Isothermal cyclic bend fatigue test method for lead free solder joints

2006 ◽  
Author(s):  
J.H.L. Pang ◽  
Fa-Xing Che
Keyword(s):  
Fatigue Test ◽  
Solder Joints ◽  
Test Method ◽  
Lead Free ◽  
Lead Free Solder ◽  
Bend Fatigue Test ◽  
Free Solder

Effect of Voids on Thermal Fatigue Reliability of Lead-Free Solder Joints

2002 ◽  
Author(s):  
Qiang Yu ◽  
Do-Seop Kim ◽  
Tadahiro Shibutani ◽  
Toshiaki Inoue ◽  
Nobuyuki Sadakata
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Fatigue Fracture ◽  
Fracture Mode ◽  
Solder Joints ◽  
Equivalent Plastic Strain ◽  
Lead Free ◽  
Lead Free Solder ◽  
Shear Fatigue ◽  
Free Solder

There have been serious debates about whether Pb should be removed from solder joints, in view of environmental problems. These debates have now developed to the extent that a remarkable movement to establish regulations for the removal of Pb has emerged, especially in European countries and Japan. Therefore, many studies are aggressively being undertaken to develop technologies for replacing Sn-Pb solder with a lead-free alternative. From the results obtained so far, it has been proven that the fatigue strength in lead-free solder joints is almost equivalent to the fatigue strength of Sn-Pb eutectic solder joints. However, the other problem is that voids are easily formed in lead-free solder joints during the reflow process, and the effects of void formation on the fatigue strength of solder joints has attracted attention. In this study, the relationship between formation of voids and fatigue fracture mode and fatigue strength of solder joints was examined using FEM (finite element method) analysis and mechanical shear fatigue test. From the results of FEM analysis, it has been found that the equivalent plastic strain and shear strain of solder joints with voids are not always larger than those of solder joints without voids and the magnitude of the strains relate to the position and size of voids in solder joints. However, the difference of the strains is not so great as to affect the fatigue strength of solder joints. It has also been proven from the mechanical shear fatigue test that the fatigue fracture mode of solder joints with voids is similar to that of solder joints without voids and fatigue strength in both cases is also almost equivalent.

Validated High Speed Pull and Shear Test Methodologies to Evaluate Pb-Free BGA Mechanical Strength

2010 ◽  
Vol 2010 (1) ◽  
pp. 000110-000118
Author(s):  
Mudasir Ahmad ◽  
Ravi Assudani ◽  
Drew Nelson ◽  
Amir Youssef
Keyword(s):  
Mechanical Strength ◽  
High Speed ◽  
Solder Joints ◽  
Test Method ◽  
Lead Free ◽  
Lead Free Solder ◽  
Mechanical Assembly ◽  
Component Level ◽  
Reliability Indicator ◽  
Free Solder

The conversion to lead free Ball Grid Array (BGA) packages has raised several new assembly and reliability issues. Lead-free solder joints are generally stiffer than tin-lead solder joints, and mechanically induced failures have become more prevalent in lead-free solder assemblies. Traditionally, assembly bend and shock testing is performed to evaluate mechanical assembly reliability. However, bend and shock tests are expensive, cumbersome and not feasible for evaluating lot-to-lot variations in mechanical strength. Consequently, there is a need for a validated, component level test method that can be used as an accurate indicator of assembly level mechanical strength. Several publications have been written to evaluate the efficacy of high speed pull and shear testing as a viable reliability indicator [1 – 10]. In this study, a comprehensive Gauge R&R study was performed to evaluate the accuracy of the test equipment, including high speed video calibration. Then, test studies were performed to compare the accuracy of the results, spread across different package constructions, solder metallurgies, ball pitch and surface finish. In addition, the effect of parameters like multiple reflows and aging on specific metallurgies and surface finishes was studied. The results were generated over more than 2000 test runs. Finally, the study rank orders all critical test parameters and articulates what precise steps can be taken to generate relevant data for standard and custom devices during early evaluation stages and during high volume manufacturing.

