Gold Solders

• Die-Attach: Thermal requirements often mandate a high-melting die-attach solder. With a melting point of 280°C, eutectic AuSn often satisfies these demands.
• Hi-Reliability Applications: AuSn is compatible with gold metallizations. Coupled with its long-term reliability, AuSn is a good choice for high-reliability applications such as microwave systems, medical and aerospace applications, and more.
• Lid Sealing: AuSn has excellent wetting properties. Its relatively low melting point (when compared to certain die-attach alloys) and its long-term reliability makes AuSn popular for lid sealing applications.
• Braze Alternative: Eutectic AuSn, with a tensile strength of 275 MPa (40,000 pounds/square inch), provides a great alternative to brazes when high strength must be achieved at soldering temperatures.

Gold and gold-based solders are available as:

• Preforms and ribbon
• Thickness from 0.0127mm (0.0005") and greater
• Tight dimensional tolerances ensure repeatable solder volume
• Flatness measurement capabilities to 0.00254mm (0.0001")
• Large die library with in-house tooling capabilities
• Tiny solid shapes from 0.152mm (0.006")
• High complexity special shapes
• Wire
• Diameter starting at 0.025mm ± 0.0127mm (0.001" ± 0.0005")
• Tight dimensional tolerances
• Packaging designed to minimize breakage of wire in soldering process
• Maximum of 80% Au
• Paste
• Powder (80Au/20Sn only)
  • Type 3 (25-45 microns)
  • Type 4 (15-38 microns)
  • Type 5 (15-25 microns)
  • Type 6 (10-20 microns)
• No-clean flux
  • NC-SMQ51SC (used in high-power LED and MEMS)
  • NC-SMQ51A (for difficult to solder surfaces in die-attach)
  • NC-SMQ75 (halogen-free and low-residue; requires <10ppm oxygen)
• Low-volume packaging
  • Jars (10g per jar)
  • Syringes (5cc syringes)
• Spheres
• Sizes starting at 0.254mm (0.010”)
• Tight dimensional tolerances down to +/- 5 microns

• Higher yields and cost per unit make gold a viable option, even though the initial cost is higher than alternative solders.
• A low oxygen/reducing atmosphere may be required if the application is flux free.
• Some applications require pressure to promote good, void-free reflow on horizontal surfaces.
• When using AuSn in conjunction with Au metallization, the composition of the AuSn solder must be altered.
• Alternative methods, such as scrubbing, forming gas or formic acid, may be needed for oxide removal of the soldered surface.

• Vacuum soldering: flux-less and void-free soldering
• Die-attach: high process temperature
• Reflow: convection, infrared, and induction
• Laser soldering: targeted soldering
• Vapor phase reflow: uniform heating
• Manual Soldering: solder iron, hot plate, ultra sonic, and dipping