PCB leakage current refers to the unintended flow of electric current between conductive elements on a printed circuit board (PCB). This leakage current occurs when an electrical charge escapes from its intended path and follows an unintended route. PCBs are designed to carry specific currents between components and traces without any leakage, but various factors can contribute to leakage current, including:

  1. Dielectric Material Properties: The dielectric material used in PCBs (typically between layers of conductive traces) has a specific resistance and can support a particular voltage level before breaking down. If the dielectric material is damaged, has impurities, or is of poor quality, it may allow current to flow where it shouldn’t.
  2. Environmental Factors: Moisture, dust, contaminants, and other environmental factors can affect the insulation properties, leading to increased PCB leakage current.
  3. Temperature: Temperature can influence the electrical properties of materials, and as temperature rises, the conductivity of some materials may increase, potentially leading to higher leakage currents.
  4. High Voltage: When PCBs are subjected to high voltage levels, they can experience what’s known as partial discharge or corona discharge, where small amounts of current leak due to electrical breakdown in the insulation.
  5. Design and Manufacturing Issues: Poor design or manufacturing processes can introduce defects in the PCB, such as tiny gaps in insulating layers or contamination during soldering. These defects can create paths for leakage current.
  6. Aging: Over time, PCBs can degrade due to various factors, including temperature fluctuations, mechanical stress, and exposure to environmental conditions. Aging can lead to an increase in PCB leakage current.

PCB designers and manufacturers take various measures to minimize leakage current and ensure the integrity and reliability of the board. This includes using high-quality dielectric materials, conforming to design specifications, and conducting quality control testing to identify and rectify any issues that could lead to leakage current. Leakage current can be a concern in sensitive electronic devices, especially those used in critical applications, as it can lead to reduced performance or even failure if not adequately managed.