PCB Waterproof Coating for Power Supply Moisture Protection
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Solution Overview
Problem
Printed circuit boards (PCBs), particularly those with FR-1 materials, are vulnerable to moisture infiltration, leading to a decrease in insulating properties when exposed to high humidity, which can cause failures in withstanding voltage tests and increase the risk of overvoltage damage from lightning.
Innovation Solution
A waterproof silk pattern is applied to critical areas of the PCB, including the power converter and AC power input portions, using a waterproof coating layer formed with silicone dielectric gel or silkscreen ink to prevent moisture infiltration and protect against overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a waterproof coating layer is applied to the PCB, then the insulating properties are maintained under humidity, but the device complexity increases
Solution Approach 1:
The waterproof coating layer is applied selectively to specific areas on the PCB where moisture infiltration is most critical, such as around the power converter and AC power input portions, rather than coating the entire board. This localized approach maintains insulating properties where needed while minimizing added complexity and cost.
2Measurement precision
If the PCB is exposed to high humidity for withstanding voltage test, then the insulating properties can be evaluated, but moisture infiltration causes test failure
Solution Approach 1:
The waterproof coating layer is applied to the PCB before conducting the withstanding voltage test under high humidity conditions. This preliminary protective measure prevents moisture infiltration during the test, allowing accurate evaluation of insulating properties without the confounding factor of moisture damage, thereby ensuring reliable test results.
3Object-affected harmful factors
If AC power input portion is protected from humidity, then overvoltage damage from lightning is prevented, but additional protective measures increase manufacturing cost
Solution Approach 1:
The waterproof coating layer is applied specifically to the AC power input portion of the PCB, targeting the area most vulnerable to moisture infiltration and subsequent overvoltage damage from lightning. This localized protection approach prevents harmful effects while minimizing manufacturing cost by avoiding unnecessary coating of the entire board.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents changes in insulating properties due to humidity, ensuring the PCB's reliability and protecting it from overvoltage damage, while being cost-effective for FR-1 materials.
Implementation Method 1
a waterproof coating layer formed in an area on the board corresponding to a position of the power converter... to prevent infiltration of moisture from an outside
Implementation Method 2
a waterproof coating layer formed in an area on the board corresponding to a position of the power input portion... to block humidity and to protect the PCB from overvoltage caused by lightning
Data Source
AI summary
A power supply device of an electronic apparatus includes: a power input portion configured to receive alternating current (AC) power; a rectifier-smoother configured to rectify and smooth the received AC power and output the AC power; a power converter configured to convert a level of a voltage output from the rectifier-smoother to supply operating power to the electronic apparatus; a board on which the power input portion, the rectifier-smoother, and the power converter are provided; and a waterproof coating layer formed in an area on the board corresponding to a position of the power converter to prevent infiltration of moisture from an outside.