鎵具備極低的熔點（29.76 °C），在接近室溫下即可由固態轉為液態，故可作為低溫接合材料使用，有效避免傳統高溫焊接過程對元件所造成的損傷。此外，液態鎵有優異的潤濕性，能與多種金屬及半導體材料形成穩定的潤濕層。憑藉其低熔點、高潤濕性、良好導電性，已成為近年來電子封裝與先進接合技術中備受關注的材料之一。本實驗室就曾研究以聲化學合成法製備次微米鎵基漿料用於接合銅金屬[1] [2]，但此方法會在次微米鎵粒子外層生成Ga2O3、Ga2O的氧化殼層，會影響接合強度同時漿料亦難以控制均勻厚度[3]。因此本實驗使用電鍍鎵製備接合層取代鎵基漿料，基材則選用半導體常見的銅。在銅與電鍍鎵間會先電鍍上一層厚度為50 nm的鎳，最後則在電鍍鎳層上透過控制電解液溫度、酸鹼值、金屬鹽濃度、電流密度等參數來形成電鍍鎵薄膜，藉由薄膜厚度輪廓測量儀、白光干涉儀確認表面粗糙度及厚度，掃描式電子顯微鏡分析電鍍薄膜的表面元素，穿透式電子顯微鏡及X光繞射儀進行相鑑定，X射線光電子能譜分析薄膜的氧含量，觀察不同參數下的電流效率與薄膜間的關係。實驗結果發現，薄膜的粗糙度和均勻性皆會因參數改變影響鎵離子在電解液中的流動性及析氫反應而發生變化，這兩者的發生跟電流效率有著密切關聯。

Gallium (Ga) possesses a low melting point (29.76 °C), excellent wettability, and high electrical conductivity, which makes it a promising material in the field of electronic packaging and advanced joining technologies. In previous work, our laboratory synthesized submicron Ga-based pastes via a sonochemical method for bonding copper substrates. However, this approach led to the formation of oxide shells (Ga₂O₃ and Ga₂O) on the surface of the Ga particles, affecting the bonding strength and making it difficult to control the paste thickness uniformly. To address these challenges, this study use electrodeposition to fabricate Ga bonding layers, replacing the conventional Ga-based pastes. Copper, a widely used substrate in semiconductor manufacturing, was selected as the base material. A 50 nm-thick nickel interlayer was first deposited onto the Cu surface to enhance interfacial compatibility. Ga films were then electrodeposited onto the Ni layer by controlling electrolyte temperature, pH, metal salt concentration, and current density. The deposited Ga films were characterized using a surface profilometer and white light interferometry (WLI) to assess thickness and surface roughness. Scanning electron microscopy (SEM)for surface morphology and elemental analysis, while transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used for phase identification. X-ray photoelectron spectroscopy (XPS) was utilized to evaluate the oxygen content of the films. In addition, this study systematically investigates the relationship between current efficiency under varying deposition parameters and the corresponding surface roughness and uniformity of the Ga films. Experimental results indicate that both the roughness and uniformity of the electrodeposited films are strongly influenced by process conditions.

1.葉哲瑜, 聲化學合成鎵基次微米粒子及其在銅對銅接合之應用. 2017.
2.廖聖民, 聲化學合成次微米鎵粒子基漿料及其在電子連結之應用. 2018.
3.陳燦文, 殼核鎵粒子漿料之轉移與開殼製程優化. 2019.
4.Hui, X., et al., A novel multiple DBC-staked units package to parallel more chips for SiC power module. CES Transactions on Electrical Machines and Systems, 2024. 8(1): p. 72-79.
5.Ji, S., Z. Zhang, and F. Wang, Overview of high voltage SiC power semiconductor devices: Development and application. CES Transactions on Electrical Machines and Systems, 2017. 1(3): p. 254-264.
6.陳引幹, 郭昌恕, and 許聯崇, 車用電子用高功率晶片之國產固晶材料開發. 2022.
7.Patelka, M., et al., Development of High Thermally Conductive Die Attach for TIM Applications. Journal of Microelectronics and Electronic Packaging, 2020. 17(3): p. 106-109.
8.Aksu, S., J. Wang, and B.M. Basol, Efficient gallium thin film electroplating methods and chemistries. 2009, Google Patents.
9.Yan, H., et al., Brief review of silver sinter-bonding processing for packaging high-temperature power devices. Chinese Journal of Electrical Engineering, 2020. 6(3): p. 25-34.
10.Tang, G., et al. Development of high power and high junction temperature SiC based power packages. in 2019 IEEE 69th Electronic Components and Technology Conference (ECTC). 2019. IEEE.
11.Dinkel, M., et al., Proceedings of the International Symposium on Superalloys. Materials Science and Engineering, 2008. 211: p. 23-35.
12.Gale, W. and D. Butts, Transient liquid phase bonding. Science and technology of welding and joining, 2004. 9(4): p. 283-300.
