Lead-free Solders and PCB Finish Effects on Solder Joint Reliability

2006 ◽  
Author(s):  
Christopher Hunt ◽  
Milos Dusek
Keyword(s):  
Solder Joint ◽  
Lead Free ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Lead Free Solders

Assessment of board level solder joint reliability for PBGA assemblies with lead‐free solders

2002 ◽  
Vol 14 (3) ◽  
pp. 46-50 ◽  
Author(s):  
Shi‐Wei Ricky Lee ◽  
Ben Hoi Wai Lui ◽  
Y.H. Kong ◽  
Bernard Baylon ◽  
Timothy Leung ◽  
...  
Keyword(s):  
Solder Joint ◽  
Lead Free ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Lead Free Solders ◽  
Board Level

scholarly journals Lead-free Solder Joint Reliability – State of the Art and Perspectives

2005 ◽  
Vol 2 (1) ◽  
pp. 72-83 ◽  
Author(s):  
Jianbiao Pan ◽  
Jyhwen Wang ◽  
David M. Shaddock
Keyword(s):  
Solder Joint ◽  
Electronics Industry ◽  
Lead Free ◽  
Lead Free Solder ◽  
Joint Failure ◽  
Solder Joint Reliability ◽  
Electronic Products ◽  
Joint Reliability ◽  
Free Solder ◽  
Lead Free Solders

There is an increasing demand for replacing tin-lead (Sn/Pb) solders with lead-free solders in the electronics industry due to health and environmental concerns. The European Union recently passed a law to ban the use of lead in electronic products. The ban will go into effect in July of 2006. The Japanese electronics industry has worked to eliminate lead from consumer electronic products for several years. Although currently there are no specific regulations banning lead in electronics devices in the United States, many companies and consortiums are working on lead-free solder initiatives including Intel, Motorola, Agilent Technologies, General Electric, Boeing, NEMI and many others to avoid a commercial disadvantage. The solder joints reliability not only depends on the solder joint alloys, but also on the component and PCB metallizations. Reflow profile also has significant impact on lead-free solder joint performance because it influences wetting and microstructure of the solder joint. A majority of researchers use temperature cycling for accelerated reliability testing since the solder joint failure mainly comes from thermal stress due to CTE mismatch. A solder joint failure could be caused by crack initiation and growth or by macroscopic solder facture. There are conflicting views of the reliability comparison between lead-free solders and tin-lead solders. This paper first reviews lead-free solder alloys, lead-free component lead finishes, and lead-free PCB surface finishes. The issue of tin whiskers is also discussed. Next, lead-free solder joint testing methods are presented; finite element modeling of lead-free solder joint reliability is reviewed; and experimental data comparing lead-free and tin-lead solder joint reliability are summarized. Finally the paper gives perspectives of transitions to totally lead-free manufacturing.

Reliability of Lead-Free Solder Joints

2006 ◽  
Vol 128 (3) ◽  
pp. 297-301 ◽  
Author(s):  
John H. Lau
Keyword(s):  
Solder Joint ◽  
Hazardous Substances ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
The World ◽  
The Future ◽  
Free Solder ◽  
Lead Free Solders

Reliability of the restriction of the use of certain hazardous substances in electrical and electronic equipment compliant products is investigated in this study. Emphasis is placed on the lead-free solder joint reliability. Solder is the electrical and mechanical “glue” of electronics assemblies. Will lead-free solders provide the characteristics necessary to allow the world to depend on it in the future? This paper cannot answer this question; however, it will help all participants in the soldering world better understand what needs to be done in order to answer this question and plan for the future.

An Experimental Study on Voids in Mixed Alloy Assemblies

2006 ◽  
Author(s):  
Felix Bruno ◽  
Purushothaman Damodaran ◽  
Krishnaswami Srihari ◽  
Guhan Subbarayan
Keyword(s):  
Solder Joint ◽  
Manufacturing Industry ◽  
Research Effort ◽  
Lead Free ◽  
Process Window ◽  
Electronics Manufacturing ◽  
Solder Joint Reliability ◽  
Process Step ◽  
Joint Reliability ◽  
Robust Process

The electronics manufacturing industry is gradually migrating towards to a lead-free environment. During this transition, there will be a period where lead-free materials will need to coexist with those containing lead on the same assembly. The use of tin-lead solder with lead-free parts and lead-free solder with components containing lead can hardly be avoided. If it can be shown that lead-free Ball Grid Arrays (BGAs) can be successfully assembled with tin-lead solder while concurrently obtaining more than adequate solder joint reliability, then the Original Equipment Manufacturers (OEMs) will accept lead-free components regardless of the attachment process or material used. Consequently, the Electronics Manufacturing Service (EMS) providers need not carry both the leaded and the unleaded version of a component. Solder voids are the holes and recesses that occur in the joints. Some say the presence of voids is expected to affect the mechanical properties of a joint and reduce strength, ductility, creep, and fatigue life. Some believe that it may slow down crack propagation by forcing a re-initiation of the crack. Consequently, it has the ability to stop a crack. The primary objective of this research effort is to develop a robust process for mixed alloy assemblies such that the occurrence of voids is minimized. Since there is no recipe currently available for mixed alloy assemblies, this research will study and 'optimize' each assembly process step. The difference between the melting points of lead-free (217°C) and tin-lead (183°C) solder alloys is the most important constraint in a mixed alloy assembly. The effect of voids on solder joint reliability in tin-lead assembly is well documented. However, its effect on lead-free and mixed alloy assemblies has not received due attention. The secondary objective of this endeavor is to determine the percentage of voids observed in mixed alloy assemblies and compare the results to both tin-lead and lead-free assemblies. The effect of surface finish, solder volume, reflow profile parameters, and component pitch on the formation of voids is studied across different assemblies. A designed experiments approach is followed to develop a robust process window for mixed alloy assemblies. Reliability studies are also conducted to understand the effect of voids on solder joint failures when subjected to accelerated testing conditions.

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