Development of an eco-friendly stripper containing organic ammonium hydroxide

Abstract

Dry film resist (DFR) is photosensitive film which is generally used for pattern formation through a photolithography process after lamination to the copper sheet of printed circuit board. DFR is made up of a binder polymer and photocurable monomers which are typically based on polyfunctional acrylates. It is cross-linked by exposure to UV light. After the pattern formation using DFR by exposure to UV light, DFR must be completely removed. To remove the DFR, stripper is used a chemical solution that removes the residual DFR after the plating processes. Most of the conventional strippers are composed of tetramethylammonium hydroxide (TMAH). TMAH is a key component of the conventional strippers. However, TMAH is a toxic material to the human body. We have suggested a novel stripper to replace the TMAH component. The novel stripper is based organic ammonium hydroxide, MEA (monoethanol amine) and glycol ether. The novel stripper is less harmful because organic ammonium hydroxide avoids the similarity of acetylcholine which is neurotransmitter. In addition, glycol ether was added in order to improve the performance of the stripper. It improves the solubility of DFR in a stripper and has the important role for better strip performance than the conventional strippers. Furthermore, we separated DFR components using column chromatography for analysis of DFR.