Depending on the particular system and material your target may require bonding. Backing plates can be fabricated to match virtually any target composition and configuration. We will perform bonding/de-bonding of targets ordered from us or of targets and backing plates provided by the customer.
Indium is the preferred solder for bonding sputtering targets because it has the best thermal conductivity.The softer solder allows some "give" when the target expands at a different rate than the backing plate.
The main limitation of the indium bond is the melting temperature of the indium solder. Indium has a melting point of 157°C so temperatures in excess of 150°C will cause the bond to melt and fail. Most materials can be indium bonded but there are a few exceptions.
Furthermore choosing the right backing plate is also essential for a successful bonding process. A backing plate is used to mechanically mount a sputtering target to the tool/ cooling device. In addition, the backing plate enhances the mechanical strength and facilitates cooling of the sputtering target and the entire sputtering target assembly. Even when not directly in contact with cooling water, the backing plate lowers the risk of cracks/ mechanical failure of the sputtering target caused by process-induced expansion/contraction or cooling water pressure distortion. Besides that some sputtering target materials (e.g. Si, HfO2) especially in larger geometries, can only be used when the invidividual tiles are properly bonded to a backing plate. In most cases, an Indium bond layer is favored bonding medium due to its reusability and excellent thermal and electrical properties. The low melting point, oxidation potential and high shear strength of indium enables the fusing of even high coefficient of thermal expansion (CTE) mismatched materials.
If your Sputter process has temperatures higher than 157°C we recommend Nano Bonding of your sputtering target.
Nano Bonding is a process for bonding components utilizing Nano Bond Foil. Activated by a small pulse of energy the bonding process is completed in a fraction of a second.
The process enables high strength, high conductivity bonds between most combinations of materials making it ideal for many joining and assembly operations.
The multilayer Nano Bond Foil is placed between two components to be bonded along with the heat from the Nano Foil’s reaction melts the solder and enables metallic bonding at room temperature.