Figure 1. Illustration of the NanoBond® / NanoFoil® heating process® (from www.indiumcorp.com)

S-Bond active solder layers have been shown in many applications to be the key ingredient that permits many ceramics and refractory metals to be bonded to largely coefficient of thermal expansion (CTE) mismatched metals such as aluminum and copper. Indium Corporation offers a NanoBond® process that uses NanoFoil ® as local heat source to remelt preplaced solder layers without the need for the bulk heating of assembled components that have large CTE mismatch. Active S-Bond solders are applied as prelayers and have Ti, Ce, Ga and Mg additions that permit them to wet any ceramic or metal surface. Once the S-Bond pre-layers are applied to ceramic and/or metallic surfaces, conventional solders can be reflowed onto the S-Bond layer to create the preplaced solder layers that are remelted and bonded via the heat emitted from an ignited NanoFoil®. Figure 1 illustrates how temperatures of over 1,400 K are generated by an ignited nano-engineered foil.

Figure 2 illustrates the use of S-Bond in the NanoBond® process in bonding sputter targets.

Figure 2. An illustration of S-Bond being applied in the NanoBond® process

NanoFoil® , sold by Indium Corporation, is used on the Nanobond® process as a heat source to only locally reheat a pre-soldered interface with an instantaneous release of heat energy for joining applications. NanoFoil® is a nano-engineered material fabricated by vapor-depositing thousands of alternating nanoscale layers of Aluminum (Al) and Nickel (Ni), as shown in Figure 1. When activated by a small pulse of local energy from electrical, optical or thermal sources, the foil reacts to precisely deliver localized heat up to temperatures of 1500°C in fractions (thousandths) of a second. As a sacrificial heat source in soldering and brazing applications, NanoFoil® is ideal for high-temperature applications. NanoFoil® becomes a non-functional part of the solder or braze joint, eliminating the need for an oven or furnace and allowing for the use of higher temperature solders.

NanoFoil® works by acting as a local heat source to melt adjacent solder layers without heating the target or backing plate materials. This allows the bonding of nearly any combination of sputter target material and backing plate material, including ceramics to metals, irrespective of the difference in coefficient of thermal expansion (CTE). S-Bond solders enable the NanoBond® process in many applications by providing an “activated / bonded layer” on the ceramic or metal interface to which conventional solders can wet and adhere.

Contact us for more information on how S-Bond can assist your NanoBond® applications.

NanoFoil® and NanoBond® are registered trademarks of Indium Corporation.

• Heat base materials to S-Bond melting temperature.
• Melt a small amount of S-Bond onto the joining surfaces.
• Add ~ 0.1g/cm2 to the opposing surfaces to be joined
• Add S-Bond to the opposing joint surface.
• Mechanically spread the S-Bond layer to completely cover the joint area (brush, spatula or ultrasonics).
• Melt “conventional” solders onto the S-Bond layer on the bottom base and agitate to assure wetting to the underlying S-Bond layer.
  NOTE: Sn-Ag, Pb-Sn, Sn-Bi, In solders can be used
• Add enough “conventional” solder to the base to “float” and slide the top surface of the joint onto the conventional solder and provide excess solder to fill any gaps.NOTE: The sliding of the molten S-Bond / solder surfaces onto one another eliminates entrapped air and mechanically shears the surfaces of the S-Bond layer to the bottom “conventional “ solder layer on the base.