61 Wettability of Cu and Cu-Sn Intermetallic Compound by Sn-Pb Solder Alloy Hisaaki Takao, Nobuyuki Yamamoto, Hideo Hasegawa CuCu-Sn Cu 150 C 2h55nmCu 2 O Cu Cu-Sn 5nm Cu-Sn Cu SnCu-Sn Wettability of Cu and Cu-Sn intermetallic compound was investigated in terms of its surface oxidation. Cu 2 O layer of about 55nm thick was formed on the surface of Cu during the heat treatment at 150 C for 2h in the air, which had a little influence on its wettability. On the other hand, the surface oxidation of Cu-Sn intermetallic compound caused an appreciable reduction in its wettability. The surface of the oxidized Cu-Sn intermetallic compound was covered with an amorphous layer of about 5nm thick. The galvanostatic coulometry analysis suggested that the amorphous layer was a Cu-Sn complex oxide, which was more difficult to reduce owing to its cathodic potential lower than Cu 2 O or SnO. Cu Cu-Sn Cu Cu Sn-Pb HAL ( Hot Air Levelling ) 0.5 40µm Cu R&D Vol. 31 No. 4 ( 1996. 12 )
62 / Cu Cu-Sn ( Cu-Sn ) Cu-Sn Cu-Sn ( Sn Pb ) Cu-Sn Cu-Sn Cu-Sn ( SEM ) X ( XRD ) ( AES ) X ( XPS ) ( TEM ) Cu 150 C 2h JIS Z 3197 ( S ) (1) ( D H ) S = 100 (%) (1) D D : ( ) H : 63Sn-37Pb ( mass% ) ( Cu Cu-Sn ) 30 30 0.3 ( mm ) 230 C30s JIS C 0053 ( ) ( ) ( Cu Cu ) Cu-Sn Cu ( 1N HCl ) Cu-Sn (a) ( 150 C 95h ) / Cu ( ) / Cu Cu 6 Sn 5 Cu Cu 3 Sn Cu 6 Sn 5 4µm Cu 3 Sn 1µm Fig. 2(b) Cu-Sn ( SEM ) 2 4µm Cu 6 Sn 5 Cu Cu-Sn Preparation of Cu-Sn intermetallic compound. R&D Vol. 31 No. 4 ( 1996. 12 )
63 ( ) 10 30 0.3 ( mm )2mm10mm/s 10s ( SEM ) X ( XRD ) ( AES ) X ( XPS ) ( TEM ) Tench, D. M. ( ph 8.4 ) Pt ( 20µA / cm 2 ) ( SCE ) 5 30 0.3 ( mm ) ( 150 C 2h ) Sn ( 99.99% ) ( 150 C 2h ) Cu Cu-Sn ( S ) Cu 88% 85% Cu Cu-Sn Microstructure of Cu-Sn intermetallic compound. (a) Optical micrograph of the cross-sectional view of 63Sn-37Pb/Cu interface after heat-treatment, (b) SEM micrograph of Cu-Sn intermetallic compound after removing the solder. Typical wetting curve in meniscograph test. R&D Vol. 31 No. 4 ( 1996. 12 )
64 92% Cu % 71% (a) (b) ( 150 C 2h ) Cu Cu Cu Cu (a) (b) Cu-Sn Cu-Sn Cu-Sn CuCu-Sn ( ) Wetting curves of Cu. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. Solder spreading on Cu and Cu-Sn intermetallic compound. Wetting curves of Cu-Sn intermetallic compound. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. R&D Vol. 31 No. 4 ( 1996. 12 )
65 Cu-Sn Cu Cu Cu-Sn Cu Cu-Sn Wetting time of Cu and Cu-Sn intermetallic compound. Cu 250 C 150 C 2h 150 C 200 C 230 C 30s Cu-Sn Cu-Sn 150 C 200 C 77% 230 C 64% 150 C ( ) Cu- Wetting force of Cu and Cu-Sn intermetallic compound. Solder spreading on Cu-Sn intermetallic compound. R&D Vol. 31 No. 4 ( 1996. 12 )
