共查询到20条相似文献,搜索用时 62 毫秒
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针对高频通讯领域对聚酰亚胺(PI)薄膜材料的应用需求,以半脂环二胺5(6)-氨基-1-(4-氨基苯基)-1,3,3-三甲基茚满(DAPI)与不同的芳香二酐反应,合成了含半脂环结构的PI并制备了对应薄膜,探究了其结构与性能的相关性。结果表明:含半脂环结构的PI具有良好的可溶解加工性,能溶于NMP、DMF、CHC13等常规有机溶剂。制备的薄膜具有良好的力学性能和耐热性,拉伸强度为64.8~82.6 MPa,玻璃化转变温度最高可超过487℃。薄膜的介电常数(Dk)为2.63~4.62(1 kHz~1 MHz)、2.46~2.75(10 GHz),介质损耗因数(Df)为0.003 1~0.020 5(1 kHz~1 MHz)、0.006 6~0.017 4(10 GHz)。其中,薄膜B-PI(BPADA-DAPI)在10 GHz下的介电常数为2.75,介质损耗因数为0.006 6,表明在PI分子主链上同时引入半脂环和双酚A结构能制备兼具高频低介电常数、低介质损耗的PI薄膜。 相似文献
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双邓型聚酰亚胺印制电路基板的研制 总被引:2,自引:0,他引:2
本文概述了双马型聚酰亚胺印制电路基板的研制,探讨了树脂、玻璃布预浸料和印制电路基板的性能,以及可制作成多层印制电路板。实验表明该印制电路板是制造高性能大型计算机用多层印制电路板和耐高温印制电路板的理想基材。 相似文献
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复介电常数是高频板材最重要的参数之一,准确测量高频板材的介电常数和损耗,对板材的实际应用十分重要。为了获得板材的损耗特性,设计了一种基于微带线的传输线电路,并对长度分别为25.4和127 mm的微带传输线进行仿真、加工和测试,得到DC-20GHz内的回波损耗S11和插入损耗S21,测试数据表明,S11值测试结果在-15 dB以下,且在20 GHz下传输线的插入损耗为24.02 dB/m。通过加工误差分析,电路参数变化50μm时,DC-20GHz内仿真S11max变化可达到6 dB左右。最后结合谐振环法对同一种板材进行测试,得到板材的相对介电常数和损耗角正切。结果表明该方法得到的损耗角正切精确度较高,且在2、10和20 GHz频段下误差小于10%。 相似文献
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该文引入小磁滞回线下磁能损耗数学模型,使用AMH-1M-S型动态磁特性测试系统测量了Fe-Co-V、Terfenol-D与Fe-Ga合金样品的高频磁滞回线,利用实验测试结果结合数学模型对比分析了三种材料的磁导率幅值、介质损耗因数、介质储能和电磁损耗变化规律。当励磁磁场频率为50kHz时,随着磁感应强度的增加,Terfenol-D和Fe-Ga合金的介质损耗因数近似线性增加,三种合金样品的电磁损耗均增大。当磁感应强度为0.03T时,随着励磁磁场频率的增加,Fe-Co-V、Fe-Ga合金磁导率幅值都先增大后减小,Terfenol-D合金的介质储能增加最快并且其电磁损耗随频率增速最快。在1~40kHz内Fe-Ga合金的电磁损耗高于Fe-Co-V合金,在40~60kHz内Fe-Ga合金电磁损耗低于Fe-Co-V合金。该文结果为磁致伸缩材料的电磁损耗分析与高频器件设计提供了依据。 相似文献
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浸渍介质介电常数和损耗因数的计算西安电力电容器研究所江正平浸渍多层介质系统的介电常数、损耗因数(损耗角正切)和各介质层上电场分布的计算,(电力电容器)刊物上曾刊载过不少论文。不少专家从不同角度对这些问题进行了论述,笔者也想谈一些看法以供参考。1浸渍纸... 相似文献
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《Dielectrics and Electrical Insulation, IEEE Transactions on》2008,15(5):1379-1384
In general, printed circuit boards (PCBs) used in power devices and system operation in low pressure environments are more susceptible to damage from surface discharges. Additionally, repetitive operation of power systems is an important factor leading to tracking failure. Whether the tracking phenomenon at low pressures is different from that at atmospheric pressure needs better understanding to ensure reliable applications. In this paper, studies of tracking failure of PCBs in a low-pressure chamber, are reported for an electrode configuration comprising a pointed end of track close to the side of a track. Test samples were made by printing these tracks onto a glass-cloth epoxy-resin laminate. Experiments were carried out using repetitive unipolar pulses to simulate voltage surges. The ambient pressure was reduced from atmospheric pressure to a very low pressure (0.6 kPa). The time to failure and the cumulative charge passing before failure were recorded as function of the pressure, temperature, pulse interval and insulation distance. The results obtained indicate that the low pressure enhances the breakdown endurance of PCBs and the breakdown phenomena at low pressure are different from those at atmospheric pressure. With the decrease of the pressure, the cumulative charge is increased but the tracking failure is delayed. At low pressures, increasing temperature has little effect on the cumulative charge, but has significant influence on the time to tracking failure. 相似文献
