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Bonding is the process to bond a sputtering target and a backing plate. Since the purpose of a backing plate is to mount the target onto a sputtering machine and to release the heat generated on the target surface, incomplete bonding process will result in the separation of the target from the backing plate, and a deterioration of the properties of coated films due to poor heat release. There are Epoxy Bonding, Solder Bonding, and Diffusion Bonding types in the bonding methods. One of these bonding types are selected depending on the target materials and their applications.
A. Epoxy Bonding
i. ApplicationConductive epoxy resins are used in Epoxy Bonding. As low bonding temperature can be adopted by the selection of epoxy materials, this epoxy bonding method is used for the targets that are fragile to temperature change.
ii. CommercializationApplied Science Corporation has developed its own materials to employ in the epoxy bonding processes. These epoxy materials have excellent thermal stabilities, high electrical and thermal conductivities - which are essential properties for excellent bonding materials for sputtering targets.
Ultrasonic Scanning Cross section of Si Target an Epoxy Bondeding Si Target
Bonding ratioe: 99.5%
B. Solder Bonding
i. ApplicationSolder Bonding is the most commonly used method to bond sputtering targets on backing plates. It takes advantage of the properties of low melting temperature metals such as indium and tin. When a metal of low melting point melts between two different metals and then is solidified, it can bond the two different materials. Since solder bonding uses metals to bond sputtering targets, it is more advantageous in terms of electrical and thermal conductivity than epoxy bonding.
The disadvantage of solder bonding method is that the process should be conducted at an elevated temperature. The bonding ratio could be lower than that of diffusion bonding.
ii. ImplementationWe can apply the solder bonding technology to the metal targets and ceramic targets such as Al, Cr, Fe, Ni, Ti, W, Si, Quarz, ZnS, and ITO. More than 99% bonding ratio has been routinely maintained with our own know-how which has been accumulated for many years
Ultrasonic Scanning of Bonded InterfaceCross section of Ni Target Solder Bonded on a Cu Backing Plateing
Bonding ratioe: 99.5%
C. Diffusion Bonding
i. ApplicationDiffusion bonding is one of the most technically difficult bonding methods. It is employed in the production of sputtering targets used in the semiconductor process, which requires high working temperatures.
It does not involve any liquid fusion. Diffusion bonding is performed by assembling a target and a backing plate together and then applying both high temperature and high pressure.
Since the target and the backing plate are joined by atomic diffusion, diffusion bonding is the most advantageous bonding method in terms of the bonding ratio and the thermal conduction.
ii. ImplementationApplied Science Corporation has profound know-hows and experiences with diffusion bonding.
We have supplied our sputtering targets to semiconductor manufacturers and received recognition for the quality of our products.
Ultrasonic Scanning of Diffusion Bonded Interface of Ti
Bonding ratioe: 100%