Influence of Substrate Surface Finish Metallurgy on Lead-Free Solder Joint Microstructure with Implications for Board-Level Reliability

2020 ◽  
Vol 49 (5) ◽  
pp. 3251-3258
Author(s):  
Marion Branch Kelly ◽  
Tapabrata Maity ◽  
A. R. Nazmus Sakib ◽  
D. R. Frear ◽  
Nikhilesh Chawla
Keyword(s):  
Solder Joint ◽  
Substrate Surface ◽  
Lead Free ◽  
Lead Free Solder ◽  
Joint Microstructure ◽  
Solder Joint Microstructure ◽  
Influence Of Substrate ◽  
Free Solder ◽  
Board Level ◽  
Board Level Reliability

Effect of Solder Composition and Substrate Surface Finish on Board Level Drop Test Reliability

2005 ◽  
Author(s):  
Don-Son Jiang ◽  
Joe Hung ◽  
Yu-Po Wang ◽  
C. S. Hsiao
Keyword(s):  
Solder Joint ◽  
Substrate Surface ◽  
Drop Impact ◽  
Drop Test ◽  
Test Reliability ◽  
Lead Free ◽  
Lead Free Solder ◽  
Snagcu Solder ◽  
Free Solder ◽  
Board Level

For handheld or portable telecommunication devices such as mobile phone, PDA, etc., board level joint reliability during drop impact is a great concern to simulate mishandling during usage. In general, solder composition and substrate surface finish would principally determine the solder joint reliability. Board level drop test reliability of two solder compositions (SnPb and lead free SnAgCu) and surface finishes (Ni/Au and OSP) were examined in this study. The result indicated SnAgCu lead free solder showed poorer reliability life than Sn-Pb solder during drop impact. The crack path in SnPb solder joint almost went through bulk solder near substrate side. However, another IMC/Ni interfacial failure mode near substrate side was found in SnAgCu solder to cause lower reliability. This difference could attribute to higher strength of SnAgCu solder and deformation with higher strain rate in drop test. Comparison between two surface finishes indicated Ni/Au is better than OSP in both SnPb and SnAgCu lead free solder joints. In SnAgCu lead free solder joint with OSP, there are thicker Cu6Sn5 IMC and many large Ag3Sn IMC plates in interface to degrade the interfacial bonding, so drop impact would easily cause the all cracks through IMC/Cu interface and then reduce the reliability.

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