、测试流程以及注意事项,指出规范操作能够保证压缩机性能测试过程的可靠性和稳定性。本研究旨在为从事汽车空调压缩机设计、制造、试验工作的人员提供参考。