Thick film initiator elements - an alternative to resistive wire initiators for automotive safety units

Safety units in cars such as airbags or seat belt pretensioners protecting passengers of cars against risks of injury in the case of an accident are equipped with detonators. They are typically activated by electro-explosive devices where resistive wire elements are generally considered as well established initiator systems. Crash sensors in cars induce, in the case of an accident, a current pulse in this resistive initiator element. As the device is heated up to a critical temperature the explosive detonates and consequently the airbag or the retention system will be released. Thick film technology has been evaluated for the realisation of appropriate resistive ignition elements as an alternative to the conventional wire elements, which are considered to be capable of meeting future requirements of the automotive industry. The performance of thick film initiator elements is evaluated on the base of numerical simulation utilizing finite element method.