Magnetic recording medium prodn. with good adhesion and uniform properties - by exposing polymer substrate to UV light from excimer source before physical vapour deposition of metal thin film

摘要

The process concerns the prodn. of magnetic recording media based on a polymeric substrate (I), opt. a metal sub-coat (II), a coherent ferrogmagnetic metal thin film (III), produced on the surface by the PVD (physical vapour deposition) process, and opt. a protective top coat. Before deposition of (III) or of (II), if used, (I) is exposed to excimer UV radiation in the 150-400 nm range, with an energy density below the ablation threshold. Pref. radiation from a UV excimer laser is used. USE/ADVANTAGE - This treatment improves the adhesion of the metal to (I) and ensures more uniform properties, even on large areas with high process spreeds. It is useful with e.g. PET, polyimide, polyethylene naphthalate, PEEK, polysulphone, polyether-sulphone, polyphenylene sulphide and thermotropic liquid crystalline polymer substrates. In an example, a 200 nm thick Co80Ni20 film was deposited on a 50 micron PET film by PVD in high vacuum. Before PVD, the PET was exposed to 3 pulses 248 nm excimer laser radiation with an energy density of (A) 5, (B) 10, (C) 15, (D) 26 mK/sq. cm. The peel strength of the metal film of, a control (E) with an untreated PET substrate was (A) 1.2, (B) 2.7, (C) 3.9, (D) over 4.5, (E) 0.9 N/