Interfacial Reaction Between Tin-Zinc Based Solders and Copper

1997 ◽  
Vol 3 (S2) ◽  
pp. 715-716
Author(s):  
G. Ghosh ◽  
M. E. Fine
Keyword(s):  
Interfacial Reaction ◽  
High Performance ◽  
Solder Joints ◽  
Physical And Mechanical Properties ◽  
Lead Free ◽  
Eutectic Alloys ◽  
Solidification Behavior ◽  
Lead Free Solders ◽  
Melting And Solidification ◽  
Intermetallic Layers

Due to the interfacial reaction between the solder and substrate, either during manufacturing or in service, the solder joints may contain one or more intermetallic layers at the interface. While such intermetallic layers may provide strong bonding, they may also be responsible for problems associated with solderability and reliability of joints. Certain physical and mechanical properties of the intermetallic may determine the integrity and reliability of solder assembly. So far detailed analysis, modelling, and testing of simulated and actual joints have been performed with Pb-Sn solders. However, in view of the increasing environmental and legislative concerns, lead-free solders are currently being developed and designed for microelectronics applications. As the solder joints in high-performance electronic circuits are expected to carry increasing mechanical, electrical and thermal burdens, it is essential to address the technological and reliability issues for lead-free solders. Among the lead-free solders, tin-zinc based alloys can be designed to achieve melting and solidification behavior similar to those of lead-tin eutectic or near eutectic alloys.

Effect of Aging on the Properties of Intermetallic Layers in SAC+Bi Solder Joints

2021 ◽  
Author(s):  
Mohammad Ashraful Haq ◽  
Mohd Aminul Hoque ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Aging Condition ◽  
Sac305 Solder ◽  
The Poor ◽  
Free Solder ◽  
Lead Free Solders ◽  
Overall Reliability ◽  
Intermetallic Layers

Abstract A major problem faced by electronic packaging industries is the poor reliability of lead free solder joints. One of the most common methods utilized to tackle this problem is by doping the alloy with other elements, especially bismuth. Researches have shown Bismuth doped solder joints to mostly fail near the Intermetallic (IMC) layer rather than the bulk of the solder joint as commonly observed in traditional SAC305 solder joints. An understanding of the properties of this IMC layer would thus provide better solutions on improving the reliability of bismuth doped solder joints. In this study, the authors have used three different lead free solders doped with 1%, 2% and 3% bismuth. Joints of these alloys were created on copper substrates. The joints were then polished to clearly expose the IMC layers. These joints were then aged at 125 °C for 0, 1, 2, 5 and 10 days. For each aging condition, the elastic modulus and the hardness of the IMC layers were evaluated using a nanoindenter. The IMC layer thickness and the chemical composition of the IMC layers were also determined for each alloy at every aging condition using Scanning Electron Microscopy (SEM) and EDS. The results from this study will give a better idea on how the percentage of bismuth content in lead free solder affects the IMC layer properties and the overall reliability of the solder joints.

Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds under Thermal Aging

2010 ◽  
Vol 2010 (1) ◽  
pp. 000314-000318
Author(s):  
Tong Jiang ◽  
Fubin Song ◽  
Chaoran Yang ◽  
S. W. Ricky Lee
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Solder Joints ◽  
Lead Free ◽  
Small Range ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Aging Test ◽  
Free Solder ◽  
Lead Free Solders

The enforcement of environmental legislation is pushing electronic products to take lead-free solder alloys as the substitute of traditional lead-tin solder alloys. Applications of such alloys require a better understanding of their mechanical behaviors. The mechanical properties of the lead-free solders and IMC layers are affected by the thermal aging. The lead-free solder joints on the pads subject to thermal aging test lead to IMC growth and cause corresponding reliability concerns. In this paper, the mechanical properties of the lead-free solders and IMCs were characterized by nanoindentation. Both the Sn-rich phase and Ag3Sn + β-Sn phase in the lead-free solder joint exhibit strain rate depended and aging soften effect. When lead-free solder joints were subject to thermal aging, Young's modulus of the (Cu, Ni)6Sn5 IMC and Cu6Sn5 IMC changed in very small range. While the hardness value decreased with the increasing of the thermal aging time.

Investigation of Solid Solubility, Hardness, and Thermal Properties of Au-Ge-Sb System

2014 ◽  
Vol 1016 ◽  
pp. 336-341
Author(s):  
Kamolchanok Thipayarat ◽  
Ekasit Nisaratanaporn ◽  
Boonrat Lohwongwatana
Keyword(s):  
High Performance ◽  
Alloy System ◽  
Fine Tuning ◽  
Lead Free ◽  
Diagram Method ◽  
Average Value ◽  
Wide Range ◽  
Lead Free Solders ◽  
Hardness Values ◽  
Fine Tune

In recent years, the Au-Ge-Sb system has been studied as a possible alternative alloy for soldering applications [1-4]. The alloy has various fbenefits such as (i) low melting temperature which allows the alloy system to be used as a drop-in solution for high performance lead-free solders, (ii) three distinct phases of different hardness values (100, 150 and 500 HV) which offer the ability to fine tune the composition and microstructure to a wide range of properties, and (iii) limited solute solubility which offers ease of control and fine-tuning of microstructure, mechanical properties and colors. Gold compositions centered around 75wt% gold were modeled and selected using the CALPHAD (CALculation of PHAse Diagram) method. Predictions were later confirmed by experimental results. The alloy solidifies in the range of 242.5-261.7 °C. The overall hardness values were measured and confirmed to be within the volume average value of all the phases combined.

