Journal articles: 'Sn rich solders'

1

Wang, Yao, Yuanxing Li, Dengquan Han, Sifu Qiu, and Hui Chen. "Microstructure evolution and mechanical properties of 6N01S-T5 aluminum alloy joints with semi-solid solders by ultrasonic soldering." International Journal of Modern Physics B 33, no. 01n03 (January 30, 2019): 1940027. http://dx.doi.org/10.1142/s0217979219400277.

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The article investigated the properties of 6N01 aluminum alloy joints with Sn-80Zn semi-solid solders by ultrasonic soldering. It was found that semi-solid solders consisted of Zn-rich phase with short rod-like dentrite, which had the lower solidus temperatures, while Zn-rich phase with long dentritic grains used the conventional solders. The joints soldered with Sn-80Zn conventional filler metal reached maximum shear strength of 73 MPa at the soldering temperature of 390[Formula: see text]C. The joint using Sn-80Zn semi-solid solder obtained higher shear strength of 90 MPa at the lower temperature of 370[Formula: see text]C. The effects of the ultrasonic time and the soldering temperature on the mechanical properties of the joints were also investigated with the Sn-80Zn semi-solid solders.

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2

Canyook, Rungsinee, and Kittichai Fakpan. "Effect of Cu and Ni Addition on Microstructure and Wettability of Sn-Zn Solders." Key Engineering Materials 728 (January 2017): 9–14. http://dx.doi.org/10.4028/www.scientific.net/kem.728.9.

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In present study, Sn–9Zn, Sn–9Zn–xCu and Sn–9Zn–xNi solders (x = 1.0, 2.0 and 3.0 wt%) were prepared via melting process. Effects of Cu and Ni addition on microstructure, thermal behavior, wettability and corrosion resistance of Sn–9Zn solders were investigated. The experimental result showed that microstructure of the Sn–9Zn was composed of β–Sn and Zn–rich phases. Addition of Cu to the Sn–9Zn solders, Cu6Sn5 and Cu5Zn8 IMCs were observed. While addition of Ni to the Sn–9Zn solders, Ni3Sn4 and Ni5Zn21 IMCs were observed. It was also found that, amount of those IMCs obviously increased with increasing of Cu and Ni contents. The results obtained from thermal analysis showed that melting temperature of the Sn–9Zn solder was 199.6°C. While melting temperatures of the Sn–9Zn–1.0Cu and Sn–9Zn–1.0Ni solders were 199.9°C and 204.2°C, respectively. The Cu and Ni contents had little effect on both spread rate and wetting angle of the Sn–9Zn–xCu and Sn–9Zn–xNi solders. However, increasing of Cu and Ni contents significantly increased the corrosion potentials of the Sn–9Zn–xCu and Sn–9Zn–xNi solders.

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Du, Chang Hua, Yi Luo, Jian Su, Li Meng Yin, Zhen Kang Li, and Bin Liu. "Microstructure and Mechanical Property of (Sn-9Zn0.05Ce)xBi Solder." Advanced Materials Research 189-193 (February 2011): 3326–30. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.3326.

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The (Sn-9Zn0.05Ce)xBi solders with different Bi contents were prepared by a new process. The characteristics of solders about microstructure, tensile strength, elongation and microhardness were studied. The results showed that addition Bi can induce acicular or granular Zn-rich precipitated phase in Sn-9Zn0.05Ce solder. To increasing Bi content caused more Zn-rich phase distributed disorderly. When the Bi content was added to 4%, the granular Bi precipitated phase was observable. The tensile strength and hardness of (Sn-9Zn0.05Ce)xBi solder will raise, but elongation descend significantly due to the Bi content increasing. It can be funded that there was a more obvious turning point as w(Bi)=2wt﹪.

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Han, Dengquan, Yuanxing Li, Yongpan He, Sifu Qiu, and Hui Chen. "Microstructure evolution and mechanical properties of 5083 aluminum alloy joints by ultrasonic soldering." International Journal of Modern Physics B 31, no. 16-19 (July 26, 2017): 1744040. http://dx.doi.org/10.1142/s0217979217440404.

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Aluminum alloy 5083 was joined with Sn–[Formula: see text]Zn ([Formula: see text], 5, 9, 30 and 60 wt.%) filler metal by ultrasonic soldering at 400[Formula: see text]C. The joint microstructure consisted of [Formula: see text]-Sn and [Formula: see text]-Al solid–solution phases when using pure Sn solder. Zn-rich phases were observed in the joints with Sn–Zn filler metal. The Zn-rich phases grew thicker and larger with the increase in Zn content in the filler metal. The joints soldered with Sn–30Zn filler metal reached a maximum shear strength of 70 MPa. Joint cracking occurred at the interface of pure Sn and Sn–9Zn solders as indicated by SEM observation of the fracture surfaces. The locations of the fracture surface moved from the interface to the seam when using the Sn–30Zn or Sn–60Zn filler metal. The coarse Zn-rich phases were also observed on the fracture surface using Sn–60Sn solder, which results in a shear strength reduction of the joints.

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Cheng, Shou Chang, and Kwang Lung Lin. "Interfacial evolution between Cu and Pb–free Sn–Zn–Ag–Al solders upon aging at 150 °C." Journal of Materials Research 18, no. 8 (August 2003): 1795–803. http://dx.doi.org/10.1557/jmr.2003.0249.

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The interfacial intermetallic formation at 150 °C between Cu and various solders, including Sn–9Zn, Sn–8.55Zn–1Ag, and Sn–8.55Zn–1Ag–XAl was investigated. The Al contents X of the quaternary solder alloys investigated were 0.01–0.45 wt.%. The compositions and the growth kinetics of intermetallic compounds (IMCs) were investigated. The IMC consisted of three layers for Sn–9Zn/Cu, Sn–Zn–Ag/Cu, and Sn–Zn–Ag–XAl/Cu specimens after aging for 100–600 h. These three layers included the Cu3(Zn, Sn) phase adjacent to the solder, the Cu6(Sn, Zn)5 phase in the middle, and the Cu–rich phase near to Cu. For long–term aging time over 1000 h, the Cu6(Sn, Zn)5 phase grew, while the Cu3(Zn, Sn) phase diminished. Al segregation formed in the IMC for all of the Sn–Zn–Ag–XAl/Cu specimens after aging.Cracks formed, when aged for 1000 h, at the solder/IMC interface or within the IMC layer for the following solders: Sn–9Zn, Sn–8.55Zn–1Ag, Sn–8.55Zn–1Ag–0.1Al, Sn–8.55Zn–1Ag–0.25Al, and Sn–8.55Zn–1Ag–0.45Al. The crack was not detected up to 3000 h for the Sn–8.55Zn–1Ag–0.01Al/Cu couple, of which the IMC growth rate was the slowest among all solders.

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Mladenovic, Srba, Desimir Markovic, Ljubica Ivanic, Svetlana Ivanov, and Zagorka Acimovic-Pavlovic. "The microstructure and properties of as-cast Sn-Zn-Bi solder alloys." Chemical Industry 66, no. 4 (2012): 595–600. http://dx.doi.org/10.2298/hemind111219015m.

