By Flexible PCBs Be Submerged in Liquids
The short answer is yes, but there are a few important considerations that you should keep in mind. Compared to rigid PCBs, flexible ones can be more sensitive to damage and can have a shorter lifespan if not protected properly.
Fortunately, many of these concerns can be alleviated by choosing the right materials, design, and manufacturing process. Flex circuits are often made from a copper core with a thin, flexible polymer film on top. The most common flex circuit substrate is polyimide (PI). While standard PI is not suited for long periods of submersion, upgrading to a newer version can reduce these issues and make the PCB more durable.
Another factor that can affect a flexible pcb board durability is the temperature in which it is stored or used. Extreme heat or cold can warp the substrate, causing broken linkages that can impede current flow. Chemical exposure can also harm a flex circuit. This is more common in situations where users store electronics with cleaning supplies, as the fumes can corrode the circuit.
Can Flexible PCBs Be Submerged in Liquids?
For these reasons, it’s recommended to avoid using solid copper traces in areas that are expected to be bended. Instead, use a gradient change in width between thinner and wider traces to improve the bending resistance of the circuit. In addition, the edges of a flex circuit should be rounded to increase its durability. Finally, you should choose a manufacturing process that offers a high level of corrosion protection.
It is essential to test the flex circuit for moisture ingress before deploying it. The most accurate way to do this is to place the PCB in a controlled environment that simulates the conditions of its final environment. Typically, this involves submerging the board in room temperature water for hours or days to see how it performs under these conditions. This can help uncover any moisture-related issues that would be difficult to detect with other testing methods.
In addition to evaluating the board for moisture ingress, you should also consider its ability to handle abrasions and vibrations. A quality flex circuit is designed to withstand these stresses, but this can be compromised by poor design or manufacturing. For this reason, it is important to review your design with an experienced engineer before submitting it for manufacturing.
After completing your PCB layout and routing the traces, it’s important to add any labels, identifiers, or markings to the design before sending it off for fabrication. This step can help ensure that all components are placed where they need to be and that the circuit is assembled correctly. In the case of a flex circuit, this may include adding reference designators to identify different parts of the board or a component’s function. This information can also be helpful for the CAD program when creating the manufacturing files. These files are used to create your finished product, so it’s crucial that they are error-free. PCBWay offers an online tool to verify that your flex circuit will meet these requirements before you submit it for production.