Design of Experiment (DOE) of Powder Metallurgy Technique in Fabricating SnCu/Carbon Lead-Free Composite Solder with Different Mixing Parameters

2014 ◽  
Vol 803 ◽  
pp. 269-272
Author(s):  
Sayyidah Amnah Musa ◽  
Norainiza Saud
Keyword(s):  
Powder Metallurgy ◽  
High Performance ◽  
Composite Solder ◽  
Mixing Time ◽  
Physical And Mechanical Properties ◽  
Optical Microscope ◽  
Lead Free ◽  
Lead Free Solder ◽  
Best Parameter ◽  
Free Solder

Physical and mechanical properties of a solder joint will be improved by adding the high performance of reinforcement particulates in the monolithic lead-free solder. In this study, 0.1wt% of activated carbon (AC) was added into Sn-0.7Cu lead-free solder which fabricated via powder metallurgy (PM) techniques. Various parameters used in PM technique such as mixing time, compacting load and sintering temperature has been carried out in fabricating the composite solder. In this study, the best mixing time has been optimized. The distribution of carbon in SnCu matrix for each mixing time was observed by using optical microscope. Microstructural observation showed that the increasing in mixing time has increased the number of AC particles to become agglomerated. It is found out that 1hour of mixing time is the best parameter to fabricate SnCu/AC composite solder via powder metallurgy route since the distribution of reinforcement particles has distributed uniformly at the grain boundaries without any agglomeration.

Strain Rate Effects and Rate-Dependent Constitutive Models of Lead-Based and Lead-Free Solders

2009 ◽  
Vol 77 (1) ◽  
Author(s):  
Fei Qin ◽  
Tong An ◽  
Na Chen
Keyword(s):  
Strain Rate ◽  
Impact Analysis ◽  
Solder Joints ◽  
High Strain ◽  
Drop Impact ◽  
Lead Free ◽  
Strain Rates ◽  
High Strain Rates ◽  
Rate Dependent ◽  
Lead Free Solders

As traditional lead-based solders are banned and replaced by lead-free solders, the drop impact reliability is becoming increasingly crucial because there is little understanding of mechanical behaviors of these lead-free solders at high strain rates. In this paper, mechanical properties of one lead-based solder, Sn37Pb, and two lead-free solders, Sn3.5Ag and Sn3.0Ag0.5Cu, were investigated at strain rates that ranged from 600 s−1 to 2200 s−1 by the split Hopkinson pressure and tensile bar technique. At high strain rates, tensile strengths of lead-free solders are about 1.5 times greater than that of the Sn37Pb solder, and also their ductility are significantly greater than that of the Sn37Pb. Based on the experimental data, strain rate dependent Johnson–Cook models for the three solders were derived and employed to predict behaviors of solder joints in a board level electronic package subjected to standard drop impact load. Results indicate that for the drop impact analysis of lead-free solder joints, the strain rate effect must be considered and rate-dependent material models of lead-free solders are indispensable.

Evolution of Lead Free Solder Material Behavior Under Elevated Temperature Aging

2007 ◽  
Author(s):  
Hongtao Ma ◽  
Jeffrey C. Suhling ◽  
Yifei Zhang ◽  
Pradeep Lall ◽  
Michael J. Bozack
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Solder Joints ◽  
Material Behavior ◽  
Lead Free ◽  
Lead Free Solder ◽  
Room Temperature Aging ◽  
Free Solder ◽  
Lead Free Solders ◽  
Temperature Aging

The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects (Ma, et al., ECTC 2006), we demonstrated that the observed material behavior variations of SAC405 and SAC305 lead free solders during room temperature aging (25 °C) were unexpectedly large and universally detrimental to reliability. Such effects for lead free solder materials are much more dramatic at the higher aging temperatures (e.g. 100–150 °C) typical of the harsh environments present in high performance computing and in automotive, aerospace, and defense applications. However, there has been little work in the literature, and the work that has been done has concentrated on the degradation of solder ball shear strength (e.g. Dage Shear Tester). Current finite element models for solder joint reliability during thermal cycling accelerated life testing are based on traditional solder constitutive and failure models that do not evolve with material aging. Thus, there will be significant errors in the calculations with the new lead free SAC alloys that illustrate dramatic aging phenomena. In the current work, we have explored the effects of elevated temperature isothermal aging on the mechanical behavior and reliability of lead free solders. The effects of aging on mechanical behavior have been examined by performing stress-strain and creep tests on SAC405 and SAC305 samples that were aged for various durations (0–6 months) at several elevated temperatures (80, 100, 125, and 150 °C). Analogous tests were performed with 63Sn-37Pb eutectic solder samples for comparison purposes. Variations of the temperature dependent mechanical properties (elastic modulus, yield stress, ultimate strength, creep compliance, etc.) were observed and modeled as a function of aging time and temperature. In this paper, we have concentrated our efforts on presenting the results for samples aged at 125 °C. In addition, the new elevated temperature aging data were correlated with our room temperature results from last year’s investigation. The results obtained in this work have demonstrated the significant effects of elevated temperature exposure on solder joints. As expected, the mechanical properties evolved at a higher rate and experienced larger changes during elevated temperature aging (compared to room temperature aging). After approximately 200 hours of aging, the lead free solder joint material properties were observed to degrade at a nearly constant rate. We have developed a mathematical model to predict the variation of the properties with aging time and aging temperature. Our data for the evolution of the creep response of solders with elevated temperature aging show that the creep behavior of lead free and tin-lead solders experience a “crossover point” where lead free solders begin to creep at higher rates than standard 63Sn-37Pb solder for the same stress level. Such an effect is not observed for solder joints aged at room temperature, where SAC alloys always creep at lower rates than Sn-Pb solder.

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