b'Engineer Innovation | Geek Hubhaving to deal with a prosthetic legare cool enough to eliminate the risk of before! Debbie found very innovativeinjury. Many times the design ways to explain the geometry and helprequirements for the outer surface visualize the aim of the project (Figuretemperature are limited by how hot the 1). surface feels. If a surface feels too warm, the end user could interpret this With the information gathered, Mikeas a malfunctioning or poorly designed used a model found on GRABCAD andunit.modified it according to Debbies descriptions. Mike took a GrabCAD example and performed some modifications until it Once the first version was useable,looked more like the physical board. He Mike shared this model with Johnalso applied some scaling features, Wilson who created the PCB. John isbecause the initial unit was smaller. the Electronics Product Specialist atThe IDF file was imported into Mentor, A Siemens Business. Simcenter FLOEFD with the Simcenter Flotherm FloEDA Bridge so that the Rather than starting from MCAD, Johnboundary conditions (materials, heat started with an image and with thesources and radiative surfaces) were help of Debbie, determined thecreated automatically, see Figure 3. approximate scales of the board andThe ambient conditions were set to higher power dissipation components.typical values of 20C and 1.01 bar. With electronics that are batteryGravity is enabled because it is cooled powered there is a need to develop aby natural convection.solution that meets the functional requirements with the lowest powerThe colored surfaces show the consumption possible. In thesetemperature distribution on the PCB. Figure 2: Board created situations the critical IC componentsThe arrows illustrate the airflow are well within their temperaturearound these components. It is caused requirements (reliability of electronicsby the natural convection, which are strongly related to both peakmeans the heated air moves upwards operating temperatures andcausing air circulation in this area.temperature cycling). Thermal design often involves ensuring that anyThe air is escaping out through the top, exposed surfaces that may be touchedbut as our physical example has a lid, Figure 3: Boundary conditions of the PCB72'