Laser bonding and characterization of Kapton^® FN/Ti and Teflon^® FEP/Ti systems

Kapton^® FN and Teflon^® FEP (fluorinated ethylene propylene) polymers are resistant to most chemical solvents, heat sealable, and have low moisture uptake, which make them attractive as packaging materials for electronics and implantable devices. Kapton^® FN/Ti and Teflon^® FEP/Ti microjoints were fabricated by using focused infrared laser irradiation. Laser-bonded samples were tested with a micro-testing machine under lap shear load and the bond strength was determined. The bond strength for the Kapton^® FN/Ti and Teflon^® FEP/Ti systems was found to be 3.32 and 8.48 N/mm², respectively. The failure mode of the mechanically tested samples was studied by using optical microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. Chemical interactions during laser bonding of Kapton^® FN to titanium were studied by using X-ray photoelectron spectroscopy (XPS). The XPS results give evidence for the formation of Ti–F bonds in the interfacial region.