Key Technologies and Application Challenges in Glass to Metal Sealing
Release time:2025-06-26
This article focuses on the applications and challenges of materials such as iron-based sealing glass and kovar sealing glass in aerospace, energy, healthcare, and industrial fields.
1. Introduction to Glass-Metal Sealing
Glass-metal sealing is a complex engineering process that fuses glass and metal components to form a sealed and highly intact connection. Unlike adhesive or mechanical seals, this technology relies on thermal and chemical compatibility, making it essential for applications where failure could lead to catastrophic consequences—from space satellite malfunctions to electric vehicle battery explosions. The core of this process depends on:
• Thermal Expansion Matching: Ensuring glass and metal expand/contract at similar rates to avoid stress-induced cracking.
• Chemical Adhesion: Forming a robust interface through oxide layer interaction during sintering.
• Environmental Tolerance: Withstanding extreme temperatures, pressures, and corrosive media.
2. Sealing Technologies and Processes
2.1 Advanced Bonding Technologies
1. Component Preparation: Metals are cleaned and etched; glass powder is screened by particle size.
2. Glass Application: Powder is applied to the metal surface via screen printing or dispensing.
3. Sintering: Heating in a controlled atmosphere melts the glass to form a bond (temperatures range from 500~980°C depending on materials).
4. Cooling: Gradual cooling minimizes thermal stress; annealing enhances durability.
5. Testing: Helium leak detection and mechanical tests ensure airtightness and strength.
2.1.1 Key Process Parameters
• Atmosphere Control: Nitrogen-hydrogen mixtures prevent metal oxidation, while oxygen-rich environments promote glass-metal interface reactions.
• Heating Rate: Slow heating reduces thermal gradients in large components, minimizing micro-cracking.
• Post-Sintering Annealing
3. Key Applications of Glass-Metal Sealing
3.1 Aerospace and Defense: Sealing in Extreme Environments
3.1.1 Satellite and Space Components
In aerospace, glass-metal seals are used in satellite transponders, sensors, and power modules. For example, iron-sealing glass is ideal for aerospace applications due to its high-temperature resistance and excellent electrical insulation. It protects precision electronic circuits from space vacuum, extreme temperature fluctuations, and radiation, ensuring reliable operation of communication, navigation, and scientific research satellite systems.
3.1.2 Defense Electronics
Military equipment such as radar systems, missile guidance devices, and avionics rely on airtight seals to withstand harsh combat environments, including impact, vibration, and exposure to moisture and chemicals. Kovar sealing glass, with a thermal expansion coefficient matching kovar alloy, is commonly used in these applications to provide durable and reliable seals for critical components.
3.2 Energy and Power: Enabling Sustainable Technologies
3.2.1 Electric Vehicles (EVs) and Battery Systems
As the EV industry continues to grow, so does the demand for efficient and safe battery systems. Glass-metal seals are used in battery terminals and connectors to prevent electrolyte leakage and ensure electrical insulation. In lithium-ion batteries, these seals protect cells from external contamination, maintaining battery performance and lifespan. The use of low-melting-point sealing glass enables precise bonding in complex battery pack designs, facilitating miniaturization and optimization of EV battery systems.
3.2.2 Renewable Energy
In solar applications, glass-metal seals are used in photovoltaic modules and inverters to protect electrical connections from moisture and dust, ensuring long-term reliability in outdoor environments. Additionally, in fuel cell technology, these seals play a crucial role in maintaining the integrity of fuel cell stacks, preventing gas leakage, and enabling efficient energy conversion.
3.3 Medical Devices: Precision Sealing for Life Sciences
3.3.1 Implantable Devices
Medical implants such as pacemakers, defibrillators, and cochlear implants require airtight seals to protect internal electronics from the harsh biological environment of the human body. Glass-metal seals offer biocompatibility, chemical resistance, and long-term reliability, ensuring these life-saving devices operate safely and effectively. Notably, kovar sealing glass is highly regarded for its compatibility with human tissues and its ability to form a secure seal that persists throughout the implant's lifespan.
3.3.2 Diagnostic and Surgical Equipment
In diagnostic equipment like MRI machines and X-ray devices, glass-metal seals are used to isolate electronic components and maintain vacuum in pipes and sensors. Surgical instruments such as laparoscopic tools also benefit from these seals, which provide a barrier during sterilization processes, ensuring equipment remains functional and safe for repeated use.
