To ignore the enclosure is to miss the big picture.

Developing a competitive electronics product requires more than an innovative design of the PCB. Yes, the PCB design is extremely important and is where an OEM can add the most value to the product by squeezing more high-performance functionality in a small form factor at reduced costs. But to get that product to market efficiently requires a cooperative effort of many disciplines: PCB design, FPGA or ASIC design, mechanical design, procurement, manufacturing, software, test, etc.

Of these disciplines, perhaps the most familiar are the design of the electronics (ECAD) and the design of the enclosure (MCAD). Over the past 40 or so years, these domains have been supported by design systems that have grown like two distinct and discrete skyscrapers, each optimizing the unique design requirements of their users. This chasm between the design systems has forced extreme effort to enable ECAD and MCAD to collaborate electronically.

Collaboration started with paper being passed back and forth, and this practice still exists in many companies. Meanwhile, industry standards have been developed, such as IDF, which enables en-masse data transfer. This standard has been used to efficiently communicate objects such as the PCB outline and mounting hole locations to the ECAD designer and component placement to the MCAD designer.

In 2008, ProSTEP published a new standard that enables the bidirectional communication of proposed incremental design changes between the domains. A change could be proposed, communicated electronically to the other discipline where it could be accepted, rejected or counter-proposed. This collaborative negotiation process could continue real time until agreement was reached and the change reflected in the respective design databases.

Feeling the heat. Many factors such as excessive heat can affect the reliability of the final product. Most of these are issues that would pass through a prototype cycle and not be discovered, but the product might fail after some period of time in the field. This type of failure could have huge effects on profits, with massive warrantee or safety problems and recalls.

Heat management affecting product reliability is more of an issue than ever because of the increasing power dissipations of today’s high-performance ICs. And excessive heat over time can drastically affect product reliability in the field. Software exists that can analyze the thermal effects on the PCB and enable the designer to modify the component placement and reduce junction temperatures. But this software only can guess at the environment (enclosure) characteristics into which the PCB(s) will be placed. The design of the complete product (enclosure, fans, heat sinks, other cooling devices, etc.) exists in the MCAD domain. An analysis of the complete product is required to determine the true heat management requirements. This is not an analysis that should wait until the design of the PCB(s) or enclosure is complete. Rather, it should start at the beginning of the PCB and enclosure design and proceed concurrently throughout the product design process.

Fig 1

Analysis should be performed not only at the board level, but again as the PCB is mounted in the enclosure. This full product conduction and convection analysis, including the enclosure, fans, heat sink, etc., can highlight potential product hot spots and enable changes to either the parts placement or the enclosure cooling mechanisms to increase reliability. This collaboration is required to efficiently bring a reliable product to market.

ECAD and MCAD are no longer separate islands where product design can be performed in a vacuum and then data passed over the wall. For the highest performing, most profitable and reliable product design, bidirectional collaboration needs to exist throughout the design process.

John Isaac is director of market development - Systems Design Division, Mentor Graphics (;This email address is being protected from spambots. You need JavaScript enabled to view it..

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