Initial Life Test of Silicone Encapsulated FR4 Printed Circuit Boards for Pre-Clinical Active Implants

Abstract

Silicone encapsulated FR4 printed circuit boards may provide a rapid solution for protecting pre-clinical prototype implant electronics. Interdigitated electrodes (IDEs) with and without solder coating were manufactured on Cu-FR4 laminates and silicone encapsulated (N = 14). IDEs were aged in saline and change in impedance was measured. Solder coated IDEs had stable 1 kHz impedances throughout the aging period with promising lifetimes for pre-clinical prototypes. A single uncoated IDE failed with a fall in impedance and verdigris. Other uncoated IDEs showed increasing impedance and dark copper(II) oxide. Failures attributable to contaminants and moisture ingress are under investigation.