PCB Thermal Analysis


In today’s extremely large and complex PCB designs, power dissipation has become a major challenge. Every printed circuit layout engineer must take into account power dissipation, ensuring that hot components are placed in a cooler area, using ‘forced-cooling’ or heat sinks to prevent the circuit board from overheating.

The fiXtress PCB Thermal Analysis module estimates, even before the layout procedure starts, the exact junction temperature for each semiconductor and IC. Using this information, the designer can place hot components in a cooler area. Additionally, assumptions can be made on exactly how much Air Flow (CFM) is needed (i.e. fan spans) in order to lower the temperature of the entire PCB.
This way, thermal engineers can ensure that the system and its electrical components are continually cooled and operating within the safe operating temperature range, without laborious manual calculations.

The amount of power consumed by some devices can cause significant design problems. For example, IC fan-out is determined by the amount of input current drawn by a gate load draws, and the output current the supplied by a driving gate. In reality, a limit will be reached where a gate output cannot drive any more current into subsequent gate inputs; attempting to cross the limit will cause the voltage to fall below the level defined for the logic level on that wire, resulting in a design failure. Another example: When the current across a resistor is increased by a design fault, and approaches its maximum power rating, the resistor will develop more voltage and dissipate more power. This can cause overheating and burning of the area around the resistor, and, in some cases cause the entire circuit to fail.