摘要
在当今电子信息技术时代,随着计算机、移动通信、卫星通讯等高速发展,电磁干扰在军用和民用电子信息领域的影响越来越大。同时为实现通信高速化,时钟脉冲频率升高,随之而来的电磁波干扰频率也越来越高。为了抑制高频发射噪声引起的电磁波泄漏,就需要开发频率高损耗大的电磁波吸收材料,有效地吸收噪声能量。
本论文简要介绍抗EMI材料吸收电磁波机理,讨论了不同材料的吸收电磁波性能。由于金属磁性材料的饱和磁感应强度高过于铁氧体,微波段的磁导率高,有利于实现薄层化, Snoek极限值所到达的频率高过于铁氧体材料,所以可以采用金属磁性材料来满足GHz频段抗干扰器件的要求。同时,金属磁性材料居里温度较高,在处理好氧化问题后,温度稳定性比铁氧体材料好。于是,近年来提出了使用橡胶或者环氧树脂作粘结剂的铁硅铝系软磁合金粉末。
本文采用扁平化工艺及绝缘包覆工艺,对铁硅铝系软磁合金粉末进行改性,详细介绍了两种改善合金微粉吸收性能的工艺流程。对实验样品进行了SEM分析,观察了颗粒形貌对材料性能的影响。总结了不同球磨时间以及不同绝缘介质含量对于材料电磁性能的影响规律。分析单层吸波材料(含导电衬底)对电磁波的反射率公式,计算不同样品反射率,结果表明,球磨扁平化工艺及绝缘包覆工艺可有效地改善铁硅铝金属粉末的微波吸收性能。经改性后的铁硅铝系软磁金属粉末在1.0-3.5GHz频段内具有较好的吸波性能,可应用于抗电磁干扰。
With the rapid development of computer science, mobile communication and satellite communication, the Electromagnetic Interference (EMI) technology has been greatly applied in military and civil fields of the electronics and information. In order to communicate in high speed, the clock-pulse frequency was raised, followed by increasing of the EMI frequency. Electromagnetic absorbing materials with high frequency and high loss are required to absorb the noise energy, aiming at restraining the electromagnetic leak induced by high-frequency emission noise.
The theory of absorbing electromagnetic wave by EMI resistance materials is introduced in this paper, and the absorbing performances of different materials are discussed. The metal magnetic material was adopted to satisfy EMI resistance equipment in GHz frequency, due to its higher saturation magnetic susceptibility than the ferrite material, lamella structure and higher frequency in Snoek limit than that of the ferrite material. Meanwhile, the temperature stability of the metal magnetic material is much better than that of the ferrite material after oxidation, as a result of the higher Curie temperature. Then soft magnetic metal powders with the Fe-Si-Al composition are employed in recent years, with the felt dope of latex or the epoxy colophony.
The electromagnetic interference resistance characteristic of the Fe-Si-Al magnetic alloy powder was improved by flattening the metallic materials and chemical coating method in this paper. Two kinds of technical flows for improving the absorbing performance of the powder were introduced in detail. SEM analysis of the sample was carried out and the influence of the grain morphology on the performance of the material was observed, as well as the influence of different boll-milling time and different additive contents of isolative medium on the electromagnetic performance of the powder. The formulas of reflection coefficient of absorbing materials with electric substrates were analyzed and the reflection coefficient of different material sample was computed. The result shows that the proposed boll-milling flattening and isolative coating technology will dramatically improve the performance of absorbing materials in the frequency of 1.0-3.5GHz, which makes it possible to apply the material to EMI resistance.
