Adhesion of electrolessly-deposited copper to photosensitive epoxy

The adhesion between electrolessly-deposited copper and photosensitive epox y was measured with a pull test designed in this work. The test pads were f abricated on the epoxy substrate using a semi-additive plating process. The pull strength was measured with a mechanical tester. A chemical treatment was used to roughen the epoxy surface; two sets of specimens were tested wi th different swelling and etching times to obtain the optimal adhesion stre ngth. Another set of specimens was tested as reference without swelling. Th e effects of the chemical treatment on surface topography and adhesion were studied. The surface topography of the epoxy was examined by optical micro scopy, scanning electron microscopy (SEM), and energy-dispersive spectrosco py (EDS). The ranges of swelling and etching times, which resulted in good adhesion, were presented. It was confirmed that the procedure of swelling a nd etching processes had to be optimized for achieving the desired epoxy su rface properties without altering the bulk properties.