Critical temperatures in thermocompression gold stud bonding.
Zhang, G. G.
Ang, X. F.
Wong, Chee C.
Date of Issue2007
School of Materials Science and Engineering
A study on temperature dependence in gold-gold (Au–Au) thermocompression bonding was performed. Gold studs were bonded to two kinds of surfaces—cofired gold on alumina and electroless nickel covered with immersion Au on silicon. A critical bonding temperature was observed for both substrates. No bonding occurs when the temperature is below this threshold value, whereas bond strength increases with bonding temperature beyond the threshold. This critical temperature can be related to the activation of organic films on the bonding surfaces. Under similar bonding conditions, the critical temperature is lower for a harder substrate than for a softer substrate, primarily because of larger interfacial shear stresses. This is supported by the observation on the interfacial shear stress distribution at the bonding interface based on finite element simulation models of substrates with different hardness.
Journal of applied physics
© 2007 American Institute of Physics. This paper was published in Journal of Applied Physics and is made available as an electronic reprint (preprint) with permission of American Institute of Physics. The paper can be found at the following DOI: http://dx.doi.org/10.1063/1.2783974. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.