引文
[1] 王定华, 赵家升. 电磁兼容原理与设计.第一版.成都: 电子科技大学出版社, 1995. 1~18
[2] Maddocks A.J.. Advances in design for EMC. Science Measurement and Technology, 1994, 141(4): 293~ 296
[3] Kerry P.J.. EMC in the new millennium. Electronics & Communication Engineering Journal, 2000, 12(2): 43~48
[4] 王庆斌, 刘萍, 尤利文等. 电磁干扰与电磁兼容技术.第一版.北京: 机械工业出版社, 1999. 192～193
[5] Butcher P.M.,Withnall S.G.. A practical strategy for EMC design.Electronics & Communication Engineering Journal, 1993,5(4): 257~264
[6] 张继松. 抗电磁干扰材料及器件的开发动向.磁性材料及器件, 1995,1: 37～44
[7] 王海泉,陈秀琴. 吸波材料的研究进展. 材料导报, 2003,S1: 177～180
[8] 周克省,黄可龙,孔德明等. 吸波材料的物理机制及其设计.中南工业大学学报, 2001, 32(6): 617～621
[9] 邓惠勇,官建国,高国华等. 雷达用隐身吸波材料研究进展.化工新型材料, 2003,31(3): 3～6
[10] 姚中,姚丽姜,虞维扬等. 吸波材料的发展及应用. 上海钢研, 2004,4: 3～8
[11] 邹联隆,易建宏,付应生等. 纯铁磁粉芯的磁特性研究.磁性材料及器件, 1999,31(1): 58～61
[12] Uchikoba F.. Multilayer EMC devices using GHz absorption of iron-resin composite materials.in: Proceedings of the IEEE/CPMT International Electronics Manufacturing Technology (IEMT) Symposium, 1997. 362～367
[13] 田民波. 磁性材料.第一版.北京: 清华大学出版社,2001. 71～78
[14] 李晋尧,何平. 提高 Ni-Zn 粉芯磁性能的研究.磁性材料及器件, 1995,26(3):18～21
[15] 苏桦,唐晓莉,张怀武. 抗电磁干扰(EMI)磁性材料及元器件技术.世界科技研究与发展, 2001,23(4): 18～20
[16] 龙毅,张正义. 新功能磁性材料及其应用.第一版.北京: 机械工业出版社, 1997. 1～11
[17] 宛德福,马兴隆. 磁性物理学.第一版.成都: 电子科技大学出版社, 1994. 44～52
[18] 张世远,路权,薛荣华等. 磁性材料基础.第一版.北京: 科学出版社, 1988. 29～35
[19] 宛德福. 磁性理论及其应用.第二版.武汉: 华中理工大学出版社, 1996. 22～34
[20] 傅晓玲. 金属磁性超细粉吸波性能研究.西安矿业学院学报, 1999,19(1): 92～96
[21] 巩晓阳,董企铭,田保红等. 纳米铁/环氧树脂复合材料的介电和吸波特性研究.机械工程材料, 2004,28(11): 32～33
[22] Huajun Y., Kejin R., Bolin Z.. Equivalent EM parameters of fiber cloth sheet absorbing material. Dianzi Keji Daxue Xuebao/Journal of University of Electronic Science and Technology of China, 1998,27(3): 280～283
[23] 姚中,姚丽姜,虞维杨等. 高导磁高品质因数磁粉芯研究.上海钢研, 1998,1: 11～17
[24] 汪俊琴. 粉末颗粒对Fe-Ni-Mo磁粉芯性能的影响.粉末冶金工业, 1998,8(4): 26～29
[25] Katsu Yanagimoto, Kazuhiko Majima, Satoshi Sunada, et al. Effect of Powder Compositions on GHz Microwave Absorption of EM Absorbing Sheets. J.Jpn.Soc.Powder Powder Metallurgy, 2004,51(4): 293～296
[26] 葛副鼎,朱静,陈利民等. 吸收剂颗粒形状对吸波材料性能的影响.宇航材料工艺, 1996,5: 42～49
[27] 钱坤明,纪松,吴敏等. 绝缘剂材料对纳米晶软磁合金磁粉芯性能的影响.金属功能材料, 2004, 11(5): 10～12
[28] 邹联隆,易建宏,付应生等. 化学包覆法制备高性能磁粉芯.材料科学与工程, 1999.17(1): 18～20
