抄録
The rate of plating of copper in an iminodiacetate bath for electroless plating use was measured with the polarization resistance method for the monitoring of aging of the bath. The polarization resistance method well accepted in the field of corrosion study has been applied to the electroless plating. The rate of copper deposition estimated from the polarization resistance method was compared with that obtained from the gravimetric method in various concentrations of copper ion and formaldehyde, at different pH values and plating time. Results showed that the polarization resistance was inversely proportional to the average plating rate estimated from weight gain, as expected from the equation of polarization resistance;
Rp=babc/2.3ipl(ba+bc)=K/ipl
where Rp is the polarization resistance, ipl the plating rate, ba and bc are the Tafel slopes of anodic and cathodic polarization curves respectively, and K a constant. The iminodiacetate bath yielded 0.12 for K, the value of which depends on the species of metallic ions, reductants and ligands. It is concluded that in laboratory tests the polarization resistance method can be used for the measurement of the rate of plating of copper in the electroless plating bath as well as for the monitoring of the aging of the electroless plating bath.
