In this article, we describe the synthesis and characterization of a new family of photoimageable dielectric insulating polymer films. Four different photoimageable thin films have been prepared from all-aromatic and aromatic/aliphatic copolyesters, which exhibit good photospeed (10-180 s, 15.5 mW/cm(2) intensity), resolution and line width (10 mu m), thermal stability (330-400 degrees C), adhesion on different substrates, mechanical strength, and reasonable glass transition temperature (120-150 degrees C). One feature of the new photoimageable copolyester is the formation of a low dielectric constant film (2.5 at 1kHz, 25 degrees C) upon curing at temperatures up to 280 degrees C. The low dielectric constant is a result of foaming arising from evolution of by-products during curing.