SnAgCu无铅焊点水相环境腐蚀行为和预防措施的研究
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摘要
现代微连接中无铅钎料的使用符合人类的环保及生态需求,是未来电子组装业的必然趋势。而电子产品中的无铅焊点在生产和使用中经常处于腐蚀环境中,所导致的腐蚀会改变其机械性能、电性能,从而引发故障,所以腐蚀问题不容忽视。本课题以硬盘磁头中无铅微焊点为对象,研究它在水环境下的腐蚀特性。本文根据焊点所处的外界环境以及钎料Sn3.0Ag0.5Cu的自身特点,研究影响焊点腐蚀的内外部因素,并提出针对性的防腐措施。
本文的研究内容主要包括以下几个方面:
(1)腐蚀产物为电化学腐蚀产生的锡的氧化物,而腐蚀产物形貌差异的主要原因是腐蚀环境中溶质的溶液过饱和度不同。
(2)腐蚀过程本身和腐蚀产物都对硬盘可靠性有较大影响。分别对腐蚀过程和腐蚀产物对硬盘可靠性造成的影响进行研究。
(3)溶液中腐蚀性离子的含量及浓度对焊点腐蚀有较大影响。而影响焊点腐蚀的腐蚀性离子主要来源于承载磁头的折片。焊接前对折片清洗,可以有效的降低焊点的腐蚀率。
(4)锡离子作为腐蚀与结晶的一个中间产物,在腐蚀过程中起着重要的作用。溶液中的锡离子为腐蚀产物的结晶提供溶液过饱和度和质量运输所需的浓度梯度。同时锡离子浓度可作为一种评价腐蚀程度的标准。
(5)焊点表面氧化膜厚度是影响腐蚀的一个最主要的内部因素。在一定范围内,氧化膜越厚,焊点表面的电导性就越差,对焊点的保护越好,电化学腐蚀就不容易发生。利用锈蚀反应原理,提高焊接能量,降低氮气保护的压力,可以有效的增加焊点表面膜的厚度,降低焊点的腐蚀率。
通过上述研究得出了腐蚀对硬盘可靠性造成的影响,揭示了在水相环境下影响无铅焊点腐蚀的内外部因素,同时对不同焊点腐蚀出现较大差异性的原因进行了解释。在此基础上,结合实际生产,制定出切实可行的防腐措施,提高了硬盘的可靠性,对实际生产具有显著意义。
The lead-free solder used in the modern microjoining accords with the human environmental protection and ecological need, so it is the necessary trend of the future electronic assembly. While the lead-free solder joints of electronic products are usually applied in the corrosive environment during the process of production and usage. The corrosion can’t be ignored, because mechanical property and electrical property could be affected, which finally result in electrical failure. Based on the lead-free solder joints of the hard disk head, this work mainly focuses on its corrosion character in the aqua environment during the process of cleaning. This paper analyses the intrinsic and extrinsic factors resulting in the solder joints’corrosion, studies the external environment of solder joints and the character of Sn3.0Ag0.5Cu solder itself. Based on this study result, some anti-corrosive measures for corrosion are raised.
The main contents of this paper include:
(1)The corrosion product is validated to be the oxide of tin and generate in the electrochemical corrosion process. The reason why corrosion products have different shape is the corrosion environments having different supersaturation of the solution.
(2)The corrosion process and corrosion product all show serious effect on the reliability of hard disk. The effect on the hard disk caused by corrosion process and product respectively are studied.
(3)The content and concentration of corrosive ion in solution have serious effect on solder joints corrosion, and they are mainly from the suspension. The solder joint’s corrosive ratio will become low if the suspension is cleaned before jointing.
(4)As the intermediate between corrosion and crystal, the tin ion concentration in the solution is very important for corrosion process. It supplies the supersaturation of the solution for crystal and concentration grads for‘mass transport’. The tin ion concentration in the solution can be used as an effective criterion of corrosion degree.
(5)The thickness of oxide-film on the surface of solder joint is a main inner factor for corrosion. In a certain range thicker oxide-film on solder joint shows worse electric property and better protection, and the electrochemical corrosion is more difficult. Base on the theory of rust reaction, the solder joint’s surface film becomes thicker by increasing jointing energy and decreasing the pressure of protection N2. That can decrease the solder joint’s corrosion ratio.
