For sputtering targets, the most preferred and optimal type of bonding is indium bonding. This allows the sputtering targets to be effectively and safely attached to backing plates, which provides several benefits.
Indium itself is a silvery, gray metal that is naturally occurring and is extremely soft and easy to work with. In its natural state indium can be easily cut with a knife and it has a very low melting point of 313.88 degrees Fahrenheit.
It is considered a rare element in the Earth when compared to other metals, but it is widely used as a solder, as in indium bonding, as well as in the manufacturing of vacuum seals and for a conductive coating that can be used on glass.
Soldering and Bonding
There are several reasons why indium bonding is so important in sputtering targets. When used as the solder, or the bond, it creates an electrical and thermal conductive bond that is stress-free, which prevents the problems with cracking with the ceramic sputtering targets.
With the use of indium bonding, even if a thermal crack should occur with ceramic, it is often possible to continue to use the bonded target even in if there is a crack. This is important in a wide range of different applications.
Keep in mind that the indium bonding also assists in a faster cooling for the ceramic material. The heat is able to pass through, and the difference between any changes in the two materials in expanding or contracting, helping to minimalize the risk of cracking as mentioned above.
Generally, this works as a solder that can be used with almost all materials. There are some exceptions with the custom alloys, but they are relatively uncommon and an experienced metallurgist can quickly identify if there will be an issue with using this process.
Considerations
While indium bonding is considered to be the soldering option of choice for sputtering targets, there are some considerations. With the relatively low melting point, the bond will fail on the sputtering target, resulting the target and backing shifting as the bond fails if used under high temperatures.
For any application, considering the effectiveness of this bonding process will be important. Working with a top company with extensive experience in indium bonding and the production of sputtering targets will the first step in ensuring the right options are being considered for the specific application.
