Abstract: A composition and method for etching a polymer substrate in particular for forming micro vias includes a dihydric alcohol having from two to five carbon atoms, a hydroxide compound selected from the group of lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide and mixtures thereof, and water. In one embodiment the composition includes glycol, potassium hydroxide and deionized water, wherein the glycol and the water are present in a ratio of from about 0.5:1 to about 8.5:1 and the potassium hydroxide is present in an amount of from about 40 to about 80 grams per 100 ml of glycol and water solution.