Corrosion Measurement of a Conductive Paste and Anisotropic Conductive Adhesive Films

We measured corrosion layer thickness on a conductive paste (CP-Ag) and anisotropic conductive adhesive films (ACFs). CP-Ag consist of epoxy resin and silver powder, and ACFs consist of epoxy resin and about 4 mum in diameter of uniform plastics particles with Ni and Au/Ni plating. Firstly the conductive paste was printed on the polyimide film, and ACFs were bonded on the glass with indium-tin-oxide (ITO) electrodes. After thermal curing, these samples were set in the condition of an acceleration corrosion test; 2 ppm of H₂S gas, 4 ppm of NO₂ gas, 30degC, 70%RH. After exposure in corrosive gases for 77.3 hours, these samples were cut to analyze the resultant corrosion, using the SAICAS (surface and interfacial cutting analysis system) slant-cut method. The sulfur component in the cut section of each sample was measured by using both the scanning electron microscope (SEM) and the energy dispersive X-ray microanalysis (EDX) component analysis method. As a result, we found that the corrosion reached a depth of about 2 mum on CP-Ag. This depth is our predictive value. But on ACFs, the sulfur component was not found. Then ACFs were set in the condition of other acceleration corrosion test; 0.07 ppm of H₂S gas, 1.4 ppm of NO₂ gas, 1.4 ppm of SO₂ gas, 0.07 ppm of Cl₂gas, 35degC, 85%RH for 96 hours. The affection of corrosive gases reached in the depth of about 1.2 mum when we paid the attention about the weight ratio for oxygen and nickel.