High-Temperature Gold Solder & Braze Materials

High-Temperature Gold Solder & Braze Materials

Indium Corporation is a leading joining and bonding materials innovator for medical, aerospace, optoelectronics, and automotive applications.

Features & Benefits

When even 10 ppm of contamination can cause process and application failures – quality counts. Indium Corporation casts our alloys, which enables us to closely control the process from start to finish and ensure purity.

High-Temperature Solder and Braze Materials Deliver:

  • Highest tensile strength of any solder
  • High melting point is compatible with subsequent reflow processes
  • Pb-free and RoHS compliant
  • Superior thermal conductivity
  • Resistance to corrosion
  • Superior thermal fatigue resistance
  • Good joint strength
  • Excellent wetting properties
  • Resistance to oxidation
Laser Opt Packaging

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 Preform Quick Turn Program

Need a gold preform right away? Contact us for our Quick Turn Program:
  • Designed to deliver parts quickly and affordably
  • New design, new tool, prototype quantities in 1-2 WEEKS
  • Engineering support from design to production
  • Gold and Gold-Based Solders in a Variety of Forms

Need a gold preform right away? Contact us for help choosing the right materials for your brazing and soldering applications.

Gold Preform Facility

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 aspect ratio and complex 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

Capillary Blocks®

  • New technology for brazing hermetic packages
  • Cost-efficient alternative to cut wire and frames
  • Doesn’t shift during movement and reflow
  • Increases yields and lowers cost of ownership


  • No-clean and water-soluble
  • Type 3-6 AuSn powder


  • Sizes starting at 0.254mm (0.010”)
  • Tight dimensional tolerances down to +/- 5 microns
Gold and Braze Materials for Hermetic Sealing
Auto LED Mod

Benefits of High-Temperature Alloys

  Attributes Alloys Temperature
Gold-Based Alloys Strong bond strength, excellent corrosion and oxidation resistance, and good thermal and electrial transfer at the braze joint. Indalloy®182 (80Au/20Sn)
Indalloy®183 (88Au/12Ge)
Indalloy®178 (82Au/18In)
Indalloy®195 (80Au/20Cu)
Braze Indalloy®B955 (50Au/50Cu)
Braze Indalloy®B9902 (65Cu/35Au)
Indalloy®200 (100Au)
280°C Eutectic
356°C Eutectic
Solidus 451°C / Liquidus 485°C
891°C Eutectic
Solidus 955°C / Liquidus 970°C
Solidus 990°C / Liquidus 1010°C
1064°C Eutectic
Silver-Based Alloys High thermal and electrical conductivity, capillaries very well into joints, and holds up well in applications with lots of stress and with CTE mismatches. Braze Indalloy®B625 (61.5Ag / 24Cu / 14.5In)
Braze Indalloy®B6851 (63Ag / 27Cu / 10In)
Indalloy®193 (72Ag / 28Cu)
Braze Indalloy®B962 (99.99Ag)
Solidus 625°C / Liquidus 705°C
Solidus 685°C / Liquidus 730°C
780°C Eutectic
962°C Eutectic
OFHC Copper
(Oxygen-Free Highly-Conductive)
Highly conductive, lower cost alternative, and capillaries well into joints for hermetic sealing applications. (99.95Cu and 99.99Cu) 1085°C Eutectic

Precision Packaging

Indium Corporation’s packaging protects your solder preforms during shipping and handling, and is designed for ease of introduction into the manufacturing process.

  • Jar or bulk pack
  • Array tray pack
  • Waffle pack
  • Bulk tray pack
  • Tape & reel

We also can create customized packaging solutions to meet your needs and processes.

Capillary Blocks® Capillary Blocks® Capillary Blocks®

Capillary Blocks®

Increase Yields, Quality in Hermetic Package Manufacturing with New Capillary Blocks® Technology

Indium Corporation’s new capillary blocks® technology delivers a simple, cost-efficient alternative to the current process of using cut wire or frame preforms in hermetic package manufacturing.

Used for brazing the hermetic package frame to the base, cut wire shifts during movement and reflow, resulting in quality issues. While a more stable option, frame preforms can be costly and have long lead times when tooling setups are required.

Capillary blocks® are designed with a patented square shape that keeps the material in place during movement and reflow. As a result, capillary blocks® increase yields and lower cost of ownership for hermetic package manufacturing.

  • Patented design offers a stable alternative to cut wire for a higher-quality solder joint
  • Reduced lead time as compared to frame preforms
  • Unique shape enables a tight joint connection to aid in the capillary action
  • .030” wide x .030” height (length is determined by the amount of braze needed for the joint)
  • Available alloys include:
    • 72Ag/28Cu
    • 72Ag/28Cu VTG
    • 99.9Ag
Gold Tin Solder Paste

Gold-Based Solder Paste

Gold-tin solder paste is used in a variety of high-reliability applications, where its high melting point, non-creep, high-tensile stress, thermal and electrical conductivity, as well as proven usage life makes it a standard "known-good" material.

  • Highest tensile strength of any solder
  • High melting point is compatible with subsequent reflow processes
  • Pb-free
  • 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 compliant
Gold-tin Solder Paste
  • 80Au/20Sn Powder
    • 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)
    • RMA-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)
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 atmosphere may be required if the application is flux free
  • Some applications require pressure to promote good, void-free reflow on horizontal surfaces.
  • In step soldering or processes that may require rework, soldering to gold plated surfaces results in an intermetallic that melts at a higher temperature than the original alloy. When using the AuSn alloy, this can be addressed by using high tin-containing alloys.
  • Alternative methods, such as scrubbing, forming gas or formic acid, may be needed for oxide removal of the soldered surface.
Processing Options
  • 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