Mentor Graphics CFD Software Enhances Product Design

Estimated reading time: 4 minutes

With the 2010 Consumer Electronics Show (CES) fresh in our minds, product design is the focus of today’s SMT interview with Erich Buergel, GM, Mechanical Analysis Division, and John Isaacs, director of market development, Mentor Graphics. Once in SMT production, each PCB is something of a standalone product — printed, populated with components, reflowed, etc., with the goal of most closely matching set circuit board assembly specifications. However, in the design field, a PCB is one of many interacting elements in a complex environment, such as a high-power gaming system, a ruggedized cell phone, a server farm, a slim flatscreen TV, etc. Designing each PCB without reference to outside elements (enclosure, movement, operating environment) would fail endless prototypes and waste design time. By integrating package/PCB/system/building design, Mentor is hoping to encourage further inter-disciplinary collaboration and more product simulation pre-prototype. When Mentor Graphics acquired Flomerics late in 2008, they entered the thermal analysis market decisively. A little over a year into the acquisition, Mentor’s Mechanical Analysis Division offers FloTHERM for PCB design, FloVENT for buildings, and FloEFD — thermal analysis embedded into mechanical design. Each of these lines is based on computational fluid dynamics (CFD) analysis and each works together in a comprehensive design flow, preventing costly errors caused by over-the-wall electro/mechanical/thermal design.

CFD is a simulation methodology that considers velocity, temperature, and pressure in a given system. This system can be as narrow as a package on a PCB, or as broad as a room full of server chassis. Industrial products with complex geometrics benefit from this numerical solving and physical testing, said Buergel.

FloTHERM offers PCB and MCAD designers bi-lateral collaboration in the product development process. Mentor has focused on ECAD/MCAD co-design since 2005, Buergel pointed out, and this product enhances the concept with the addition of thermal data simulation. Combining electrical and mechanical designs knocks out errors that otherwise would have gone to prototype — PCB edge rubbing on an enclosure, odd-form component too tall for the case, etc. — but less visually detectable faults can remain. Does the fan system cool hot components sufficiently? Is a connector blocking airflow to a high-power BGA? This is where FloTHERM adds design verification and enhanced simulation. It can be used in conjunction with the T3Ster for package, heatsink/heatpipe, etc. characterization or the TERALED for characterization of LED assemblies.

FloEFD targets the designer or engineer who is not an expert in CFD. These designers want CFD as an additional button in the MCAD toolbox to verify designs or red-flag problems. Buergel noted that 2 days is generally sufficient training time when incorporating FloEFD into the mechanical design workflow.

Combined with FloVENT as appropriate (for designs going into cleanrooms, data centers, hospital buildings, etc.), the CFD suite enables a device-to-enterprise thermally tested design. Significant cost savings can be realized with effective electronics design and thermal management, rather than trying to cool poorly designed systems after the fact. Beyond this, reliability can be improved, as designers discover dangerously over-heating components, insufficient air flow patterns, a hot component on one PCB directly below a sensitive component on another, etc.

Mentor also says that the concurrent CFD flow (embedded in the CAD) implemented in these products can cut down time-to-manufacture by 25–35%. This enables product designers to work with the concept more, playing with structural, electrical, and thermal properties in simulation without time or material penalties. Buergel acknowledges that this has led to entirely new design concepts, with cost, quality, manufacturability, and other tradeoffs easily tested in the design ‘sandbox’. A major consumer electronics OEM was able to use FloTHERM to experiment with various LED placements and cooling mechanisms in a flatscreen TV design, Bruegel cites as one example (see Video).

A flatscreen TV's LED system is modeled in CFD.

In another example, Azonix, a division of Crane Co., makes highly engineered computers and displays designed for extremely harsh environments. The company’s newest Terra computer is totally sealed to eliminate failures due to contamination and is designed to operate at temperatures up to 60°C. This design provides the tough thermal management challenge of keeping components that dissipate approximately 60 Watts of power inside the case from exceeding a 90°C surface temperature limit. Azonix could not accommodate a dedicated thermal analysis staff, and instead chose CFD software to evaluate various iterations of the design. Without CFD software, the company would have built up to a dozen thermal prototypes to evaluate various design alternatives or hired a consultant to simulate the design at a cost of perhaps $5,000, Mentor reports. Read the full case study here: http://www.mentor.com/products/mechanical/success/azonix-success/fileContent/Azonix_LR.pdf

CES 2010 saw better attendance numbers after the economic recession quashed interest in consumer electronics back in 2009. According to preliminary figures, the Consumer Electronics Show had more than 120,000 attendees, the Consumer Electronics Association said. The resounding message is that consumer electronics are no longer synonymous with disposable electronics, with a general expectation of quality and durability rising each year. When the new products reach tradeshows and eventually retail shelves, well-made, durable, unique, and lower-cost are all on the checklist. One with a faulty case design, an exterior button that is accidentally heated by a PCB heatpipe, a clunky shape to accommodate all the necessary features, or any other demonstrable faults will be passed over by the consumer. A product that reaches design goals is good for the consumer and the producer.

About Erich Buergel

Beurgel is the general manager of the Mentor Graphics Mechanical Analysis Division. He joined the company in August 2009. He has more than 20 years experience in product development, product marketing, sales, and business development with global organizations. He spent 4 years at MSC Software as VP and director of sales, and 12 years at SDRC/EDS. He also has worked in systems integration and professional training. Buergel holds a Ph.D. in applied mechanics/fluid dynamics from Technical University Clausthal and an executive BBA from GSBA in Zurich.

SMT, January 2010