Microstructures and Mechanical Properties of Lead-free Solder Joints in Pin Through Hole Components
Effects of minor Ni addition (0.05 wt.%) on the microstructures and mechanical reliability of the lead-free solder joints in the rework pin through hole (PTH) components were carefully investigated using a scanning electron microscope (SEM),field-emission electron probe X-ray microanalyzer,and pull tester.The PTH walls (i.e.,Cu) of printed circuit boards (PCBs) were coated with organic solderability preservative (OSP) or electroless nickel/immersion gold (ENIG) surface finish before soldering reaction.During soldering,the pins of the electronic components were inserted into the PTHs treated with OSP or ENIG first and then were joined using Sn-3Ag-0.5Cu (SAC) solder bath through a typical wave soldering process.After the wave soldering,a rework (the 2nd wave soldering) was performed,where a SAC or Sn-0.7Cu-0.05Ni (SCN) solder bath was employed.It was found that the SCN joints possessed a higher tensile strength than the SAC ones in the OSP case.The sluggish growth of Cu3Sn along with very few Kirkendall voids at the solder/Cu interface due to minor Ni addition into the solder alloy (i.e.,SCN) was believed to be the root cause responsible for the increase in the strength value.However,the strength of the PTH components revealed insensitive to the solder composition in the alternative case,where an ENIG was deposited.The implication of this study revealed that minor addition of Ni into the solder is very beneficial for the solder/Cu joints but the solder/Ni(P) system.
Lead-free soldering Sn-3Ag-0.5Cu (SAC) Sn-0.7Cu-0.05Ni (SCN) OSP ENIG Kirkendall voids pull test
Cheng-Wei Liao Chin-Hung Kuo Kuen-Song Lin Yen-Chen Lin Cheng-En Ho
School of Physics and Technology,Wuhan University,Hubei,China;Department of Chemical Engineering & M Department of Chemical Engineering & Materials Science,Yuan Ze University,Taiwan,R.O.C
国际会议
西安
英文
1-6
2012-10-01（万方平台首次上网日期，不代表论文的发表时间）