Printed Circuit Boards (PCBs) are essential components in modern electronics, but they can face challenges when exposed to high temperatures. In this article, we will provide a high-level overview of designing a high-temperature circuit board and highlight some of the options available when designing for such conditions.
The first consideration for high-temperature PCB design is the material used for manufacturing. The most common material used is FR-4, which can withstand between 90 to 110 degrees Celsius. However, if the application requires exposure to temperatures above boiling point, we need to upgrade to high-temperature FR-4 or polyimide, which can withstand temperatures between 130 to 260 degrees Celsius. Furthermore, we need to use lead-free solder paste to avoid the risk of components falling off the board due to melting of the solder paste.
When designing for high-temperature conditions, we need to consider the placement of heat-creating components to avoid creating pockets of additional heat. Logic components may not function properly in extreme temperatures, so we need to add a temperature parameter when selecting components. Ventilation and heat dissipation methods, such as heat sinks, strategically placed vias, and the use of thermal insulation and shielding materials, may also be necessary.
In addition to designing for high-temperature environments, some components require significant heat dissipation, which can impact the reliability and service life of the board. Therefore, heat-creating components should be placed far apart, and adequate ventilation should be ensured, including the use of case-fans and heat sinks. Vias filled with conductive paste can also be used to attach the thermal mass of a part to the ground plane for improved thermal conductivity.
While these practices are not exhaustive, they provide a starting point for designing high-temperature PCBs. Armed with this knowledge, engineers can simplify the design process and create boards that can survive high-temperature conditions.