| 摘要 |
<p>Electrical contact materials are provided which belong to the general category of copper that is overplated with a noble metal, usually gold. The improvement resides in the provision of an electroless nickel deposit laid down between the copper basis metal and the gold layer, which electroless nickel deposit acts as a barrier layer and is laid down from a particular class of nickel-boron or nickel-phosphorus baths. The nickel-phosphorus bath should have, as well as conventional additives, an unsaturated carboxylic acid tensile stress reducing agent, preferably at between 0.005 and 0.1 mol/litre, and the nickel-boron bath should include zirconyl or vanadyl ion as boron deposition enhancer preferably at between 0.001 and 0.1 mol/litre. The thickness of this layer is preferably not more than 800 microinches. There may be also an electroless deposit of an underlayer between the basis metal and the barrier layer.</p> |
