Geopolymer adhesives for DUV LED packaging: Synthesis and bonding mechanism

Qinglei Sun; Can Cui; Jianing Li; Fuchu Liu; Boyuan Chen; Yingxia Liu; King-Ning Tu; Hongyong Jiang

doi:10.1016/j.jallcom.2025.181903

Geopolymer adhesives for DUV LED packaging: Synthesis and bonding mechanism

Qinglei Sun, Can Cui, Jianing Li, Fuchu Liu, Boyuan Chen, Yingxia Liu, King-Ning Tu, Hongyong Jiang^*

^*Corresponding author for this work

Department of Systems Engineering

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

Abstract

In the post-pandemic era, awareness of disinfection and sterilization had heightened, driving an increased demand for ultraviolet (DUV) light-emitting diodes (LEDs). Geopolymers effectively addressed the reliability issues of existing organic materials under DUV radiation. This study focused on investigating the bonding mechanism of geopolymer adhesive with DUV LEDs packaging alumina substrate. The bonding strengths of geopolymers with varying Si/Al and Na/Al molar ratios to alumina were tested through orthogonal experiments, identifying a sample with a maximum strength of 47.0 ± 9.0 MPa. Fourier transform infrared spectroscopy bands at 1026 and 869 cm⁻¹ confirm geopolymerization in this highest-strength sample, which has a Si/Al molar ratio of 2.2 and a Na/Al molar ratio of 1. Scanning electron microscopy and nuclear magnetic resonance analyses show that this sample possesses a denser microstructure and the highest Q⁴(3Al) peak area fraction, indicating a more homogeneous geopolymerization reaction compared to other samples. Transmission electron microscopy clarified the bonding mechanism between the geopolymer and alumina. Fast Fourier transform showed the overlap of alumina's hexagonal crystal structure with the amorphous geopolymer gel. Energy-dispersive X-ray spectroscopy revealed significant overlaps of Al and Si elements at the bonding interface. Together, these techniques provided strong evidence of chemical bonding at the interface. This study enriches the theory of heterogeneous material interconnections in fully inorganic DUV LED packaging, with the potential to further enhance packaging reliability.

Original language	English
Article number	181903
Journal	Journal of Alloys and Compounds
Volume	1036
Online published	30 Jun 2025
DOIs	https://doi.org/10.1016/j.jallcom.2025.181903
Publication status	Published - Jul 2025

Funding

The authors would like to thank the support from National Natural Science Foundation of China (52302032), Guangzhou Nansha District Science and Technology Project (2024ZD010), Natural Science Foundation Grant of Hubei Province (2023AFB007), Guangdong Basic and Applied Basic Research Foundation (2022A1515110323, 2024A1515013258), and China Postdoctoral Science Foundation (2022M722936).

Research Keywords

Geopolymer
Bonding mechanism
Alumina ceramic
DUV LED
Electronic packaging

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title = "Geopolymer adhesives for DUV LED packaging: Synthesis and bonding mechanism",

abstract = "In the post-pandemic era, awareness of disinfection and sterilization had heightened, driving an increased demand for ultraviolet (DUV) light-emitting diodes (LEDs). Geopolymers effectively addressed the reliability issues of existing organic materials under DUV radiation. This study focused on investigating the bonding mechanism of geopolymer adhesive with DUV LEDs packaging alumina substrate. The bonding strengths of geopolymers with varying Si/Al and Na/Al molar ratios to alumina were tested through orthogonal experiments, identifying a sample with a maximum strength of 47.0 ± 9.0 MPa. Fourier transform infrared spectroscopy bands at 1026 and 869 cm−1 confirm geopolymerization in this highest-strength sample, which has a Si/Al molar ratio of 2.2 and a Na/Al molar ratio of 1. Scanning electron microscopy and nuclear magnetic resonance analyses show that this sample possesses a denser microstructure and the highest Q4(3Al) peak area fraction, indicating a more homogeneous geopolymerization reaction compared to other samples. Transmission electron microscopy clarified the bonding mechanism between the geopolymer and alumina. Fast Fourier transform showed the overlap of alumina's hexagonal crystal structure with the amorphous geopolymer gel. Energy-dispersive X-ray spectroscopy revealed significant overlaps of Al and Si elements at the bonding interface. Together, these techniques provided strong evidence of chemical bonding at the interface. This study enriches the theory of heterogeneous material interconnections in fully inorganic DUV LED packaging, with the potential to further enhance packaging reliability.{\textcopyright} 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies. ",

keywords = "Geopolymer, Bonding mechanism, Alumina ceramic, DUV LED, Electronic packaging",

author = "Qinglei Sun and Can Cui and Jianing Li and Fuchu Liu and Boyuan Chen and Yingxia Liu and King-Ning Tu and Hongyong Jiang",

year = "2025",

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doi = "10.1016/j.jallcom.2025.181903",

