In the last 5 years, multi-core processors become more and more available to the wide public. Support for multi-core processors becomes de facto a standard for computation-intensive applications. In this paper, we present a parallel implementation of the UniCalc solver for non-linear engineering problems. Unlike the existent solvers of non-linear constraints, our parallel implementation scales well for sparse systems of non-linear constraints. We give scalability data for a quad-core processor.