Power converter package with enhanced thermal management

#This invention relates to the packaging and assembly of electrical components, and more particularly to the packaging and assembly for power converters with enhanced thermal management, high electrical interconnection density and low profile.

#Please refer to FIG. 1. FIG. 1 shows one approach to package electric components in a power converter according to the prior art. As shown in FIG. 1, power-dissipating devices such as 9b, 9d and a magnetic element 9c are mounted directly on a metal base-plate 6 by a thermally conductive insulator 8 for better heat transfer. The power components are electrically connected with a PCB 5a by single-lateral leads 12. The magnetic element 9c is electrically connected to PCB 5a by leaded terminals. And, other necessary components such as 9a, 9e are mounted to one side or both sides of the PCB 5a. The assembly may be encapsulated within a capsule (not shown), which acts as a heat spreader and mechanical support.

#One drawback of the packaging art in FIG. 1, however, is that since the power-dissipating devices 9b, 9d are electrically connected with the PCB 5a by the single-lateral leads 12, it will be difficult to keep these devices co-planar during the mounting process, which would make the overall manufacturing process more complex, and thus would undesirably increase the manufacturing cost. Meanwhile, the leaded electrical connections of power dissipation devices as well as magnetic element will cause high interconnection parasites, which will result in additional connection resistance loss and poor converter performance especially for high current converter packaging. Moreover, the power-dissipating devices 9b, 9d are comparatively in a bigger footprint, which would inevitably cause a lower power density packaging.

#FIG. 1 is a cross-sectional side view of the prior art for a power converter package wherein a power dissipation device with single-lateral leads is attached to a metal base-plate;

#FIG. 2 is a cross-sectional side view of the prior art for a power converter package wherein heat from a power dissipation device is transferred through copper coated vias of a PCB;

#FIG. 3 is a cross-sectional side view of a power converter packaging according to the present invention, wherein the sub-package with power dissipating chips are mounted to one side of a PCB;

#FIG. 3 is a cross-sectional side view of a preferred embodiment of the power converter package according to the present invention. As shown, all the electrical connections for a power converter are achieved by fully being mounted onto a multi-layer PCB 402 in order to have a high interconnection density. A heat spreader 404 is directly attached onto a bare top heat-slug 405 of the sub-packages 401 and magnetic element 407 through a thermally conductive insulator 406. The magnetic element 407 can be mounted into cutouts of the PCB 402 or be mounted onto top-side of the PCB 402. The control device 408 and passive part 409 can be mounted onto one side or both sides of the PCB 402, and the heater spreader 404 can also be attached onto them. A hard epoxy cover 410 may be applied to isolate the components from environment.

#As can be seen, in the present invention, the sub-package 401 is disposed between the multi-layer PCB 402 and the heat spreader 404. In this way, the multi-layer PCB 402 is adapted to be electrically connected with the leads 403 of the sub-package 401 to provide an electrically conductive pathway therebetween. The heat spreader 404 is adapted to be thermally connected with the heat-slug 405 of sub-package 401 through a thermally conductive insulator 406 to provide a thermally conductive pathway therebetween.

#The heat from the sub-package 401 can be directly transferred to the attached heat spreader 404 by the bare top heat-slug 405 of the sub-package 401, and further transferred to the outside. The electrical connection, however, is only occurred between the leads 403 of the sub-package 401 and the multi-layer PCB 402. This assembly of the package realizes that the electrically conductive pathway is separate from the thermally conductive pathway, and hence achieves an enhanced thermal management.