Bonding the target to an adequate backing plate is recommended to avoid cracking or warping of the sputtering target caused by inadequate cooling. The thermal and mechanical integrity of the bond between the backing plate and the sputtering target is critical in order to provide optimal sputtering performance. PhotonExport offers both metallic bonding and elastomer bonding services.
Indium bonding is considered a soldering process. It operates at temperatures of 170 degrees Celsius and is the preferred method for bonding sputtering targets with the best thermal conductivity. This process is highly efficient at dissipating heat from the target. Cracking is also reduced, thanks to the softer solder that allows for some flexibility if the target expands at a different relative rate compared to the backing plate. The relatively low melting point of 156.6 degrees Celcius is the main limitation of this solder, as temperatures above 150 degrees Celcius will provoke melting and failure of the bond.
The rear side metallization of substrates results in a void-free bond with high reliability. The Tri-Layer coating offers excellent adhesion to all substrates, and the resulting barrier layer prevents undesirable alloying with the Iridium. The result is improved adhesion and enhanced thermal conductivity.
Key advantages include: low melting point, ability to creep and remove stress as dissimilar materials cool and reduced warpage.