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Research on the lead-free solders has attracted wide attention, mostly as the result of the implementation of the Directive on the Restriction of the Use of Hazardous Substances in Electrical and Electronic Equipment. The Sn-Zn solder alloys have been considered to be one of the most attractive lead-free solders due to its ability to easily replace Sn-Pb eutectic alloy without increasing the soldering temperature. Furthermore, the mechanical properties are comparable or even superior to those of Sn-Pb solder. However, other problems still persist. The solution to overcoming these drawbacks is to add a small amount of alloying elements (Bi, Ag, Cr, Cu, and Sb) to the Sn-Zn alloys. Microstructure, tensile strength, and hardness of the selected Sn-Zn-Bi ternary alloys have been investigated in this study. The SEM-EDS was used for the identification of co-existing phases in the samples. The specimens? microstructures are composed of three phases: Sn-rich solid solution as the matrix, Bi-phase and Zn-rich phase. The Bi precipitates are formed around the Sn-dendrit grains as well as around the Zn-rich phase. The amount of Bi segregation increases with the increase of Bi content. The Sn-Zn-Bi alloys exhibit the high tensile strength and hardness, but the values of these mechanical properties decrease with the increase of Bi content, as well as the reduction of Zn content. The results presented in this paper may offer further knowledge of the effects various parameters have on the properties of lead-free Sn-Zn-Bi solders.

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Uenishi, Keisuke, and Kojiro F. Kobayashi. "Interfacial Reaction between Sn-Ag Based Solders and Au/Ni Alloy Platings." Materials Science Forum 502 (December 2005): 411–16. http://dx.doi.org/10.4028/www.scientific.net/msf.502.411.

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The microstructure and strength for the micro joints of Pb free Sn-Ag based solders with Au/Ni alloy platings were investigated. For the joint using Sn-Ag solder, Ni3Sn4 reaction layer formed at the solder/pad interface and also P-rich layer formed in Ni-P plating. The P-rich layer was confirmed to be composed of Ni-P-Sn ternary compound layer and crystallized Ni3P layer. Both of them introduced defects, which degraded the joint strength. Addition of Cu to Sn-Ag solders suppressed the formation of such a P rich layer while the (Cu, Ni)6Sn5 reaction layer was formed at the solder/pad interface. These different interfacial reactions would affect the changes in the joint strength during heat exposure at 423K. On the contrary, addition of Co to Ni platings enhanced the interfacial reaction and the Sn-Ag solder completely transformed to the intermetallic compounds under higher melting temperature even by heating to 543K. The addition of Co in Ni could change the interfacial reaction layer from Ni3Sn4 to (Ni, Co)Sn2 with higher diffusivity of Ni which enhanced formation of intermetallic phases. The control of interfacial reaction by the alloying elements is important to obtain ideal micro joints.

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Chin, L. T., Peter Hing, K. S. Tan, and A. O. Olofinjana. "Overview and Functional Characterization of Pb–Free Solders." Defect and Diffusion Forum 297-301 (April 2010): 169–79. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.169.

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There are now new legislations emerging or being contemplated to restrict the use of Pb in electronic devices. This development has provided the impetus for the development of Pb- free solder alloys and efforts are now geared towards characterizing their operational and functional properties. The most common alloys being recommended and investigated are those primarily based on the Sn-Ag-Cu (SAC) system. These SAC alloys generally have higher melting points than conventional Pb-Sn alloy. Additionally they are susceptible to microstructural evolution of inter-metallic compounds that have been implicated in thermal fatigue life, mechanical strength and fracture toughness of the soldered joints. We have studied the Sn rich corner of the Sn-Ag-Cu system with minor additions aimed at minimizing detrimental microstructural development and improving the solderability and the mechanical strength of soldered joints. Some of the SAC alloys with minor additions showed some interesting properties. Their shear strength measured ranged from 30 – 60 MPa. The combined properties of strength and conductivity recorded compared favorably with that of traditional Pb-Sn solders.

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Yoon, Jeong-Won, Jun Hyung Lim, Hoo-Jeong Lee, Jinho Joo, Seung-Boo Jung, and Won-Chul Moon. "Interfacial reactions and joint strength of Sn–37Pb and Sn–3.5Ag solders with immersion Ag-plated Cu substrate during aging at 150 °C." Journal of Materials Research 21, no. 12 (December 2006): 3196–204. http://dx.doi.org/10.1557/jmr.2006.0390.

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Joint reliability of immersion Ag with two different solders, Sn–37Pb and Sn–3.5Ag, were evaluated. We first compared the interfacial reactions of the two solder joints and also successfully revealed a connection between the interfacial reaction behavior and mechanical reliability. The Sn–Pb solder produced a Pb-rich phase along the interface between the solder and the Cu substrate during aging. In contrast, the Sn–Ag solder exhibits an off-eutectic reaction to produce the eutectic phase and Ag3Sn precipitate. The shear test results show that the Sn–Pb solder joint fractured along the interface showing brittle failure indications possibly due to the brittle Pb-rich layer. In contrast, the failure of Sn–Ag solder joint was only through the bulk solder, providing evidence that the interface is mechanically reliable. The results from this study confirm that the immersion Ag/Sn–Ag solder joint is mechanically robust, and thus the combination is a viable option for a Pb-free package system.

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10

Song, Jenn-Ming, Yu-Lin Shen, and Hsin-Yi Chuang. "Sedimentation of Cu-rich intermetallics in liquid lead-free solders." Journal of Materials Research 22, no. 12 (December 2007): 3432–39. http://dx.doi.org/10.1557/jmr.2007.0431.

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This study investigated the behavior of Cu-containing intermetallic compounds (IMCs) in liquid Sn–Ag and Sn–Zn solders. Experimental results show that for the intermetallics investigated, Cu–Sn and Cu–Zn compounds, the occurrence of settling was dominated by the crystalline temperature of IMCs, buoyancy due to difference in densities, and dissolution potential for the compounds into the liquid. The complete dissolution of Cu–Zn compounds, which took place in the Sn–Zn solders when the Cu content exceeded a critical value, might be ascribed to the depletion of Zn in the melt.

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Abd El-Rehim, Alaa F., Ashraf S. Mahmoud, and Shereen M. Abdelaziz. "Influence of Sb2O3 Nanoparticles Addition on the Thermal, Microstructural and Creep Properties of Hypoeutectic Sn–Bi Solder Alloy." Science of Advanced Materials 13, no. 1 (January 1, 2021): 20–29. http://dx.doi.org/10.1166/sam.2021.3831.

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Here we investigate the effects (thermal, microstructural, and creep properties) of adding Sb2O3 nanoparticles to a hypoeutectic Sn-5 wt% Bi solder alloy. The Sb2O3-containing solder alloy was prepared by mechanically incorporating 0.5 wt% Sb2O3 nanoparticles into the Sn-5 wt% Bi solder alloy. The addition of nano-sized Sb2O3 particles to the Sn–Bi solder alloy increases the melting temperature, but only slightly. The main phases of the investigated solder alloys include the β-Sn and Bi-rich phases in addition to the crystalline phase of Sb2O3 nanoparticles. No other intermetallic compounds were observed in the β-Sn matrix. The tensile creep experiments have been carried out in the 303–363 K temperature interval under constant stresses ranging from 5.1 to 7.64 MPa. The creep parameters of both solders increased gradually with increasing creep temperature up to 333 K, after which they increased rapidly with relatively higher values. The creep parameters of the Sb2O3-containing solder alloys are smaller than that of Sb2O3-free solder alloys. The present solder alloys exhibit class-M creep behavior. The calculated stress exponent values and activation energy data for both solders could be related to dislocation climb through core diffusion as the dominant operating mechanism.

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Liu, Xiao Ying, Ming Liang Huang, and Ning Zhao. "Interfacial Reactions between Sn-Ag-Cu-Fe Composite Solder and Cu Substrate." Advanced Materials Research 706-708 (June 2013): 138–41. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.138.

