  This study presents techniques for the mass production of large-sized GEM
foils for the CMS phase-2 upgrade by the Korean CMS group. The foil production
facility is designed with a focus on mass production, including the adoption of
the double-mask technique. A polyimide wet etching technology that uses mono
ethanolamine is reported, providing a safer working environment due to its
lower inhalation toxicity compared to ethylene diamine. The study also covers
the denaturation of the etchant over time and the process of retuning. Finally,
R&D results on soldering surface mount resistors with hot air for faster
production are discussed.
