Fundamental Study of Polymer to Metal Bonding in Integrated Circuit Packaging

Nowadays microelectronic packaging has become a billion dollar business. Due to the increased material and production costs per package, manufacturing yield loss in this state-of-art business is expected to be at a bare minimum which is tough to persevere in a high volume manufacturing environment. Additionally, high performance and varied power computing needs in the electronic business demands microprocessors with different form factors and complex package designs. One of the most common joint which is extensively used in such a complicated package is the polymer to metal bonding. In the latest technology products involving high package warpage, interfacial bonding has to be strong enough to withstand the dynamic warpage and high mechanical stresses associated with it and hence the reliability of polymer to metal adhesion is critical. In this paper, fundamental mechanisms related to adhesion phenomena of polymer-metal interface are proposed. Adhesive failure modes related to polymer-metal bonding and key variables influencing the bonding of silicone based polymer material to nickel electroplated on copper in an integrated circuit heat spreader assembly are experimentally studied. Factors modulating polymer to metal bonding including interfacial chemistry, surface contamination and material roughness are evaluated.