Flexible PCBs From Humidity
Printed circuit boards are delicate, and interference from dust, humidity, or moisture can damage them. The damage could cause electronic components to fail, which would render the entire device useless. The good news is that flexible pcb board can be protected against these threats through proper manufacturing, storage, and shipping practices.
Humidity: Moisture in air causes electrical resistance to increase, which affects the ability of components to conduct electricity. It also promotes mold growth, which can damage the board and cause failure.
Heat: Temperature extremes are dangerous for PCBs because the substrate expands and contracts at different rates, which can disconnect the circuit. Additionally, metal debris and corrosion can form on the surface of the PCB and interfere with current flow.
Protecting Flexible PCBs From Humidity
Chemicals: Chemical fumes from reagents stored in warehouses or other types of storage areas can corrode the surface and circuit of flexible PCBs. Additionally, chemicals in the water supply or even in the air can contaminate the flexible PCB.
Physical Forces: The physical stress of bending can damage flexible PCBs, especially when the copper is not properly plated and soldered. This can lead to shorts, intermittent connections, or complete failure.
Design and Manufacturing Errors: The design of a flexible PCB must be carefully planned and the manufacturing process must be well-controlled to ensure that it will work reliably when bent. This is because the PCB must be able to bend without breaking, and the circuit wiring must be able to handle the bending.
Electrical Damage: In addition to causing short circuits, moisture can cause other electrical problems. It can corrode metals, which can reduce the conductivity of wires and lead to a short circuit. It can also contaminate the ground plane, which will reduce the effective voltage of the circuit and create an uncontrolled current.
To prevent moisture damage, it is critical to use waterproof barriers to isolate the electronics from the environment. These barriers can be accomplished by using conformal coatings that seal the surfaces of a circuit board, providing an extra layer of protection against contaminants and ensuring that all of the critical components are positioned correctly. To further protect against moisture, it is essential to test the performance of the potting or sealing in a circuit board’s enclosure by pressurizing the internal cavity and monitoring the rate at which moisture is allowed through the waterproof barrier.
This will help to ensure that the potting or sealing performs as expected over a long service life. Additionally, waterproof coatings should be thoroughly tested before application to ensure that all parts of a circuit board are fully covered. Any thin spots or cracks in the coating can compromise the effectiveness of the waterproofing. This can be done by visual inspection or by using optical magnification to check the quality of the coating. This will help to identify any spots that require additional reworking or coating.
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