Microstructure and mechanical properties of lead-free solders and solder joints used in microelectronic applications

2005 ◽  
Vol 49 (4.5) ◽  
pp. 607-620 ◽  
Author(s):  
S. K. Kang ◽  
P. Lauro ◽  
D.-Y. Shih ◽  
D. W. Henderson ◽  
K. J. Puttlitz
Keyword(s):  
Mechanical Properties ◽  
Solder Joints ◽  
Lead Free ◽  
Microstructure And Mechanical Properties ◽  
Lead Free Solders

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.

Formation and Mechanical Properties of Intermetallic Compounds in Sn-Cu High-Temperature Lead-Free Solder Joints

2010 ◽  
Vol 654-656 ◽  
pp. 2450-2454 ◽  
Author(s):  
De Kui Mu ◽  
Hideaki Tsukamoto ◽  
Han Huang ◽  
Kazuhiro Nogita
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Intermetallic Compounds ◽  
Solder Joints ◽  
Nickel Content ◽  
Lead Free ◽  
Lead Free Solder ◽  
Nickel Addition ◽  
Free Solder ◽  
Lead Free Solders

High-temperature lead-free solders are important materials for electrical and electronic devices due to increasing legislative requirements that aim at reducing the use of traditional lead-based solders. For the successful use of lead-free solders, a comprehensive understanding of the formation and mechanical properties of Intermetallic Compounds (IMCs) that form in the vicinity of the solder-substrate interface is essential. In this work, the effect of nickel addition on the formation and mechanical properties of Cu6Sn5 IMCs in Sn-Cu high-temperature lead-free solder joints was investigated using Scanning Electron Microscopy (SEM) and nanoindentation. It was found that the nickel addition increased the elastic modulus and hardness of the (Cu, Ni)6Sn5. The relationship between the nickel content and the mechanical properties of the IMCs was also established.

scholarly journals Effect of Co-Addition of Ag and Cu on Mechanical Properties of Sn–5Sb Lead-Free Solder

2021 ◽  
Author(s):  
Biao Yuan ◽  
Zhimin Liang ◽  
Zongyuan Yang ◽  
Fei Shen ◽  
Da Xu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Room Temperature ◽  
Solder Joints ◽  
Young's Modulus ◽  
Lead Free ◽  
Unloading Rate ◽  
Free Solder ◽  
Co Addition ◽  
Lead Free Solders

AbstractSn–Sb lead-free solders are considered to substitute the tin–lead solders due to their great mechanical properties. At room temperature, the mechanical properties of Ni/Au/Sn–5Sb/Au/Ni and Ni/Au/Sn–5Sb–0.3Ag–0.05Cu/Au/Ni linear solder joints were investigated by nanoindentation experiments at different loads. The results showed that the Sn–Sb intermetallic compound (IMC) was distributed in the β-Sn matrix in Ni/Au/Sn–5Sb/Au/Ni solder joints. Co-addition of Cu and Ag resulted in the formation of the rod-shaped Cu6Sn5 and the fine granular Ag3Sn IMCs. At the same load and loading/unloading rate, the indentation depth and residual indentation morphologies of Ni/Au/Sn–5Sb–0.3Ag–0.05Cu/Au/Ni solder joints were smaller than those of Ni/Au/Sn–5Sb/Au/Ni solder joints. The hardness of the two kinds of solder joints decreased with the increase in load, while the Young’s modulus was independent of load. In addition, compared to the Ni/Au/Sn–5Sb/Au/Ni solder joints, the hardness, Young’s modulus and stress exponents of Ni/Au/Sn–5Sb–0.3Ag–0.05Cu/Au/Ni solder joints achieved an improvement due to the co-addition of Ag and Cu.

Time-Lapse Imagery and Quantitative Analysis of Microstructural Evolution of SAC305 BGA Joints During Extreme High Temperature Aging

2020 ◽  
Author(s):  
KM Rafidh Hassan ◽  
Mohammad S. Alam ◽  
Jing Wu ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
Aging Time ◽  
Microstructural Evolution ◽  
Solder Joints ◽  
Time Lapse ◽  
Lead Free ◽  
Aging Effects ◽  
Extreme High Temperature ◽  
Lead Free Solders ◽  
Temperature Aging

Abstract Solder joints provide mechanical support, electrical and thermal interconnection between packaging levels in microelectronics assembly systems. Proper functioning of these interconnections and the reliability of the electronic packages depend largely on the mechanical properties of the solder joints. Lead free solders are common as interconnects in electronic packaging due to their relatively high melting point, attractive mechanical properties, thermal cycling reliability, and environment friendly chemical properties. However, environmental conditions, such as, operating temperature, aging temperature, and aging time significantly affect these properties due to the microstructural evolution of the solder that occurs during aging. Moreover, electronic devices, sometimes experience harsh environment applications including well drilling, geothermal energy, automotive power electronics, and aerospace engines, where solders are exposed to very high temperatures from T = 125–200 °C. Mechanical properties as well as microstructural study of lead free solders at elevated temperatures are limited in literature. Previous investigations on the microstructural evolution mainly emphasized on aging at temperatures up to 125 °C. In addition, those studies were limited on investigating the coarsening of Ag3Sn IMC particles within the beta-Sn matrix. In this work, the microstructural evolutions of SAC305 (96.5Sn-3.0Ag-0.5Cu) BGA joints were investigated for different aging conditions utilizing Scanning Electron Microscopy (SEM). In particular, our approach has been to monitor aging induced microstructural changes occurring within fixed regions in selected lead free solder joints and to create time-lapse imagery of the microstructure evolution. Aging was performed at T = 125, 150, and 175 °C for several durations up to 20 days, and the topography of the microstructure of a fixed region was captured using the SEM system. This process generated several images of the microstructure as the aging progressed. We have also explored the Mechanical behavior, and aging effects of SAC305 solder joints at the extreme high testing temperature of T = 150 °C using the method of nanoindentation. To study the aging effects, solder joints were preconditioned for 0, 1, 5, 10, and 30 days at T = 125 °C in a box oven. Nanoindentation testing was then performed on the aged specimens at a test temperature of T = 150 °C to extract the elastic modulus, hardness, and creep performance of the aged material. As expected, the analysis of the evolving SAC305 BGA microstructure showed a significant amount of diffusion of silver and copper in the beta-tin matrix during aging. In addition, a very remarkable growth of copper-tin layer at solder joint and copper pad interface in the PCB side has been visualized and measured with aging time and temperature. The Quantitative analysis of the evolving microstructure showed that the particles coalesced during aging leading to a decrease in the number of particles. This caused an increase in the average diameter of the particles, which helped us to build a model to guide the growth of IMC particles at extreme high temperature aging. Nanoindentation test results also showed a huge degradation in mechanical properties with aging time increment.

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