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The growth kinetics and morphology of intermetallic compound (IMC) between Sn-3Ag-0.5Cu -xFe (x= 0, 0.5wt.%, 1wt.%) composite solders and Cu substrate were investigated in the present work. The Sn-Ag-Cu-Fe/Cu solder joint were prepared by reflowing for various durations at 250°C. During soldering process, Fe particles quickly deposited in the vicinity of IMC, resulting in the formation of Fe-rich area. It was shown that Fe could effectively retard the growth of interfacial Cu6Sn5 and Cu3Sn layers during liquid-state reaction and reduce the size of Cu6Sn5 grains. Small cracks were observed in the Cu6Sn5 grains of Sn-Ag-Cu/Cu interface after reflowing for 30 min while they were not found in the other composite solders.

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Jiang, Tong, Fubin Song, Chaoran Yang, and S. W. Ricky Lee. "Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds under Thermal Aging." International Symposium on Microelectronics 2010, no. 1 (January 1, 2010): 000314–18. http://dx.doi.org/10.4071/isom-2010-tp4-paper5.

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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.

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Sun, Jia, Huaxin Liang, Shaofu Sun, Juntao Hu, Chunyu Teng, Lingyan Zhao, and Hailong Bai. "Pattern Formation by Spinodal Decomposition in Ternary Lead-Free Sn-Ag-Cu Solder Alloy." Metals 12, no. 10 (September 29, 2022): 1640. http://dx.doi.org/10.3390/met12101640.

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In comparison to Pb-based solders which have a toxic effect, the tin-silver-copper (SAC) family of alloys have relatively strong reliability and are widely used in the electronics industry. Phase separation and coarsening phenomenon on the surface of 96.5 wt. % Sn-3.0 wt. % Ag-0.5 wt. % Cu (SAC305) solder products exhibit special microstructural features and offer opportunities for the microstructure control of microelectronic interconnects. However, the formation mechanism of such morphological patterns is still unknown. Here, we applied a combination of experimental and phase field methods to study how such patterns form. It was observed that the pattern was Sn-rich and exhibited the characteristic morphology of spinodal decomposition. Contrary to earlier findings that only binary systems like Sn-Pb and Sn-Bi experienced such phenomena, spinodal decomposition was firstly observed in ternary solder system Sn-Ag-Cu. Morphology of Sn-rich patterns depended on whether the spinodal decomposition reacted completely. SAC305 solder alloy was easily decomposed by Sn component after being heated to roughly 260 °C. The above conclusions could offer theoretical support for quantitatively controlling the microstructure of solder alloys and would enhance the quality of related products.

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Chen, Kang I., Shou Chang Cheng, and Chin Hsiang Cheng. "The Effects of Small Additions Ga and Al on the Microstructure and Tensile Properties of Sn-Zn Based Lead-Free Solders." Advanced Materials Research 800 (September 2013): 265–70. http://dx.doi.org/10.4028/www.scientific.net/amr.800.265.

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The melting temperature, microstructures, and mechanical properties of the Sn-Zn-0.5Ag-0.5Ga, Sn-Zn-0.5Ag-0.45Al and Sn-Zn-0.5Ga-0.45Al lead-free solders were investigated. The results indicate that the addition of 0.5 wt% Ag to the Sn-Zn based alloys destroy the eutectic structure and results in the formation of Ag-Zn compound and hypoeutectic structure. The variation in the microstructure lowers the UTS. By the addition of Al the UTS and elongation of the 0.5Ag-0.45Al alloy can be decreased due to the Al diffused to the interface of the Ag-Zn compound/Sn-Zn eutectic structure to form Al-Zn compound. The 0.5Ga-0.45Al alloy shows a typical eutectic structure with the light contract β-Sn and the darker needle-like phase, as well as a small amount of Al-Zn phase with a near diamond shape. Gallium uniformly distributes in the Sn matrix and Zn rich phases. The 0.5Ga-0.45Al solder had the highest UTS and elongation, while 0.5Ag-0.45Al had the lowest UTS and elongation. The results indicate that Ga and Al exhibits prominent influence on the microstructure as well as the mechanical properties of the solders.

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Jang, Jin-Wook, Ananda P. De Silva, Jong-Kai Lin, and Darrel R. Frear. "Tensile fracture behaviors of solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps." Journal of Materials Research 19, no. 6 (June 2004): 1826–34. http://dx.doi.org/10.1557/jmr.2004.0235.

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The tensile fracture behavior for solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps was examined. The annealing temperatures were in the range of 125–170 °C for 500 h. Prior to solid state annealing, the eutectic Sn–37Pb (SnPb) and Sn–0.7Cu (SnCu) solders showed fracture through the bulk solder. Brittle interfacial fracture occurred in the Sn–3.5Ag (SnAg) solder. After solid-state annealing, the fracture behavior changed dramatically. For eutectic SnPb solder, the fracture modes gradually changed from cohesive solder failure to interfacial fracture with increasing annealing temperature. The fracture mode of the SnCu solder showed greater change than the SnPb and SnCu solders. After annealing at 125 °C, the SnAg solder had a ductile taffy pull fracture, but an increase in temperature resulted in brittle interfacial fracture again. The SnCu solder maintained the same ductile taffy pull mode up to170 °C annealing, independent of the under bump metallization (UBM) type. Microstructure analysis showed that the interfacial fracture of the SnPb and SnAg solder bumps was ascribed to Pb-rich layer formation and Ag embrittlement at the interface, respectively. The bulk solder fracture of SnAg annealed at 125 °C appeared to be a transient phenomenon due to the abrupt breakdown of the hard lamella structure. The eutectic SnCu solder bumps had no significant change in the interfacial structure, except for interfacial intermetallic growth.

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17

Li, Chia-Ying, and Jenq-Gong Duh. "Phase Equilibria in the Sn-Rich Corner of the Sn–Cu–Ni Ternary Alloy System at 240 °C." Journal of Materials Research 20, no. 11 (November 2005): 3118–24. http://dx.doi.org/10.1557/jmr.2005.0391.

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The interfacial reactions between solders and under bump metallization (UBM) have been of great interest recently in flip chip technology. Intermetallic compounds (IMCs), i.e., (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4, usually formed between solders and UBM. To fully understand the interfacial reactions and phase transformation phenomenon, a suitable phase diagram concerning solders, IMCs, and UBM materials is required. In particular, a Sn-rich phase region in the Sn–Cu–Ni ternary diagram is very critical in determining the concentration tendency of x and y values in (Ni1−x,Cux)3Sn4 and (Cu1−y,Niy)6Sn5 compounds. In this study, ternary Sn–Cu–Ni alloys were prepared and annealed at 240 °C. Three equilibrium phases, Sn, Ni3Sn4, and Cu6Sn5, were identified by x-ray diffraction analysis and also showed in backscattered electron imaging. Using electron probe microanalysis quantitative analysis, three acme compositions of the ternary region in the Sn–Cu–Ni isotherm near the Sn-rich corner were determined as 98.5 at.% Sn, (Ni0.80, Cu0.20)3Sn4 and (Cu0.59,Ni0.41)6Sn5. In addition, the solubility of Cu and Ni in (Ni,Cu)3Sn4 and (Cu,Ni)6Sn5 compounds was evaluated. Finally, the isothermal section of the ternary Sn–Cu–Ni system at 240 °C was proposed on the basis of experimental results in this study.

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Summers, T. S. E., and J. W. Morris. "Isothermal Fatigue Behavior of Sn-Pb Solder Joints." Journal of Electronic Packaging 112, no. 2 (June 1, 1990): 94–99. http://dx.doi.org/10.1115/1.2904364.

