Study On Sn-Zn-In-Bi-Al Alloy Used For Rotating Target Bonding

The rotating cylindrical sputtering targets are widely concerned nowadays by the coating industry due to their high efficiency and high utilization in producing large-area thin films.The fabrication of such targets needs integrating several short tubes of the target material to the base tube(i.e.bonding process).At present,there are some problems in bonding process,such as high cost,poor conductivity and poor thermal conductivity of bonding solders.Aiming at these problems,in this dissertation,Sn-Zn-In-Bi-Al bonding solder alloys were prepared.The microstructure,melting point,wettability with Ni matrix,electrical conductivity as well as thermal conductivity of the alloys with different Zn and In content were studied.Compared with traditional In and Sn solder,it was confirmed that Sn-7.0Zn-5.0In-3.8Bi-0.2Al is suitable for a sputtering target bonding solder.The wettability of Sn-7.0Zn-5.0In-3.8Bi-0.2Al alloy on Ni matrix after heated at 250°C and 300°C and in different time was investigated.(1)The microstructures of Sn-xZn-5.0In-3.8Bi-0.2Al(x=6.0,6.5,7.0,7.5)and Sn-7.0Zn-yIn-3.8Bi-0.2Al(y=0,4.5,5.0,5.5)alloys mainly consisted of gray matrix,black granular structure and black acicular structure.In addition,there was white granular structure in the alloy without In element.The gray matrix was tetragonal Sn based solid solution,and the black granular structure and the black acicular structure were hexagonal Zn solid solution,and the white granular structure was monoclinic Bi based solid solution.(2)With the increase of Zn content,the melting point of the solder alloy decreased and the electrical conductivity and thermal conductivity rose.However,the wettability between the alloys and Ni matrix gradually became worse.On the other hand,as the In content increased,the melting point reduced,and the wettability,electrical conductivity and thermal conductivity of the solder alloy were improved.(3)According to the study results,Sn-7.0Zn-5.0In-3.8Bi-0.2Al was the optimal alloy,whose properties met for the technical requirements of bonding solder for rotating cylindrical sputtering target.(4)NiO formed on the surface of the nickel substrate on heating made worse the wettability between Sn-7.0Zn-5.0In-3.8Bi-0.2Al and Ni.Higher the heating temperature and longer the heating time,stronger the effect was.The contact angle of Sn-7.0Zn-5.0In-3.8Bi-0.2Al on Ni after heated at 300 ? for 80 min was 59.2°,less the expected requirement 60°.