WETTABILITY OF AL2O3 BY LIQUID CU AS INFLUENCED BY ADDITIVES AND PARTIAL TRANSIENT LIQUID-PHASE BONDING OF AL2O3

The effect of additions (Cr, Ni and 80Ni . 20Cr alloy) on the wetting characteristics of liquid Cu on A(l)2O(3) has been studied using a ses sile drop method in a vacuum at 1150 degrees C. Through the use of mic rodesigned multilayer Cu/80Ni . 20Cr/Cu interlayers, PTLP (Partial Tra nsient Liquid-Phase) bonding of Al2O3 has been achieved in a vacuum at 1150 degrees C. 80Ni . 20Cr alloy and Cr additions reduced the contac t angle of liquid Cu on an Al2O3 substrate. For Cu with 10 mass%8ONi . 20Cr alloy and with 6 mass%Cr added, contact angles decreased with ti me reaching values of less than or equal to 90 degrees and less than o r equal to 70 degrees, respectively, at the end of the measurements. F rom SEM and EPMA observations, dissolution of the additions occurred, and thereby introduced Ni and Cr into liquid Cu droplets. The uniform distribution of Ni throughout the Cu droplet and the segregation of Cr at the Cu droplet/Al2O3 interface were observed in the solidified spe cimen. The average strength for Cu/80Ni . 20Cr/Cu interlayer bonded Al 2O3 was 137 MPa with a standard deviation of +/- 33 MPa. Failure of th ese samples occurred along the Al2O3/interlayer interface. From SEM an d EPMA observations, some dissolution of 80Ni . 20Cr core layer into l iquid Cu film and the diffusion of liquid Cu into 80Ni . 20Cr core lay er occurred, however, because of the thicker Cu layers used, homogeniz ation was incomplete. The results demonstrate that at the bonding temp erature, the dissolution of Cr into liquid Cu film improved the wettab ility of liquid Cu film on Al2O3 and facilitate the formation of relia bly strong joint of PTLP bonded Al2O3 using Cu/80Ni . 20Cr/Cu interlay er.