Nickel-free final finishes in the electronics industry

Since the introduction of the final finish “Electroless Nickel/Immersion Gold” (ENIG) more than 20 years ago, there has been a soaring rise in the demands on the surface metallisation. In the past, features like surface planarity and pad solderability were firmly in the focus, but today there are more and more particular cases in the field of high frequency signal processing, medical applications and fine line technology, where electroless nickel layers have been banned completely from the surface metallisation of substrates. For all of them, new processes were introduced successfully into the market: “Electroless Palladium/Immersion Gold” (EPIG) and “Immersion Silver/Immersion Gold” (ISIG). Both final finishes use a semi-autocatalytic gold electrolyte to cope with the technological advance to the processability of the surface metallisations. Resulting metallisations exhibit an excellent soldering and bonding performance. The crucial layer characteristics will be displayed and discussed in respect to the soldering and bonding performance, gained in the field.