- Ultra-high reliability for joining and sealing
- Fluxless soldering processes
- Hermetic sealing
- Joining gold-plated surfaces
- Highest tensile strength of any solder
- High melting point is compatible with subsequent reflow processes
- Superior thermal conductivity
- Resistance to corrosion
- Superior thermal fatigue resistance
- Good joint strength
- Excellent wetting properties
- Resistance to oxidation
- AuSn is compatible with precious metals
- AuSn is RoHS complaint
- Pure Au is inert
Gold-tin (AuSn) 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
- 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
- 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)
- Sizes starting at 0.254mm (0.010”)
- Tight dimensional tolerances down to +/- 5 microns
|Thermal Conductivity (W/mK)||318||57||44||27|
|Tensile Strength (PSI)||20,000||40,000||26,835||36,975|
|Shear Strength (PSI)||20,000||40,000||26,825||31,900|
|Thermal Expansion Coefficient @20°C (PPM/°C)||14||16||13||12|
Alternative Methods of Using AuSn
|Characteristics||Solder Paste||Solder Preform||Evaporation||Alloy Plating||Plating by Layers|
|Minimum bondline thickness||25.00μm||12.00μm||0.01μm||0.25μm||2.50μm|
|Cleanliness||Low cleanliness (flux surface contamination)||High cleanliness (when no flux used)||High cleanliness||Good cleanliness (trace of organic impurities only)||Good cleanliness (organic co-deposit impurities)|
|Deposition equipment||Stencil printer or dispenser||Manual or pick & place||Evaporation chamber||Plating line||Plating line|
|Device heat exposure||>280°C||>280°C||>Ambient||Ambient||Ambient + diffusion heating step|
|Strengths||Low-cost equipment; manual or automated assembly; rapid deposition rate||High purity; manual or automated assembly; preforms designed to match deposition footprint||Very high purity; rapid deposition; low-cost equipment; thin to thick layers||Good purity; deposition targeted to conducting surfaces||Good purity; deposition targeted to conducting surfaces|
|Weaknesses||Flux residue inclusion; thick deposits only; requires diffusion step; requires cleaning; refrigerated storage||Expensive automation equipment; thick depositions only; accurate manual placement difficult, may require flux or reducing atmosphere||Wide area deposition (material loss); may require diffusion step||Expensive equipment; difficult to control composition; low deposition rates||Expensive equipment; difficult to control composition; low deposition rates; requires diffusion step|
Factors to consider
- 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
For more information contact firstname.lastname@example.org.
Gold Solders Technical Documents
Product Data Sheets
Safety Data Sheets
Solder Blog Posts
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