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Views: 0 Author: Site Editor Publish Time: 2026-08-20 Origin: Site
11. Sealing is Only the “First Half” — What’s Still Missing? Surface Treatment
Hermeticity determines whether a product can isolate from the environment, while surface treatment determines whether the product can maintain stable performance during long-term operation.
Metal components after sintering (such as Kovar housings, pins) have three problems:
High-temperature oxide layer — surface oxides cannot be soldered
Insufficient corrosion resistance — rusting in humid environments
Oxide layer or impurities present — high contact resistance
All three problems point to the same solution: surface treatment.
12. How to Plate? Two Processes
Process | Principle | Application Scenario |
Electroplating | External current drives deposition | Mass-produced standard parts |
Electroless Plating | Chemical autocatalytic deposition, no current needed | Complex irregular parts, deep hole cavities |
Kovar is the most commonly used metal material — what exactly should be plated?
13. Standard Solution for Kovar: Nickel First, Then Gold
Plating Layer | Thickness | Function |
Nickel (Ni) Underlayer | 3~5 μm | Good adhesion, blocks element diffusion, basic corrosion protection |
Gold (Au) Surface Layer | 0.05~1.3 μm | Solderability, low contact resistance, long-term oxidation resistance |
Gold layer is not the thicker the better — excessive thickness causes the “gold embrittlement effect.” During soldering, an overly thick gold layer dissolves into the solder, generating large amounts of hard and brittle “tin-gold” and “lead-gold” crystals. These crystals, like broken glass mixed in glue, make originally ductile solder joints brittle and prone to cracking under stress, actually reducing solder joint reliability.
With processes and plating solutions in place, how to choose for specific projects?
14. Final Decision: Full-Scenario Application Quick Reference Table
Application Field | Applicable Process | Key Consideration |
Sensors (pressure/infrared/gas) | CTMS, GTMS | Cost, mass production, room temperature |
Optical Communications | CTMS, GTMS | Hermeticity, multi-pin |
High-power Laser Diodes | CTMS, GTMS | Thermal conductivity (heat dissipation first) |
Microwave/RF Modules | CTMS | Dielectric loss (signal integrity) |
Hybrid Integrated Circuits (HIC) | CTMS | High integration + high reliability |
Aerospace Electronics | CTMS, GTMS | Wide temperature range, vibration resistance |
Downhole Oil Equipment | CTMS, Composite Packaging | High-temperature corrosion resistance, high pressure |
15. Trends and Conclusion
Hermetic packaging is evolving toward smaller sizes, higher frequencies, and higher reliability.
No single solution fits all scenarios. The core is understanding how application requirements, material characteristics, and process boundaries match.
[Series Complete] The hermetic packaging series is now complete. From “why it is needed” to “how it is achieved,” from GTMS to CTMS, from surface treatment to full-scenario selection, we hope this content provides valuable reference for your technical decisions in projects. For further discussion, please feel free to contact our technical team.