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Isothermal fatigue data were collected for the compositions 5Sn-95Pb, 20Sn-80Pb, 40Sn-60Pb, 50Sn-50Pb and 63Sn-37Pb within the binary Sn-Pb system. All of these compositions are commercially available and include those most commonly used. Because Sn-rich solders are rarely used, they were not investigated here. The fatigue life was defined by a 30 percent load drop. The solders were tested in a double shear configuration joined to copper at 75° C. The displacement rate chosen was 0.01 mm/min, which corresponds to a strain rate of 1.5 × 10−4s−1 for our specimen configuration, over a 10 percent plastic strain range. Additionally, the microstructural changes during fatigue are presented. The various solder compositions studied exhibit strikingly different as-solidified microstructures. These differences are discussed in terms of their effect on the isothermal joint failure mechanism and joint isothermal fatigue life.

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Islam, M. N., Y. C. Chan, and A. Sharif. "Interfacial reactions of Sn–Cu and Sn–Pb–Ag solder with Au/Ni during extended time reflow in ball grid array packages." Journal of Materials Research 19, no. 10 (October 1, 2004): 2897–904. http://dx.doi.org/10.1557/jmr.2004.0399.

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Lead-free solders with high Sn content cause excessive interfacial reactions at the interface with under-bump metallization during reflow. The interface formed after reflow affects the reliability of the solder joint. For this paper, we investigated the interfacial reactions of Sn0.7Cu and Sn36Pb2Ag solder on electrolytic Ni layer for different reflow times. The traditionally used Sn36Pb2Ag solder was used as a reference. It was found that during as-reflowed, the formation of Cu-rich Sn–Cu–Ni ternary intermetallic compounds (TIMCs) at the interface of Sn0.7Cu solder with electrolytic Ni is much quicker, resulting in the entrapment of some Pb (which is present as impurity in the Sn–Cu solder) rich phase in the TIMCs. During extended time of reflow, high (>30 at.%), medium (30-15 at.%) and low (<15 at.%) Cu TIMCs formed at the interface. The amount of Cu determined the growth rate of TIMCs. Cu-rich TIMCs had higher growth rate and consumed more Ni layer. By contrast, the growth rate of the Ni–Sn binary intermetallic compounds (BIMCs) in the Sn36Pb2Ag solder joint was slower, and the Ni–Sn BIMC was more stable and adherent. The dissolution rate of electrolytic Ni layer for Sn0.7Cu solder joint was higher than the Sn36Pb2Ag solder joints. Less than 3 μm of the electrolytic Ni layer was consumed during molten reaction by the higher Sn containing Sn0.7Cu solder in 180 min at 250 °C. The shear strength of Sn–Pb–Ag solder joints decreased within 30 min of reflow time from 1.938 to 1.579 kgf due to rapid formation of ternary Ni–Sn–Au compounds on the Ni–Sn BIMCs. The shear strength of Sn0.7Cu solder joint is relatively stable from 1.982 to 1.861 kgf during extended time reflow. Cu prevents the resettlement of Au at the interface. The shear strength does not depend on the thickness of intermetallic compounds (IMCs) and reflow time. Ni/Sn–Cu solder system has higher strength and can be used during prolonged reflow.

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Choi, Hyeokgi, Chang-Lae Kim, and Yoonchul Sohn. "Diffusion Barrier Properties of the Intermetallic Compound Layers Formed in the Pt Nanoparticles Alloyed Sn-58Bi Solder Joints Reacted with ENIG and ENEPIG Surface Finishes." Materials 15, no. 23 (November 26, 2022): 8419. http://dx.doi.org/10.3390/ma15238419.

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Pt-nanoparticle (NP)-alloyed Sn-58Bi solders were reacted with electroless nickel-immersion gold (ENIG) and electroless nickel-electroless palladium-immersion gold (ENEPIG) surface finishes. We investigated formation of intermetallic compounds (IMCs) and their diffusion barrier properties at reaction interfaces as functions of Pt NP content in the composite solders and duration of solid-state aging at 100 °C. At Sn-58Bi-xPt/ENIG interfaces, typical Ni3Sn4/Ni3P(P-rich layer) microstructure was formed. With the large consumption of the Ni-P layer, the Ni-P and Cu layers were intermixed and Cu atoms spread over the composite solder after 500 h of aging. By contrast, a (Pd,Ni)Sn4/thin Ni3Sn4 microstructure was observed at the Sn-58Bi-xPt/ENEPIG interfaces. The (Pd,Ni)Sn4 IMC effectively suppressed the consumption of the Ni-P layer and Ni3Sn4 growth, functioning as a good diffusion barrier. Therefore, the Sn-58Bi-xPt/ENEPIG joint survived 500 h of aging without microstructural degradation. Based on the experimental results and analysis of this study, Sn-58Bi-0.05Pt/ENEPIG is suggested as the optimum combination for future low-temperature soldering systems.

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Athichalinthorn, Panaaek, Jidsucha Darayen, Wachira Puttichaem, Ratchatee Techapiesancharoenkij, and Boonrat Lohwongwatana. "The Thermal-Aging Effect on the Microstructure Evolution and Shear Strength of the Sn-Rich Au-Sn Soldering between Altic and Si Substrate in Microelectronics." Key Engineering Materials 751 (August 2017): 3–8. http://dx.doi.org/10.4028/www.scientific.net/kem.751.3.

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The Au-Sn soldering alloys are commonly used in microsoldering process for microelectronic industry due to fluxless process and relatively low melting temperature with good eutectic microstructures. This study investigated the microstructures of Au-Sn soldering between AlTiC and Si substrates with Ti/Pt/Au under bump metallization (UBM). The microstructures of the solder samples under three conditions: before bonding, after bonding and after thermal-cycle aging, were investigated. The shear strength values of pre-aging and post-aging soldering were compared. The thermal-cycling temperatures were ranged from -40 to 125 °C for 300 cycles. The intermetallic compounds (IMCs) of the AuSn solders consist of AuSn, AuSn2, and AuSn4. After thermal-cycle aging, the bonding strength was increased due to the improved IMC bonding between solders and UBM; the shear surfaces were rougher due to the growth of AuSn and AuSn2.

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Rerek, T., L. Skowronski, M. Kobierski, M. K. Naparty, and B. Derkowska-Zielinska. "Microstructure and opto-electronic properties of Sn-rich Au-Sn diffusive solders." Applied Surface Science 451 (September 2018): 32–39. http://dx.doi.org/10.1016/j.apsusc.2018.04.209.

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Tang, Wenming, Anqiang He, Qi Liu, and Douglas G. Ivey. "Fabrication and Microstructures of Sequentially Electroplated Sn-Rich Au-Sn Alloy Solders." Journal of Electronic Materials 37, no. 6 (February 27, 2008): 837–44. http://dx.doi.org/10.1007/s11664-008-0401-z.

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Chuang, C. M., T. S. Lui, and L. H. Chen. "Effect of lead content on vibration fracture behavior of Pb–Sn eutectic solder." Journal of Materials Research 16, no. 9 (September 2001): 2644–52. http://dx.doi.org/10.1557/jmr.2001.0363.

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According to resonant vibration fatigue tests, near-eutectic and Pb-rich hypoeutectic Pb–Sn specimens have higher crack-propagation resistance. The tensile flow stress of Pb–Sn solders that are near eutectic composition increases with decreasing Pb content. The solders were tested after either stabilizing at 373 K or natural aging for 20 days, which gave similar results. The naturally aged specimens show that the crack-propagation resistance increases with increasing aging time. A striated deformation was found to occur in Sn grain of the lower Pb specimen. This phenomenon is correlated with a deterioration of crack-propagation resistance.

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Zhang, Hongwen, Samuel Lytwynec, Huaguang Wang, Jie Geng, Francis Mutuku, and Ning-Cheng Lee. "A Novel Design of High-Temperature Lead-Free Solders for Die-Attachment in Power Discrete Applications." International Symposium on Microelectronics 2021, no. 1 (October 1, 2021): 000356–61. http://dx.doi.org/10.4071/1085-8024-2021.1.000356.