The above studies obtains the corrosion effect on hard disk reliability; reveals intrinsic and extrinsic factors that affect the corrosion of lead-free solder joints in the aqua environment; explains the obvious different corrosion degree among different solder joint. In the end, some feasible anti-corrosive measures are put forward, which will improve the reliability of hard disk, and it has significant meaning to the practical production.
本文的研究内容主要包括以下几个方面:
(1)腐蚀产物为电化学腐蚀产生的锡的氧化物,而腐蚀产物形貌差异的主要原因是腐蚀环境中溶质的溶液过饱和度不同。
(2)腐蚀过程本身和腐蚀产物都对硬盘可靠性有较大影响。分别对腐蚀过程和腐蚀产物对硬盘可靠性造成的影响进行研究。
(3)溶液中腐蚀性离子的含量及浓度对焊点腐蚀有较大影响。而影响焊点腐蚀的腐蚀性离子主要来源于承载磁头的折片。焊接前对折片清洗,可以有效的降低焊点的腐蚀率。
(4)锡离子作为腐蚀与结晶的一个中间产物,在腐蚀过程中起着重要的作用。溶液中的锡离子为腐蚀产物的结晶提供溶液过饱和度和质量运输所需的浓度梯度。同时锡离子浓度可作为一种评价腐蚀程度的标准。
(5)焊点表面氧化膜厚度是影响腐蚀的一个最主要的内部因素。在一定范围内,氧化膜越厚,焊点表面的电导性就越差,对焊点的保护越好,电化学腐蚀就不容易发生。利用锈蚀反应原理,提高焊接能量,降低氮气保护的压力,可以有效的增加焊点表面膜的厚度,降低焊点的腐蚀率。
通过上述研究得出了腐蚀对硬盘可靠性造成的影响,揭示了在水相环境下影响无铅焊点腐蚀的内外部因素,同时对不同焊点腐蚀出现较大差异性的原因进行了解释。在此基础上,结合实际生产,制定出切实可行的防腐措施,提高了硬盘的可靠性,对实际生产具有显著意义。
The lead-free solder used in the modern microjoining accords with the human environmental protection and ecological need, so it is the necessary trend of the future electronic assembly. While the lead-free solder joints of electronic products are usually applied in the corrosive environment during the process of production and usage. The corrosion can’t be ignored, because mechanical property and electrical property could be affected, which finally result in electrical failure. Based on the lead-free solder joints of the hard disk head, this work mainly focuses on its corrosion character in the aqua environment during the process of cleaning. This paper analyses the intrinsic and extrinsic factors resulting in the solder joints’corrosion, studies the external environment of solder joints and the character of Sn3.0Ag0.5Cu solder itself. Based on this study result, some anti-corrosive measures for corrosion are raised.
The main contents of this paper include:
(1)The corrosion product is validated to be the oxide of tin and generate in the electrochemical corrosion process. The reason why corrosion products have different shape is the corrosion environments having different supersaturation of the solution.
(2)The corrosion process and corrosion product all show serious effect on the reliability of hard disk. The effect on the hard disk caused by corrosion process and product respectively are studied.
(3)The content and concentration of corrosive ion in solution have serious effect on solder joints corrosion, and they are mainly from the suspension. The solder joint’s corrosive ratio will become low if the suspension is cleaned before jointing.
(4)As the intermediate between corrosion and crystal, the tin ion concentration in the solution is very important for corrosion process. It supplies the supersaturation of the solution for crystal and concentration grads for‘mass transport’. The tin ion concentration in the solution can be used as an effective criterion of corrosion degree.
(5)The thickness of oxide-film on the surface of solder joint is a main inner factor for corrosion. In a certain range thicker oxide-film on solder joint shows worse electric property and better protection, and the electrochemical corrosion is more difficult. Base on the theory of rust reaction, the solder joint’s surface film becomes thicker by increasing jointing energy and decreasing the pressure of protection N2. That can decrease the solder joint’s corrosion ratio.
The above studies obtains the corrosion effect on hard disk reliability; reveals intrinsic and extrinsic factors that affect the corrosion of lead-free solder joints in the aqua environment; explains the obvious different corrosion degree among different solder joint. In the end, some feasible anti-corrosive measures are put forward, which will improve the reliability of hard disk, and it has significant meaning to the practical production.
