Conflict management is an unavoidable stage of the collaborative design process. We assume that classifying conflict causes can help conflict prevention as well as detection and resolution strategies. Our approach proposes a crossed classification of conflict causes and the correspondent mitigation strategies and implements this classification in order to enable conflict detection in the earlier phases of the design process. Emphasis is put on capture and use of design rationale and knowledge to help conflict mitigation. Based on this approach, a conflict mitigation module integrated in an advanced architecture for concurrent design and manufacturing is presented. A case study on the design of an electric connector illustrates the use of this module.