We where looking at this two years ago. A company working in telecommunication asked us to qualify this process, because it is very convenient to have gold plated pads if the contacts for the dialling contacts must be gold plated too. We had several PCB's produced. Some with gold plated pads, some with HAL surface and some with an organic coating of the pads. These specimen where subject to thermal cycling. ( -20°C / 100°C; 80°C / min.; no dwell time ). The results of the crack propagation was, that after 10'000 thermal cycles the solder joints on gold plated pads showed cracks approx. 2x longer than in the solder joints on HAL pads those in the joints on pads covered with organic compound had cracks approx. 2.5x the cracks in the solder joints on HAL pads. Microsections showed some AuSn intermetallich compounds and SnNi Intermetallics. No reidues of the gold layer where visible.Note, that we have no information how thick the Au layer was. It war sold as "Gold Flash on Nickel", whatever the PCB supplier meant with that term. However, we suggested, that the technology would be adequate for indoor telecom equipment since the thermal stress is not as severe as tested. Problems occurred after one year, when the company switched the entire production to the Gold plating process. One customer decided to place a telephone switching box outside. After one winter the equipment failed and when the box was opened there was heavy rainfall of components off the vertical mounted PCB.The rupture surface showed lots of AuSn and NiSn intermetallics. Unfortunately we could not organise additional founds to continue with our research in this field. In the meantime we successfully produced 500 PCB's with a testpattern containing 0.5mm pitch QFP's and HAL pads. The stencil printing was tricky but well possible. Right now we work on 0.3mm but it seems as if HAL is difficult to print. G.Grossmann [log in to unmask]