A thermal cooling device for cooling electronic components of a circuit board, the electronic components comprising a primary electronic component, and one or more secondary electronic components, the device comprising: a first cooling component comprising a first cooling member (410, 510) configured to contact a thermal contact surface of the primary electronic component, the first cooling member being further configured to be in fluid communication with a fluid to effect an operative convective cooling of the thermal contact surface of the primary electronic component, the first cooling component comprising a microjet array defining a convection cooling area at least partially overlapping with the thermal contact surface of the primary electronic component and within which pressurised fluid operatively directly contacts the thermal contact surface to dissipate heat away from the thermal contact surface; and a second cooling component comprising a second cooling member (420, 520) having a cooling distal region configured to contact a respective thermal surface of the one or more secondary electronic components to effect an operative conduction cooling of the one or more secondary electronic components, the second cooling member having a cooling proximal region thermally coupled to the first cooling member, wherein each of the first and second cooling members are separate and distinct members, the second cooling member physically abutting the first cooling member; characterized in that the first cooling member comprises a thermal base plate and the second cooling member comprises a conduction plate, the conduction plate configured to act as a thermal bus to conduct heat from the secondary electronics to the thermal base plate, wherein the conduction plate has an opening configured to receive the thermal base plate, the thermal base plate configured to fit the receiving opening of the conduction plate, and where the convection cooling operatively effected by the first cooling component has a first cooling effectiveness, the conduction cooling operatively effected by the second cooling component has a second cooling effectiveness lower than the first cooling effectiveness so as to operatively form a temperature depression at a perimeter of the first cooling component, wherein operatively a thermal joint region is defined between each of the first cooling component and the second cooling component, the thermal joint region extending about the perimeter of the first cooling component forming the temperature depression at the perimeter of the first cooling component. a first cooling component comprising a first cooling member (410, 510) configured to contact a thermal contact surface of the primary electronic component, the first cooling member being further configured to be in fluid communication with a fluid to effect an operative convective cooling of the thermal contact surface of the primary electronic component, the first cooling component comprising a microjet array defining a convection cooling area at least partially overlapping with the thermal contact surface of the primary electronic component and within which pressurised fluid operatively directly contacts the thermal contact surface to dissipate heat away from the thermal contact surface; and a second cooling component comprising a second cooling member (420, 520) having a cooling distal region configured to contact a respective thermal surface of the one or more secondary electronic components to effect an operative conduction cooling of the one or more secondary electronic components, the second cooling member having a cooling proximal region thermally coupled to the first cooling member, wherein each of the first and second cooling members are separate and distinct members, the second cooling member physically abutting the first cooling member; characterized in that the first cooling member comprises a thermal base plate and the second cooling member comprises a conduction plate, the conduction plate configured to act as a thermal bus to conduct heat from the secondary electronics to the thermal base plate, wherein the conduction plate has an opening configured to receive the thermal base plate, the thermal base plate configured to fit the receiving opening of the conduction plate, and where the convection cooling operatively effected by the first cooling component has a first cooling effectiveness, the conduction cooling operatively effected by the second cooling component has a second cooling effectiveness lower than the first cooling effectiveness so as to operatively form a temperature depression at a perimeter of the first cooling component, wherein operatively a thermal joint region is defined between each of the first cooling component and the second cooling component, the thermal joint region extending about the perimeter of the first cooling component forming the temperature depression at the perimeter of the first cooling component.