{"title":"用SnO2纳米粒子增强的低熔点导热Sn-Bi-Ag焊料，用于可靠的微型led微系统","authors":"Jiwan Kang, Ashutosh Sharma, Jae Pil Jung","doi":"10.1007/s10854-025-14658-6","DOIUrl":null,"url":null,"abstract":"<div><p>In this work, low-temperature Sn-57.6wt%Bi-0.4wt%Ag (Sn-Bi-Ag) solder alloy was enhanced with SnO<sub>2</sub> nanoparticles (NPs, 0 to 0.7wt%) using low energy milling and melting process. The developed solders were reflowed to join Cu/Ni pad of 1608 mini-light emitting diode (LED) chips at 238 °C. The morphology, melting temperature, thermal conductivity, and electrical properties of the developed alloys were evaluated. The findings revealed a depression in melting point of Sn-Bi-Ag/SnO<sub>2</sub> solder by 1.1 °C compared to the pristine Sn-Bi-Ag alloy. Microstructural analysis indicated a refinement in the β-Sn and Bi-rich phase in Sn-Bi-Ag alloy after the addition of SnO<sub>2</sub> NPs (≈0.5wt%), accompanied by a decrease in β-Sn area fraction (0.49) with a mild increase in Bi-rich area (0.46). Additionally, the thermal diffusivity and conductivity were significantly enhanced, with the values of 13.2 mm<sup>2</sup>/s and 14.2 J/K/g all of which outperformed the Sn -Bi -Ag alloy. The electrical resistivity of the developed samples was in the range of 5.0 × 10<sup>–7</sup> to 3 × 10<sup>–7</sup> Ω.cm. To further assess solder joint reliability, the SnO<sub>2</sub> NPs-modified solder was applied to a 1608 mini-LED chip and bonded onto the Cu/Ni pad of a fiber glass reinforced printed circuit board (FR4-PCB). The solder joint characteristics was evaluated by shear strength tests by examining the post fractured joint morphology of the specimens. The shear tests showed an increasing trend with the fraction of SnO<sub>2</sub> NPs in the Sn-Bi-Ag matrix. The shear strength was improved by ≈10–11%, respectively, over Sn-Bi-Ag alloy. The fracture morphology revealed a mixed ductile and brittle fracture at 0.5wt.%SnO<sub>2</sub> NPs in the matrix while brittle fracture dominates at a higher fraction of SnO<sub>2</sub> NPs (0.7wt.%) is added to the matrix alloy. It is inferred from this investigation that an optimum amount of 0.5wt.% is desired for realizing high thermal conductivity, low-melting, and reliable solder joints in future microelectronics mini-LED packaging.</p></div>","PeriodicalId":646,"journal":{"name":"Journal of Materials Science: Materials in Electronics","volume":"36 12","pages":""},"PeriodicalIF":2.8000,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Low-melting and thermal-conducting Sn-Bi-Ag solder enhanced with SnO2 nanoparticles for reliable mini-LED microsystems\",\"authors\":\"Jiwan Kang, Ashutosh Sharma, Jae Pil Jung\",\"doi\":\"10.1007/s10854-025-14658-6\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>In this work, low-temperature Sn-57.6wt%Bi-0.4wt%Ag (Sn-Bi-Ag) solder alloy was enhanced with SnO<sub>2</sub> nanoparticles (NPs, 0 to 0.7wt%) using low energy milling and melting process. The developed solders were reflowed to join Cu/Ni pad of 1608 mini-light emitting diode (LED) chips at 238 °C. The morphology, melting temperature, thermal conductivity, and electrical properties of the developed alloys were evaluated. The findings revealed a depression in melting point of Sn-Bi-Ag/SnO<sub>2</sub> solder by 1.1 °C compared to the pristine Sn-Bi-Ag alloy. Microstructural analysis indicated a refinement in the β-Sn and Bi-rich phase in Sn-Bi-Ag alloy after the addition of SnO<sub>2</sub> NPs (≈0.5wt%), accompanied by a decrease in β-Sn area fraction (0.49) with a mild increase in Bi-rich area (0.46). Additionally, the thermal diffusivity and conductivity were significantly enhanced, with the values of 13.2 mm<sup>2</sup>/s and 14.2 J/K/g all of which outperformed the Sn -Bi -Ag alloy. The electrical resistivity of the developed samples was in the range of 5.0 × 10<sup>–7</sup> to 3 × 10<sup>–7</sup> Ω.cm. To further assess solder joint reliability, the SnO<sub>2</sub> NPs-modified solder was applied to a 1608 mini-LED chip and bonded onto the Cu/Ni pad of a fiber glass reinforced printed circuit board (FR4-PCB). The solder joint characteristics was evaluated by shear strength tests by examining the post fractured joint morphology of the specimens. The shear tests showed an increasing trend with the fraction of SnO<sub>2</sub> NPs in the Sn-Bi-Ag matrix. The shear strength was improved by ≈10–11%, respectively, over Sn-Bi-Ag alloy. The fracture morphology revealed a mixed ductile and brittle fracture at 0.5wt.