Electro-Spec Blog

While single-metal plating has been used for many years for a variety of industries, “White Bronze” or tri-metal (Tri-M3) plating is quickly becoming a suitable alternative. White Bronze plating offers superior corrosion resistance, low electrical resistance, non-magnetic properties, and extremely high hardness characteristics. It’s a less expensive approach to using silver and offers definitive health safety advantages compared to nickel. Due to its cost effectiveness and performance White Bronze is rapidly becoming the preferred plating for RF Connectors.

White Bronze centers around an alloy ratio of 55% copper, 30% tin, and 15% zinc. It offers the same bright white finish as plated alloys that contain nickel, silver, or rhodium. It produces smooth, low friction surfaces with non-porous characteristics and is also non-magnetic. White Bronze is ideal for soldering applications as it is lead-free, can be soldered with or without flux, and offers excellent leveling characteristics. The most important factor for tri-metal alloys in electroplating is the ability to control the % alloy mixture to achieve specific performance characteristics and properties. This has resulted in an increase use of White Bronze for the electronics and telecommunications industries and is a significant replacement to traditional tin and copper-tin alloy plating via silver or nickel.

Precious metal plating is an expensive process, especially because the standard method for improving corrosion is to increase the plating thickness. With self-assembled molecules (SAM’s), however, metal plating can be reduced significantly without losing corrosion protection. In addition to enhanced corrosion protection, SAM’s will also allow plated components to have increased conductivity.

Conductivity and Reduced Metal Thickness

Precious metal plated items, and in fact any plated item, experience increased resistivity because of uneven surfaces. This resistivity becomes even worse when the plating is thicker. Most manufacturers are forced to increase the thickness of the plating to stop corrosion, but this can decrease the performance of the item while increasing the cost of production. SAM’s addresses both of these issues. The molecular shield provided through SAM’s helps slow the corrosion process down and allows manufactures to use a thinner plating deposit.

When this happens, the conductivity of the plated item improves as well. This is because the plating is thinner and the molecular shield provides a more even surface that lowers resistance. Contact resistance due to uneven surfaces caused by thicker plating creates localized heating. With SAM’s, however, this problem is solved because the molecular shield fills the voids in any uneven surfaces of the plated component. The surface then becomes smoother, enhancing conductivity.

One of the major benefits of SAM’s is increased solderability, which is a result of increased corrosion protection the post-plate process gives the plated component. When precious metal experiences corrosion, it affects anything soldered to the metal. When the metal coating is protected by SAM’s, however, it resists corrosion for longer periods of time and improves solderability.