A study of titanium thin films in transmission laser micro-joining of titanium-coated glass to polyimide

• Published in: Thin solid films 2010-03, Vol.518 (10), p.2632-2636
• Main Authors: Sultana, Taslema, Newaz, Golam, Georgiev, Grigor L., Baird, Ronald J., Auner, Gregory W., Patwa, Rahul, Herfurth, Hans J.
• Format: Article
• Language: English
• Subjects: Atomic force microscopy; Cathodic arc physical vapor deposition; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Crystallites; Deposition; Deposition by sputtering; Electron beam evaporation; Exact sciences and technology; Glass; Lasers; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; Titanium; Transmission laser joining; Vapor phase epitaxy; growth from vapor phase; X-ray photoelectron spectroscopy
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2009.08.004

Electron beam evaporation (EB-PVD) and cathodic arc physical vapor deposition (CA-PVD) techniques were used for the preparation of titanium (Ti) thin films onto Pyrex borosilicate 7740 glass wafers and the deposited films were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) techniques. The microstructure and surface morphology of the films were studied as a function of the film deposition techniques. Film properties such as, adherence, microstructure and roughness were interconnected to the laser joint strength between Ti coated glass wafers and polyimide films. Ti thin films on glass had a natural oxide layer on the surface as found from XPS. AFM study showed the formation of a uniform Ti coating consisted of packed crystallites with average size of 35 nm by EB-PVD. The root-mean-square surface roughness of the films was 1–2 nm. Whereas, films prepared by CA-PVD had crystallites with an average size of 120 nm and defects in the form of macro-particles which is a common attribute of this deposition system. The surface roughness of the film was 125 nm. The laser joint strength was found to be influenced by the Ti film quality on the glass substrate.