摘要随着电子产品越来越小型化、多功能化，因此所用的钎料所需要满足的功能也越来越多。传统的含铅钎料已经逐渐被淘汰，而单一的无铅钎料在性能上已渐渐跟不上电子产品的要求，于是人们开始了复合焊料的研究。在电子产品中，焊点部位随着电子产品的发展，所承受的电流密度也随之增加，在高电流密度的作用下，材料内部会产生电迁移现象，从而影响电路正常运行。因此复合焊料电迁可靠性的研究成为了电子封装的重要研究对象。本文对SnAgCu/SnBi结构混合焊点和成分混合焊点两种焊点进行研究。通过在常温下分别对试样进行电流加载33h、66、99、132h，电流密度为104A/cm2，通电完成后，对其进行微观形貌的观察，得出结论。电迁移导致Bi在在阳极富集，并且随着通电时间的增加，在阳极Bi的富集越来越明显，而Sn3。0Ag0。5Cu对Bi的扩散有着很大的影响。86381

毕业论文关键字：复合焊点；电迁移；可靠性 

Abstract With the increasing miniaturization and multifunctional of electronic products,the functions that used solders needed in materials have a growing trend。Conventional solders which containing plumbum have been gradually weeded out , meanwhile in the performance , single solders without plumbum can't keep up with the requirements of electronic products。 That's why composite solders turn out。In the field of electronics,the electric current density which bonding pad portion withstanded increases with the development of electronic products。 When high electric current density,the phenomenon of electro migration inside the material will occurs,accordingly this will have an impact on operation of the circuit。 Obviously, it's vital to do research for reliability of electro migration for composite solders。 This paper has been pided into two parts for mixed welding spot of SnAgCu/SnBi, one is in structure,the other is in composition。 At room temperatures, no matter how long we loaded currents on the sample , the electric current density always remain unchanged , as 104A/cm2。 After power is completed, by observing micro topography ,conclusions can be arrived at。 Electro migration can cause Bi enriched at positive pole。 In the meantime, with the increasing time of powering on, the phenomenon is becoming  more and more obvious that Bi enriching at positive pole。 So Sn3。0Ag0。5Cu has a great impact on Bi diffusion。

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Keywords: Composite solder joint, electromigration, reliability

目 录

第一章 绪论 1

1。1 电子封装无铅化 1

1。1。1 微电子封装无铅化 1

1。1。2 无铅焊料的概述 2

1。1。3 复合焊料 4

1。2 电迁移理论 4

1。2。1 电迁移定义 4

1。2。2 电迁移的物理机制 4

1。2。3 影响电迁移的因素 5

1。2。4 国内外研究现状 6

1。2。5可靠性研究 9

1。3 本论文的研究目的和内容 9

1。3。1研究目的 9

1。3。2研究内容 9

第二章 实验方案及研究方法 10

2。1引言 10

2。2 试样的制备 10

2。2。1 Cu/Sn58Bi/Cu微焊点制备