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Abstract Development of high-temperature lead-free (HTLF) solders to replace high-lead solders for die-attachment in power device applications is driven by (1) the harmful effects of lead to human health and the environment, and (2) the demand of the improved bonding materials serving under high-power density and high-junction temperatures, especially for wide-band-gap power devices. A novel design, based on a mixed solder powder paste technology—Durafuse™—has been developed to deliver a Sn-rich HTLF paste, presenting the merits of both constituent powders. The combination of the rigid, high-melting SnSbCuAgX and the ductile, low-temperature Sn-rich solder in one paste enables reflow at a relatively low temperature (barely above the liquidus temperature of the final joint composition) and maintains the joint strength above 15MPa in the temperature range between 270°C and 295°C. The sufficient high-temperature strength has demonstrated the capability of maintaining the joint integrity during subsequent multiple SMT reflows below the 270°C peak temperature, regardless of the existence of a partial melting phase. Both X-ray inspection and cross-section microstructure have not shown any damage in the Si die or any noticeable cracks in the bonding joint, even after 3000 cycles of TCT (−40 to 150°C). In summary, Durafuse™ HT, the novel design of the high-temperature lead-free pastes, has shown the feasibility as a drop-in solution to replace high-lead solders for die-attachment in power discrete applications.

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Sidhu, R. S., and N. Chawla. "Thermal Fatigue Behavior of Sn-Rich (Pb-Free) Solders." Metallurgical and Materials Transactions A 39, no. 4 (February 16, 2008): 799–810. http://dx.doi.org/10.1007/s11661-008-9480-y.

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Hirose, Akio, Tomoyuki Hiramori, Mototaka Ito, Yoshiharu Tanii, and Kojiro F. Kobayashi. "Interfacial Microstructure and Joint Strength of Sn-Ag and Sn-Ag-Cu Lead Free Solders Reflowed on Cu/Ni-P/Au Metallization." Materials Science Forum 512 (April 2006): 355–60. http://dx.doi.org/10.4028/www.scientific.net/msf.512.355.

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Sn-3.5Ag (Sn-Ag) and Sn-3.5Ag-0.75Cu (Sn-Ag-Cu) solder balls were reflowed on electroless Ni-P/Au plated Cu pad with varying thickness of Au layer (0 to 500nm). In the Sn-Ag solder joint, a P-rich layer including voids, which resulted from Ni diffusion from the Ni-P plating to form Ni3Sn4 interfacial reaction layer, formed at the interface regardless of Au plating thickness. This caused the degradation of the joint strength. On the contrary, the Sn-Ag-Cu solder joint had no continuous P-rich layer formed and showed a higher joint strength than the Sn-Ag solder joint in the case of Au plating of 50nm or less. Cu alloying to the solder promote the formation of (Cu, Ni)6Sn5 instead to Ni3Sn4 as the interfacial reaction layer. The (Cu, Ni)6Sn5 reaction layer can suppress the diffusion of Ni from the N-P plating and thereby inhibit the formation of the P-rich layer. However, in the case of thick Au plating of 250nm or more, a thin P-rich layer formed at the interface even in the Sn-Ag-Cu solder joint and the joint strength was degraded. Au dissolving into the solder from the Au plating during the reflow process may encourage the diffusion of Ni from the Ni-P plating into the solder. As a result, the Sn-Ag-Cu solder joints with 50nm Au coating provided the best joint strength, although its joint strength considerably degraded after the aging treatment at 423K.

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Shaik Osman, Shazlin, and Mohd Sharif Nurulakmal. "Effect of Alloying Elements on the Microstructure and IMC Formation of SnAgCu Solder on Ni (P) Substrate." Advanced Materials Research 545 (July 2012): 251–55. http://dx.doi.org/10.4028/www.scientific.net/amr.545.251.

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When the use of lead was banned, the development of lead-free solders began to rise and was greatly explored. Presently, majority of the eutectic Pb-free solders are Sn-based and the most promising is ternary SnAgCu (SAC) solder. However, SnAgCu solder tends to become brittle in nature and excessive solder interfacial reactions. An attractive approach is by introducing alloying elements such as Ce, Fe and Zn into the SnAgCu solder, which allows for an increase of the mechanical properties and refine the solder microstructure as well as improve the wetting properties. The present work focuses on the effects of a series of elemental additions of 0.5% Ce, Fe and Zn into the basic Sn3.0Ag0.5Cu solder, in attempt to reduce the intermetallic compound (IMC) growth as well as joint reliability and reflow properties of the solder on Ni-P surface finish. The intermetallic compound Cu6Sn5, containing a small amount of dissolved Ni, was found to form preferentially on the Ni coating. This compound layer served as a barrier for direct reaction of Sn with the Ni-P coating. The P-rich Ni layer acts as a good diffusion barrier layer, which decreases the dissolution rate of the Ni-P layer hence decreases the growth of IMC thickness layer. It is also expected that with the addition of alloying elements, the wetting properties will be further enhanced.

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Peng, Yan Zhi, Cai Ju Li, Jiao Jiao Yang, Jia Tao Zhang, Ju Bo Peng, Guang Ji Zhou, Cun Ji Pu, and Jian Hong Yi. "Effects of Bismuth on the Microstructure, Properties, and Interfacial Reaction Layers of Sn-9Zn-xBi Solders." Metals 11, no. 4 (March 26, 2021): 538. http://dx.doi.org/10.3390/met11040538.

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In electronic packaging, Sn-Zn lead-free solder has great application prospects. Sn-9Zn-xBi alloys were obtained by smelting. This paper details a systematic study of the effect of Bi on the microstructure, melting behavior, wettability, mechanical behavior, antioxidant properties, and electrical conductivity of Sn-9Zn-xBi alloy, as well as the interfacial reaction in Sn-9Zn-xBi/Cu joints. The coarse Zn-rich phase became larger with an increase in the addition of Bi, which is harmful to the oxidation resistance of the solders. The melting temperature, solidus temperature, and liquidus temperature decreased with the increase in the addition of Bi, but the melting range increased. Adding a proper amount of Bi could substantially improve the spreading rate of Sn-9Zn, but reduce its oxidation resistance. Because of the solid solution effect of Bi element, the tensile strength of the Sn-9Zn solders could be enhanced, but the plastic and electrical conductivity was decreased. The IMC layer of the Sn-9Zn and Cu joints consisted of the ε-CuZn5 phase and the γ-Cu5Zn8 phase. With an increase in the Bi element, the thickness of the interfacial reaction layer was firstly increased. When the Bi element content exceeded 3 wt.%, the inhibitory effect of the aggregated Bi elements on the formation of IMC was greater than the positive effect of the longer reaction time, and the thickness of the IMC decreased.

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Islam, M. N., Y. C. Chan, M. O. Alam, and A. Sharif. "Comparative Study of the Dissolution Kinetics of Electrolytic Ni and Electroless NiP Layers by Molten Sn3.5Ag Solder Alloy." Journal of Electronic Packaging 127, no. 4 (December 22, 2004): 365–69. http://dx.doi.org/10.1115/1.2056567.

