Whitepapers

Fortunately for makers of PCBs with high-speed signals, Ansys recently enhanced its SIwave stackup-based simulation software with the ability to include the effect of temperature on AC electrical simulations in addition to the existing ability to do so with DC sims. In this whitepaper, written for hardware, RF, and digital design engineers, project managers, and QA professionals at companies whose PCBs generate heat or operate in high-heat environments, we highlight the importance of this type of simulation and present an example workflow that shows how the software can be used to identify a problem in a design, mitigate the problem, and then test the updated design. Thermal Performance Goals for Electronic Designs All materials' electrical properties are a function of temperature to some extent. Despite this, temperature dependence can sometimes fall by the wayside when one is focused on their primary design goals. However, the proper handling of heat generated by a design can be critical to achieve top performance, and even those who use simulation enabled workflows can be blindsided by reduced performance if they have simply assumed room temperature throughout their design. Heat with the potential to impact a system falls into two broad categories: externally and internally generated. Both can impact your design in many ways: phase transitions of solder to liquid, burning of components, changing of transistor operating points, degradation of solid state components, cracks near interfaces between two materials due to varying coefficients of thermal expansion, and many others. Keeping these temperatures in the rated levels for your components and PCB is important to avoid these pitfalls. In the category of externally generated heat, there are three commonly understood temperature ranges used by electronics manufacturers to describe the ranges in which their products are rated to operate: ► Commercial: 0 ° to 70 °C ► Industrial: −40 ° to 85 °C ► Military: −55 ° to 125 °C Being able to expand the operating temperature range of one's device can expand its market, as well as increase yield and reduce warranty claims among a current base of consumers. Heat is also generated by all electronic designs and is important to account for in the context of any temperature range a designer will provide. This heat is what can create the most acute problems and is most commonly mitigated through heat sinks, fans, and liquid cooling. As embedded devices get smaller, higher bandwidth, and higher power, more integrated circuits will require these dedicated cooling solutions. Understanding thermal performance isn't just useful for the purposes of the operation of one's design. Rather, proper thermal performance is also needed for regulatory compliance; especially in the medical industry. There, engineers are expected to test that their products maintain a certain temperature inside and outside of the enclosure for safety reasons. Information Technology Equipment Safety IEC 60950-1 and Test Equipment Safety IEC 61010-1 standards regulate how hot the exterior of a device can be, and if a device will be in contact with a patient, Medical Safety Standard IEC 60601-1 must be satisfied. Failure to do so may result in costly delays and additional unplanned testing. Being confident about your products' thermal performance is faster, easier, and less expensive than ever before with Ansys SIwave.

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