引文
1肖鹭.钎料球喷射连接过程中钎料液滴飞溅机理的研究.哈尔滨工业大学硕士论文. 2006:1~3
2 I. E. Anderson, B. A. Cook. 2nd EU Lead-free Soldering TechnologyRoadmap and Framework for an International Lead-free Soldering Roadmap.Soldertec at Tin Technology, 2003, (2):78~82
3 J. Glaser. Microstructure and mechanical properties of Pb-free solder alloysfor low-cost electronic assembly: A review. J.Electron.Mater. 2001, 23(8):693~702
4 K. Suganuma. The Current Status of Lead-free Soldering. ESPECTechnology Report.2003.13 (2): 13-22
5马鑫,董本霞.无铅焊料发展现状.电子工艺技术. 2002, 23(2):47~52
6 K Suganuma. Advance in Lead-Free Electronic Soldering. Solid State andMaterials Science. 2001, (5):55~64
7 J. M. Koo, S. B. Jung. Effect of Substrate Metallization on MechanicalProperties of Sn-3.5Ag BGA Solder Joints with Multiple Reflows.Microelectronic Engineering. 2005, (82):569~574
8郭福.无铅钎焊技术应用.科学出版社, 2005:129~143
9 I. E. Anderson, B. A. Cook, Harringa J. Sn-Ag-Cu Solders and Solder Joints: Alloy Development Microstructure, and Properties. J Electron Master, 2006, 31(31):1166~1174
10曹星,易丹青,工颖,卢斌,杜若听. Sn-Ag基无铅焊料的研究与进展.四川有色金属. 2001, 3(12):5~12
11石素琴,董占贵,钱乙余.软钎焊钎料的最新发展动态.电子工艺技术. 2000, 21(6):231~234
12庄鸿寿.无铅软钎料的新进展.电子工艺技术, 2001,22(5):192~195
13刘道新.材料的腐蚀与防护.西北工业大学出版社, 2006:20~109
14秦毅.无铅焊点表面氧化亚锡相产生的机理研究.哈尔滨工业大学硕士论文. 2007:10~13
15任侃.金属腐蚀手册[M].上海科学技术出版社, 1987:22~34
16朱日彰.金属腐蚀学[M].冶金工业出版社, 1989:30~35
17洪广言.无机固体化学.科学出版社, 2004:92~207
18 J. W. Osenbach. Sn Corrosion and Its Influence on Whisker Growth. Electronics Packaging Manufacturing. 2007, (1):23~35
19赵品.材料科学基础教程.哈尔滨工业大学出版社,2002:3~24
20夏志东,穆楠,史耀武.锡锌钎料的腐蚀行为[J].中国腐蚀与防护学报.2003,23(4):234~237
21 L. Paul, F. Akira. Laser-Diode Based Soldering System with VersionCapabilities. IEEE. CPMT Inter. Electronics Manufacturing TechnologySymposium. 1995:324-328
22 A. Flanagan, A. Conneely, T.J. Glynn, G. Lowe. Laser Soldering andInspection of Fine Pitch Electronic Components. Journal of MaterialsProcessing Technology. 1996, (56):531~541
23 I. V. Zsolt. Laser Processing for Microelectronics Packaging Aapplications.Microelectronics Reliability. 2001, (41):563~570
24 S. Hofmann. Surf. Interface Analysis 1994, (21):673
25 J. Thomas, A. John, and K. Wetzig. Nanoscale Co/Cu MultilayersInvestigated by Analytical TEM and AES. Mikrochim. 2000:131-135
26 W. Lisowski, M. Smithers. SEM and AES depth profile studies of thintitanium and titanium oxide films covered by nanoscale evaporated Aulayers. Fresenius J Anal Chem. 1999, 365:231-235
27 K. P. Yarkey, K. P. Yijayakumar, J. Imai, T. Yoshida and Y. Kashiwaba.Depth profiling of CdS homojunction using AES analysis. Bull.Mater.Sci.1997, (9):1085~1087
28陈铮.材料连接原理.哈尔滨工业大学出版社,2001:160~192
29 D. H. Kim, P. Elenius. Solder Joint Reliability and Characteristics ofDeformation Scott Barrett and Crack Growth of Sn-Ag-Cu Versus EutecticSn-Pb on a WLP in a Thermal Cycling Test. IEEE TransactionsonElectronics Packaging Manufacturing. 2002, (25):84~90
30 W. Wang, F. J. Hong, and H. H. Qiu. Prediction of Solder Bump FormationSolder Jet Packaging Process. IEEE Transactions on Components andPackaging Technologies. 2006, 29(3):486~493
