Characterization of Lead-Free Solder Interconnects Reliability Under Torsional Loads

2009 ◽  
Author(s):  
Vikram Srinivas ◽  
Moustafa Al-Bassyiouni ◽  
Michael Osterman ◽  
Michael Pecht
Keyword(s):  
Rapid Assessment ◽  
Lead Free ◽  
Solder Paste ◽  
Solder Interconnects ◽  
Portable Electronics ◽  
Snpb Solder ◽  
Torsional Loads ◽  
Free Solder ◽  
Lead Free Solders

Mechanical torsion loads often arise in portable electronics under life cycle conditions. With increased market pressure, drive to reduce time to market, and varying use conditions, it is critical to develop accelerated tests to evaluate reliability quickly. Mechanical torsion testing can provide a rapid assessment technique to characterize solder interconnect durability. This paper presents an evaluation of select lead-free solders, SAC305 (96.5Sn-3.0Ag-0.5Cu) and SN100C (99.25Sn-0.7Cu-0.05Ni+Ge), under mechanical torsion loading. For comparison, SnPb (63Sn-37Pb) solder was also evaluated. Common test vehicles with resistor 2512 packages were used for these tests. For the mechanical cycle tests, no statistical difference in reliability was observed between SAC305 and SnPb solder paste while SN100C solder pastes were found to exhibit lower durability during Weibull analysis.

Synthesis and Characterization of Nano-Composite Lead-Free Solder

2005 ◽  
Vol 23 ◽  
pp. 145-150 ◽  
Author(s):  
D.C. Lin ◽  
C.Y. Kuo ◽  
T.S. Srivatsan ◽  
M. Petraroli ◽  
G.X. Wang
Keyword(s):  
Composite Solder ◽  
Nano Particles ◽  
Lead Free ◽  
Microstructural Development ◽  
Solder Paste ◽  
Second Phases ◽  
Series Of Experiments ◽  
Free Solder ◽  
Particle Reinforced Composite

A series of experiments conducted on a lead-free eutectic solder (Sn-3.5%Ag) have shown that addition of trace amounts of nanometer-sized particles does have an influence on mechanical properties of materials. In this study, three different types of nanoparticles (copper, nickel and iron) were chosen as the reinforcing candidate. For each particulate reinforcement the reflow process was performed under identical cooling conditions. Addition of trace amounts of nano-particles alters the kinetics governing solidification of the composite solder paste while concurrently exerting an influence on microstructural development, particularly the formation and presence of second phases in the solidified end product. The nano-sized powder particle-reinforced composite solder revealed an increase in microhardness compared to the unreinforced monolithic counterpart.

scholarly journals Phase equilibria investigation and alloys characterization in Sn-In-Ag system

2008 ◽  
Vol 62 (3) ◽  
pp. 148-152
Author(s):  
Aleksandra Milosavljevic ◽  
Dragana Zivkovic ◽  
Dragan Manasijevic ◽  
Nadezda Talijan ◽  
Aleksandar Grujic ◽  
...  
Keyword(s):  
Phase Equilibria ◽  
Xrd Analysis ◽  
Lead Free ◽  
Solder Alloys ◽  
Standard Lead ◽  
Free Solder ◽  
Dsc Method ◽  
Lead Free Solders ◽  
Thermocalc Software

Lead-free soldering has become very popular in the world recently, especially in electronics, because of high ecological demands in industry. Some of lead-free solder alloys are already used in electronic industry, but despite that investigations are still going in order to find suitable replacement for Pb-Sn standard solder. In this paper phase equilibria and characterization of Sn-In-Ag alloys in section In:Ag = 7:3 are investigated. The results of phase diagram calculation are obtained by ThermoCalc software, and characteristic temperatures by DSC method. The results of XRD analysis, optical microscopy, microhardness and electrical conductivity are also presented. These results are given in order to contribute the knowledge about lead-free solders, especially Sn-In-Ag solder alloys, which are potential candidates for replacement standard lead solders.

Cohesive Fracture Mechanics Based Finite Element Analysis to the Performance of Lead Free Solders in BGA Packaging Under Drop Impact

2012 ◽  
Author(s):  
Yao Yao
Keyword(s):  
Finite Element ◽  
Solder Alloy ◽  
Drop Impact ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Interconnects ◽  
Solder Interconnect ◽  
Lead Free Solder Alloy ◽  
Free Solder ◽  
Lead Free Solders