3.4 Industrial and Manufacturing: Sealing at the Forefront of Harsh Industries
3.4.1 High-Temperature Environments
In industrial furnaces, boilers, and chemical reactors, glass-metal seals are used to connect sensors, thermocouples, and control systems. These seals must withstand extreme temperatures and resist chemical corrosion from corrosive gases and liquids. Iron-based sealing glass, with its high softening point and chemical stability, is the preferred choice for these demanding industrial applications, ensuring continuous monitoring and control of process parameters.
3.4.2 Vacuum Technology
Vacuum systems, such as those used in semiconductor manufacturing and scientific research, rely on airtight seals to maintain low-pressure environments. Glass-metal seals provide a reliable barrier against air leakage, enabling precise control of vacuum levels required for processes like thin-film deposition, electron microscopy, and mass spectrometry.
4. Technical Challenges
Thermal Cycling Fatigue: Repeated expansion/contraction in aerospace applications can lead to micro-cracking.
Solution: Using gradient-index glass-metal composites with customized thermal distribution.
5. Sinopride's Technological Leadership
As a global leader in sealing, Sinopride(www.spcera.net)'s strengths lie in:
5.1 Sinopride Glass-Metal Sealing Materials
For detailed material specifications, explore Sinopride's iron-sealing glass and kovar sealing glass solutions.
NO. | Model | Glass System | True Density (g/cm³) |
Sintering Temperature (Tm/°C) | TEC (10⁻⁷/°C, 30-300°C) |
Color | Application |
1 | ST015 | SiO₂-Na₂O-K₂O | 2.58 | 950~960 | 10.6±0.5 | Black | Refrigeration compressor terminal sealing, etc. |
2 | ST408 | SiO₂-Na₂O-K₂O | 2.695 | 920~930 | 10.5±0.5 | Black | Refrigeration compressor terminal sealing, etc. |
3 | SH604 | SiO₂-BaO-K₂O | 2.52 | 930~960 | 9.6±0.5 | Black/White/ Blue/Green |
Stainless steel/carbon steel compression seals, lithium-ion battery caps, TO sockets, etc. |
4 | SK016 | SiO₂-Na₂O-K₂O | 2.25 | 970~980 | 5.0±0.5 | Green/Blue/ White/Brown |
Kovar metal sealing: TO tube socket, crystal oscillator base, connector, etc. |
5 | LC-1 | Bi₂O₃-ZnO-B₂O₃ | 6.7 | 500~530 | 11±0.5 | Dark-green | Vacuum insulation cup, low-temperature sealing, slurry, etc. |
6 | SL-B52 | SiO₂-BaO | 3.19 | 850~860 | 8.8±0.5 | White | LTCC Firing Aid |
7 | SL-G01B | SiO₂-BaO-CaO | 3.03 | 850~860 | 10±0.5 | White | LTCC Firing Aid |
8 | FJ16D | SiO₂-Na₂O-K₂O | 2.55 | 850~900 | 10.5±0.5 | Black | Coating slurry |
5.2 R&D Capabilities
• Multiple Innovation R&D Production Centers: 2 major innovation R&D production centers in Shenzhen and Ganzhou.
• Advanced Testing Facilities: Capabilities include thermal shock testing, leak testing, and adhesion testing.
• 11 R&D Personnel: Including 2 PhDs and 2 Masters.
• 39+ Patent Certificates
6. Conclusion
Glass-metal sealing is a core driver of modern technological progress, widely enabling critical fields such as aerospace communication, electric vehicles, and medical implants, supporting high-reliability system operation with its precise airtight characteristics. As industries upgrade toward miniaturization and high-toughness, demand for this technology continues to rise. Industry pioneers like Sinopride, with their material science accumulation and innovative R&D, are tackling cutting-edge sealing challenges in quantum computing, biocompatibility, and more. The future of technology will focus on integrating scientific rigor with industrial practicality, while system integrity will always depend on the ultimate reliability of glass-metal bonding—highlighting its foundational role in technological innovation.
Contact
Reach out to Sinopride(www.spcera.net)'s technical team today to visit our testing laboratories. Together, we'll design the next generation of sealing solutions.
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