For most of the time, people consider the purity, and maybe the shape, of the sputtering target when they are purchasing the target materials. But one thing should not be ignored is the target bonding. Well, you think it unnecessary and costly? Then just think about what to do when your target is broken.
Target bonding is necessary
Maybe you can use a copper plate to stick the broken pieces of the target and then polish the target so that the broken areas have minimum exposure to plasma. The second step is very important because the power would suddenly breakdown to zero when plasma strike to broken area of target. And obviously, the film quality will be affected if breakdown is frequent. Although it may help solve the problem when the target is broken, it is still a remedial measure. To avoid target from breaking, you need to give a target bonding service to the target. It is necessary for those brittle targets, and is not expensive compared with the losses of the broken target.
What is target bonding?
Target bonding refers to soldering the target to the back target with solder. Technically, targets with a flat surface and can be metallized can be bonded to improve the heat dissipation and target utilization of the sputtering process.
Target bonding materials
Metallic bonds provide good thermal and electrical conductivity and are recommended for most sputtering applications. Indium is the preferred method for bonding sputtering targets due to its high thermal conductivity and is the high efficiency at drawing heat away from targets. Indium is also more malleable than alternative bonding solders. The main limitation of an indium bond is the melting temperature of an indium solder. Indium has a melting point of 156.6°C, and temperatures over 150°C will cause the bond to melt and fail. Most materials can be indium bonded, however, there are a few exceptions. The elastomer is an alternative bonding method that touts a higher temperature capability over indium bonds. Elastomer bonds are recommended when customers are consistently melting indium bonds. Elastomer bonding is also suitable for low melting point target materials, temperature sensitive compounds and targets that have either low density or are especially fragile.
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