Physical and chemical factors governing dissolution of novolak resin films

The authors have investigated the dissolution of a series of novolac resins with different structures and properties with various quaternary ammonium hydroxides using a new technique called Spectroscopic Dissolution Rate Monitoring (SDRM). This technique allows direct spectral measurement of an absorption band attributed to cation complex formation. The rate of formation of this complex is used as an approximation or surrogate for cation diffusion. The rate of formation of the complex is approximately the same as the rate of dissolution when using a rinse. This evidence supports cation diffusion as the rate determining step even in TMAH development of high ortho, ortho bonded systems. Our studies also suggest that polymer flexibility and microstructure exert a strong influence on the cation diffusion rate.