Abstract
Palladium-coated copper wire with a flash-gold layer (PCA) is an oxidation-resistant fine wire that simultaneously has the properties of palladium-coated copper wire (PCC) and gold-coated copper wire. This research used an extreme sulfidation test to compare corrosion resistance between the PCC and PCA wires. In addition to closely examining the morphology of the wires, the internal matrix after the sulfidation test is also discussed. In doing so, the PCA wire was bonded onto the aluminum pads and the sulfidation test was conducted. Then, we observed its morphology and elemental distribution and found that the flash-gold layer of the PCA wire effectively enhanced resistance to sulfidation corrosion. Because the copper ball had an alloying effect on the ball bonding, it produced different shapes of sulfide after the sulfidation test. The degree of corrosion on the wedge bond was different because of the presence or absence of the coated layer. In contrast, the flash-gold layer of the PCA wire enhanced the bonding force and retained low resistance characteristics after the sulfidation test.
Highlights
Due to the high price of gold (Au), lower-cost copper (Cu) and aluminum (Al) wires have gradually become the main bonding wires [1,2,3,4]
Ultrasonic wedge bonding of Al wire is the preferred method for electrical connections between devices and chip carriers [5]
Al wire is oxidized and is not conducive to forming free air balls (FABs), which deteriorates the reliability of the wire bonding
Summary
Due to the high price of gold (Au), lower-cost copper (Cu) and aluminum (Al) wires have gradually become the main bonding wires [1,2,3,4]. Al wire is oxidized and is not conducive to forming free air balls (FABs), which deteriorates the reliability of the wire bonding. Shortcomings of Cu wire include its high hardness and easy oxidation, it can be improved by annealing and coating with an antioxidant layer [6]. Used Cu-based wires include the palladium (Pd)-coated Cu wire (PCC) and the Au-coated Cu wire. Both can improve oxidation, some reliability problems remain with the processes. If the Au-coated layer is too thick, the free air ball (FAB) will be spear-like (lemony shape) and an Au-Al intermetallic compound will form after bonding [10]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
