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Sapphire Metallization

Basics of Metallizing Sapphire

Single crystal sapphire is a high purity, optically clear form of aluminum oxide (Al2O3) that can be used in many harsh environments. In applications where sapphire needs to be bonded to metal, epoxy or other gluing methods can be used, but brazing is usually a much better option.  Unlike gluing, brazing creates a hermetic, high-temperature seal – ideal for harsh or vacuum applications.  Due to its purity, bare sapphire will not attach to braze or solder alloys on its own, so an intermediary metal, usually molybdenum/manganese (Mo/Mn), is needed. Our Mo/Mn matrix is specifically made for brazing sapphire and will create a bond that can withstand extreme temperatures (-40°C to 800°C) and provide a hermetic seal down to 10-9 torr.l/sec.  

Elcon Precision metallizes and electroplates sapphire lenses, windows, and wafers to prepare them for hermetic brazing into a metal housing. The thick film metallization is applied using various methods including brush, spray, screen printing or our dual station robot. In order to preserve the optical properties of the sapphire lens or wafer, we typically only metalize and braze the outer diameter of the part. 


For complex parts in quantities of less than about 500 parts, hand painting by skilled operators is our usual process. For high-volume, simple parts, automation can start to provide benefits.  Most round sapphire windows have a geometry that is ideal for automated OD metallization, which can greatly reduce lead times, increase application uniformity and lower costs, especially at high volume.  Cost savings start to be realized once run volumes reach 1000 parts or more.

Learn more about Metallization Automation

Benefits of Metallized Sapphire

  • Allows for a brazed hermetic seal
  • Vacuum leak-tight bond 5 times stronger than epoxy
  • Can be soldered or brazed in air or vacuum furnaces
  • Ideal for sapphire optics applications
  • Most commonly brazed to Kovar & Alloy 42
  • Can be brazed to molybdenum, AlSiC, copper, Alloy 194, & copper-tungsten
Sapphire Metallizing Guidelines

Attributes of Sapphire

  • High mechanical strength
  • Temperature stability (withstands exposure up to 2000°C)
  • Wear resistance
  • Chemical inertness
  • Hardness = 9 Mohs, which is only exceeded by Diamond
  • Refractive Index = 1.76 – 1.77


Common Applications

Due to its high strength, durability, and optical clarity, common uses for Sapphire include:

  • Endoscopes, Medical Imaging
  • Optical Lens and Windows
  • Sensor Optics in Military Electronics
  • Lasers
  • Pressurized Optical Windows
  • Vacuum and Furnace Viewports
  • Submersible Optics
  • Oil & Gas analysis
  • Point of Sale Barcode Readers
Sapphire Window Lens Diagram

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Other Services

Photochemical Machining

We have over four decades of experience in manufacturing photochemically etched components for the military and aerospace markets.

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Brazed Assembly

Elcon has been producing some of the most challenging brazed assemblies for over 30 years.

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Metallization of Ceramics

Elcon uses proprietary technology to provide industry-leading metallized ceramics and sapphires.

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