This paper contributes to an emerging literature aiming to understand the behavioral patterns that lead to the formation of social networks. We introduce a strategic model of inter-individual collaborations formation which is a variation of the Connections model. Heterogeneous agents benefit from knowledge spillovers flowing through the network and bear the costs of maintaining their direct links which increase with geographic distance. We show that this simple model generates emergent networks that share the main structural properties observed in most real social networks. Moreover, we bring the model to co-invention networks data and find that the model fits quite well the data through the various structural measures used. In particular, it provides a consistent explanation of the observed asymmetry in the distribution of neighborhood sizes and of the high concentration of connections in local areas while some distant connections are formed.