Anritsu has modeled the thermal performance of its products for a number of years but in the past thermal simulation was not fast enough to keep up with the rapid pace at which the company designs PCBs. So, thermal design had to wait until the prototype was built and mechanical engineers created thermal photographs and measured temperatures of the boards. At the same time engineers also modeled the product at the systems level with Flomerics’ Flotherm software. Typically, the simulation identified hot spots or other problems on boards. Engineers then went back and repositioned components, rerouted traces, and built a new prototype. The extra board spin added directly to the time required to bring the product to market.
 
About a year ago, Anritsu became one of the first users of FLO/PCB, a software package that makes it practical to perform thermal modeling during PCB design. Electronic engineers now provide mechanical engineers with placement information and data sheets on key components of the PCB. The mechanical engineers then quickly model the board and simulate its performance under standard airflow and temperature conditions. They often reposition components at this stage or add a heat sink and, when they are satisfied, then plug the FLO/PCB model into a Flotherm system model, which usually already exists, and determine the thermal performance of the board under actual conditions.
 
“Modeling PCBs during the design stage makes it possible to get the board design right from a thermal standpoint every time,” Whiting said. “This has eliminated the need for a second thermal prototype and saved us 4 to 6 weeks in bringing every product to market. In a typical example, FLO/PCB showed us that junction temperatures were too high on a couple of voltage regulators. The system level simulation showed us exactly where we needed to reposition the boards to get enough airflow. We provided that information back to the EEs designing the board, so they were able to get the layout right the first time.”