J. H. Hsieh, L. H. Fong, H. Hsiung S. Yi* and S. P. Mong*

Gintic Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075
jhhsieh@gintic.gov.sg

*School of Mechanical & Production Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798

Plasma cleaning is known to be an effective way to enhance the adhesion of moulding compound to leadframe in electronic packages. In this study, cold plasma was used to treat Au-plated copper leadframes prior to moulding. After treatment, two types of liquids, DI water and Glycerol, were used to measure the contact angle. The main aim of this measurement is to study aging effect after plasma treatment, as functions of polar and non-polar surface tension. The change of polar and non-polar surface tension was correlated with the result of adhesion measurement using pull testing. The results show that Ar/O treated leadframes can keep low contact angle for eight hours while Ar and Ar/H treated leadframes have a sharp increase in contact angle right after plasma treatment. In pull testing, it shows that in general the adhesion improved. The improvement increases with the decrease in time delay prior to moulding. The difference in polar and non-polar surface tensions also contributes certain degree of effect on adhesion.