How Do Electronic Circuit Boards Handle Moisture and Humidity?
Electronic Circuit Boards
As the name suggests, an electronic circuit board is a multilevel laminated substrate that provides mechanical support and specific electrical properties. These include dielectric constant, temperature decomposition resistance, arc resistance and loss tangent that impact circuit performance. However, electronic circuit boards are sensitive to moisture and humidity and can fail due to excessive exposure during storage or assembly. To mitigate this problem, a combination of design choices and proper handling during manufacturing is needed to keep moisture from damaging PCBs.
The first step in electronic circuit board is to lay out a bare circuit board and drill holes for mounting components. The bare circuit board is then etched, which is a chemical process that removes parts of the board that are not required for the assembly process. This leaves behind a conductive path for electricity to flow through the circuit. Once the circuit board has been etched, it is ready to be soldered.
This is a process that involves both SMT and THT and uses wave and reflow soldering to make strong connections between component pins and the corresponding solder pads on the circuit board. Both soldering processes produce high temperatures, which help to mitigate the potential effects of excess moisture. Once the components have been soldered, they are then inspected and tested to ensure that all of the connections are secure. If any of the components are sensitive to moisture, a special treatment is necessary to keep moisture from damaging them.
How Do Electronic Circuit Boards Handle Moisture and Humidity?
Depending on the nature of the circuit, the PCB may require special treatments to prevent moisture infiltration and uptake. For example, surface-mount components that are prone to moisture damage often use conformal coatings. These are specially designed to protect against moisture and other environmental contaminants. Other components may be protected with epoxy or other sealants.
The best way to protect against moisture damage is to prevent it from ever entering a circuit board. This means incorporating moisture-proof design strategies into the board itself, starting with the choice of base material. A common option is FR4, which offers both mechanical support and specific electrical properties, including dielectric constant, temperature decomposition resistance and arc resistance.
Moisture and humidity are a major issue for electronic circuit boards, especially those that contain sensitive moisture-sensitive components like resistors, capacitors and transistors. The presence of moisture can cause a variety of problems, including corrosion on the track and pad surfaces of the board, which can lead to short circuits and failure.
Moisture can also affect the internal circuitry of a PCB by depositing deposits of metal on its surfaces that can inhibit electric current flow. This can lead to a short circuit, which could result in a complete failure of the circuit. To protect against this, circuit boards need to be stored and assembled in a controlled environment that is free of moisture and humidity. While this is not a foolproof method to avoid moisture-related issues, it can significantly reduce the risk of damage during assembly, storage and operation.