Abstract
In the past, outer dimensions of new automobiles grew steadily as the feature content of new vehicles increased. Todays markets no longer accept cars to increase in size. While the cars dimensions remain constant, the customer still expects the vehicle to perform better in terms of roominess, comfort, safety and fuel efficiency. As a result the available package space to mount components such as climate control units and electronic control modules decreases.
The available packaging space decreases as the speed at which new systems are introduced offset successes to reduce existing hardware in size and weight. This scenario requires specific packaging technologies that also take the growing demand for quality and reliability of electronic modules and their interconnecting technologies into consideration.
A concept challenging standard electronic packaging concepts, with numerous functional and design advantages for certain application areas, is the injection moulded circuit board or
Moulded Interconnect Device (MID). MIDs are highly integrated devices incorporating a conductive circuit pattern, housing as well as various mechanical and electrical components. The injection moulding process yields the advantage to manufacture three dimensional MID substrates in a cost effective manner. MIDs use thermoplastic resins to form the substrate as opposed to thermosetting polymers currently in use for rigid printed circuit boards. The use of thermoplastic resins facilitates three dimensional substrates. Thermoplastic resins can be recovered and recycled more easily than thermosetting polymers. However, the temperatures associated with standard soldering processes call for high temperature thermoplastic resins. High temperature thermoplastic resins are chemically more stable and, hence, more difficult to metalise than regular resin grades.
This paper summarises the results of the development of a novel metallising process for high temperature thermoplastic resins. A modified thermal spray process is used to apply electrically conductive metal coatings onto high temperature thermoplastic substrates. Initial results show that high temperature thermoplastic resin can be successfully metallised in a rapid and environmentally friendly manner. The required strong bond between high temperature plastic substrate and thermal spray metal overcoat can be achieved. The functional coating is electrically conductive and solderability is good.