The present invention is directed to phosphorus containing (or "halogen free") flame retardant photoimagable compositions useful as a coverlay material in a flexible electronic circuitry package. These compositions are generally photosensitive and comprise phosphorus containing acrylates and phosphorus-containing photo-initiators mixed with a polymer binder. The compositions of the present invention typically comprise elemental phosphorus in an amount between, and including, any two of the following numbers 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, 5.0, 5.2, 5.4, 5.6, 5.8 and 6.0 weight percent.