Based on introducing the underfill process of flip chip, the effects of such factors as glue viscosity, processing temperature, storage period and flow speed on the underfill quality were analyzed. Experimental results show under room temperature, the filling rate of adhesive in FPA ultraviolet detector achieves 100% under the conditions of storage time of less than 1 hour and flow speed of 0.2mg/min. 95% the devices pass the electrical parametric testing.