Effects of Pd Surface Coating on the Strength and Fracture Behavior of Cu Micro Bonding Wires
- PDF / 2,460,940 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 55 Downloads / 236 Views
In the microelectronic packaging industry, metallic micro bonding wires are the most commonly used material for interconnecting integrated circuit (IC) pads in microelectronic packaging.[1,2] However, during long-term service, intermetallic compounds (IMCs) will form, and cause de-bonding failure.[3–6] In response to the great demand for reliability of electronics packaging, researchers have developed Cu as an alternative bonding wire material. Because the Cu offers multiple advantages: (1) Cu micro bonding wires exhibit greater strength and hardness than Au and Ag micro bonding
HAOKUN YANG is with the Hong Kong Branch of National Precious Metals Material Engineering Research Center, City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong, P.R. China and also with the Department of Mechanical Engineering, City University of Hong Kong. KE CAO is with the Department of Mechanical Engineering, City University of Hong Kong. JIAN LU and YANG LU are with the Hong Kong Branch of National Precious Metals Material Engineering Research Center, City University of Hong Kong, and with the Department of Mechanical Engineering, City University of Hong Kong, and also with the Center for Advanced Structural Materials, City University of Hong Kong Shenzhen Research Institute, 8 Yuexing 1st Road, Shenzhen, P.R. China. Contact e-mails: [email protected]; [email protected] Manuscript submitted December 6, 2018. Article published online May 7, 2019 METALLURGICAL AND MATERIALS TRANSACTIONS A
wires, enabling a reduction of the wire diameter and cost savings.[7–9] (2) Cu has a lower interdiffusion rate between Cu and Al, which reduces IMC growth.[10–12] (3) Cu exhibits high thermal conductivity, which enables a shorter heating affected zone and avoids necking failure within the heat affected zone.[13,14] However, Cu micro bonding wires also have drawbacks that merit attention. Firstly, Cu micro bonding wires are easily oxidized, so that the adequate preservation of products is required.[6,15] Furthermore, the inert gas needs to be used during the bonding procedure to avoid oxidation and the formation of an unreliable joint.[7,9] Recently, an approach of coating Pd onto the surface of Cu micro bonding wires was developed. Lin et al.[16] found that a Pd coating enhanced the bonding reliability of Cu micro bonding wires even after longterm aging. In addition, Hu et al.[17] reported that a Pd layer reduced electromigration, thereby delaying void formation and prolonging the bonding service life.[18,19] Previously, Clauberg et al.[20] studied the bonding strength and Kaimori et al.[21] investigated the bondability and reliability of Pd-coated Cu micro bonding wires. However, the effects of a Pd coating on the mechanical properties and fracture mechanism of Cu micro bonding wires are rarely investigated. Therefore, in the present study, we focus on these two aspects for further investigation. Commercial high-purity Cu (> 99.9 wt pct) and Pd-coated Cu micro bonding wires from ShenZhen Cnuti Precious Metal Materials Co. Ltd. were chosen. The n
Data Loading...
