Burn-in & Test Socket Workshop - BiTS Workshop

CAF Formation• Glass/epoxy bonds degrade – due to mechanical stress,poor quality coupling agent, etc.• In a humid environment, water absorption occurs and createsan aqueous medium that provides an electrochemicalpathway that facilitates the transport of corrosion products.• Water acts as the electrolyte, copper circuitry as anode &cathode and operating voltage as driving potential.• H+ (pH lower) and OH- (pH higher) creates a pH gradient.• Copper is passivated in region of pH 7 to 11 but becomescorrosive at pH below 7 and potentials greater than 0.2V.• The anodic copper ions travel along the epoxy/fiber interfaceattracted to the cathode.Anthony WongHL Kon/Low KWBiTS 2003 5