Bonding mechanisms of laser‐fabricated titanium/polyimide and titanium coated glass/polyimide microjoints

Abstract

In this study, two bimaterial joining systems, namely, titanium coated glass/polyimide (TiGPI) and titanium/polyimide (TiPI) are considered. The joints were prepared by employing transmission type laser-joining procedure. Both the TiGPI and TiPI bimaterial systems were subjected to tensile loading using a microtester, and failure loads per unit bond length were documented. The average failure strengths of the TiPI and TiGPI samples were found to be 5.1 and 7.3 N/mm, respectively. It is thus clear from the failure data that the TiGPI joints are stronger (1.4 times) than the TiPI joints although same chemical bonds between titanium and polyimide (PI) exist for both the systems. It is thus believed that material surface morphology has contributed to such variation in the microjoint strengths. Later, atomic force microscopy (AFM) of titanium surfaces of both titanium coated glass and titanium foil was performed, and was observed that they had root mean squared (RMS) surface roughnesses of 220 and 55 nm, respectively. The surface roughness provides improved surface contact area, number of chemical bonds, and mechanical interlocking that may have resulted in higher bond strength for the TiGPI system.

Welding methods for joining thermoplastic polymers for the hermetic enclosure of medical devices

“…A number of studies by a group that assess transmission laser welding of thermoplastic polyimide to titanium coated glass for the purpose of microscale hermetic encapsulation are the only studies that investigate the key issues associated with polymeric enclosures, which include hermeticity and in vivo strength longevity [103][104][105][106][107][108][109]. Even though these studies do not assess complete polymer to polymer joining, they present important steps toward achieving this goal.…”

Postimplantation pressure testing and characterization of laser bonded glass/polyimide microjoints

“…A transmission joining configuration1–10 was used in which, the joining material combination includes one absorbent and one transparent part at the laser wavelength. Laser energy penetrates the transparent part and is absorbed by the absorbing part, so that the heat is induced directly at the interface.…”

“…Our group has previously demonstrated that titanium and polyimide,2–6 and titanium‐coated glass and polyimide6–10 can be joined to form microbonds among bimaterials using lasers. The x‐ray photoelectron spectroscopy (XPS) results published in references1, 2 showed that titanium‐oxygen and titanium‐carbon chemical bonds are present at the laser joining interface.…”

XPS analysis of the interface between AA2024‐T3/CF‐PPS friction spot joints

“…Moreover, to the best knowledge of the authors, besides a few works carried out on the laser welding, the metal–polymer interfacial bond formation for welding‐based joining technologies has not been extensively explored. In Georgiev et al .…”