Critical Considerations for Varistors in PCB Assembly Design
Understanding the specific demands concerning varistors in PCB assembly (PCBA) design is essential. Here’s a breakdown of what PCBA design demands from varistors:
Operating Temperature/Storage:
Maintain the working temperature of the circuit within the specified range outlined in the product’s specifications. After assembly, store the circuit within the product’s specified temperature range when it’s not operational. Avoid using temperatures higher than the specified maximum operating temperature.Operating Voltage:
Keep the voltage applied across the varistor terminals below the maximum permissible voltage. Incorrect usage might result in product failure, short circuits, or potential heating issues. Although the usage voltage should be below the rated voltage, in cases of continuous high-frequency or pulse voltage, thoroughly assess the varistor’s reliability.Component Heating:
Ensure that the surface temperature of the varistor remains below the highest specified operating temperature (considering temperature elevation caused by the component’s self-heating) as dictated in the product specifications. Confirm varistor temperature elevation due to circuit conditions under the actual operational state of the equipment.Restricted Usage Areas:
- Varistors shouldn’t be used in the following environments:
- Places with water or saltwater.
- Areas prone to condensation.
- Locations with corrosive gases (such as hydrogen sulfide, sulfur dioxide, ammonia, etc.).
- Conditions where the vibration or shock exceeds the specified range in the product specifications.
