PCB007 Magazine


Issue link: https://iconnect007.uberflip.com/i/1050827

Contents of this Issue


Page 69 of 111

70 PCB007 MAGAZINE I NOVEMBER 2018 Dry Film Resist Complexities Before delving into the bullet points listed above, it would be a good idea to get an under- standing of resist technology in general. Photo- resist is a complex mix of chemicals. Photore- sists are commonly composed of acrylic resins, polyvinyl cinnamates, diazo compounds, phe- nol-formaldehydes, or other similar film-form- ing materials. Photoresists can be applied dry or wet to a substrate. After the exposure pro- cess of step, the photoresist-covered copper- clad laminate sandwich goes through the de- veloping step. The entire panel is exposed to carbonate-based chemistry, which reacts with and dissolves the unexposed portions of the photoresist. The exposed portions of the pho- toresist do not react with the carbonate-based developer chemistry. What is left behind is the In Part 1 of this series on resist stripping, I presented some of the basics related to resist stripping chemistry. The pH curves of the per- formance of generic resist strippers were used to illustrate stripping behavior during the pro- cess as well as the best method to control the stripping process. In Part 2, I will focus on some additional performance properties of the resist stripping, such as: • "Cleanliness" of stripping • Size of stripper skins (i.e., the stripped particles) • Tarnishing of the copper surface • Attack/activation of tin or tin-lead etch resists (this will be explored in a future column) The Art and Science of Resist Stripping, Part 2 Trouble in Your Tank by Michael Carano, RBP CHEMICAL TECHNOLOGY

Articles in this issue

Links on this page

Archives of this issue

view archives of PCB007 Magazine - PCB007-Nov2018