Drop test reliability improvement of lead-free fine pitch BGA using different solder ball composition

We present drop test results based on the JEDEC method JESD22-B111 for a laminate based lead-free fine pitch ball grid array (FBGA). We especially focus on the influence of substrate technology and solder ball composition. For all our tests we determine the electrical drop test failure rates until end-of-life and the main failure modes by means of cross sectioning. We compare the results for Sn4AgO.5Cu solder joints, which typically show intermetallic layer cracking along the package pad, with Sn36Pb2Ag solder joints on electroplated NiAu substrates, which typically fail in ductile mode. We find excellent drop test results on Cu-OSP and NiAu substrate finishes using the solder ball composition Sn1.2Ag0.5Cu0.05Ni. With this alloy no intermetallic cracks occurred. The Sn1.2Ag0.5Cu0.05Ni creates different intermetallic composition and is able to absorb more shock stress in its bulk material compared to Sn4AgO.5Cu. This advantageous behavior is confirmed by a dedicated drop test monitoring experiment and by temperature cycling tests using reference alloys

[2]  Masazumi Amagai,et al.  High solder joint reliability with lead free solders , 2003, 53rd Electronic Components and Technology Conference, 2003. Proceedings..

[3]  E. Bradley,et al.  Effect of Reflow Profiles on the Board Level Drop Reliability of Pb-Free (SnAgCu) BGA Assemblies , 2005, Proceedings Electronic Components and Technology, 2005. ECTC '05..

[4]  Seung Mo Kim,et al.  A methodology for drop performance prediction and application for design optimization of chip scale packages , 2005, Proceedings Electronic Components and Technology, 2005. ECTC '05..

[5]  E.H. Wong,et al.  Board level drop test reliability of IC packages , 2005, Proceedings Electronic Components and Technology, 2005. ECTC '05..

[6]  Y. Mui,et al.  Impact of substrate finish on Sn/Ag/Cu alloy solder joint , 2004, Proceedings of 6th Electronics Packaging Technology Conference (EPTC 2004) (IEEE Cat. No.04EX971).

[7]  J. N. Tey,et al.  Reaction of Sn-3.5Ag-0.7Cu-xSb solder with Cu metallization during reflow soldering , 2004, IEEE Transactions on Electronics Packaging Manufacturing.

[8]  T. Chiu,et al.  Effect of thermal aging on board level drop reliability for Pb-free BGA packages , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).

[9]  Yi-Shao Lai,et al.  Experimental studies of board-level reliability of chip-scale packages subjected to JEDEC drop test condition , 2006, Microelectron. Reliab..

[10]  M. Amagai,et al.  High drop test reliability: lead-free solders , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).

[11]  C. Kao,et al.  The effect of Ni on the interfacial reaction between Sn-Ag solder and Cu metallization , 2002, Proceedings of the 4th International Symposium on Electronic Materials and Packaging, 2002..