A method of forming a semiconductor package device includes: providing a substrate; bonding a first die to an upper surface of the substrate through a bonding layer; bonding a second die to the upper surface of the substrate through the bonding layer, the second die laterally separated from the first die; depositing an insulation material between the first die and the second die and filling a gap measured between sidewalk of the first die and the second die; forming a first interconnect layer over the first die and the second die to form the semiconductor package device; and performing a testing operation on semiconductor package device with the substrate in place. A Young's modulus of the substrate is greater than that of the insulation material.