Adhesional bonding of fine gold wires to metal substrates

Abstract

The transition from the adhesional elastic contact to the elasto-plastic contact is discussed, using Au wires as cylindrical bodies. The simple compensation for elasto-plastic contact was numerically carried out to obtain smooth transition profiles from elastic to elasto-plastic contact, depending on the applied force f. Au wires with a diameter of 100 μm were contacted to Au plates and Si substrates after they were irradiated with Ar+ ions. It was found that the experimental contact width 2a was nearly equal to the theoretical adhesional elastic contact width 2aj when f was small enough (f < 500 N/m) but the contact width 2a gradually became greater than 2aj as f increased (f > 500 N/m), and became nearly equal to the elasto-plastic contact width a ep . On the other hand, the actual fracture strength was much less than the theoretical fracture (pull) strength of the adhesional contact and it was also found that the experimental bond strength increased with increasing the holding time after bonding (contacting).