title: Non-hermetic encapsulation for implantable electronic devices based on epoxy.
abstract: Hermetic and non-hermetic implant packaging are the two strategies to protect electronic systems from the humid conditions inside the human body. Within the scope of this work twelve different material combinations for a non-hermetic, high-reliable epoxy based encapsulation technique were characterized. Three EPO-TEK (ET) epoxies and one low budget epoxy were chosen for studies with respect to their processability, water vapor transmission rate (WVTR) and adhesion to two different ceramic-based substrates as well as to one standard FR4-substrate. Setups were built to analyze the mentioned properties for at least 30 days using an aging test in a moist environment. As secondary test subjects, commercially available USB flash drives (UFD) were successfully encapsulated inside the epoxies, soaked in phosphate buffered saline (PBS, pH=7.4), stored in an incubator (37°C) and tested for 256 days without failure. By means of epoxy WVTR (0.0278 g/day/m(2)) and degrease of adhesion (24.59 %) during 30 days in PBS, the combination of the standard FR4-substrate and the epoxy ET 301-2 was found to feature the best encapsulation properties. If a ceramic-based electronic system has to be used, the most promising combination consists of the alumina substrate and the epoxy ET 302-3M (WVTR: 0.0588 g/day/m(2); adhesion drop: 49.58 %).
authors.forename: Fabian
authors.initials: F
authors.lastname: Boeser
authors.forename: Juan S
authors.initials: JS
authors.lastname: Ordonez
authors.forename: Martin
authors.initials: M
authors.lastname: Schuettler
authors.forename: Thomas
authors.initials: T
authors.lastname: Stieglitz
authors.forename: Dennis T T
authors.initials: DT
authors.lastname: Plachta
mesh_terms: D004853:Epoxy Resins; D019064:Product Packaging; D019736:Prostheses and Implants; D015035:Zinc Oxide-Eugenol Cement
chemical_list: D004853:Epoxy Resins; C510255:Hermetic; D015035:Zinc Oxide-Eugenol Cement