This report shows trends in PCB prototype sales and growth based on data from IPC's North American PCB Statistical Program covering 2014 through mid-2017. Data on prototype sales percentages by month compared to regular-production PCB sales, and estimates of North American prototype market sizes, are reported for all PCBs as well as for rigid PCBs and flexible circuits separately. The vertical market percentages for the industry's PCB sales overall are included for reference. 29 pages. Published October 2017