How Do RF Circuit Boards Resist Moisture and Corrosion?

RF Circuit Boards Resist Moisture and Corrosion

In an electronic device, exposure to moisture can cause corrosion and a failure of the circuit board. While this is often due to the environment in which a device operates, moisture can also occur during manufacturing or storage of the board. This is why it is important for rf circuit board to be designed with features that will resist moisture uptake and corrosion. These design features include protective circuit board materials, layout design and the use of specialized PCB manufacturing processes.

RF circuit boards have different requirements when it comes to moisture resistance than conventional printed circuit boards (PCBs). RF PCBs must be able to support high-speed signal transmission while maintaining impedance and other specifications. This means that the underlying material and copper must be able to handle higher temperatures, withstand greater stress and be able to resist moisture uptake.

The RF layer of a circuit board is typically composed of a conductive copper substrate with dielectric material on both sides. The thickness of this copper layer will determine the signal speed and integrity that can be achieved. For optimum performance, the RF layer should be made from a material that offers low loss and has an appropriate coefficient of thermal expansion to avoid cracking or breaking during assembling and final operation.

How Do RF Circuit Boards Resist Moisture and Corrosion?

To prevent corrosion, a protective coating can be applied to the conductive copper surface. A variety of resins are available, including acrylic, polyurethane and perylene. These coatings offer a number of benefits including flexibility, chemical resistance and dielectric strength. When selecting a coating, the manufacturer must make sure that it is compatible with the underlying copper and has low water absorption rate to prevent uptake and cracking.

Another way to reduce the risk of corrosion is by using a special type of solder mask on the RF layer. This special solder mask will not allow any copper traces to touch other metals or solder pads, which would create an unintended connection and potentially lead to a short circuit. It will also help protect the bare copper from the hands of the manufacturer or any other handling during assembly and storage.

Corrosion occurs when oxygen bonds with a metal, such as copper. This leads to the formation of copper oxide, which is a non-conductor of electricity. Corrosion of a copper track can damage the board and affect its performance. To minimize the risk of corrosion, the copper-to-copper contact area should be as small as possible to minimize the gap between the conductive tracks and their shielding material.

The best way to prevent corrosion of a circuit board is to design the layout to maximize the electrical performance of the RF layer. This includes routing RF lines as short as possible, avoiding routes near high-speed digital traces and power planes, and minimizing the distance between RF traces to reduce reflections and interference. In addition, RF traces should be carefully routed to avoid overlapping or crossing with other signals and components.

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