The present invention relates to the insulated mounting of an electronic component to a base structure, and more particularly to a low conductivity mounting stud and method for mounting an electronic component such as a transistor to a base structure such as a heat sink that eliminates the need for insulating washers and other insulators.
Semiconductor devices such as transistors and other electronic components often are mounted to base structures such as heat sinks with a mounting stud threaded to a nut. A problem encountered in the prior art is that two or more semiconductor devices are not insulated from one another if both are mounted to the same heat sink, unless insulators are used not only to insulate the device from the heat sink but also to insulate the device from the mounting stud. Typically, the back of the electronic component and the base structure both are electrically conductive. Therefore, when two or more components are mounted to the same base structure, there is a need to insulate each of the electronic components from one another.
In the prior art, an insulating washer generally is used to insulate the head of the mounting stud from the electronic component. Another insulating washer is used to insulate the nut from the heat sink. A mica insulator or layer of thermal grease insulates the electronic component from the heat sink. Additionally, an insulating sleeve is generally used around the shaft of the mounting stud to insulate the shaft from the electronic component and the heat sink. Alternatively, an insulating shoulder washer is used to insulate the head and shaft of the mounting stud.
A problem with the prior art therefore results from the substantial assembly work of numerous small parts including insulating washers and other insulators. Another problem with the prior art results when the washer between the mounting stud and the electronic component is torqued down, and the washer compresses resulting in a torque loss that is needed to hold the transistor firmly against the heat sink.
Other methods of insulated mounting of an electronic component to a heat sink or other base structure include a spring clip which bears on the top surface of the plastic body of the component and is connected to slots in the heat sink on either side of the component. A mica insulator or layer of thermal grease is used to insulate the component from the heat sink.
Thus, a need exists for a low conductivity mounting stud and method for mounting electronic components to heat sinks or other base structures with fewer insulating parts while preventing electrical contact between the components.