Abstract
The contributions of volume and surface diffusion in high temperature sintering of copper were evaluated experimenta11y, using the sintering model compact developed by Ichinose and Kuczynski. A fine copper wire was plated with molybdenum, and then plated with copper, the thickness of which was varied to 3, 1 and 0.5 μm. Three wires thus treated with the same thick copper layer were twisted and then sintered in the slightly reducing nitrogen atmosphere.
In this case, the molybdenum layer acts as an inert marker. The neck boundaries were eliminated in this model compact, thus the operating diffusion mechanisms would be volume and/or surface diffusion. The aim of this experiment is as follows; if surface diffusion prevails, the neck growth rate would not be dependent on the thickness of plated copper layer, but if volume diffusion is predominant, it would be dependent on the thickness.
The observed neck growth follows Kuczynski's 5th power relation for volume diffusion. The neck growth rate is greatly dependent on the thickness of plated copper layer, and the expected value at thin layer is extremely small. In the case of 0.5 and 1 μm platedlayer, the neck growth was observed to stop in the latter stage, and the plated copper near the neck was exhausted. These results strongly support that volume diffusion controls the process. (Received February 25, 1988)
