Gold-Tin Alloys for Brazing

Joining Technology

Gold-Tin Alloys for Brazing

Gold-tin brazing alloys for high reliability sealing / bonding. Our gold-tin alloys are available in various shapes and sizes.

Our gold-tin alloy is suitable as a bonding material for high frequency devices and optical communication devices and as a substitute for high temperature lead-free solder. This gold-tin alloy not only can be supplied as brazing filler metals but also can be processed into sputtering targets and vapor deposition materials. In addition, the gold-tin alloy can be fused, only in the quantity needed, to metals or ceramics and shipped as fusion products.


  • Gold-tin alloys of various compositions are available to suit each application.
  • Improved gold-rich layer
  • Excellent sealing reliability with fewer defects such as voids
  • Sealed devices can be mounted on circuit boards using lead-free solder.


Composition Melting point Vickers hardness Specific gravity
AuSn18 278-360℃ 145 14.89
AuSn20 278-300℃ 135 14.52
AuSn21 278℃ 135 14.35
AuSn21.5 278℃ 135 14.26
AuSn90 217℃ 17 7.78

Compositions other than those listed above are available.

Processed Products

Shape Minimum dimensions
Ribbon 15µm thick
Preform 15µm thick
Wire φ0.06mm
Ball φ0.1mm
Sputtering target 2.5mm thick

The minimum dimension differs depending on the type, composition, shape, etc.


Semiconductor laser modules, optical devices, SAW filters, crystal oscillators, microwave radar components, lead frames, lead pins, ceramic packages, etc.

Gold-tin brazing lids for crystal oscillating devices (Window type)

Gold-tin brazing lids for crystal oscillating devices (Window type)

Application Example – Fusion Products


  • The gold rich layer can be improved (bonding and sealing properties) by optimally adjusting gold and tin compositions according to the thickness of gold on the material surface.
  • Can be fused not only to ceramics but also to metalized substrates and conductive surfaces.
  • High dimensional accuracy with up-to-date equipment
  • Shorter assembly process and improved product yields
Changes in the cross-sectional structure of the lid with different Au/Sn compositions




Examples of fused products

  • Customer supplied materials
    • Conductive surfaces of ceramics
    • Heat sinks and lead frames
    • Semiconductor or compound devices
  • Lead pins (Ni/Au plating) … Base materials: Kov, FeNi, Cu, Fe, etc.
  • Lids (plates/stamped pieces) … Base materials: ceramic, Kov, FeNi, etc.
  • Gold-tin brazing lids for package sealing (left picture)
  • Our developed lid for sealing small crystal oscillating devices (Window type) is designed so that gold-tin alloy does not flow into the lid when it is sealed, providing a highly reliable seal with a smaller amount of gold-tin alloy.

Quartz glass lid with AuSn for deep ultraviolet LEDs

New product “SKe-Lid”
*Registered Trademark

Glass lid with gold-tin (AuSn) for use with SMD type diodes