What is Hermetic Sealing: Benefits, Types, Applications, and Common Methods

What is Hermetic sealing?

Hermetic sealing refers to the process of creating a completely airtight and gas-tight seal between 2 or more components. This prevents the ingress of gases, moisture or other contaminants.  This type of seal is often used in a wide variety applications.

Hermetic seals are achieved using specific materials and methods that ensure the seal remains impermeable to the elements under a variety of conditions. This is often critical in industries where environmental exposure could degrade performance, such as aerospace, electronics, medical devices, and automotive applications.

Benefits of Hermetic Sealing

Hermetic sealing provides a reliable and effective way to protect and preserve products, enhance performance, ensure safety, and comply with industry standards:

Protection: Protects sensitive devices from environmental hazards like moisture, dust, gases, and pressure changes. This helps minimize the need for repairs and replacements due to component failures or contamination.
Longevity: Increases the lifespan of devices, due to the protection benefits listed above.

Safety: Prevents the leakage of dangerous materials, such as toxic chemicals or high-pressure gases. May help with adherence to regulatory standards and industry best practices, ensuring product safety and quality.

Common Applications of Hermetic Sealing

• Electronics: To protect sensitive components from moisture, dust, and other contaminants that can cause malfunctions.
  
• Medical devices: To ensure sterility and prevent contamination of medical equipment and pharmaceuticals.
  
• Food packaging: To maintain freshness, prevent spoilage, and extend shelf life.
  
• Automotive components: To protect electrical systems and other sensitive parts from environmental factors.
  
• Aerospace: To maintain the integrity of sealed systems and prevent leaks that could compromise performance or safety.

Types of Hermetic Seals and Materials Used

The effectiveness of hermetic seals depends heavily on both the type of seal and the materials involved. Below are common types of hermetic seals along with the materials typically used in their construction:

• Glass-to-Metal Seals: This type relies on thermal expansion compatibility between glass and metal. Common materials include borosilicate or aluminosilicate glass and metals like Kovar, nickel, or stainless steel, often used in electronics and aerospace.
• Ceramic-to-Metal Seals: These seals use ceramics like alumina bonded to metals (e.g., titanium or Kovar) and are known for high strength and thermal stability, often used in high-pressure or high-temperature environments.
• Epoxy Resin Seals: A more economical option, these seals use synthetic epoxy resins to bond materials like metals, plastics, or glass. They are suitable for low-pressure applications and are common in sensors and connectors.
• Glass-to-Glass Seals: In this type, two pieces of glass are fused together, typically using heat. Materials include various types of technical glass, offering excellent insulation and chemical resistance, ideal for vacuum systems or laboratory equipment.
• Metal-to-Metal Seals: These seals rely on precision machining and compression between two metal surfaces, often using materials like copper, aluminum, or stainless steel. They are widely used in ultra-high vacuum systems and cryogenics.
• Elastomeric Seals (with Metal Enclosure): While not truly hermetic on their own, elastomeric seals can be housed in metal to improve hermeticity. Materials include silicone or fluorocarbon elastomers combined with metal cases, useful in applications requiring flexibility and moderate sealing performance.

FAQs About Hermetic Sealing

What materials are used in hermetic sealing? Hermetic seals often use a combination of metals (such as stainless steel, Kovar, and copper), technical glasses (like borosilicate), ceramics (e.g., alumina), and epoxy-based compounds. Resin Formulators provides advanced epoxy formulations tailored for high-performance sealing in demanding environments.

How long do hermetic seals last? The lifespan of a hermetic seal depends on factors like material selection, application environment, and stress exposure. In aerospace or electronics, properly applied hermetic epoxy compounds can maintain performance for decades under stable conditions.