An application specific inflexible FPGA (ASIF) is an FPGA with reduced flexibility and improved density. An ASIF is reduced from an FPGA for a predefined set of applications that operate at mutually exclusive times. This work presents a new tree-based ASIF and uses a set of 16 MCNC benchmarks to explore the effect of lookup table (LUT) and arity size on it and results are then compared with those of mesh-based ASIF. For tree-based ASIF, LUT size is varied from 3 to 7 while arity size is varied from 4 to 8 and 16. Experimental results show that smaller LUTs with higher arity sizes produce good area results but poor performance results. Finally experimental results show that LUT 4 with arity 16 gives best area-delay product and compared to mesh-based ASIF, this combination gives 12% routing area gain.