JOINT PROPERTIES OF Sn-3.5Ag SOLDER BALLS WITH SURFACE EMBEDDED CARBON NANOTUBE
Authors: Chang-Woo Lee, Young-Ki Ko, Jung-Hwan Bang, and Sehoon Yoo Company: Korea Institute of Industrial Technology Date Published: 10/4/2009
Abstract: Carbon nanotubes (CNTs) were embedded onto the surface of solder ball by ultra sonic dispersion and ball mill process. Sn-3.5Ag was used for solder ball materials. Ball mill process was conducted to insert CNTs onto the solder balls. The rotation speed was 300 rpm. Ball mill time was varied with 6, 12, 24, and 36 hours. Solder balls with surface CNTs were attached on ENIG finished copper pads by reflow process. Microstructure and joining strengths were also observed with SEM and shear tester. From the SEM results, the CNTs were inserted on the Sn-3.5Ag solder balls after ball mill process. As the ball mill time increased, amount of surface-inserted CNTs increased. Shear strength of CNT inserted Sn3.5Ag solder balls increased by 10 % after 24 hour-ball mill process. Cross sections of fracture were examined and ductile fracture was dominant for CNT inserted Sn3.5Ag solder ball.