Overmoulding of Electronics for End of Life Recovery

Abstract

With the increasing use of electronic control systems in automotive applications, the environments in which they are required to operate are becoming evermore demanding. For improved functionality and to reduce the number of interconnections it is desirable to place the electronic control units (ECUs) as close as possible to the sensors and actuators they interact with, and they can increasingly be found mounted on engine, transmission and chassis components. The electronics are therefore exposed to high/low temperatures, high humidity, vibration and corrosive fluids. In order to protect the electronics and maintain reliability in safety critical areas, great lengths are taken to mount the devices in ways that will prevent the ingress of moisture, cushion shocks and dissipate heat. Potting of electrical devices with thermosetting polymers has been a commonplace method to install a protective layer over the circuit assemblies, which are often mounted in separate boxes within the vehicle. However, with the drive to reduce vehicle weight and increase recyclability, there has been much interest in the use of overmoulding with thermoplastic polymers, not only to provide protection, but to enable the electronics to be mounted into a structural component of the vehicle thereby saving space and weight and eliminating a level of packaging. While this has been shown to be a practical way forward in terms of reliability, the recyclability of the thermoplastic polymer is compromised by the intermixed electronics that are hard to separate economically.