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TY - JOUR

T1 - Geopolymer adhesives for DUV LED packaging

T2 - Synthesis and bonding mechanism

AU - Sun, Qinglei

AU - Cui, Can

AU - Li, Jianing

AU - Liu, Fuchu

AU - Chen, Boyuan

AU - Liu, Yingxia

AU - Tu, King-Ning

AU - Jiang, Hongyong

PY - 2025/7

Y1 - 2025/7

N2 - In the post-pandemic era, awareness of disinfection and sterilization had heightened, driving an increased demand for ultraviolet (DUV) light-emitting diodes (LEDs). Geopolymers effectively addressed the reliability issues of existing organic materials under DUV radiation. This study focused on investigating the bonding mechanism of geopolymer adhesive with DUV LEDs packaging alumina substrate. The bonding strengths of geopolymers with varying Si/Al and Na/Al molar ratios to alumina were tested through orthogonal experiments, identifying a sample with a maximum strength of 47.0 ± 9.0 MPa. Fourier transform infrared spectroscopy bands at 1026 and 869 cm−1 confirm geopolymerization in this highest-strength sample, which has a Si/Al molar ratio of 2.2 and a Na/Al molar ratio of 1. Scanning electron microscopy and nuclear magnetic resonance analyses show that this sample possesses a denser microstructure and the highest Q4(3Al) peak area fraction, indicating a more homogeneous geopolymerization reaction compared to other samples. Transmission electron microscopy clarified the bonding mechanism between the geopolymer and alumina. Fast Fourier transform showed the overlap of alumina's hexagonal crystal structure with the amorphous geopolymer gel. Energy-dispersive X-ray spectroscopy revealed significant overlaps of Al and Si elements at the bonding interface. Together, these techniques provided strong evidence of chemical bonding at the interface. This study enriches the theory of heterogeneous material interconnections in fully inorganic DUV LED packaging, with the potential to further enhance packaging reliability.© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

AB - In the post-pandemic era, awareness of disinfection and sterilization had heightened, driving an increased demand for ultraviolet (DUV) light-emitting diodes (LEDs). Geopolymers effectively addressed the reliability issues of existing organic materials under DUV radiation. This study focused on investigating the bonding mechanism of geopolymer adhesive with DUV LEDs packaging alumina substrate. The bonding strengths of geopolymers with varying Si/Al and Na/Al molar ratios to alumina were tested through orthogonal experiments, identifying a sample with a maximum strength of 47.0 ± 9.0 MPa. Fourier transform infrared spectroscopy bands at 1026 and 869 cm−1 confirm geopolymerization in this highest-strength sample, which has a Si/Al molar ratio of 2.2 and a Na/Al molar ratio of 1. Scanning electron microscopy and nuclear magnetic resonance analyses show that this sample possesses a denser microstructure and the highest Q4(3Al) peak area fraction, indicating a more homogeneous geopolymerization reaction compared to other samples. Transmission electron microscopy clarified the bonding mechanism between the geopolymer and alumina. Fast Fourier transform showed the overlap of alumina's hexagonal crystal structure with the amorphous geopolymer gel. Energy-dispersive X-ray spectroscopy revealed significant overlaps of Al and Si elements at the bonding interface. Together, these techniques provided strong evidence of chemical bonding at the interface. This study enriches the theory of heterogeneous material interconnections in fully inorganic DUV LED packaging, with the potential to further enhance packaging reliability.© 2025 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

KW - Geopolymer

KW - Bonding mechanism

KW - Alumina ceramic

KW - DUV LED

KW - Electronic packaging

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DO - 10.1016/j.jallcom.2025.181903

M3 - RGC 21 - Publication in refereed journal

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SN - 0925-8388

VL - 1036

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

M1 - 181903

ER -

Geopolymer adhesives for DUV LED packaging: Synthesis and bonding mechanism

Abstract

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