International patent citations, its firm-led network

This paper presents a database with USPTO patents for selected years between 1991 and 2009, totaling 1,022,490 patents, 786,780 patents with international citations and 4,064,995 cross-border citations - links in our analysis. We evaluate a network from those international links, with nodes that are institutions - patent assignees. The literature review organizes arguments for patent citations as knowledge flows and acknowledges problems such as differences between applicants and examiners citations - an exercise to deal with this problem is presented. This network has firms as the dominant institution. An inter-temporal analysis shows the network growth over time and the preservation of its scale-free structure, evidence of its resilience. Over time, this network evolves, changing the leading sectors in a matrix of interaction between citing and cited patents - indications of changes caused by the emergence of new sectors.