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Title: An experimental study of die attach polymer bleedout in ceramic packages
Authors: Marks, M.R. 
Thompson, J.A. 
Gopalakrishnan, R. 
Keywords: Gold
Nickel oxide
Surface energy
Issue Date: 15-Nov-1994
Citation: Marks, M.R.,Thompson, J.A.,Gopalakrishnan, R. (1994-11-15). An experimental study of die attach polymer bleedout in ceramic packages. Thin Solid Films 252 (1) : 54-60. ScholarBank@NUS Repository.
Abstract: The phenomenon of die attach polymer bleedout in gold plated ceramic packages poses a serious problem to the wire bonding process. Bleedout is basically a surface wetting process between the liquid die attach polymer and the gold plating. Two methods may be employed to eliminate bleedout: the surface energy reduction of the gold plating or-the improvement in the cohesiveness of the polymer die attach. The surface effects of vacuum baking at 200°C and 0.1 mbar, which is a widely used method to reduce the plating surface energy, were investigated. It was found that vacuum baking for 4 h was sufficient to eliminate bleedout through the formation of a nickel oxide film on the plating surface. However, the oxide film can detrimentally affect wire bonding quality and, as such, vacuum baking is not recommended. An alternative method to eliminate bleedout is by increasing the cohesiveness of the polymer matrix. This can be achieved by increasing the intermolecular attractive energy through the presence of functional groups with high dipole moments in high concentrations. Phenol-cured epoxy, polyimide and polycyanurate were found to have good bleedout resistance, presumably owing to the high dipole moments of epoxide and hydroxyl in phenol-cured epoxy, carbonyl and hydroxyl in polyimide, and nitrile and carbonyl in polycyanurate. The use of such polymers makes vacuum baking or other surface treatment of the gold plating unnecessary. © 1994.
Source Title: Thin Solid Films
ISSN: 00406090
Appears in Collections:Staff Publications

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