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Sn-based, Pb-free solders with high a Sn content and high melting temperature often cause excessive interfacial reactions at interfaces. Sn-3.5Ag solder alloy has been used to identify its interfacial reactions with two-metal layer flexile substrates. In this paper the dissolution kinetics of Sn3.5Ag solder on the electrolytic Ni and electroless NiP layer are investigated. It is found that during 1 min reflow the electrolytic Ni layer dissolves much less than the electroless NiP layer due to the formation of Ni3Sn and Ni3Sn2 intermetallic compounds (IMCs) on the electrolytic Ni layer. The faster nucleation of Ni3Sn4 IMC on the NiP layer is proposed as the main reason for the higher initial dissolution rate of the electroless NiP layer. A P-rich Ni layer is formed underneath the Ni3Sn4 IMC due to the solder-assisted reactions. This P-rich Ni layer acts as a good diffusion barrier layer, which decreases the dissolution rate of the NiP layer as compared to that of the Ni layer, but weakens the interface of solder joints and reduces the ball shear load and reliability. Below a certain thickness, the P-rich Ni layer breaks and an increase in the diffusion of Sn atoms through the fractured P-rich Ni layer occurs that increases the growth rate of IMCs again, and thus the dissolution rate of the NiP layer becomes higher again than for the Ni layer. It is found that a 3μm thick NiP layer cannot protect the Cu layer for more than 120 min reflow at 250°C. An electrolytic Ni∕solder system has a relatively higher shear load, a lower dissolution rate of the Ni layer, and is more protective for the Cu layer during extended times of reflow.

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He, M., A. Kumar, P. T. Yeo, G. J. Qi, and Z. Chen. "Interfacial reaction between Sn-rich solders and Ni-based metallization." Thin Solid Films 462-463 (September 2004): 387–94. http://dx.doi.org/10.1016/j.tsf.2004.05.062.

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32

Huang, M. L., F. F. Huang, and Y. C. Yang. "Composition design of Sn-rich Sn–Au–Ag solders using cluster-plus-glue-atom model." Journal of Materials Science: Materials in Electronics 28, no. 15 (April 27, 2017): 11192–201. http://dx.doi.org/10.1007/s10854-017-6907-5.

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33

Ventura, Tina, Young Hee Cho, and Arne K. Dahle. "Solidification Mechanisms in the Sn-Cu-Ni Lead-Free Solder System." Materials Science Forum 654-656 (June 2010): 1381–84. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1381.

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Pb-free solders based on near-eutectic Sn-0.7Cu-xNi alloys provide excellent solderability during wave soldering with cost advantages compared to Ag-containing alternatives. However, there is only limited knowledge of the solidification mechanisms in this alloy system and, furthermore, the ternary Sn-Cu-Ni phase diagram is not yet fully established. In this study, unidirectional solidification has been conducted in a Bridgman furnace using both binary alloys from the Sn-Cu6Sn5 system and ternary Sn-rich Sn-Cu-Ni alloys. The influence of Ni additions on the solidification mechanisms is assessed by comparing the microstructures of the ternary and binary alloys. The results are used to discuss the contrasting Sn-Cu-Ni phase diagrams reported in the literature. The results demonstrate the complex phase relations in the Sn-Cu alloy system, and the important role of trace amounts of various solute elements.

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Huang, M. L., Y. C. Yang, Y. Chen, and C. Dong. "Microstructure and mechanical properties of Sn-rich Au-Sn solders designed using cluster-plus-glue-atom model." Materials Science and Engineering: A 664 (May 2016): 221–26. http://dx.doi.org/10.1016/j.msea.2016.03.123.

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35

Cheung, Noé, Amauri Garcia, and José Eduardo Spinelli. "Microstructure and Mechanical Properties of Directionally Solidified Unmodified and Ni-Modified Sn-0.7wt%Cu Lead-Free Solder Alloy." Defect and Diffusion Forum 333 (January 2013): 107–15. http://dx.doi.org/10.4028/www.scientific.net/ddf.333.107.

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Lead containing solders (SnPb eutectic alloys) are widely used in electronic devices due to their good mechanical properties and low manufacturing cost. However, two European Union regulations (Waste from Electrical and Electronic Equipment and Restriction of Hazardous Substances) banned the use of lead in electrical and electronic equipment because of the toxic effect on human health and the environment. Nowadays, it is particularly important to find replacements for Pb containing solder materials. In that respect, copper is used as an alloying element and the composition Sn-0.7wt%Cu is of particular interest. Small Ni additions can be interesting since they would be included into the composition of the commercial solder SN100 and can also avoid the presence of coarse and deleterious Cu6Sn5 particles for Sn-Cu alloys in the hypoeutectic range of compositions. In the present investigation, growth rate, cooling rate, interfacial heat transfer coefficient (hi), the scale of the microstructure and morphologies, ultimate tensile strength and elongation have been experimentally determined for Sn-0.7wt%Cu and Sn-0.7wt%Cu-0.1wt%Ni alloys solidified in a water-cooled vertical upward unidirectional solidification system. Further, interrelations of thermal parameters, microstructure and tensile properties may be established. A higher time-dependent hi profile was found for the Sn-0.7wt%Cu-0.1wt%Ni alloy which seems to indicate that a higher fluidity was obtained with small Ni addition. Higher fluidity values may characterize better physicochemical affinity between the melt and the mould surface. The modified Sn-Cu alloy propitiates higher ultimate tensile strength values to be obtained. This may be due to the prevalence of eutectic two-phase cells along the casting associated with fine Cu-rich particles close to the water-cooled surface.

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Yang, Wenchao, Jun Mao, Yueyuan Ma, Shuyuan Yu, Hongping He, Da Qi, and Yongzhong Zhan. "Effects of Yttrium Addition on the Microstructure Evolution and Electrochemical Corrosion of SN-9Zn Lead-Free Solders Alloy." Materials 14, no. 10 (May 14, 2021): 2549. http://dx.doi.org/10.3390/ma14102549.

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Electrochemical corrosion behavior of ternary tin-zinc-yttrium (Sn-9Zn-xY) solder alloys were investigated in aerated 3.5 wt.% NaCl solution using potentiodynamic polarization techniques, and the microstructure evolution was obtained by scanning electron microscope (SEM). Eight different compositions of Sn-9Zn-xY (x = 0, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, and 0.30 wt.%) were compared by melting. The experimental results show that when the content of Y reached 0.06 wt.%, the grain size of Zn-rich phase became the smallest and the effect of grain refinement was the best, but there was no significant effect on the melting point. With the increases of Y content, the spreading ratio first increased and then decreased. When the content of Y was 0.06 wt.%, the Sn-9Zn-0.06Y solder alloy had the best wettability on the Cu substrate, which was increased by approximately 20% compared with Sn-9Zn. Besides, the electrochemical corrosion experimental shows that the Y can improve the corrosion resistance of Sn-9Zn system in 3.5 wt.% NaCl solution, and the corrosion resistance of the alloy is better when the amount of Y added is larger within 0.02–0.30 wt.%. Overall considering all performances, the optimal performance can be obtained when the addition amount of Y is 0.06.

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Pietrzak, K., A. Klasik, M. Maj, A. Wojciechowski, and N. Sobczak. "Microstructural Aspects of Fatigue Parameters of Lead-Free Sn-Zn Solders with Various Zn Content." Archives of Foundry Engineering 17, no. 1 (March 1, 2017): 131–36. http://dx.doi.org/10.1515/afe-2017-0024.

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Abstract The study includes the results of research conducted on selected lead-free binary solder alloys designed for operation at high temperatures. The results of qualitative and quantitative metallographic examinations of SnZn alloys with various Zn content are presented. The quantitative microstructure analysis was carried out using a combinatorial method based on phase quanta theory, per which any microstructure can be treated as an array of elements disposed in the matrix material. Fatigue tests were also performed using the capabilities of a modified version of the LCF method hereinafter referred to in short as MLCF, which is particularly useful in the estimation of mechanical parameters when there are difficulties in obtaining many samples normally required for the LCF test. The fatigue life of alloys was analyzed in the context of their microstructure. It has been shown that the mechanical properties are improved with the Zn content increasing in the alloy. However, the best properties were obtained in the alloy with a chemical composition close to the eutectic system, when the Zn-rich precipitates showed the most preferred morphological characteristics. At higher content of Zn, a strong structural notch was formed in the alloy because of the formation in the microstructure of a large amount of the needle-like Zn-rich precipitates deteriorating the mechanical characteristics. Thus, the results obtained during previous own studies, which in the field of mechanical testing were based on static tensile test only, have been confirmed. It is interesting to note that during fatigue testing, both significant strengthening and weakening of the examined material can be expected. The results of fatigue tests performed on SnZn alloys have proved that in this case the material was softened.

