Better CAF Acceleration Equation

Classic CAF (Conductive Anodic Filamentation) is a two-step process, firstly the creation of a pathway by hydrolysis followed by electrochemical filament growth. Where there is no pathway there can be no CAF, hence existing acceleration factor equations which model the process as a single step are clearly incorrect. The project will determine a better acceleration factor equation for CAF and quantify the effects of voltage, temperature and humidity hopefully enabling shorter testing time for CAF material qualification.

Project stage: 
Lead company: 
i3 Electronics

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Idea Information

Background: 
  • “Classic” CAF (Conductive Anodic Filament) growth is a two step process;
    • Creation of a path by hydrolysis. (temperature and humidity effects resulting in “debonding” of the glass to resin interface creating a path for CAF)
    • Electrochemical growth. (CAF can also occur along other paths – hollow fibers, resin cracks, triple points etc., but these are typically existing paths and not “classic” CAF)
  • If there is no path, there is NO CAF!
  • When we have “pre-existing” paths, the data for 100V/65°C/85% RH suggests these fail in roughly 100-150 hours or less at this test condition.
  • Current acceleration factor equations are clearly incorrect as they attempt to model this process as a single step.

 

Click to view project kick-off presentation.

Problem: 

Current CAF acceleration equations do not separate path formation from electrochemical filament growth and do not therefore provide an adequate model that properly quantifies the influence of voltage, temperature and humidity on CAF growth.

Definition Information

Public