共查询到19条相似文献,搜索用时 78 毫秒
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由于传统焊接技术使用的Sn-Pb焊料中的铅会对环境造成污染而被禁止使用,近年来无铅焊料成为了研究热点。文中介绍了运用于电子产品中的无铅焊料的发展背景、特点及要求。根据应用温度不同,无铅焊料可以分为低温、中温和高温无铅焊料。文章综述了它们各自的应用特点、场合及存在的问题和发展前景。 相似文献
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相对于传统的Sn-Pb焊料,无铅焊料更容易氧化,润湿性较差,从而影响波峰焊接质量.N2保护可以降低无铅焊料的氧化,提高无铅焊料的润湿性,从而提高波峰焊接质量.从润湿性的机理分析了N2保护提高无铅焊料润湿性的原因,并通过润湿性实验和波峰焊接试验证实了N2保护的优越性. 相似文献
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无铅波峰焊设备的特点 总被引:1,自引:0,他引:1
相对于传统的Sn-Pb焊料,无铅焊料需要较高的焊接温度,而且润湿性差,另外免清洗助焊剂和水溶性助焊剂的固体含量低,活性温度高和活性区间窄。无铅焊料和助焊剂的特性决定了无铅波峰焊设备在结构和材料选用上有很大不同。通过对无铅波峰焊设备的各个部分的特点进行分析,为传统的旧波峰焊设备的改造提供参考。 相似文献
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Sn-Zn无铅焊料由于熔点接近Sn-Pb,价格低廉、无毒性、力学性能优良等特点,倍受人们的关注。然而由于Zn的表面活性高,在钎焊过程中焊料容易氧化,导致了润湿性能下降。本文综述合金元素对Sn-Zn无铅焊料氧化性能、润湿性的影响。并对Sn-Zn焊料今后的研究方向进行了简要分析。 相似文献
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含铅焊料应用在电子产品上已超过50年的时间。然而出于环境方面的考虑,在未来的几年含铅焊料的使用将被禁止。作为替代,必须发明不含铅的焊料。对无铅焊料总的要求类似于含铅焊料。它们要求类似的诸如焊接温度及时间工艺参数窗口和相当于含铅焊料或更好的特性。科学家们已研究了许多不同类型的无铅焊料,从中我们选取Sn3、5Ag0.7Cu作为本次研究的对象,因为它可能目前是在欧洲应用最广泛的一种无铅合金。通过下面几项工作中我们研究了Sn3.5Ag0.7Cu的疲劳特性。制成板(PCBA)温度循环(热冲击)试验:用Sn3.5Ag0.7Cu无铅焊料在不同的焊接气氛下将各种不同类型的器件焊在有不同可焊性表面覆层的印制板上,做成试验制成板(PCBA)。将125℃到-15℃的温度循环(热冲击)施与试验制成板并研究板上焊点在经受不同次数的温度循环后其微观组织结构及变化。模型焊点的机械应力循环试验:室温条件下利用特别设计的环一插针模型焊点,Sn3.5Ag0.7Cu无铅焊点被施加机械应力循环并和传统的Sn-Pb焊点进行比较。包含不同铅含量的焊点也被研究以确认铅杂质对无铅焊点特性的影响。比起传统的Sn-Pb焊料,Sn3.5Ag0.7Cu有更好的疲劳特性。然而研究同时发现一个2%-5%的铅杂质含量对无铅焊点的寿命是有害的。 相似文献
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Sn-Ag系电子无铅软钎料的超电势研究 总被引:3,自引:0,他引:3
随着微电子表面组装技术(SMT)的迅速发展和公众环境意识的增强,无铅软钎料成为近年来研究的焦点。主要研究了Sn-Ag系合金钎料的超电势电化学性能,并且与传统的Sn-Pb近共晶合金进行了对比。试验证明在酸、碱两种不同的溶液环境中,无铅软钎料在Sn-Pb合金的超电势有明显的差异。并指出含铋的钎料的超电势随着铋的含量的增加而降低,从而提出了在无铅软钎料研究中应当考虑因超电势变化而引起的问题。 相似文献
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(上接2004年第5期第201页) 3.2 锡炉的腐蚀性问题 波峰焊接PCB上的插装电子元器件,当采用无铅焊料时,由于无铅焊料的焊接温度比Sn-Pb合金焊料高约30 ℃~50 ℃,另外无铅焊料中Sn的含量大幅度提高,一般都在95 %以上,造成了波峰焊时无铅焊料对锡炉和喷口的腐蚀性加强.国内一般锡炉采用的材料是SUS304和SUS316型不锈钢.实验表明,不锈钢材料在高温条件下6个月就被高Sn无铅焊料明显腐蚀.最容易受到腐蚀的是与流动焊料接触的部位,如泵的叶轮、输送管和喷口. 相似文献
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Nanoparticles of the Lead-free Solder Alloy Sn-3.0Ag-0.5Cu with Large Melting Temperature Depression
Chang Dong Zou Yu Lai Gao Bin Yang Xin Zhi Xia Qi Jie Zhai Cristina Andersson Johan Liu 《Journal of Electronic Materials》2009,38(2):351-355
Due to the toxicity of lead (Pb), Pb-containing solder alloys are being phased out from the electronics industry. This has
lead to the development and implementation of lead-free solders. Being an environmentally compatible material, the lead-free
Sn-3.0Ag-0.5Cu (wt.%) solder alloy is considered to be one of the most promising alternatives to replace the traditionally
used Sn-Pb solders. This alloy composition possesses, however, some weaknesses, mainly as a result of its higher melting temperature
compared with the Sn-Pb solders. A possible way to decrease the melting temperature of a solder alloy is to decrease the alloy
particle size down to the nanometer range. The melting temperature of Sn-3.0Ag-0.5Cu lead-free solder alloy, both as bulk
and nanoparticles, was investigated. The nanoparticles were manufactured using the self-developed consumable-electrode direct
current arc (CDCA) technique. The melting temperature of the nanoparticles, with an average size of 30 nm, was found to be
213.9°C, which is approximately 10°C lower than that of the bulk alloy. The developed CDCA technique is therefore a promising
method to manufacture nanometer-sized solder alloy particles with lower melting temperature compared with the bulk alloy. 相似文献
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Lead (Pb)-free solders for electronic packaging 总被引:2,自引:0,他引:2
The harmful effects of lead on the environment and human health, coupled with the threat of legislation, have prompted a serious
search for lead-free solders for electronic packaging applications. At present, Sn-Pb eutectic and other Pb-containing solders
find widespread use in printed circuit board assembly. Several Pb-free solder alloys which appear to have the potential for
