{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,25]],"date-time":"2026-03-25T01:22:33Z","timestamp":1774401753841,"version":"3.50.1"},"reference-count":31,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2023,12,15]],"date-time":"2023-12-15T00:00:00Z","timestamp":1702598400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"STI 2030-Major Projects","award":["2022ZD0209200"],"award-info":[{"award-number":["2022ZD0209200"]}]},{"name":"STI 2030-Major Projects","award":["NKLJC-K2023-12"],"award-info":[{"award-number":["NKLJC-K2023-12"]}]},{"name":"STI 2030-Major Projects","award":["62074132"],"award-info":[{"award-number":["62074132"]}]},{"name":"project of MOE Innovation Platform","award":["2022ZD0209200"],"award-info":[{"award-number":["2022ZD0209200"]}]},{"name":"project of MOE Innovation Platform","award":["NKLJC-K2023-12"],"award-info":[{"award-number":["NKLJC-K2023-12"]}]},{"name":"project of MOE Innovation Platform","award":["62074132"],"award-info":[{"award-number":["62074132"]}]},{"name":"Open Research Fund of China National Key Laboratory of Materials for Integrated Circuits","award":["2022ZD0209200"],"award-info":[{"award-number":["2022ZD0209200"]}]},{"name":"Open Research Fund of China National Key Laboratory of Materials for Integrated Circuits","award":["NKLJC-K2023-12"],"award-info":[{"award-number":["NKLJC-K2023-12"]}]},{"name":"Open Research Fund of China National Key Laboratory of Materials for Integrated Circuits","award":["62074132"],"award-info":[{"award-number":["62074132"]}]},{"name":"National Natural Science Foundation of China","award":["2022ZD0209200"],"award-info":[{"award-number":["2022ZD0209200"]}]},{"name":"National Natural Science Foundation of China","award":["NKLJC-K2023-12"],"award-info":[{"award-number":["NKLJC-K2023-12"]}]},{"name":"National Natural Science Foundation of China","award":["62074132"],"award-info":[{"award-number":["62074132"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Flip chip bonding technology on gold\u2013tin (Au-Sn) microbumps for MEMS (Micro Electro Mechanical Systems) and 3D packaging is becoming increasingly important in the electronics industry. The main advantages of Au-Sn microbumps are a low electrical resistance, high electrical reliability, and fine pitch. However, the bonding temperature is relatively high, and the forming mechanism of an intermetallic compound (IMC) is complicated. In this study, Au-Sn solid-state diffusion (SSD) bonding is performed using the thermal gradient bonding (TGB) method, which lowers bonding temperature and gains high bonding strength in a short time. Firstly, Au-Sn microbumps with a low roughness are prepared by using an optimized process. Then, Au-Sn bonding parameters including bonding temperature, bonding time, and bonding pressure are optimized to obtain a higher bonding quality. The shear strength of 23.898 MPa is obtained when bonding in the HCOOH environment for 10 min at the gradient temperature of 150 \u00b0C\/250 \u00b0C with a bonding pressure of more than 10 MPa. The IMC of Au-Sn is found to be Au-Sn and Au5Sn. The effect of annealing time on the IMC is also investigated. More and more Au5Sn is generated with an increase in annealing time, and Au5Sn is formed after Sn is depleted. Finally, the effect of annealing time on the IMC is verified by using finite element simulation, and the bonding strength of IMC was found to be higher when the bonding temperature is 150 \u00b0C at the cold side and 250 \u00b0C at the hot side. The temperature in the bonding area can reach 200 \u00b0C, which proves that the Au-Sn bonding process is solid-state diffusion because the temperature gradient reaches 2500 \u00b0C\/cm.<\/jats:p>","DOI":"10.3390\/mi14122242","type":"journal-article","created":{"date-parts":[[2023,12,15]],"date-time":"2023-12-15T03:16:33Z","timestamp":1702610193000},"page":"2242","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["A Method for Fast Au-Sn Bonding at Low Temperature Using Thermal Gradient"],"prefix":"10.3390","volume":"14","author":[{"given":"Wenchao","family":"Wang","sequence":"first","affiliation":[{"name":"State Key Laboratory of Integrated Chips and Systems, School of Microelectronics, Fudan University, Shanghai 200433, China"},{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ziyu","family":"Liu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Integrated Chips and Systems, School of Microelectronics, Fudan University, Shanghai 200433, China"},{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Delong","family":"Qiu","sequence":"additional","affiliation":[{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhiyuan","family":"Zhu","sequence":"additional","affiliation":[{"name":"School of Electronic Information Engineering, Southwest University, Chongqing 404100, China"},{"name":"National Key Laboratory of Materials for Integrated Circuits, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai 200050, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Na","family":"Yan","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Integrated Chips and Systems, School of Microelectronics, Fudan University, Shanghai 200433, China"},{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shijin","family":"Ding","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Integrated Chips and Systems, School of Microelectronics, Fudan University, Shanghai 200433, China"},{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David Wei","family":"Zhang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Integrated Chips and Systems, School of Microelectronics, Fudan University, Shanghai 200433, China"},{"name":"Jiashan Fudan Institute, Jiaxing 314100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,12,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1182","DOI":"10.1016\/j.microrel.2011.12.020","article-title":"Studies on various chip-on-film (COF) packages using ultra fine pitch two-metal layer flexible printed circuits (two-metal layer FPCs)","volume":"52","author":"Suk","year":"2012","journal-title":"Microelectron. 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