Environmentally friendly thick film layers for a micro-fluid ejection head and micro-fluid ejection heads are disclosed. The environmentally friendly thick film layer includes a negative photoresist layer derived from a composition comprising a multi-functional epoxy compound, a low molecular weight polymeric difunctional epoxy compound, a monomeric difunctional epoxy compound, a methide-based photoacid generator that does not contain antimony, a chromophore and an aryl ketone solvent. Optionally the photoresist layer contains an adhesion enhancer. The negative photoresist layer is environmentally friendly and provides good resolution, well defined critical dimensions, straight side walls, and a large processing window.