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Cho, Moon Gi, Hyun You Kim, Sun-Kyoung Seo, and Hyuck Mo Lee. "Enhancement of heterogeneous nucleation of β-Sn phases in Sn-rich solders by adding minor alloying elements with hexagonal closed packed structures." Applied Physics Letters 95, no. 2 (July 13, 2009): 021905. http://dx.doi.org/10.1063/1.3177335.

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Cho, Moon Gi, Sun-Kyoung Seo, and Hyuck Mo Lee. "Undercooling, Microstructures and Hardness of Sn-Rich Pb-Free Solders on Cu-xZn Alloy Under Bump Metallurgies." MATERIALS TRANSACTIONS 50, no. 9 (2009): 2291–96. http://dx.doi.org/10.2320/matertrans.m2009127.

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Wentlent, Luke A., James Wilcox, and Xuanyi Ding. "Strain Rate Sensitivity of Mixed SAC-SnBi Solder Joints." International Symposium on Microelectronics 2019, no. 1 (October 1, 2019): 000480–87. http://dx.doi.org/10.4071/2380-4505-2019.1.000480.

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Abstract As the electronics industry continues to evolve a concerted effort has developed to implement lower melting point solders. The ability to minimize the thermal exposure that an assembly is subjected to affords significant benefits with respect to both the reliability and the materials that can be used. One of the most popular low melt solder alloys currently being investigated by the industry is the Bi-Sn eutectic system, which has a melting point of 139°C. The BiSn system itself is not particularly novel as it was posited as a SAC alternative during the initial shift from Pb based solders. While a body of knowledge currently exists regarding this system, and the near eutectic variant BiSnAg, there are still concerns regarding its ductility, especially as a function of thermal exposure and strain rate. Bismuth is widely acknowledged as a brittle element and its presence in such quantities raises concerns of not just Cu6Sn5 embrittlement but also solder fragility in high strain rate types of environments. A challenge with regards to near term implementation is that most packages are not available with BiSn solder bumps. Therefore, it will be necessary to use components already balled with SAC 305 solder. This means that the resulting solder interconnect, reflowed below conventional SAC reflow temperatures, will form a type of mixed hybrid microstructure. This non-equilibrium microstructure will be composed of two regions, one Bi-rich region which is well past saturation and a second region which is Bi-deficient. It is of specific industrial interest then to not just investigate the BiSn solder system but also within the context of a realistic mixed interconnect. Recent work by several researchers has shown that this hybrid microstructure is unstable and quite active with respect to the movement and localized concentration of the Bismuth. The degree of mixing of these two regions has been shown to be highly dependent upon reflow temperature and the paste to ball volume ratio. Mixed SAC-BiSn solder joints were formed by placing SAC 305 spheres on BiSn paste deposits for a paste to ball volume ratio of .18. These samples were then reflowed at either 175°C or 200°C. SAC 305 control samples were also made using a conventional Pb-free reflow profile with a peak temperature of 247°C. A 22 mil Cu-OSP pad on a 1.0 mm thick FR4 substrate was used for all samples. A selection of the solder joints were then isothermally aged at 90°C for 200 hours. Using a joint level micromechanical tester, ball shear tests were conducted at a range of strain rates for samples in the as-reflowed and aged state. Using this information, the strain rate sensitivity of the interconnects was mapped and correlated with the observed failure modes. Investigations into the fracture mechanisms were conducted by examining the shear fracture surface with optical and scanning electron microscopy. Additionally, the evolution of the microstructure was characterized. Results showed a clear transition from ductile solder failure to a brittle separation failure at the higher strain rates.

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Saud, N., and A. Jalar. "Sn-rich phase coarsening during isothermal annealing for as-soldered Sn–Ag–Cu solder." Journal of Materials Science: Materials in Electronics 21, no. 10 (December 10, 2009): 1083–89. http://dx.doi.org/10.1007/s10854-009-0032-z.

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Shen, Yu-An, and John A. Wu. "Effect of Sn Grain Orientation on Reliability Issues of Sn-Rich Solder Joints." Materials 15, no. 14 (July 21, 2022): 5086. http://dx.doi.org/10.3390/ma15145086.

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Sn-rich solder joints in three-dimensional integrated circuits and their reliability issues, such as the electromigration (EM), thermomigration (TM), and thermomechanical fatigue (TMF), have drawn attention related to their use in electronic packaging. The Sn grain orientation is recognized as playing an important role in reliability issues due to its anisotropic diffusivity, mechanical properties, and coefficient of thermal expansion. This study reviews the effects of the Sn grain orientation on the EM, TM, and TMF in Sn-rich solder joints. The findings indicate that in spite of the failure modes dominated by the Sn grain orientation, the size and shape of the solder joint, as well as the Sn microstructures, such as the cycling twining boundary (CTB), single crystals, and misorientations of the Sn grain boundary, should be considered in more detail. In addition, we show that two methods, involving a strong magnetic field and seed crystal layers, can control the Sn grain orientations during the solidification of Sn-rich solder joints.

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Scandurra, Antonino, Antonino Licciardello, Alberto Torrisi, Antonio La Mantia, and Orazio Puglisi. "Fatigue failure in Pb–Sn–Ag alloy during plastic deformation: A 3D-SIMS imaging study." Journal of Materials Research 7, no. 9 (September 1992): 2395–402. http://dx.doi.org/10.1557/jmr.1992.2395.

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Three-dimensional chemical maps by Secondary Ion Mass Spectrometry (3D-SIMS), XPS spectroscopy, and SEM-EDAX microscopy were employed in order to investigate the effects of accelerated fatigue tests on crack formation in 95.5% Pb–2% Sn–2.5% Ag and 95% Pb–5% Sn solder joints. These alloys are used in the die bonding of electronic power device assemblies. The results show that cracks form by Sn-depletion from the inner regions of the soldered joint. Simultaneously, there is a recrystallization of the Pb-rich phase in the same regions of the joint. The crack occurs at a critical number of cycles when a Sn-depleted region is formed, yielding weaker inner layers with lower shear strength. A possible explanation of the Sn-depletion is also discussed.

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Gan, Guisheng, Da-quan Xia, Xin Liu, Cong Liu, Hanlin Cheng, Zhongzhen Ming, Haoyang Gao, Dong-hua Yang, and Yi-ping Wu. "Influence of thermal shock cycles on Sn-37Pb solder bumps." Soldering & Surface Mount Technology 31, no. 2 (April 1, 2019): 85–92. http://dx.doi.org/10.1108/ssmt-08-2018-0026.

