Interfacial Structure and Hermeticity of Kovar Alloy-Glass Seals via Pre-Oxidation Temperature Control

doi:10.16552/j.cnki.issn1001-1625.2025.0694

Abstract

Abstract:

This study systematically investigated the influence mechanism of pre-oxidation temperature on the interfacial microstructure and mechanical properties of 4J29 Kovar alloy-borosilicate glass seals. 4J29 Kovar alloy samples were pre-oxidized at 550， 700， 850， and 1 000 ℃ in a wet nitrogen atmosphere using a continuous mesh belt oxidation furnace. The research investigated the formation mechanism of the oxide film on the surface of 4J29 Kovar alloy at different pre-oxidation temperatures， the evolution of phase composition， and the impact on the bending resistance and sealing heameticity of electronic component sealing base pins. The results show that the pre-oxidation temperature is a key factor in regulating the interface bonding mechanism： at the lower temperature range of 550~700 ℃， fewer oxides are formed， which are mainly distributed at grain boundaries， with the primary component being Fe₃O₄. In contrast， at higher temperatures of 850 and 1 000 ℃， a dense oxide film forms on the alloy surface， primarily composed of FeO and Fe₃O₄ phases， promoting the formation of a chemical bonding structure with a distinct iron diffusion zone at the sealing interface. Mechanical performance tests testing indicates that samples pre-oxidized at 850 ℃ retain good hermeticity after enduring 10 N bending force for 3 cycles， demonstrating excellent interface bonding strength. However， high-temperature treatment at 1 000 ℃ causes the formation of numerous bubbles at the sealing interface， along with glass climbing phenomenon， which compromises interface integrity and long-term reliability.

Key words: Kovar alloy, pre-oxidation temperature, glass-to-metal sealing, interface microstructure, hermeticity

CLC Number:

TQ171

NIE Zhijian, WANG Qiang, YANG Xiufu, MA Xing, SHI Lei, LI Shixin. Interfacial Structure and Hermeticity of Kovar Alloy-Glass Seals via Pre-Oxidation Temperature Control[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(1): 299-308.

Figures/Tables 9

Fig.1 Schematic diagram of base part of relay

Fig.2 SEM images and O element distribution of oxide layer on 4J29 alloy surface at different pre-oxidation temperatures

Fig.3 Unit weight gain of 4J29 alloy at different

Fig.4 XRD patterns of 4J29 alloy at different pre-oxidation temperatures pre-oxidation temperatures

Fig.5 Metallographic interface of 4J29 alloy sealed with glass at different pre-oxidation temperatures

Fig.6 Linear scanning of interface elements in 4J29 alloy sealed with glass at different pre-oxidation temperatures

Fig.7 Appearance and morphology of 4J29 alloy sealed with glass at different pre-oxidation temperatures

Fig.8 Leakage rate of 4J29 alloy sealed with glass at different pre-oxidation temperatures

Fig.9 Schematic diagram of glass-to-metal sealing interface

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