After four years of R&D, a team led by Taiwan’s National Cheng Kung University (NCKU) professors has overcome problems such as the poor conductivity and ductility of aluminum and developed fine aluminum wires for use in ball wire bonding. This provides an alternative to the conventional copper systems used in semiconductor packaging. The use of aluminum instead of gold or copper in ball wire bonding could help chip-makers significantly reduce their production costs.
Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Typical wire diameters start at 15 µm and can be up to several hundred micro-metres for high-powered applications.
While copper wire is considered a cheaper alternative to gold wire for ball wire bonding used in semiconductor packaging, the process based on aluminum wire has been developed by NCKU to further reduce production costs. This could be the next thing in reducing production costs by a significant amount. Large scale roll out of the technology could lead to the IC’s being much cheaper and hence better availability of technology.
What’s different in the new wires?
The key to the breakthrough technology is aluminum wires coated with a layer of nano-zinc, NCKU disclosed. The diameter of the aluminum wire is about 18 micrometers, and the purity of aluminum has been enhanced to improve the material’s thermal conductivity, ductility and toughness. Reducing the wire such thinness, caused the wires to break, but the research has lead to wires being thinner than ever before, allowing for such thin wires without compromising the ductility.
NCKU also claimed it has been granted a patent for the aluminum ball bonding technology in Taiwan. The university has also applied for a patent in China.
NCKU’s research paper regarding the aluminum ball bonding technology will be published in July 2016.