The disclosure describes a heat-dissipating object having a reservoir structure so that a reservoir system can be formed in an electronic device, allowing for a liquid TIM in the gap between the heat-dissipating object and the heat-generating object of the electronic device. The reservoir structure comprises a seal ring, a connecting hole and a reservoir which is a space for taking in a liquid material and releasing it again when needed. As a specific case of the heat-dissipating object and the electronic device, a lid having a reservoir structure and a lidded flip chip package based on the lid are particularly described in details of the embodiments of the present invention.