31 K. Zeng, K. N. Tu. Six Cases of Reliability Study of Pb-lead Solder Joints inElectronic Packaging Technology. Materials Science and Engineering. 2002,2955(105):2~19
32 K. N. Tu, F. Ku, T. Y. Lee. Morphology stability of solder reaction productsin flip chip technology. J.Electr.Mater. 2001, 30(9): 1129-1132
33田君. SnAgCuEr系钎料的抗腐蚀性研究. China Academic JournalElectronic Publishing.2007:29~32
34 P. Bush, G. L. Jones, and I. Boguslavasky. Relationship of copper diffusionand surface oxide formation to tin whisker growth. In Proc. APEX, Anaheim,CA. 2002
35 W. L. Lin.The electrochemical corrosion behavior of Pb-free Al-Zn-Snsolders in NaCl solution. Materials Chemistry and Physics. 1998, 56:171-176
36 A. Grigoriev, O. Shpyrki, C. Steimer, P. S. Pershan, B. M. Ocko, M.Deutsch, B. Lin, M. Meron, T. Graber, and J. Gebhardt. Surface oxidation ofliquid Sn. Surf.Sci., vol. 575. 2005:223-232
37刘永岳.喷射钎料球键合接头成型特征研究.哈尔滨工业大学硕士论文.2007:29
38 D. toet, P. M. Smith. Experimental and Numerical Investigations of aHydrogen-Assisted Laser-Iinduced Materials Transfer Procedure. J. Appl.Phys., 2000, 87(7):3537~3546
39 J. H. Lee, J. H. Park, Y. H. Lee, Y. H. Kim, D. H. Shin. Stability of channelsat a scallop like Cu6Sn5 layer in solder interconnections. J.Mater. Res. 2001, 16(5):1227~1230
40 W. Liu, C. Q. Wang, M. Li, L. Ling. Effect of Laser Input Energy onWetting Areas of Solder and Formation of Intermetallic Compounds atSn3.5AgO.75Cu/Au Right-angled Joint Interface. International Conferenceon Asian Green Electronics. 2005:197-201
43 R. A. T. DE Greef, L. J. J. Janssen. Electrochemical dissolution of tin inmethanesulphonic acid solutions. Jurnal of Applied Electrochemistry. 2001, 31:693-702
44 D. Toskovic, M. B. Rajkovic, I. Ciric. Corrosion of Tin Plate in BrineSolutions. Russian Journal of Applied Chemistry. 2002, Vol. 75, (ll):1808~1811
45 D. Brazinskiene, V. Pautieniene, and A. Survila. Tin Corrosion in HighlyAcidic Solutions Containing Ethylene Glycol Oligomers and Halides: AnElectrochemical Quartz Crystal Microbalance Study. Russian Journal ofElectnochemishy. 2007, hoi. 43, (l):64-69
46 N. Ntahimperaa, J. K. Hackerb, L. L. Wilsona, F. R. Hallb, L. V. Maddena.Characterization of Splash Droplets from Different Surfaces with a PhaseDoppler Particle Analyzer. Agricultural and Forest Meteorology. 1999,97:9-19
47 S. Amada, T. Ohyagi, M. Haruyama. Evaluation of splat profile for dropletimpingement. Surface and Coatings Technology. 1999, 115:184-192
48 A. Fujisawa, M. Nara, M. Hirata, K. Kiyoharaz, M. Hyodo. Development ofGlass substrates with Tin Oxide Films for A-SI Solar Modules. 3rd WorldConference on Photovoltaic Energy Conversion. 2003, (5): 11-18
49 E. Comini, S. Bianchi, G. Faglia. Functional nanowires of tin oxide. Appl.Phvs. 2007, (89):73-76
50 A. K. Ray, S. M. Tracey. Photoelectric Measurements on ChloroaluminiumPhthalocyanine/Titanium Oxide Heterojunctions. Journal of Sol-Gel Scienceand Technology. 2001, (22): 15-22