Lead free solders are replacing lead rich solders in the electronic industry, the performance and safety of lead free solder joints in electric packaging under drop impact becomes a critical concern of semiconductor and electronic product manufacturers. Compared with the lead rich solder alloy, lead free solder alloy typically has higher rigidity and lower ductility. The presence of the Intermetallic Compound (IMC) layer can also affect the drop impact response of the solder interconnect, which may lead to quasi-brittle solder/IMC interfacial fracture. The traditional drop test is expensive and time consuming, and it is quite difficult to observe the full dynamic responses during the drop impact. In the present study, numerical analysis is performed to investigate drop impact effect on ball grid array (BGA) electronic packaging with the intention of predicting the performance of solders under drop impact and providing the fundamental understanding required to design a reliable electric packaging. A three dimensional finite element model is developed to simulate the solder interconnect and electronic packaging failure under board-level drop impact. An impact analysis procedure coupled with sub-modeling technique is established. The Cu6Sn5 and Cu3Sn IMC layers are incorporated in the solder interconnects model; cohesive fracture mechanics based method is applied to predict the crack initiation and propagation near the IMC/solder interface. A lead-free solder alloy constitutive relationship comprising elastic and rate dependent plastic effects is incorporated in the computational model. The mechanical shock is the main failure mechanism of solder joint during drop impact. The susceptible failure location is concluded at the interface between the solder and intermetallic compound based on the stress criteria. The developed model can be used to compare the drop impact performance of different components and solder alloys, which can guide the proper selection of component and optimize the layout of BGA electric packing. The behavior of electric packaging and different types of solder interconnects under drop impact can be predicted with corresponding material parameters determined from experiment.

The Effect of Multiple Reflow Times on Lead-Free Solder Joint Microstructure

2003 ◽  
Author(s):  
Sami T. Nurmi ◽  
Janne J. Sundelin ◽  
Eero O. Ristolainen ◽  
Toivo K. Lepisto¨
Keyword(s):  
Solder Joint ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Snagcu Solder ◽  
Silver Copper ◽  
Free Solder ◽  
Tin Silver Copper ◽  
Lead Free Solders

As environmental issues are raising more interest and are becoming crucial factors in all parts of the world, more and more environmental-friendly electronics products are emerging. Usually this means the introduction of products with lead-free solders. However, the reliability of lead-free solders is still a serious concern despite the vast research done in this field. This paper will describe the interconnect reliability of three kinds of solder joints respectively prepared with lead-free solder paste and lead-free PBGA components, lead-free solder paste and tin-lead-silver PBGA components, and tin-lead solder paste and tin-lead-silver PBGA components. Lead-free and tin-lead solders were composed of eutectic tin-silver-copper and tin-lead, respectively. In addition, the study also presents the effect of multiple reflow times. The study focuses on the microstructures of different assemblies. The particular interest is on the assemblies soldered with lead-free solder paste and tin-lead-silver PBGA components, since the SnPbAg solder on the bumps of the PBGA components were exposed to the reflow profile meant for the lead-free SnAgCu solder. Thus, these SnPbAg solder bumps were in the molten state almost twice as long as the rest of the solders. This had a notable effect on the reliability of these solder joints as we will be showing later in this paper. The test boards were temperature-cycled for 2500 cycles between −40 and +125°C (a 30-minute cycle). PBGA solder joint failures were monitored with a real time monitoring system. Optical and scanning electron microscopy was used to inspect the broken solder joints and their microstructure. The results of tests indicate that the number of reflow times can significantly affect the lifetime of PBGA solder joints. The most notable changes can be seen in the solder joints made with tin-lead-silver PBGA components and tin-silver-copper solder paste soldered with a lead-free reflow profile. The general trend was that the reliability of the solder joints increased in proportion to the number of reflow times. Mainly two factors are believed to have the major effect on the reliability of PBGA solder joints, voids, and microstructural changes in solder.

Effect of aluminum content on structure, transport and mechanical properties of Sn-Zn eutectic lead free solder alloy rapidly solidified from melt.

2015 ◽  
Vol 10 (1) ◽  
pp. 2641-2648
Author(s):  
Rizk Mostafa Shalaby ◽  
Mohamed Munther ◽  
Abu-Bakr Al-Bidawi ◽  
Mustafa Kamal
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Lead Free ◽  
Al Alloy ◽  
Lead Free Solder ◽  
Pronounced Increase ◽  
Mass Unit ◽  
Size Refinement ◽  
Free Solder ◽  
Lead Free Solders

The greatest advantage of Sn-Zn eutectic is its low melting point (198 oC) which is close to the melting point. of Sn-Pb eutectic solder (183 oC), as well as its low price per mass unit compared with Sn-Ag and Sn-Ag-Cu solders. In this paper, the effect of 0.0, 1.0, 2.0, 3.0, 4.0, and 5.0 wt. % Al as ternary additions on melting temperature, microstructure, microhardness and mechanical properties of the Sn-9Zn lead-free solders were investigated. It is shown that the alloying additions of Al at 4 wt. % to the Sn-Zn binary system lead to lower of the melting point to 195.72 ˚C.  From x-ray diffraction analysis, an aluminium phase, designated α-Al is detected for 4 and 5 wt. % Al compositions. The formation of an aluminium phase causes a pronounced increase in the electrical resistivity and microhardness. The ternary Sn-9Zn-2 wt.%Al exhibits micro hardness superior to Sn-9Zn binary alloy. The better Vickers hardness and melting points of the ternary alloy is attributed to solid solution effect, grain size refinement and precipitation of Al and Zn in the Sn matrix.  The Sn-9%Zn-4%Al alloy is a lead-free solder designed for possible drop-in replacement of Pb-Sn solders.  

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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