Effect of Voids on Thermal Fatigue Reliability of Lead Free Solder Joint

2005 ◽  
Author(s):  
Doseop Kim ◽  
Qiang Yu ◽  
Yusuke Kobayashi ◽  
Tadahiro Shibutani
Keyword(s):  
Fatigue Strength ◽  
Fatigue Test ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Fatigue Reliability ◽  
Shear Fatigue ◽  
Free Solder ◽  
The Relationship

There have been serious debates about whether Pb should be removed from solder joints, in view of environmental problems. These debates have now developed to the extent that a remarkable movement to establish regulations for the removal of Pb has emerged, especially in European countries and Japan. Therefore, Many studies have been aggressively undertaken to develop technologies for replacing Sn-Pb solder with lead-free alternative. From the results obtained so far, it has been proven that the fatigue strength in lead-free solder joints is almost equivalent to the fatigue strength of Sn-Pb eutectic solder joints. However, a new problem is that voids are very easily formed in lead-free solder joints during the reflow process, and the effect of the voids on the fatigue strength of solder joints has attracted attention. In this study, the relationship between the voids and fatigue strength of solder joints was examined using mechanical shear fatigue test and FEM (finite element method) analysis. Using the mechanical shear fatigue test, the effect of the position and size of voids on fatigue crack initiation and crack propagation has been investigated. And quantitative evaluation of fatigue life of solder joints with the voids has been enabled by Manson-Coffin’s law and Miner’ rule.

Isothermal Cyclic Bend Fatigue Test Method for Lead-Free Solder Joints

2007 ◽  
Vol 129 (4) ◽  
pp. 496-503 ◽  
Author(s):  
John H. L. Pang ◽  
F. X. Che
Keyword(s):  
High Temperature ◽  
Solder Joint ◽  
Room Temperature ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Bending Fatigue ◽  
Bend Fatigue Test ◽  
Bend Tests ◽  
Free Solder

Isothermal three-point and four-point cyclic bend fatigue test methods have been developed for Sn–Ag–Cu solder joints. Reported bend tests from the literature were conducted at room temperature (25°C) and there is lack of data for lead-free solder joints. In this study, very-thin quad flat no-lead (VQFN) assembly with Sn–Ag–Cu lead-free solder was tested under three-point and four-point cyclic bending loads at both room temperature (25°C) and high temperature (125°C). The correlation between three-point and four-point bend tests was developed. Two different board surface finishes of electroless Ni and immersion gold (ENIG) and organic solderability preservatives (OSP) were investigated. Bending fatigue resistance of VQFN with OSP finish is slightly better than ENIG finish case. The acceleration factor of failure at high temperature (125°C) is higher than that at room temperature (25°C). Finite element analysis modeling and simulation were performed for different test conditions to investigate the solder joint stress-strain behavior. Volume-averaged energy density was used as a fatigue damage parameter and energy-based bending fatigue models were developed for VQFN with Sn–Ag–Cu solder joint under cyclic bending load at both 25°C and 125°C.

Void Formation and Their Effect on Reliability of Lead-Free Solder Joints on MID and PCB Substrates

2017 ◽  
Vol 66 (4) ◽  
pp. 1229-1237 ◽  
Author(s):  
P. Wild ◽  
T. Grozinger ◽  
D. Lorenz ◽  
A. Zimmermann
Keyword(s):  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder

Quantitative Evaluation of Voids in Lead Free Solder Joints

2015 ◽  
Vol 772 ◽  
pp. 284-289 ◽  
Author(s):  
Sabuj Mallik ◽  
Jude Njoku ◽  
Gabriel Takyi
Keyword(s):  
Solder Bump ◽  
Solder Joints ◽  
Void Formation ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
X Ray ◽  
Size And Shape ◽  
Solder Bumps ◽  
Free Solder

Voiding in solder joints poses a serious reliability concern for electronic products. The aim of this research was to quantify the void formation in lead-free solder joints through X-ray inspections. Experiments were designed to investigate how void formation is affected by solder bump size and shape, differences in reflow time and temperature, and differences in solder paste formulation. Four different lead-free solder paste samples were used to produce solder bumps on a number of test boards, using surface mount reflow soldering process. Using an advanced X-ray inspection system void percentages were measured for three different size and shape solder bumps. Results indicate that the voiding in solder joint is strongly influenced by solder bump size and shape, with voids found to have increased when bump size decreased. A longer soaking period during reflow stage has negatively affectedsolder voids. Voiding was also accelerated with smaller solder particles in solder paste.

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