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Purpose With continuous concerning on the toxic of element Pb, Pb-free solder was gradually used to replace traditional Sn-Pb solder. However, during the transition period from Sn-Pb to Pb-free solder, mixing of Sn-Pb and Pb-free is inevitable occurred in certain products, and in China where Sn-Pb solder was still used extensively in certain areas especially. Correspondingly, understanding reliability of Sn-Pb solder joints was very important, and further studies were needed. Design/methodology/approach Thermal shock test between −55°C and 125 °C was conducted on Sn-37Pb solder bumps in the BGA package to investigate the microstructure evolution and the growth mechanism of interfacial intermetallic compound (IMC) layer. The effects of thermal shock on the mechanical property and fracture behavior of Sn-37Pb solder bumps were discussed. Findings Pb-rich phase was coarsened and voids were increased at first; Pb-rich phase was refined and voids were decreased secondly with the increase of thermal shock cycles; the shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67MPa at 2,000 cycles; interfacial IMCs of solder bumps was from typical scallop-type into smooth, the composition of IMCs was from Cu6Sn5 into Cu6Sn5 and Cu3Sn after thermal shock with 1,500 and 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure respectively. Originality/value Compared with the board level test method, the impact shear test for the single solder bump is more convenient and economical and is actively pursued by the industries. The shear strength of solder bumps was slightly decreased after thermal shock, but was back up to 73.67 MPa at 2,000 cycles; 20.0 per cent of solder bumps at 1,500 cycles and 9.5 per cent of solder bumps at 2,000 cycles were failure.

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Chantaramanee, Suchart, Worawit Sriwittayakul, and Phairote Sungkhaphaitoon. "Effects of Antimony and Indium Addition on Wettability and Interfacial Reaction of Sn-3.0Ag-0.5Cu Lead Free Solder on Copper Substrate." Materials Science Forum 928 (August 2018): 188–93. http://dx.doi.org/10.4028/www.scientific.net/msf.928.188.

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The effects of antimony and indium addition on wettability and interfacial reaction of Sn-3.0Ag-0.5Cu lead free solder on copper substrate were investigated. The experimental results showed the melting point of solder alloy containing 0.5 wt.% In and 0.5 wt.% Sb were slightly increased about 3.66°C. The pasty range of solder alloys were increased about 6°C while the undercooling of solder alloys were decreased. The microstructures of solder alloy were contained of In and Sb consists of Ag3Sn, Cu6(Sn,In)5, SnIn, Ag3(Sn,In) and SnSb intermetallic compounds (IMCs) dispersed on Sn-rich phase. The wettability of solder alloys were improved by increasing soldering times. In addition, the thickness of intermetallic compounds (Cu6Sn5) were obviously increased with increasing soldering times.

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Song, Ho Geon, John W Morris, Jr., and Fay Hua. "Anomalous Creep in Sn-Rich Solder Joints." MATERIALS TRANSACTIONS 43, no. 8 (2002): 1847–53. http://dx.doi.org/10.2320/matertrans.43.1847.

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Sungkhaphaitoon, Phairote, and Thawatchai Plookphol. "Effect of Cooling Rate on the Microstructure and Mechanical Properties of Sn-0.7wt.%Cu Solder Alloy." Key Engineering Materials 675-676 (January 2016): 513–16. http://dx.doi.org/10.4028/www.scientific.net/kem.675-676.513.

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The dependence of microstructure and mechanical properties of Sn-0.7wt.%Cu solder alloys on different cooling rates were investigated. Two cooling rates were employed during solidification: 0.04 °C/s (mold-cooled system) and 1.66 °C/s (water-cooled system). The results showed that the ultimate tensile strength of Sn-0.7wt.%Cu solder alloy increased but the elongation decreased when water-cooled system was used. The microstructure of Sn-0.7wt.%Cu solder alloys solidified by both cooling systems exhibited two phases of Sn-rich and Cu6Sn5 intermetallic compounds (IMCs). However, finer grains were observed in the water-cooled specimens.

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Leong, Wai Keong, Ahmad Azmin Mohamad, and Muhammad Firdaus Mohd Nazeri. "Effect of the nickel coated precipitated calcium carbonate addition on microstructure, phase and wettability of Sn-9Zn solder." Journal of Physics: Conference Series 2169, no. 1 (January 1, 2022): 012031. http://dx.doi.org/10.1088/1742-6596/2169/1/012031.

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Abstract This paper presents the effect of nickel-coated precipitated calcium carbonate (Ni-coated PCC) on the wettability, microstructure and phase change of Sn-9Zn solder. The microstructure and phase analysis of the material plays a very important role as it determines the physical and mechanical behavior of materials. Both Sn-9Zn and Ni-coated PCC/Sn-9Zn produced almost similar microstructure, which contain needle-like, dark phase Zn-rich phase and distributed evenly in beta-Sn rich matrix. However, compared to pure Sn-9Zn, the addition of Ni-coated PCC produce finer size of Zn rich phase needle-like structure. The presence of new phases of nickel tin and calcium carbonate compounds was also found with the addition of Ni-coated PCC. This believed to help in refining the size of Zn-rich needle structure, while retaining the original phases of Sn and Zn of the Sn-9Zn solder, Furthermore, Ni-coated PCC/Sn-9Zn have a smaller contact angle compared to pure Sn-9Zn. This can be explained that, Ni-coated PCC reinforced particle was the interfacial active element and decrease the interfacial energy between the solid and liquid. The microstructure and phase analysis of the material plays a very important role as it determines the wettability behavior of the material

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Liu, Yeh-Hsiu, and Kwang-Lung Lin. "Damages and Microstructural Variation of High-lead and Eutectic SnPb Composite Flip Chip Solder Bumps Induced by Electromigration." Journal of Materials Research 20, no. 8 (August 1, 2005): 2184–93. http://dx.doi.org/10.1557/jmr.2005.0271.

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The electromigration behavior of the high-lead and eutectic SnPb composite solder bumps was investigated at 150 °C with 5 × 103 A/cm2 current stressing for up to 1711 h. The diameter of the bumps was about 125 μm. The underbump metallization (UBM) on the chip side was sputtered Al/Ni(V)/Cu thin films, and the Cu pad on the board side was plated with electroless Ni/Au. It was observed that damages occurred in the joints in a downward electron flow (from chip side to the substrate side), while those joints having the opposite current polarity showed only minor changes. In the case of downward electron flow, electromigration damages were observed in the UBM and solder bumps. The vanadium in Ni(V) layer was broken under current stressing of 1711 h while it was still intact after current stressing of 1000 h. The electron probe microanalyzer (EPMA) elemental mapping clearly shows that the Al atoms in the trace migrated through the UBM into the solder bump during current stressing. Voids were found in the solder bump near the UBM/solder interface. The Sn-rich phases of the solder bumps showed gradual streaking and reorientation upon current stressing. This resulted in the formation of uniaxial Sn-rich phases in the middle of the solder bump, while the columnar and fibrous Sn-rich phases were formed in the surrounding regions. The formation mechanism of electromigration-induced damage to the UBM structure and solder bump were discussed.

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Chantaramanee, Suchart, Phairote Sungkhaphaitoon, and Thawatchai Plookphol. "Influence of Indium and Antimony Additions on Mechanical Properties and Microstructure of Sn-3.0Ag-0.5Cu Lead Free Solder Alloys." Solid State Phenomena 266 (October 2017): 196–200. http://dx.doi.org/10.4028/www.scientific.net/ssp.266.196.

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Abstract:

In this research, we investigated the influence of indium and antimony additions on the microstructure, mechanical and thermal properties of Sn-3.0Ag-0.5Cu lead free solder alloys. The results revealed that the addition of 0.5 wt.%InSb into SAC305 solder alloys resulted to a reduced melting temperature by 3.8 °C and IMCs phases formed new Ag3(Sn,In) and SnSb in the Sn-rich matrix with a decreased grain size of 28%. These phases improved the mechanical properties of solder alloys. In addition, the mechanical properties of SAC305 solder alloys increased by adding 0.5 wt.%InSb, resulting in an increase of ultimate tensile strength of 24%, but the percent elongation decreased to 45.8%. Furthermore, the Vickers microhardness slightly increased of the SAC305 solder alloys.

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Journal articles on the topic 'Sn rich solders'

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