Interfacial reactions and mechanism properties between SAC 405 and SACNG lead-free solders with Au/Ni(P)/Cu substrates reflowed by CO<inf>2</inf> laser

ABSTRACTRecently, it was reported that adding Zn to solder was an effective way for reducing the formation of both Cu3Sn and Cu6Sn5 and inhibiting Kirkendall voids formation. The objective of this study is to investigate this Zn effect in detail. Three Sn-xZn solders (x = 0.5, 0.7, and 2 wt. %) were reacted with Cu substrates at 250°J for 2-10 mins. A slight variation in the Zn concentration changed the reaction product formed at the interface. When the Zn concentration was low (x = 0.5 wt. %), the reaction product was Cu6Sn5. At high Zn concentration (x = 2 wt. %), the reaction product became Cu5Zn8. When Zn concentration was in-between (x = 0.7 wt. %), Cu6Sn5 and CuZn co-existed. The above findings are explained using the Cu–Sn–Zn phase diagram. The implication is that the type of compound forms at the interface can be controlled by adjusting the Zn concentration of the Sn-based solders.

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Interfacial reactions between Sn–8Zn–3Bi–xNi lead-free solders and Cu substrate during isothermal aging

Materials Chemistry and Physics ◽

10.1016/j.matchemphys.2010.05.028 ◽

2010 ◽

Vol 123 (2-3) ◽

pp. 629-633 ◽

Cited By ~ 13

Author(s):

Lijuan Liu ◽

Wei Zhou ◽

Baoling Li ◽

Ping Wu

Keyword(s):

Isothermal Aging ◽

Interfacial Reactions ◽

Lead Free ◽

Cu Substrate ◽

Lead Free Solders

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Interfacial reactions of Sn–58Bi and Sn–0.7Cu lead-free solders with Alloy 42 substrate

Microelectronics Reliability ◽

10.1016/j.microrel.2013.09.003 ◽

2014 ◽

Vol 54 (1) ◽

pp. 233-238 ◽

Cited By ~ 8

Author(s):

Yee-Wen Yen ◽

Ruo-Syun Syu ◽

Chih-Ming Chen ◽

Chien-Chung Jao ◽

Guan-Da Chen

Keyword(s):

Interfacial Reactions ◽

Lead Free ◽

Lead Free Solders

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Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

Materials Science Forum ◽

10.4028/www.scientific.net/msf.830-831.265 ◽

2015 ◽

Vol 830-831 ◽

pp. 265-269

Author(s):

Satyanarayan ◽

K.N. Prabhu

Keyword(s):

Solder Joint ◽

Solder Matrix ◽

Lead Free ◽

Lead Free Solder ◽

Solder Alloys ◽

Cu Substrate ◽

Cu Substrates ◽

Free Solder ◽

Substrate Surfaces ◽

Lead Free Solders

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

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