replacing Sn-Pb solders are receiving increased attention from the electronic assembly community. Recently, numerous studies
have been published detailing the wetting characteristics, tensile and shear strength, and creep and low-cycle fatigue properties
of these alloys. It is the purpose of this paper to review these results and assess the suitability of the solders for electronic
packaging from the viewpoints of process technology and reliability. 相似文献
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S. Choi T. R. Bieler J. P. Lucas K. N. Subramanian 《Journal of Electronic Materials》1999,28(11):1209-1215
Single shear lap joints were made with four different solders, Sn-Pb and Sn-Ag eutectic solders, and their composites containing
about 20 vol.% in-situ Cu6Sn5 intermetallic phases about 3–8 micrometers in diameter. Two sets of experiments were performed:
In the first set, all of the above four solder joints were aged at 150°C for periods ranging to 5000 h and the intermetallic
growth was monitored periodically. In the second set, each of the above four solder joints was aged at five different temperatures
for 4000 h. The interfacial layers between solders and the Cu substrate were examined using optical and scanning electron
microscopy. The growth kinetics of intermetallic interfacial layers formed between solder and Cu substrate was characterized.
The effect of in-situ Cu6Sn5 intermetallic phases on the growth rate is discussed. The growth rate of the intermetallic layers in the eutectic Sn-Pb composite
was slower for the first 150 h as compared to the eutectic Sn-Pb non-composite. The growth rate of the intermetallic layers
were similar for both the eutectic Sn-Ag and eutectic Sn-Ag composite throughout the aging duration. The activation energies
for Cu6Sn5 layer growth for the eutectic Sn-Pb and Sn-Ag solder joints are evaluated to be 111 kJ/mol and 116 kJ/mol, respectively.
The eutectic Sn-Pb and Sn-Ag composite solder joints exhibit higher activation energies of 161 kJ/mol and 203 kJ/mol. 相似文献
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Flux development for lead-free solders containing zinc 总被引:1,自引:0,他引:1
New lead-free solders containing zinc are promising candidates to replace near-eutectic tin-lead solders because the solders
melt at lower temperatures than Sn-Ag-base solders. They also possess good mechanical and fatigue properties and are less
expensive. However, the contact angle on copper for Sn-Zn solders is high when fluxes used for Sn-Pb solders are utilized.
A novel approach for flux development to improve wetting of copper surfaces by tin-zinc eutectic solder was developed: tin
containing organic compounds, which decomposes at soldering temperatures and produces metallic tin on surfaces to be soldered
was added to several specially formulated fluxes. This process improves wetting of copper surfaces by molten tin-zinc eutectic
solder. Fluxes were developed that give a contact angle as low as 20°. 相似文献
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Production method and properties of lead-free ball-grid array (BGA) balls in comparison to standard BGA balls with the eutectic
Sn-Pb composition are presented. Lead-free BGA balls can also be produced by an innovative process that allows the production
of solder balls directly from the melt. In contrast to Sn-Pb solder balls, the surface of lead-free balls is not perfectly
shiny but appears partly rough. This is caused by a different solidification behavior. The stability of Sn-based solder balls
against darkening caused by oxidation effects during movement is far more pronounced than for Sn-Pb balls. The patent situation
concerning Sn-based soft solders is not critical any more because of an existing “older” patent that covers comparable alloy
types. 相似文献
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Ag对Sn-Pb电子钎料合金性能的影响 总被引:2,自引:0,他引:2
研究了Ag的合金化对Sn-Pb钎料合金材料性能的影响。并从钎料的润湿性能,机械性能及抗腐蚀性能等方面讨论了Ag的有利作用,研究表明,在一些特定条件下的电子元件的焊接,Sn-Pb-Ag钎料可部分地或全部地替代昂贵的遗金属钎料合金。 相似文献