Instructions for Magnetron Sputtering Target Bonding Backplate:
What is bonding?
Bonding is the soldering of a target to a backplate with a solder. There are three main ways of doing this: crimping, brazing and conductive adhesive.
Brazing: In general, when using soft brazing materials, sputtering power of less than 20W/㎝2 is required. Brazing materials commonly used are In, Sn and In -Sn, and the thickness of indium solder is approximately 0.2mm.
Why bond?
1) brittle targets such as ITO, SiO2, ceramics and sintered targets, to prevent the target from being unevenly heated and shattered.
2）Soft metal targets such as tin, indium, etc., to play a supporting role.
3）The target is too thin, the target is too expensive, etc., to save costs.
Choice of backplate
Material: Oxygen-free copper is often used.
Thegood electrical conductivity: often oxygen-free copper, which has better thermal conductivity than purple copper.
Sufficient strength: too thin, easily deformed, not easy to vacuum seal.
Moderate thickness: about 3mm, too thick, consuming part of the magnetic strength; too thin, easy to deform.
Factors may causing the backplate falling-off
1) high sputtering temperature, oxygen-free copper is susceptible to oxidation and warpage, resulting in the target will crack when sputtering at high temperatures.
(2) The current is too high, the heat conduction is too fast causing the temperature to be too high and the solder to melt, causing the solder to fall off unevenly.
(3) the temperature of the circulating cooling water outlet should be <35℃, high temperature of circulating water will cause poor heat dissipation and shedding.
(4) the dense density of the target material itself, when the dense density of the target material is very high, it is not easy to adsorption, no gaps, the back target is easy to fall off.
Precautions to prevent the backing plate from falling off:
1) The sputtering temperature should not be too high
2）The current should be increased slowly
3）Circulating water should be below 35°