51 Y. B. Kamenev, M. V. Lushina, A. V. Kiselevich, A. I. Rusin, E. I.Ostapenko. Protective Properties of Lead Coating with Tin Sublayer forCopper Current Leads of Negative Electrodes in Lead-acid Batteries.Russian Journal of Applied Chemistry. 2001, (2):224-228
52 C. N. Tsai, J. C. Chou, T. P. Sun, and S. K. Hsiung. Study on the TimeDependent Slow Response of the Tin Oxide PH Electrode. IEEE SensorsJournal. 2006, (5): 1243-1249
2 I. E. Anderson, B. A. Cook. 2nd EU Lead-free Soldering TechnologyRoadmap and Framework for an International Lead-free Soldering Roadmap.Soldertec at Tin Technology, 2003, (2):78~82
3 J. Glaser. Microstructure and mechanical properties of Pb-free solder alloysfor low-cost electronic assembly: A review. J.Electron.Mater. 2001, 23(8):693~702
4 K. Suganuma. The Current Status of Lead-free Soldering. ESPECTechnology Report.2003.13 (2): 13-22
5马鑫,董本霞.无铅焊料发展现状.电子工艺技术. 2002, 23(2):47~52
6 K Suganuma. Advance in Lead-Free Electronic Soldering. Solid State andMaterials Science. 2001, (5):55~64
7 J. M. Koo, S. B. Jung. Effect of Substrate Metallization on MechanicalProperties of Sn-3.5Ag BGA Solder Joints with Multiple Reflows.Microelectronic Engineering. 2005, (82):569~574
8郭福.无铅钎焊技术应用.科学出版社, 2005:129~143
9 I. E. Anderson, B. A. Cook, Harringa J. Sn-Ag-Cu Solders and Solder Joints: Alloy Development Microstructure, and Properties. J Electron Master, 2006, 31(31):1166~1174
10曹星,易丹青,工颖,卢斌,杜若听. Sn-Ag基无铅焊料的研究与进展.四川有色金属. 2001, 3(12):5~12
11石素琴,董占贵,钱乙余.软钎焊钎料的最新发展动态.电子工艺技术. 2000, 21(6):231~234
12庄鸿寿.无铅软钎料的新进展.电子工艺技术, 2001,22(5):192~195
13刘道新.材料的腐蚀与防护.西北工业大学出版社, 2006:20~109
14秦毅.无铅焊点表面氧化亚锡相产生的机理研究.哈尔滨工业大学硕士论文. 2007:10~13
15任侃.金属腐蚀手册[M].上海科学技术出版社, 1987:22~34
16朱日彰.金属腐蚀学[M].冶金工业出版社, 1989:30~35
17洪广言.无机固体化学.科学出版社, 2004:92~207
18 J. W. Osenbach. Sn Corrosion and Its Influence on Whisker Growth. Electronics Packaging Manufacturing. 2007, (1):23~35
19赵品.材料科学基础教程.哈尔滨工业大学出版社,2002:3~24
20夏志东,穆楠,史耀武.锡锌钎料的腐蚀行为[J].中国腐蚀与防护学报.2003,23(4):234~237
21 L. Paul, F. Akira. Laser-Diode Based Soldering System with VersionCapabilities. IEEE. CPMT Inter. Electronics Manufacturing TechnologySymposium. 1995:324-328
22 A. Flanagan, A. Conneely, T.J. Glynn, G. Lowe. Laser Soldering andInspection of Fine Pitch Electronic Components. Journal of MaterialsProcessing Technology. 1996, (56):531~541
23 I. V. Zsolt. Laser Processing for Microelectronics Packaging Aapplications.Microelectronics Reliability. 2001, (41):563~570
24 S. Hofmann. Surf. Interface Analysis 1994, (21):673
25 J. Thomas, A. John, and K. Wetzig. Nanoscale Co/Cu MultilayersInvestigated by Analytical TEM and AES. Mikrochim. 2000:131-135
26 W. Lisowski, M. Smithers. SEM and AES depth profile studies of thintitanium and titanium oxide films covered by nanoscale evaporated Aulayers. Fresenius J Anal Chem. 1999, 365:231-235
27 K. P. Yarkey, K. P. Yijayakumar, J. Imai, T. Yoshida and Y. Kashiwaba.Depth profiling of CdS homojunction using AES analysis. Bull.Mater.Sci.1997, (9):1085~1087
