This paper introduces an approach to study the coupling structure between the design parameters and design objectives of a LED system-in-package (SiP) design concept . The LED SiP is an integrated device that combines the LED chip with driver chips and potential other components in a single package, simplifying the design of lighting products and reducing the packaging costs. Due to the miniaturized design of the LED SiP, the interactions between the several components of heterogeneous nature become more dominant in the product behaviour, which complicates a proper design of such products. To overcome these complications the nature and intensity of the interactions between the different components must be clarified. Therefore a study was done on the coupling structure of these components in the LED SiP. A parameterization scheme is introduced to relate the design parameters to the design objectives. Two intermediate response levels are introduced to represent the physics-based behaviour inside the LED SiP. A Critical Parameter Sheet (CPS) like approach is adopted to analyse the influence of the couplings between the design parameters, the design objectives and the introduced physics-based response levels.