Here is the abstract you requested from the HITEC_2018 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Influence of Initial Shear Strength on Time to Failure of Copper (Cu) Wire Bonds in Thermal Aging Condition|
|Keywords: Copper wire bond, Shear Strength , Accelerated Test|
|Copper (Cu) wire bonding is now widely accepted as a replacement for gold (Au). Cost savings mainly drive the transition to Cu wire bonding, although there are other advantages to Cu such as better electrical and thermal conductivity and slower intermetallic compound (IMC) formation. High temperature applications such as automotive, industrial and aerospace application, however, are still reluctant to adopt Cu wire bonded products due to perceived risks of wire and bond pad cracks, the potential for corrosion, and a lack of understanding about its reliability in extreme temperature conditions. Shear strength and IMC coverage are being widely used as an indicator of good quality bond that will eventually lead to high reliability, however there is no clear relationship between the two. High shear strength is a result of large IMC coverage laterally, under the ball bond and the reliability of the bond is related to longitudinal growth of IMC. There is absence of information between lateral and longitudinal formation of IMC leading to effect on reliability. This work involves studying effect of shear strength on reliability of ball bonds by performing temperature aging experiments on test devices, of QFN packages, consisting of different IMC coverage leading to a range of shear strength. The wire bonds are made by altering power and time used with ultrasonic that leads to different IMC coverage. For each bonding parameter used, shear strength of the bonds are measured on one set (about 10) of bonds while another set of bonds are aged in temperature condition of 150�C, 175�C and 200�C. Thus, a total of 40 test packages are monitored for resistance change at specific intervals by performing four point resistance measurement. Failure of the device will be correlated to the initial shear strength of the bonds and relationship between shear strength and time to failure will be made.|
University of Maryland
College Park, MD