Solid State Science and Technology, Vol. 16, No 2 (2008) 173-179
Corresponding Author: email@example.com 173
EFFECT OF ULTRASONIC ENERGY AND FORCE ON INTERMETALLIC GROWTH PATTERNS FOR 2N GOLD WIRE
A. Jalar and M. F. Rosle
Advanced Semiconductor Packaging (ASPAC) Research Laboratory
Universiti Kebangsaan Malaysia
43600 UKM Bangi, Selangor, Malaysia
Intermetallic formation between gold wire and Al pad is well documented to represent mechanical strength of ballbond. Bonding achieved when these two metals come into intimate contact between each other by interactions of ultrasonic energy, force, temperature and time. Under elevated temperature and time, theoretically the intermetallic phase can thicken and growth due reactive diffusion activated by temperature. This paper presents effects on ultrasonic energy and force to the intermetallic growth patterns for gold wire with 99% composition of Au. Samples were prepared by different variables of ultrasonic energy and force with constants bonding temperature at 240°C. Investigation was carried out by baking the samples in the high thermal storage (HTS) chamber at 175 °C. Measurements for ballbond mechanical strength and observations on intermetallic growth patterns were carried out using ball shear and ball pull tester, optical microscope and scanning electron microscope (SEM). The results showed that, variables of ultrasonic energy and force at elevated time of HTS play significant influence to the intermetallic growth patterns and bonding strength.
. C. D. Breach, S. G. Mhaisalkar, T. Sritharan, F. Wulff and C. Xu, (2004); Oxidation of Bulk Au-Al Intermetallics, Thin Solid Films, Vol 462-463, pp. 357-362.
. C. D. Breach and F. Wulff, (2004); New Observations on Intermetallic Compound Formation in Gold Ball Bonds: General Growth Patterns and Identification of Two Forms of Au4Al. Microelectronics Reliability, Vol 44 pp. 973-981.
. G. G. Harman, (1997); Wire Bonding in Microelectronics, Materials, Processes, Reliability and Yield (2nd ed.), USA: McGraw-Hill.
. L. Jun-hui, H. Lei and Z. Jue, (2004); Studies of Microstructure Characteristics and Evolutions at the Bond Interfaces in Bonding Technology, IEEE-Proceeding of HDP, pp.316-321.
. S. Murali, (2006); Formation and Growth of Intermetallics in Thermosonic Wire Bonds: Significance of Vacancy–Solute Binding Energy. Alloys and Compounds, Vol 426, pp. 200-204.
. L. Jun-hui, W. Fu-Liang, H. Lei, D. Ji-an and Z. Jue, (2005); Atomic Diffusion Properties in Wire Bonding, Trans. of Nonferrous Met. Soc. China, vol. 16, pp.463-466.
. T. Y. Tee and X. Zhang (2005); Numerical and Experimental Correlation of High Temperature Reliability of Gold Wire Bonding to Intermetallics (Au/Al) Uniformity, Thin solid Films, Vol 504 pp. 355-361.
. J. F. Shackelford, (2000); Introduction to Materials Science for Engineers (5th ed.), New Jersey: Upper Saddle River.