Why Is Hermetic Packaging Needed? — The Environmental Protection Foundation for Electronic Component Reliability

1. Why is Hermetic Packaging Needed?

In applications such as aerospace, deep-sea exploration, medical devices, and optical communications, electronic components face harsh environments with high humidity, salt spray, corrosive gases, and extreme temperature variations. Moisture, oxygen, hydrogen sulfide, salt spray, and other external substances constantly attempt to penetrate the package interior — each one potentially becoming the trigger for electronic component failure.

Therefore, the protection strategy for electronic components must cut off all external media penetration paths at the root, rather than merely providing localized protection. Our protection objective is clear: effectively isolate the internal chip from the external environment to achieve highly reliable hermetic sealing.

2. How “Sealed” is Sealed Enough?

In everyday usage, “sealed” simply means preventing visible dust or water droplets from entering. Hermetic sealing in electronic packaging has much more stringent standards.

According to MIL-STD-883 Method 1014 “Seal,” high-reliability electronic packages must meet specified fine leak rate and gross leak rate test requirements, with typical fine leak detection levels reaching the 1×10⁻⁹ Pa·m³/s order of magnitude. This means that even if leak channels exist, only an extremely small number of gas molecules are allowed to pass through per second on average, achieving true molecular-level sealing.

Given such stringent requirements, the next question naturally arises: what materials can achieve this?

3. Why Can’t Traditional Organic Materials Meet Hermetic Requirements?

Organic polymer materials have free volume between molecular chains, through which small molecules such as moisture, oxygen, and hydrogen sulfide gradually diffuse like “navigating a maze.” Moreover, organic materials age — UV radiation, thermal oxidation, and hydrolysis cause polymer chain breakage, leading to continuous degradation of sealing performance.

Materials used in high-reliability hermetic packaging must possess dense structure, low permeability, and long-term stability. In the field of high-reliability hermetic packaging, the two main inorganic materials that have been validated through long-term use are glass and ceramic: glass-to-metal sealing and ceramic-to-metal sealing. These materials, with their dense atomic-level structures, physically block the diffusion channels of various gases and ions.

Conclusion of this section: To achieve high-reliability, low-leak-rate hermetic sealing, it is typically necessary to use glass or ceramic with metal to form a reliable sealing structure. Based on this underlying logic, the industry has developed two main processes.

[Next Article Preview] In the next article, we will examine the first process — Glass-to-Metal Sealing (GTMS) — how it achieves molecular-level sealing.