[29] Erhu N., Weiwei L.,Tiemao S.,et al. Measuring permittivity and permeability of high-loss solid materials at microwave frequency. IEEE Transaction on Magnetics, 1998,25(4): 543～545
[30] 吴安国. 铁粉芯磁介质粉芯粘结软磁.磁性材料及器件, 1999,30(6): 55～56
[31] Suran G.,Naili H., Naili M.,et al. Magnetic properties of CoFeZr amorphous thin films. Journal of Magnetism and Magnetic Materials, 1996,157~158:223～224
[32] 邓联文,江建军,范少春. 非晶态 CoFeZr 合金的制备及其微波吸收性能研究.金属功能材料, 2003,10(5): 9～12
[33] Thoumire O., Atmani H., Teilet J.,et al. Structural,mechanical and magnetic properties of nitrided FeSi and FeSiAl sheets. Journal of Magnetism and Magnetic Materials, 1999,196: 346～348
[34] 甘治平,官建国,王维. 单层均匀吸波材料电磁参数的匹配研究.航空材料学报, 2002,22(2): 37～40
[35] 杨志民,毛昌辉,杜军. Fe4N 电磁波吸收剂的合成及其吸波性能的研究.稀有金属, 2003,26(2): 103～107
[36] 杨志民,毛昌辉,杨剑等. 低频(3GHz)微波吸收材料电磁参数匹配特性的研究.稀有金属, 2004,28(6): 1006～1009
[37] 穆武第,程海峰,唐耿平等. 添加导电纤维对羰基铁粉吸波性能的影响.材料科学与工程学报, 2005,23(4): 557～560
[38] Yoshida S., Ono H., Ando S.,et al. Control of magnetic loss profile for RF noise suppression sheets. Electromagnetic Compatibility, 2003,2(11~16): 962 ～ 965
[39] Budai A.G..,Knysh V.P.,Maly S.V.. Development and study of absorbers of electromagnetic waves. Microwave and Telecommunication Technology, 2004.13~17: 555 – 556
[40] 周海涛,张怀武. 片式抗电磁干扰滤波器 Ni-Zn 铁氧体材料与工艺研究.磁性材料及器件, 2003,34(4): 7～9
[41] 舒阳会,任伊飞,俞永. 高频纯铁磁粉芯的工艺研究.航天制造技术, 2005,1: 10～11
[42] Daval J., Bechevet B., Arroyo J.,et al. Thick and stress-free Sendust films on silicon for recording head cores. IEEE Transactions on Magnetics, 1994,30(6): 3930～3932
[43] 舒阳会,孙义霞,庞小球等. 雾化纯铁磁粉芯的关键工艺.航天制造技术, 2002,5: 7～9
[44] 李志华,陈文智. 预退火对超微磁合金稳定性的影响.金属功能材料, 1995,Z(1): 174～175.
[45] 张甫飞,纪朝廉,张洛等. 铁基纳米晶合金粉末及磁粉芯研究.磁性材料及器件, 2000,31(4): 1～5
[46] Tadeusz Kulik,梁秀兵,Jarosaw Ferenc 等. 纳米晶铁钴基软磁材料的研究.中国表面工程, 2004,5:1～4
[47] 丘渝青,王正. Fe73.5Cu1Mo3Si13.5B9 超微晶磁粉芯的研究.金属功能材料, 1997: 71～74.
[48] 张娴,蒋全兴. 抑制微波干扰的电源滤波器设计.微波学报, 2000,16(3): 291～294
[49] 邱扬,鬲莉,田锦等. 电感器磁性材料特性的参数分析法.安全与电磁兼容, 2002,6: 32～34
[50] Ono H., Takase Y., Yoshida S.,et al. Analysis on noise suppression effect of the composite magnetic sheet for the use in near field. Electromagnetic Compatibility, 2003,2(11~16): 938～941
[51] Kakehashi Y., Yu M.,et al. Theory of metallic magnetism from crystals to amorphous structure. Journal of magnetism and Magnetic Materials, 1995,140: 251~252