28陈铮.材料连接原理.哈尔滨工业大学出版社,2001:160~192
29 D. H. Kim, P. Elenius. Solder Joint Reliability and Characteristics ofDeformation Scott Barrett and Crack Growth of Sn-Ag-Cu Versus EutecticSn-Pb on a WLP in a Thermal Cycling Test. IEEE TransactionsonElectronics Packaging Manufacturing. 2002, (25):84~90
30 W. Wang, F. J. Hong, and H. H. Qiu. Prediction of Solder Bump FormationSolder Jet Packaging Process. IEEE Transactions on Components andPackaging Technologies. 2006, 29(3):486~493
31 K. Zeng, K. N. Tu. Six Cases of Reliability Study of Pb-lead Solder Joints inElectronic Packaging Technology. Materials Science and Engineering. 2002,2955(105):2~19
32 K. N. Tu, F. Ku, T. Y. Lee. Morphology stability of solder reaction productsin flip chip technology. J.Electr.Mater. 2001, 30(9): 1129-1132
33田君. SnAgCuEr系钎料的抗腐蚀性研究. China Academic JournalElectronic Publishing.2007:29~32
34 P. Bush, G. L. Jones, and I. Boguslavasky. Relationship of copper diffusionand surface oxide formation to tin whisker growth. In Proc. APEX, Anaheim,CA. 2002
35 W. L. Lin.The electrochemical corrosion behavior of Pb-free Al-Zn-Snsolders in NaCl solution. Materials Chemistry and Physics. 1998, 56:171-176
36 A. Grigoriev, O. Shpyrki, C. Steimer, P. S. Pershan, B. M. Ocko, M.Deutsch, B. Lin, M. Meron, T. Graber, and J. Gebhardt. Surface oxidation ofliquid Sn. Surf.Sci., vol. 575. 2005:223-232
37刘永岳.喷射钎料球键合接头成型特征研究.哈尔滨工业大学硕士论文.2007:29
38 D. toet, P. M. Smith. Experimental and Numerical Investigations of aHydrogen-Assisted Laser-Iinduced Materials Transfer Procedure. J. Appl.Phys., 2000, 87(7):3537~3546
39 J. H. Lee, J. H. Park, Y. H. Lee, Y. H. Kim, D. H. Shin. Stability of channelsat a scallop like Cu6Sn5 layer in solder interconnections. J.Mater. Res. 2001, 16(5):1227~1230
40 W. Liu, C. Q. Wang, M. Li, L. Ling. Effect of Laser Input Energy onWetting Areas of Solder and Formation of Intermetallic Compounds atSn3.5AgO.75Cu/Au Right-angled Joint Interface. International Conferenceon Asian Green Electronics. 2005:197-201
43 R. A. T. DE Greef, L. J. J. Janssen. Electrochemical dissolution of tin inmethanesulphonic acid solutions. Jurnal of Applied Electrochemistry. 2001, 31:693-702
44 D. Toskovic, M. B. Rajkovic, I. Ciric. Corrosion of Tin Plate in BrineSolutions. Russian Journal of Applied Chemistry. 2002, Vol. 75, (ll):1808~1811
45 D. Brazinskiene, V. Pautieniene, and A. Survila. Tin Corrosion in HighlyAcidic Solutions Containing Ethylene Glycol Oligomers and Halides: AnElectrochemical Quartz Crystal Microbalance Study. Russian Journal ofElectnochemishy. 2007, hoi. 43, (l):64-69
46 N. Ntahimperaa, J. K. Hackerb, L. L. Wilsona, F. R. Hallb, L. V. Maddena.Characterization of Splash Droplets from Different Surfaces with a PhaseDoppler Particle Analyzer. Agricultural and Forest Meteorology. 1999,97:9-19
47 S. Amada, T. Ohyagi, M. Haruyama. Evaluation of splat profile for dropletimpingement. Surface and Coatings Technology. 1999, 115:184-192
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