Embedded electronics
10/01/2000
BY DANIEL K. WARD
Contrary to conventional wisdom, the term "embedded electronics" does not just refer to the TV remote you just dropped into your pizza or the stereo earphones sticking in your ear canals - it denotes a whole new concept of electronic packaging.
In a previous column, I spoke about "mechatronics," in which electronics systems are designed into mechanical mechanisms as part of the final mechanism package. The concept of embedded electronics takes this idea one step further. The electronic control and the mechanical function now become "as one" by sharing common package features. Therefore, traditional mechanics and electronics can become indistinguishable in such designs.
For example, take the cellular phone. What if the plastic housing of the phone also became the circuit substrate where the electronic circuit traces and components are placed? Is the plastic housing an electrical or mechanical component? A second example could be a car radio where the amplifier circuitry resides on the metal radio chassis enclosure. Is this chassis a protective case, a circuit substrate or a heat sink?
Business Drivers
What are the business drivers for embedded electronics? In the automotive electronics marketplace, they can be summarized into four major categories: reduced size and weight, reduced cost, improved quality, and improved system-level performance.
Reduced product size and weight will be realized through a decrease in the number of individual components and internal interconnects. External connector and harness requirements can also be significantly reduced in many vehicle systems. This results in reduced space and weight requirements of the final product, as installed. As automobiles become more electronically complex, and at the same time smaller and lighter to increase fuel efficiency, these size and weight issues become more important.
Cost reductions will also be realized from both reduced component and interconnect part count. A shared design for electronic and mechanical functions can facilitate shared thermal sinking, seals and mechanical structures that reduce the number of system assembly steps, thus reducing total assembly cost.
Final testing of a completed embedded electronic system as a single component, rather than part of a total car electrical system, can generate another significant advantage: System defects are now found and corrected at the supplier. Therefore, completely assembled and tested functional systems are easily assembled into the vehicle with high initial quality and lower final assembly costs. This is definitely an item on every vehicle manufacturer's "must" list.
The elimination of redundant electrical interconnects and wiring harnesses improves initial "as assembled" quality and can significantly improve system performance. This is especially true where high currents are required. Shorter conductor paths reduce the voltage drop in high current lines. Also, when high currents are switched, shorter conductor paths can substantially reduce emitted electromechanical noise. Shorter conductor path lengths improve noise-sensitive electrical circuit performance by reducing the amount of electrical noise induced in low-current lines.
Examining the Hurdles
All of these benefits do not come without potential obstacles. The design and manufacturing of embedded electronic products generate a number of significant technical and business challenges.
Design is no longer electrical and mechanical design - it is electro/mechanical design. These designs will undoubtedly be more complex, take longer to complete and become more difficult to prototype because of "special" part requirements. Secondly, in automotive applications, there's the constant battle of temperature extremes. Smaller volume and mass designs could very well mean hotter internal operating temperatures, which can have a negative effect on the electronic components embedded in the system when coupled with harsh application temperatures seen in the automobile.
Production sources for any new special electrical/mechanical components will have to be developed. This means that new component specifications will have to be understood and written, vendors found, and purchasing agreements made. Any electrical or mechanical changes to these parts after production begins can result in delays and increased costs.
Traditional electronic assembly methods may need to be modified to handle electro/mechanical component assembly. Component shape, mass and base materials might require unique component assembly and soldering processes, rather than standard SMT processes on standard equipment.
Field or warranty repair becomes problematic with embedded electronics, as well. Electro/mechanical designs will be more difficult to troubleshoot because of electro/mechanical interdependencies. After diagnosis, repair will undoubtedly become more difficult because of special processes required to disassemble and reassemble the integrated systems.
The Bottom Line
Therefore, as with most technology advancement, there are good reasons to change and as many good reasons not to change. I believe that the demands of the automotive marketplace will dictate the use of embedded electronics concepts in many applications. We will not be able to design and manufacture the vehicles of the future with the technologies of the past. AP
 |
DANIEL K. WARD is manager of advanced electronic packaging for Delphi Delco Electronics Systems, One Corporate Center, P.O. Box 9005, Mail Station: D-16, Kokomo, IN 46904-9005; 765-451-3093; Fax: 765-451-3115; E-mail: [email protected].