13.Cook III, G.O. and C.D. Sorensen, Overview of transient liquid phase and partial transient liquid phase bonding. Journal of materials science, 2011. 46(16): p. 5305-5323.
14.Pace, M., Au-Sn electrodeposition for MEMS oriented wafer eutectic bonding. 2016.
15.Hong, S., et al., Under bump metallization development for eutectic Pb-Sn solders. MRS Online Proceedings Library (OPL), 1998. 515: p. 73.
16.Chidambaram, V., H.B. Yeung, and G. Shan, Reliability of Au-Ge and Au-Si eutectic solder alloys for high-temperature electronics. Journal of electronic materials, 2012. 41(8): p. 2107-2117.
17.Bae, H.C., et al., Fine‐Pitch Solder on Pad Process for Microbump Interconnection. ETRI Journal, 2013. 35(6): p. 1152-1155.
18.Lin, S.-k., C.-l. Cho, and H.-m. Chang, Interfacial Reactions in Cu/Ga and Cu/Ga/Cu Couples. Journal of electronic materials, 2014. 43(1): p. 204-211.
19.Lin, S.-k., et al., High-strength and thermal stable Cu-to-Cu joint fabricated with transient molten Ga and Ni under-bump-metallurgy. Journal of Alloys and Compounds, 2017. 702: p. 561-567.
20.Chang, C.-C.B. and C. Kao, Phase Equilibria Related to NiGa5 in the Binary Ni-Ga System. Materials, 2024. 17(4): p. 883.
21.Schmetterer, C., et al., The system Ga–Ni: A new investigation of the Ga-rich part. Intermetallics, 2010. 18(2): p. 277-285.
22.Lin, S.-k., C.-y. Yeh, and M.-j. Wang, On the formation mechanism of solid-solution Cu-to-Cu joints in the Cu/Ni/Ga/Ni/Cu system. Materials Characterization, 2018. 137: p. 14-23.
23.Yamaguchi, A., Y. Mashima, and T. Iyoda, Reversible size control of liquid‐metal nanoparticles under ultrasonication. Angewandte Chemie International Edition, 2015. 54(43): p. 12809-12813.
24.Wilcox, G. and D. Gabe, Faraday's laws of electrolysis. Transactions of the IMF, 1992. 70(2): p. 93-94.
25.Romankiw, L.T. and E.J. O’Sullivan, Plating techniques. Handbook of Microlithography, Micromachining, and Microfabrication, 1997. 2: p. 197-298.
26.Pinner, W., G. Soderberg, and E. Baker, Nickel Plating. Transactions of The Electrochemical Society, 1941. 80(1): p. 539.
27.Sadiku-Agboola, O., E.R. Sadiku, and O.F. Biotidara, The properties and the effect of operating parameters on nickel plating. Int. J. Phys. Sci, 2012. 7(3): p. 349-360.
28.Chang, L., C.-H. Chen, and H. Fang, Electrodeposition of Ni–P Alloys From a Sulfamate Electrolyte: Relationship Between Bath PH and Structural Characteristics. Journal of The Electrochemical Society, 2007. 155(1): p. D57.
29.Tambe, C.E., Electrochemical deposition and dissolution of nickel from electroforming solutions. 2023.
30.Fogg, H., A review of the electrochemistry of gallium. Transactions of The Electrochemical Society, 1934. 66(1): p. 107.
31.Liu, Z., et al., Electrochemical behavior of gallium electrodeposition and inhibition of hydrogen evolution reaction in alkaline electrolyte. Journal of Applied Electrochemistry, 2023. 53(4): p. 847-860.
32.Sharma, A., et al., A study on the effect of pulse electrodeposition parameters on the morphology of pure tin coatings. Metallurgical and Materials Transactions A, 2014. 45(10): p. 4610-4622.
33.Cai, Z., et al., Electrochemical behavior of silicon in the (NaCl-KCl-NaF-SiO2) molten salt. Metallurgical and Materials Transactions B, 2010. 41(5): p. 1033-1037.
34.Sharma, A., Y. Jang, and J. Jung, Effect of current density on morphology of electroplated tin. Surface Engineering, 2015. 31(6): p. 458-464.
35.Mandich, N. and A. Fellow, pH, Hydrogen evolution & their significance in electroplating operations. Plating and surface finishing, 2002. 89(1): p. 54-58.
36.Zhong, S., et al., Sodium citrate enhancing electrodeposition of metallic arsenic from toxic trivalent arsenic and the mechanism understanding. Journal of Environmental Sciences, 2025. 151: p. 79-87.
37.Herbadji, A., et al., The concentration effect of complexing agent on the morphology and optoelectronic properties of electrochemically deposited n-type Cu2O thin films. Journal of Electronic Materials, 2019. 48(8): p. 4830-4839.