Effect of La Doping on SnAg Solder Microstructure Evolution

2007 ◽  
Author(s):  
Min Pei ◽  
Jianmin Qu
Keyword(s):  
Volume Fraction ◽  
Eutectic Phase ◽  
Lead Free Solder ◽  
Doping Amount ◽  
Particle Spacing ◽  
La Doping ◽  
Multiple Length Scales ◽  
Snag Solder ◽  
Solder Microstructure ◽  
Free Solder

In this paper, quantitative microstructure studies were performed on multiple length scales to investigate effect of La doping on SnAg lead free solder materials. Variables considered in this paper include doping amount, aging temperature and aging time. It was found that La doping refines the microstructure and reduces microstructure coarsening rate, but the inter-particle spacing remains unaffected. Therefore, higher La doping level leads to higher volume fraction of the eutectic phase due to the increased total number of Ag3Sn particles.

A Multiscale Modeling Method for the Creep Behavior of SnAg Solder Alloys

2007 ◽  
Author(s):  
Min Pei ◽  
Jianmin Qu
Keyword(s):  
Multiscale Modeling ◽  
Creep Test ◽  
Eutectic Phase ◽  
Creep Model ◽  
Length Scale ◽  
Length Scales ◽  
Multiple Length Scales ◽  
Model Predictions ◽  
Snag Solder ◽  
Micrometer Size

In this paper, a microstructure-dependent creep model is developed that accounts for the hierarchal microstructure at multiple length scales. The model considers three distinguishable phases in the solder alloy at two different length scales: at the larger scale Sn dendrites of micrometer size are embedded in a homogeneous eutectic phase; at a much smaller length scale the eutectic phase consists of submicron size Ag3Sn particles embedded in a homogeneous Sn matrix. The model predictions agree well with creep test data of RE doped SnAg solders.

Real Time Synchrotron X-Ray Imaging for Nucleation and Growth of Cu6Sn5 in Sn-7Cu-0.05Ni High Temperature Lead-Free Solder Alloys

2012 ◽  
Vol 626 ◽  
pp. 200-204 ◽  
Author(s):  
Kazuhiro Nogita ◽  
Hideyuki Yasuda ◽  
Stuart D. McDonald ◽  
Kentaro Uesugi
Keyword(s):  
High Temperature ◽  
Real Time ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
X Ray ◽  
X Ray Imaging ◽  
Solder Microstructure ◽  
Free Solder ◽  
Solidification Pathway

This paper demonstrates how recent progress for real-time solidification observation at SPring-8 synchrotron has contributed to the development of Sn-7wt%Cu-0.05wt%Ni high temperature lead-free solder alloys. Lead-free solder alloys in the composition range Sn-0.7 to 7.6wt%Cu that consist of primary Cu6Sn5in a eutectic Sn-Cu6Sn5matrix have been proposed as solders for application at temperatures up to 400°C for the assembly high current semiconductors. It is shown that trace levels of Al have a marked effect on the solder microstructure and refine the size of the primary Cu6Sn5. The solidification pathway that leads to the refinement was observed in real-time using X-ray synchrotron observations.

Oscillatory and Creep Recovery Test on Nano-Composite Lead-Free Solder Pastes (Nickel and Platinum Powder)

2011 ◽  
Vol 471-472 ◽  
pp. 257-262
Author(s):  
R. Durairaja ◽  
Kau Chee Leong ◽  
Lim Chia Wea ◽  
Wong Mee Chu
Keyword(s):  
Volume Fraction ◽  
The Other ◽  
Lead Free ◽  
Elastic Behaviour ◽  
Creep Recovery ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Stencil Printing ◽  
Free Solder ◽  
Sample System

This study investigates the relationship of rheological properties of nanoparticles added to lead-free solders paste. For lead-free solder paste, a large number of combinations can be made from different elements. Every ingredient plays a role of the paste and the rheological properties. The effect of filler concentration was studied in this present investigation. Creep recovery, stress is applied on samples for a period of time and later release in order for it to recovery itself. In the other words, creep recovery involves a tensile specimen under constant load maintained at a constant temperature. Oscillatory tests were carried out to study the visco-elastic behaviour and paste stability. The visco-elastic behaviour of the paste lies between solid and liquid characteristic of the paste, which could be used to study the flow behaviour of paste during stencil printing process. From this study, it was found that the solid characteristic, G' is higher than liquid characteristic, G'' for all the samples. In addition, the results from the study showed that the 0.06 volume fraction sample system with a large yield point which G'= G'' has a higher cohesiveness and hence resulting in poor withdrawal of the paste during stencil printing process. The phase angle, δ was used to correlate the quality of the dense suspensions to the formulation of solder paste materials. Lower value of phase angle for 0.06 volume fraction sample system may indicating that the paste is very tacky compare to the other samples. As the demand for lead-free pastes increases rheological measurements can assist with the formulation of new pastes.

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.  

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