Flexible PCBs Can Withstand Harsh Environments
While rigid PCBs have been used for interconnecting electronic devices since the 1950s, flexible pcb are becoming increasingly popular. Flex circuits have a malleable base that allows them to be shaped, bent and twisted into almost limitless configurations. This flexibility makes them a great choice for products that need to be compact, lightweight and durable. They can also be used in harsh environments such as aerospace and defence, where strict size and weight restrictions are often imposed.
Flex PCBs must be designed carefully to ensure that they are able to withstand various environmental conditions, including temperature fluctuations and vibrations. This is made possible by selecting the right materials, such as polyimide substrates, high-quality conductive traces and dielectric layers. By adhering to industry standards and best practices, engineers can optimize the mechanical robustness and functionality of flex PCBs for diverse applications.
One of the key factors in a flex PCB’s ability to withstand harsh environments is its bend radius. A correctly calculated bend radius can help to prevent damage and ensure that a flex circuit board continues to function properly throughout its lifespan. A bending radius that is too small can cause the copper traces to lift off from the PCB, which may lead to a loss of electrical continuity. For this reason, it is essential to use a manufacturer calculator to determine the appropriate bend radius for your application.
How Flexible PCBs Can Withstand Harsh Environments
Another important factor in a flex circuit’s ability to withstand harsh environments is the type of surface finish that is applied to it. A PCB’s surface finish helps to protect it from moisture, dust and other contaminants that could corrode or oxidize the copper conductors. The most common finish is Electroless Nickel Immersion Gold (ENIG).
As well as protecting the underlying copper conductors, the surface of a flex circuit’s ENIG finish also acts as an effective barrier against radiation and harmful chemicals. The coating is also designed to be solderable, which makes it easy to rework components on the PCB during repairs and upgrades.
Finally, the thickness of a flex circuit’s substrate and conductive materials can have a significant impact on its ability to withstand harsh environments. Thicker materials tend to have a higher glass transition temperature and offer greater protection against heat and radiation.
For example, a copper trace on a flex circuit is held in place by the polyimide coverlay, which is used as an insulator and provides thermal stability. A thinner copper layer is more susceptible to lifting, so it is essential that engineers select a suitable thickness for their application. This can be done by using a thinner, more durable copper alloy or by adding an additional plated through hole (via) to provide extra support for the copper. In addition to this, a hatched copper design will improve the adhesion of a flex PCB to its underlying substrate, which can help to reduce stress on the material and increase the board’s durability.
