Anritsu Co. has reduced the time required to develop communications test solutions 4 to 6 weeks, eliminating a printed circuit board (PCB) re-spin by modeling thermal management at the board and systems level during the early design process. In the past, Anritsu engineers were not able to address thermal issues at the board level until the prototype stage when physical testing was performed. "Now we use Flomerics' FLO/PCB software to optimize component placement before prototyping," said Teresa Whiting, mechanical design engineer for Anritsu. "The result is that no additional prototypes have been required for thermal reasons since this method has been used."

Anritsu designs and builds a wide range of test and measurement systems for wireless communications, RF and microwave, optical communications and data communications. The company frequently introduces new products with higher capabilities as required by the rapid changes taking place in the communications industry. Generally, the higher performance delivered by each new generation requires that they dissipate more power yet enclosure size is remaining constant or in some cases even shrinking.

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."