Title :
Experimental characterizations for the shear strength of Pb-free solder balls on a PZT substrate with Pd/Ag pads
Author :
Huang, Xing Jia ; Lee, Shi-Wei Ricky ; Tse, Wan Sze
Author_Institution :
Dept. of Mech. Eng., Hong Kong Univ. of Sci. & Technol., Kowloon, China
Abstract :
Two lead-free solder alloys, 95.5Sn-3.8Ag-0.7Cu and 91.8Sn-3.4Ag-4.8Bi, and the conventional 63Sn-37Pb eutectic solder were reflowed on a PZT ceramic substrate with Pd/Ag solder pad metallization. The specimens were subjected to thermal aging for 1000 hours at temperatures of 85°C, 125°C and 150°C, respectively. Ball shear tests were performed to evaluate the effects of thermal aging on the various solders. In general, experimental data indicated that the shear strength of the solder balls gradually decreased with respect to increase in thermal aging temperature. Also, the longer the thermal aging time, the lower the ball shear strength. The shear strength of 95.5Sn-3.8Ag-0.7Cu solder balls was found to be the least sensitive to thermal aging. After thermal aging for 250 hours, with a few exceptions, the predominant failure mode in the ball shear tests appeared to be fracture at the interface between the Pd/Ag metallization and the PZT substrate. After thermal aging for 1000 hours, all specimens failed at the aforementioned interface. Using high magnification SEM inspection, a mixed-mode failure was observed. Further EDX analysis of the fracture surface confirmed the identified failure mode
Keywords :
X-ray chemical analysis; ageing; assembling; bismuth alloys; ceramic packaging; copper alloys; failure analysis; fracture; hybrid integrated circuits; inspection; integrated circuit interconnections; integrated circuit metallisation; integrated circuit packaging; integrated circuit testing; reflow soldering; scanning electron microscopy; shear strength; silver alloys; thick films; tin alloys; 1000 hr; 125 C; 150 C; 250 hr; 85 C; Ag; EDX analysis; PZT; PZT ceramic substrate; PZT substrate; Pb-free solder balls; PbZrO3TiO3; Pd; Pd/Ag metallization-PZT substrate interface fracture; Pd/Ag pads; Pd/Ag solder pad metallization; Pd/Ag thick film metallization; Sn-Ag-Bi Pb-free solder balls; Sn-Ag-Cu Pb-free solder balls; Sn-Pb eutectic solder; SnAgBi; SnAgCu; SnPb; ball shear strength; ball shear tests; failure mode; fracture; fracture surface; high magnification SEM inspection; lead-free solder alloys; mixed-mode failure; predominant failure mode; shear strength; solder balls; solder reflow; thermal aging; thermal aging temperature; thermal aging time; Aging; Ceramics; Environmentally friendly manufacturing techniques; Failure analysis; Inspection; Lead; Metallization; Performance evaluation; Temperature sensors; Testing;
Conference_Titel :
Electronics Packaging Technology Conference, 2000. (EPTC 2000). Proceedings of 3rd
Print_ISBN :
0-7803-6644-1
DOI :
10.1109/EPTC.2000.906354
