When you design the electrical characteristics of your layout, you need to recognize that the materials are not similar with a PCB. This also means that the circuit’s electrical characteristics are different. The same layout, one made with IMSE and the other with a traditional PCB, has different electrical characteristics. Traces have big differences in terms of conductivity and are one of the most important design parameters. In addition, the plastics used in IMSE creating the mechanical structure are electrical components as well, and these are worth considering in the design.
An IMSE stack-up contains
Calculation methods used in PCBs, for example, relating impedance, are not applicable for IMSE. IMSE sets certain limitations on how to build stack-up, but also what kind of a grounding structure we can use. Designing the IMSE stack-up is different compared to the PCB world, since the IMSE stack-up is also a mechanical structure of a product and typically an optical light guide, as well. So it is not designed only by an electrical engineer, but a mechanical engineer and an optical engineer together.
Materials used in IMSE are not similar to those used in PCBs. This means that the manufacturing methods are different. In IMSE, traces are printed with silk screen printing, the assembled electrical circuit is 3D formed and finally the electronics are encapsulated inside the plastic by injection molding. All of these impact on how to consider design for manufacturing. Make sure that your design can be manufactured by understanding the IMSE manufacturing steps.
An IMSE part is an integration of electronics, optics, mechanics, graphics, antennas, etc. All disciplines are integrated into a one solid piece, and all have critical parameters, which need to be designed properly. Design work is a close collaboration between all engineers, and compromises should be done. Things become easier if all understand well what the technology limitations are and where we need to be strict and what items can be flexible.
These four key points set the foundation for IMSE electronics design. For a PCB designer, this is not a side step. It is just learning something new and different.
