Introduction

Industrial silver plating: The working environment for car electronics has gotten increasingly severe in recent years, requiring ambient temperatures for electronic vehicle components to exceed 150°C. Because most electronic modules operate better when installed as close to the motor or gearbox as feasible (that is, closer to the heat source), the physical connection to the electronic modules must now tolerate high temperatures up to 200°C. In addition, the connections to the power electronics in hybrid cars must operate reliably up to 200°C.

A perfect electrical connection with good electrical conductivity, aesthetic attractiveness, solderability, and corrosion resistance is created when silver (Ag) is coated over a nickel (Ni) barrier above bulk copper (Cu) substrates. When such Ag-coated components are frequently exposed to temperatures above 150°C, however, oxidation of Ni beneath the Ag occurs for unknown reasons.

Industrial electroplating services

Electroplating is mostly applied to modify the surface of an object; this can also be used to add thickness to the object. Industrial electroplating adds a variety of advantages. One of the most obvious benefits of plating is the capacity for adding a new experience to any object, for example, costing antiques with gold, silver, copper or brass and making them look like they have just been created for the first time. There are a variety of Industrial electroplating services like gold plating, silver plating, copper plating, Tin and Nickel plating, Electroless Nickel plating, Brass plating etc. Electroplating can be done on many parts like switches, connectors, slip rings, tubes, brackets etc.

Industrial silver plating technology driving 200 C automotive apps.

There appear to be inherent lifetime temperature limits on Ag plating on Cu substrates with a Ni diffusion barrier: delamination between the Ag coating and Ni underlayer occurs after just 200 hours @180°C due to Ag-accelerated oxidation of Ni, whereas new automotive specifications require coatings capable of sustaining 200°C for 1,000 hours with no adhesion issues. In addition, pure Ag with minimum contact resistance must be utilised instead of Ag alloys for coating electrical wires when the application requires the high-current-carrying capability.

Dow launched a comprehensive set of rigorous tests to discover the optimum approach to integrating an oxidation barrier into the metal stack with these restrictions in mind. We found that a thin tin (Sn) layer can act as an adhesion booster after exploring with fragile barriers of other metals with little success. Before depositing Ag, a thin film of Sn is deposited next to the Ni barrier layer to avoid oxidation of the Ni and, therefore, metal stack adhesion failure during high-temperature applications. 

Our investigations have revealed that when using the Sn strike to provide high-temperature resistance for Ag on Cu with a Ni diffusion barrier layer, there are two essential factors to consider:

  • Sn that is too thin may not be enough to guarantee adequate adhesion; and
  • The thicknesses of the Ag and Sn layers must have a ratio higher than 2. Otherwise, Sn will diffuse to Ag’s surface, lowering the surface conductivity.

Leading customers conduct product prototyping in a variety of sectors. For example, a prominent connector manufacturer has already passed acceptance and reliability testing on an automobile connection product made with this metal stack. Other high-temperature electronic connection applications, such as electric cars and high-power LEDs, might benefit from this revolutionary technique. We are delighted that this Ni-Sn-Ag layer structure and technique has been awarded European and US patents.

The patent application is pending in additional countries such as China and Japan. This unique method necessitates the plating of Ni, Sn, and Ag in a specific order. Dow provides plating chemistry for Ni, Sn, and Ag baths and assistance with Sn, strike layer integration into manufacturing lines using a variety of plating methods, including reel-to-reel continuous plating equipment.