%SnO<sub>2</sub> NPs in the matrix while brittle fracture dominates at a higher fraction of SnO<sub>2</sub> NPs (0.7wt.%) is added to the matrix alloy. It is inferred from this investigation that an optimum amount of 0.5wt.% is desired for realizing high thermal conductivity, low-melting, and reliable solder joints in future microelectronics mini-LED packaging.</p></div>\",\"PeriodicalId\":646,\"journal\":{\"name\":\"Journal of Materials Science: Materials in Electronics\",\"volume\":\"36 12\",\"pages\":\"\"},\"PeriodicalIF\":2.8000,\"publicationDate\":\"2025-04-21\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Materials Science: Materials in Electronics\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://link.springer.com/article/10.1007/s10854-025-14658-6\",\"RegionNum\":4,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ENGINEERING, ELECTRICAL & ELECTRONIC\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Materials Science: Materials in Electronics","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s10854-025-14658-6","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, ELECTRICAL & ELECTRONIC","Score":null,"Total":0}
Low-melting and thermal-conducting Sn-Bi-Ag solder enhanced with SnO2 nanoparticles for reliable mini-LED microsystems
In this work, low-temperature Sn-57.6wt%Bi-0.4wt%Ag (Sn-Bi-Ag) solder alloy was enhanced with SnO2 nanoparticles (NPs, 0 to 0.7wt%) using low energy milling and melting process. The developed solders were reflowed to join Cu/Ni pad of 1608 mini-light emitting diode (LED) chips at 238 °C. The morphology, melting temperature, thermal conductivity, and electrical properties of the developed alloys were evaluated. The findings revealed a depression in melting point of Sn-Bi-Ag/SnO2 solder by 1.1 °C compared to the pristine Sn-Bi-Ag alloy. Microstructural analysis indicated a refinement in the β-Sn and Bi-rich phase in Sn-Bi-Ag alloy after the addition of SnO2 NPs (≈0.5wt%), accompanied by a decrease in β-Sn area fraction (0.49) with a mild increase in Bi-rich area (0.46). Additionally, the thermal diffusivity and conductivity were significantly enhanced, with the values of 13.2 mm2/s and 14.2 J/K/g all of which outperformed the Sn -Bi -Ag alloy. The electrical resistivity of the developed samples was in the range of 5.0 × 10–7 to 3 × 10–7 Ω.cm. To further assess solder joint reliability, the SnO2 NPs-modified solder was applied to a 1608 mini-LED chip and bonded onto the Cu/Ni pad of a fiber glass reinforced printed circuit board (FR4-PCB). The solder joint characteristics was evaluated by shear strength tests by examining the post fractured joint morphology of the specimens. The shear tests showed an increasing trend with the fraction of SnO2 NPs in the Sn-Bi-Ag matrix. The shear strength was improved by ≈10–11%, respectively, over Sn-Bi-Ag alloy. The fracture morphology revealed a mixed ductile and brittle fracture at 0.5wt.%SnO2 NPs in the matrix while brittle fracture dominates at a higher fraction of SnO2 NPs (0.7wt.%) is added to the matrix alloy. It is inferred from this investigation that an optimum amount of 0.5wt.% is desired for realizing high thermal conductivity, low-melting, and reliable solder joints in future microelectronics mini-LED packaging.
期刊介绍：
The Journal of Materials Science: Materials in Electronics is an established refereed companion to the Journal of Materials Science. It publishes papers on materials and their applications in modern electronics, covering the ground between fundamental science, such as semiconductor physics, and work concerned specifically with applications. It explores the growth and preparation of new materials, as well as their processing, fabrication, bonding and encapsulation, together with the reliability, failure analysis, quality assurance and characterization related to the whole range of applications in electronics. The Journal presents papers in newly developing fields such as low dimensional structures and devices, optoelectronics including III-V compounds, glasses and linear/non-linear crystal materials and lasers, high Tc superconductors, conducting polymers, thick film materials and new contact technologies, as well as the established electronics device and circuit materials.
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