Coin insertion technology for PCB thermal solution

The thermal management of electronic products is always a headache to the high power electronics design engineer. Since all electronic components are assembled on the PCB, it´s important to develop a good solution to dissipate the heat from PCB to the chassis with conduction method. There are many material and process used for PCB thermal dissipation in the industry now. Some of them like IMS (Insulated Metal Substrate), can be used only for simple circuits like LED substrate. Some like metal bonded PCB that is heavy and expensive. The standard thermal pad/via is not capable for high thermal density components like QFN. It is necessary to develop a simple PCB construction to solve the thermal problem. This paper introduces new design which embeds a small piece of metal coin inside PCB under the high power components. The attached component, like power transistor, sits on the exposed coin surface of the new developed PCB. During operation, the heat created from the components can be effectively dissipated through the coin to another side of the PCB. The heat can then be dissipated to the chassis of equipment or another heat sink. The system thermal problem can be solved for the low thermal resistance of the heat path. Since the coin is small and light weight, it has great advantage of lower cost and very goof performance. Even component with dimension as small as 3 mm long can be applied. Besides, the coin can be electrically connected to the PCB ground layer with different methods. Its electrical performance runs very well in power amplifier PCB for telecommunication industry. This paper will also simulate the thermal performance of different PCB thermal design, include four different coin insertion constructions and its comparison with thermal via PCB and IMS laminate. This technology has been used in the PCB of cell phone base station, point-to-point radio and military radar system. It is also under testing for IC substrate application now.