Gold ballbonding is an enabling technology in electronics packaging that accounts for around 90% of the world demand for packaged IC's. Thinner IC packaging demands lower wire loops and the stacked dies used for example in mobile telecommunications applications require a range of loop heights from very high to very low. In addition, multi-tier wirebonding also demands ultra low loop profile for its application. The lowest achievable loop heights are physically constrained by the wire dimensions and the plastic deformation behaviour of the wire. Ultra low loops result in extensive plastic deformation in the heat affected zone (HAZ). This paper examines the correlation between the wire properties (break load, modulus, hardness, grain size. HAZ length) and looping 'performance. The springback height of the lifted ball due to tension in the wire from bonding, and how it affects the looping behaviour is also discussed.

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The paper discusses on the bondability and reliability of aluminum (Al) wedge-to-wedge bonding using fine ceramic capillary and ball bonder. Initial trials revealed aluminum build-up and poor capillary life with touch down of 20K or less. Optimizing the process parameters, switching on air-scrub, reducing shape angle to 20° instead of usual 35° and using Al-1wt%Si wire processed with refined grains revealed better capillary life with touch down of 200K without surface burrs. The method is capable of bonding complex looping and sharp acute bends. The data comprising of 1st and 2nd wedge dimensions, wedge pull, wedge shear and fracture mode for 20μm and 50μm Al-1wt%Si wires are presented. High temperature storage of aluminum wedge bonding to different substrate surfaces such as Al-0.5wt%Cu metallization, bare copper and gold plating revealed stable bond. From the wedge pull and tensile data, floor and shelf life of the wire is recommended to be 7days and 6months respectively. Evaluation of gold, copper and silver base bonding wires by this method showed feasible to bond and needs detailed studies to practice. The fusing current of Al-1wt%Si wire for varying diameter from 0.6 to 3mil and wire length from 1 to 20mm are also stated.