Abstract: The present disclosure provides a method of measuring a plurality of voids in an underfill material of an underfill package. The method includes operations of obtaining a welding angle profile of the underfill package; obtaining a simulated void profile of the underfill package according to the welding angle profile; determining a plurality of high-risk void regions according to the simulated void profile; simulating, according to a selected pressure and a selected temperature of the underfill material, a first high-risk void region of the plurality of high-risk void regions to generate an updated void profile; and determining whether the updated void profile meets a void requirement of the underfill package.