Thermal Solution

Electronic assemblies must dissipate thermal energy from components to prevent premature failure due to overheating. Renxin Thermal Products specializes in designing and building innovative custom heat sink designs that help to solve thermal problems. Recently, a manufacturer of Bitcoin miner products asked Renxin to help cool a pluggable PCB's (computing power board) ) that was overheating. We engineers simulated the design with ANSYS Icepak and FloThermal electronics cooling simulation software.Using simulation, the team discovered that the fin density on the heat sinks in the original design prevented air from reaching downstream components and that variations in component height reduced the effective thermal conductivity. Engineers redesigned the cooling system using a larger number of smaller heat sinks attached to single components. They employed the ICEPAK  and FloThermal  parameter manager to optimize the number of fins, fin thicknesses and other design parameters. The optimized design operates safely at ambient temperatures that are 35 °C higher than the original design.


The manufacturer of telecommunications products designed a pluggable card with several integrated circuits and heat sinks that fit into an Advanced Telecommunications Computing Architecture (ATCA) rack mount chassis. Simulation showed that the heat sinks cooled the chips they were attached to, but other components experienced excessive temperatures. We engineers began addressing this issue by obtaining information from the manufacturer such as the space available for heat sinks, dissipated power, power supply size, fan size and placement, target ambient temperature, attachment methods, and maximum allowable junction temperatures for the components. The maximum junction temperature is the highest internal temperature that a component is rated to withstand without damage. Traditionally, thermal management design is based on engineering experience and instinct. In the past, companies usually needed to build and test numerous prototype designs to understand and resolve thermal problems. Advanced simulation tools like ANSYS Icepak or FloThermal enable engineers to reduce costs and time to market by verifying a design’s proof of concept with accurate thermal results prior to building a prototype. In this case, the manufacturer had already created a relatively simple heat- sink design and performed a thermal simulation with a non-Thermal simulation tool. The simulation results showed that junction temperatures were too high but did not provide a clear path to resolve the thermal issues. Renxin engineers decided to add a heatpipe, which efficiently transfers heat from a hot spot to a heat sink located some distance away. A heatpipe contains a liquid that turns into vapor when it absorbs heat from a thermally conductive surface attached to a hot component. The vapor travels to the other end of the heat pipe, which is much cooler, and condenses back into a liquid. The liquid then returns to the hot interface through capillary action, and the cycle repeats. Simulation showed that the heat pipe provided further performance improvements. The Icepak model was updated, and a new simulation showed that the final design achieved a 80 °C reduction in temperature in the hottest area on the board.

Renxin.Thermal Technology-based manufacturing facility provided initial prototype heat sinks within three days. The manufacturer performed final physical tests that matched the simulation results and accepted the Renxin design. The product is now on the market with a maximum junction temperature of 85 °C at 55 °C ambient. Renxin is manufacturing the production heat sinks in its Asia facilities, and the thermal performance of the product has been verified in the field.