66 Sn 200 C30s Cu-Sn ( 25 C 40 60%RH ) Cu-Sn 92% 6 91% Cu-Sn (a) (b) ( 150 C 2h ) Cu AES Cu nm ( Fig. 10(a) ) 50nm ( Fig. 10(b) ) XRDCu 2 O (a) (b) Cu-Sn Cu ( Fig. 10 ) Cu-Sn Sn nm SEM XRD Cu Sn Cu SnCu-Sn ( 150 C 2h ) CuSn AES depth profiles of Cu. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. AES depth profiles of Cu-Sn intermetallic compound. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. R&D Vol. 31 No. 4 ( 1996. 12 )
67 ( ) ( ) Cu ( Fig. 12(a) ) 2 ( : 0.35V 0.48V ) XRD Cu 2 O 0.48V ( ) Cu 2 O 0.35V CuO ( Cu(OH) 2 ) Cu 2 O 55nm CuO 0.3nm Sn ( Fig. 12(b) ) SnO 0.86V 15nm Cu-Sn CuSn ( Fig. 12 ) 0.71V 0.95V 2 Fig. 12 Fig. 13 Cu-Sn ( 0.35V 0.48V ) ( 0.86V ) Cu Sn Cu-Sn Cu-Sn ( 0.95V ) Cu ( Fig. 4 7 ) Sn ( Sn : 92% : 200 C ) Cu-Sn (a) (b) Cu-Sn TEM 150 C Galvanostatic coulometry curves. (a) Oxidized Cu, (b) Oxidized Sn, at 150 C for 2h in air. Galvanostatic coulometry curves for Cu-Sn intermetallic compound. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. R&D Vol. 31 No. 4 ( 1996. 12 )
68 2h ( Fig. 14(a) ) ( Fig. 14(b) ) Cu-Sn 3 5nm Cu-Sn nm Cu-Sn Cu-Sn XPS Cu-Sn 150 C 2h Cu C Cu Sn OCu Sn Cu-Sn Surface analysis of Cu-Sn intermetallic compound. TEM images of the surface of Cu-Sn intermetallic compound. (a) As fabricated, (b) Oxidized at 150 C for 2h in air. Sn Cu Matal Oxide O C As fabricated 7.5 3.6 15 45 28 After oxidized 2.9 3.0 22 50 23 Halogen flux treated after oxidized 9.7 2.7 12 41 34 Halogen free flux treated after oxidized 0.9 2.2 23 54 20 (at%) R&D Vol. 31 No. 4 ( 1996. 12 )
69 Cu / Cu Cu-Sn CuCu-Sn (1) Cu150 C 2h 55nmCu 2 O Cu (2) Cu-Sn ( 3 5nm ) (3) Cu-SnCu SnCu-Sn Cu-Sn 1 1),,,, :, (1993), 459 466 2) : Uyemura Tech. Rep., No.30(1994), 12 17 3) Billot, M. and Clement, S. : Tin and its Uses, (1982), 1 3 4) Yenawine, D. L., Dunnigan, J. S. and Howarth, R. A. : 7th Soldering Technol. Seminar Proc., (1983), 207 219 5) Davis, P. E., Warwick, M. E. and Kay, P. J. : Plat. and Surf. Finish., (1982), 72 76 6) Davis, P. E., Warwick, P. E. and Muckett, S. J. : Plat. and Surf. Finish., (1983), 49 53 7) Sunwoo, A. J., Hayashigatani, H., Morris, J. W., Jr. and Lucey, G. K., Jr. : JOM, June, (1991), 21 24 8) Sunwoo, A. J., Morris, J. W., Jr. and Lucey, G. K., Jr. : Metall. Trans. A, (1992), 1323 1332 9) Sunwoo, A. J., Morris, J. W., Jr. and Lucey, G. K., Jr. : Circuit World, (1992), 26 32 10) Sunwoo, A. J., Morris, J. W., Jr. and Lucey, G. K., Jr. : J. Electro. Mat., (1992), 549 557 11), : 35, (1992), 23 32 12), :,, (1991), 319 13) Tench, D. M. and Anderson, D. A. : Plat. Surf. Finish., (1990), 44 46 1967 7 1942 1987 7 R&D Vol. 31 No. 4 ( 1996. 12 )