HIGH DENSITY FLIP CHIP WITH ADHESIVES ON CERAMICS

摘要

With regard to Mgh density and environmental-friendly chip-assembly processes, a new isotropic conductive adhesive (ICA) - non-conductive adhesive (NCA) flip chip technology was developed to meet those demands. This technology was already used on FH4 [1] and low-temperature substrates [2] with success. In this paper, the use of this ICA-NCA flip chip process on 96% Al{sub}2O{sub}3 will be described. A single layer test substrate has been made for a chip layout with staggered bonding pad layout and a pitch of 200μm. Four-point and daisy chain resistance measurement structures were available on this chip. Using standard thick-film screenprinting technologies, a conductive layer pitch below 250μm is difficult to achieve. In order to combine the high-density flip chip process with the thick-film technology, some other product had to be found. The product we used was the Heraeus KQ500 etchable gold conductor. The pitch of the flip chip assembly could easily be achieved with that gold conductor. The processing steps in that new flip chip assembly process are: the deposition and drying of the ICA, dispensing of the NCA, placement and thermocompression of the chip. In the area of thick film on ceramics, the speed and cost-effectiveness of the assembly process is very important. Therefore we believe we have developed a suitable process that takes into account all these demands.