The Effect Of Processing Property And Interface Behavior In The Joints Of The Sn-based Lead Free Solder With Additional Elements

This paper studies the effect of processing property and interface behavior in the joint of the Sn-based lead free solder with additional elements. It mostly containstwo parts: firstly, it appends Bi to Sn3.5Ag eutecuc alloy solder to improve it's alloying performance. The experimentation researches the influence of melting point, wetting, fluidity, mechanical property and heat fatigue property for the accession of Bi and analyses the Sn37Pb solder contrastively;Secondly, it appends Ag, Ce to Sn-based duality solder and researches the IMCs in the binary solder and the soldered fitting of Cu, Ni based board, and it also discusses the influence mechanism to IMCs of their thickness, component and appearance of the accession of Ag, Ce and study the influence of the soldering procedure parameter to the interface behavior in the soldered fitting. The experimentation gets the conclusions as follows:(1) accession of Bi reduce the melting point of Sn3.5Ag eutectic solder and improve it's fluidity, wetting, heat fatigue property, intension and extensibility. The accession quantity of Bi should be about 5%.(Wt.%),overmuch Bi can enhance the solder brittleness and decline it toughness, and while the quantity of Bi exceed 5%, the effect of solder melting point should be weakness.(2)While Sn-Ag soldered Cu, the thickness of IMC is smaller and smaller when the content of Ag is more and more;and when the content over 1.5%, the Cu6Sn5 IMC grains adsorb much more nm-Ag3Sn grains, meanwhile the thickness of IMC is turn round. While Sn-Ag soldered Ni, the thickness of IMC is smaller and smaller when the content of Ni is more and more;when the reaction of Sn-3.5Ag and Cu at 260℃.280℃.400℃, the surface of CU6Sn5 IMC adsorb much Ag3Sn grains. The temperature and time of solder effect the size of adsorbed Ag3Sn highly. Whensoldered at low temperature, the size of Ag3Sn is smaller and smaller while the time is longer and longer, contrariwise is reverse.(3) While Sn-Ce soldered Cu, the thickness of IMC is smaller and smaller apparently when the content of Ce is more and more;While Sn-Ce soldered Ni, when the content of Ce is more and more, the shape of Ni3Sn is turn grain to stick and the size is more uniformity;the accession of Ce can reduce the thickness of IMC apparently, but when the content gets 0.1 %, the thickness of IMC gets the max;the accession of Ag and Ce effect apparently to the alive degree of Sn and the thickness of IMC, and the effect of Ag is more apparently.