Product platforms are used in many industries to allow a variety of products to be offered to the market while levering commonality in components. The reported approaches to designing product platforms assume mature and stable design and manufacturing technologies. Consequently, product platforms are not applicable in the semiconductor equipment manufacturing industries, where the technologies keep evolving and cannot be frozen in the product development process. In response to the application limitations of traditional platforms, a concept of function-technology (FT) platform is put forward to assist semiconductor equipment manufacturers to efficiently design product families by reusing, in a structured way, functions and technologies. To shed light on the diverse constituent elements and the complex relationships inherent in an FT platform, this study focuses on its structural representation. A formalism of FT platform representation is developed based on the unified modelling language (UML). It consists of a generic functional structure, a generic technology structure and the mapping relationships in-between. An application case in a well-known semiconductor equipment manufacturer is also reported to present the structure of an FT platform and its representation based on the UML.