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讨论了高硫环境中电路板浸银表面的蔓延腐蚀失效问题.发现焊盘与阻焊膜之间的相对位置关系影响了浸银层的覆盖程度,导致枝状腐蚀物的生成、蔓延长度及主要成分的不同.探讨了采用含硫粘土作为腐蚀源,驱动电路板浸银焊盘蔓延腐蚀的模拟实验方法.并采用两参数威布尔分布统计蔓延腐蚀物的长度,以特征长度定量评估浸银电路板抗蔓延腐蚀能力.分别... 相似文献
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高性能印刷电路板用氰酸酯树脂研究进展 总被引:2,自引:1,他引:1
综述了国外高性能印刷电路板用氰酸酯树脂研究的新进展,包括催化剂对双氰酸酯单体发生环化三聚反应形成三嗪环的高度交联网络结构的大分子-三氮杂苯氰酸酯树脂的影响、氰酸酯树脂的增韧、氰酸酯树脂的湿/热性能、新型氰酸酯单体的合成及其树脂的性能等。氰酸酯单体的固化受催化剂的影响,催化剂能促进固化反应,又能降低氰酸酯树脂的湿/热性能。氰酸酯树脂的增韧改性包括共混增韧改性和化学增韧改性。氰酸酯树脂表现出热突变效应和反转热效应的湿/热性能特征。新型氰酸酯单体的合成及其树脂的发展方向是进一步提高氰酸酯树脂的热性能和加工性能并降低其成本。 相似文献
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随着电子设备的小型化,印制电路板的导线间距变小,使得导线间电化学迁移失效问题更加突出。同时,大气污染严重,尘土颗粒沉积吸附在电路板上,其中的可溶性盐会改变电路板表面吸附水膜的离子浓度,从而改变线间绝缘失效机理和失效时间。使用浸银Y形电路板,采用不同浓度氯化钠溶液和尘土溶液水滴实验的方法来研究电路板表面存在可溶性盐溶液的情况下导线间绝缘失效特征与失效时间的变化规律。发现随着溶液离子浓度的升高,电路板绝缘失效机理由电化学迁移转变为离子性导电,失效时间呈现先减小后增大再陡降的趋势。存在促进阳极金属快速形成电化学迁移的可溶性盐溶液浓度Ca、由电路板阳极金属离子迁移形成晶枝导电向离子导电为主导转换的盐溶液浓度Cb及直至完全抑制电化学迁移的盐浓度Cc。 相似文献
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特快速暂态过电压下变压器绕组高频电路模型的研究 总被引:9,自引:3,他引:9
变压器绕组的高频模型对于分析特快速暂态过电压对变压器的影响是非常重要的。从易于高频测量的散射参数出发,提出了一种建立变压器绕组高频电路模型的方法。该方法首先由散射参数计算绕组各匝的电压传输函数,并利用矢量匹配法对得到的电压传输函数进行有理函数逼近;其次,对得到的有理函数形式的传输函数进行阶数缩减,得到变压器绕组电压传输函数的降阶模型;最后,运用网络综合技术建立变压器绕组的高频电路模型。该电路模型简单、通用,仅由R、L、C和理想变压器构成,其模型参数可以根据电压传输函数的极点和留数非常方便地得出。通过对电路模型的仿真结果与实际测量结果进行比较,验证了文中方法的正确性。 相似文献
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Effect of Ground Pattern Size on FM‐Band Crosstalk Between Two Parallel Signal Traces of Printed Circuit Boards for Vehicles 下载免费PDF全文
It is well known that electromagnetic disturbances in vehicle‐mounted radios are mainly caused by conducted noise currents flowing through wiring harnesses from vehicle‐mounted printed circuit boards (PCBs) with common ground patterns containing slits. To suppress the noise current outflow from these kinds of PCBs, we previously measured noise current outflow from simple two‐layer PCBs having two parallel signal traces and different ground patterns with and without slits to reveal that making slits with open ends on the ground patterns in parallel with the traces can reduce the conducted noise currents. In the present study, using FDTD simulation we investigated the reduction effects of ground pattern size on the FM‐band crosstalk noise levels between two parallel signal traces by using four types of simple PCB models having different ground patterns formed in different numbers but containing the same planar dimension slits parallel to the traces, in addition to two types of PCB models with different ground patterns divided into two parts parallel to the traces. It was found that the crosstalk noise currents for the above six types of PCBs decrease by 6.9 to 8.5 dB compared to the PCB which has a plain ground with no slits. We found that a contributing factor to the above‐mentioned crosstalk reduction is reduction of the mutual inductance between the two parallel traces. In addition, in this study it is interesting to note that noise current leakage from PCBs is more significantly reduced when the size of the return ground of each signal trace is small. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 11–17, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22316 相似文献
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通过降低印制电路板的基板表层的溴含量并加入氢氧化铝,显著提高了基板的相比漏电起痕指数(CTI),并同时提高了基板的尺寸稳定性、耐热性、玻璃化温度。 相似文献