title: Molecular behavior at buried epoxy/poly(ethylene terephthalate) interface.
abstract: Epoxies are widely used as main components in packaging underfills for microelectronics. Their strong adhesion to different substrate materials is an important factor for the functioning of electronic devices. Amines are commonly used cross-linking agents for epoxides. However, the molecular mechanisms of epoxide-amine mixture adhesion to substrate materials remain unclear. In this research we investigated the adhesion mechanism of epoxide-amine mixtures at poly(ethylene terephthalate) (PET) interfaces using attenuated total-internal reflection Fourier transform infrared (ATR-FTIR) spectroscopy and sum frequency generation (SFG) vibrational spectroscopy. Results show that both epoxide and amine could diffuse into the PET film. They could also dissolve or modify the PET film at the interphase region. In the process of epoxy curing on PET, epoxide molecules could cross-link with the modified PET film, providing strong adhesion. This hypothesis was further confirmed by adding reactive and nonreactive silanes to the epoxies and measuring the adhesion strengths of such mixtures to PET. The reactive silanes could cross-link with the system, showing good adhesion, while the nonreactive silane prevented sufficient cross-linking, showing poor adhesion. This research developed an in-depth insight for molecular behaviors at the epoxy/PET interface which helped clarify the related adhesion mechanism.
authors.affiliation: Department of Chemistry, University of Michigan , 930 North University Avenue, Ann Arbor, Michigan 48109, United States.
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.forename: John N
authors.initials: JN
authors.lastname: Myers
authors.forename: Zhan
authors.initials: Z
authors.lastname: Chen
mesh_terms: D004852:Epoxy Compounds / Q000737:chemistry*; D008567:Membranes, Artificial; D011093:Polyethylene Terephthalates / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D004852:Epoxy Compounds; D008567:Membranes, Artificial; D011093:Polyethylene Terephthalates