I seeking any information on the effects that changing from difunctional epoxy FR-4 to tetrafunctional epoxy (UV-blocking) FR-4 on high frequency circuits in the 200MHz to 600MHz range. The industry is forcing this change and we have many customers that will require requalification of products to them if component changes are necessary. We are presently designing experiments for testing various parameters based on a typical high frequency pattern. Any information and suggestions are appreciated.