| abstract |
The present disclosure is directed to a coverlay comprising a polyimide film and an adhesive layer. The polyimide film is composed of a polyimide and a sub-micron filler. The polyimide is derived from at least one aromatic dianhydride component selected from rigid rod dianhydride, non-rigid rod dianhydride and combinations thereof, and at least one aromatic diamine component selected from rigid rod diamine, non-rigid rod diamine and combinations thereof. The mole ratio of dianhydride to diamine is 48-52:52-48 and the ratio of X:Y is 20-80:80-20 where X is the mole percent of rigid rod dianhydride and rigid rod diamine, and Y is the mole percent of non-rigid rod dianhydride and non-rigid rod diamine. The sub-micron filler is less than 550 nanometers in at least one dimension; has an aspect ratio greater than 3:1; is less than the thickness of the film in all dimensions. |