Galvanic Plating of Electrical Contacts – Process and Properties

Haomiao Yuan did a doctorate under the supervision of Professor Dr.-Ing. Jian Song in the Department of Mechanical Engineering and Mechatronics, TH OWL, in cooperation with RWTH Aachen under the supervision of Professor Dr. Ing. Dr. h.c. Bernd Friedrich. The title of the dissertation was “Galvanic Plating of Electrical Contacts – Process and Properties.”

Haomiao Yuan

With the development of cyber-physical systems, such as autonomous and networked vehicles and smart factories, the number of terminals such as sensors in the system is surging, which leads to a large quantity of electrical connectors required to connect the terminals. Therefore, the reliability and the lifetime of the electrical connectors influence the system reliability greatly. The electrical contacts are the critical components in the electrical connectors. As a result, the investigations with regard to electrical contacts’ lifetime and reliability and methods of improving the lifetime and reliability are of great importance and interest for both research and industry.

In the real operation of electrical contacts, platings are usually used to protect the base materials and to improve the performance of the electrical contacts. In general, platings can be divided into two groups: non-noble platings and noble platings. With regard to the use in electrical contacts, platings can be selected based on the operating conditions as well as cost factors.

In order to extend the application area of platings, the method of improving their performance and lifetime by modifying the fabrication process is of great interest. Galvanic plating is one of the most important and widely used plating methods for electrical contacts due to low cost and easy operation. In this way, it is meaningful to investigate methods to improve the performance of the plating used in electrical contacts by modifying the galvanic process. Since for non-noble and noble plating materials, the failure mechanisms are different and the cost to fabricate the platings varies largely, the key points with regard to design and manufacturing of these platings are different.

The aim of the dissertation was to investigate new approaches to improve performance regarding the lifetime and reliability of electrical contacts with platings using the galvanic process and to describe the influence on the performance mathematically and analytically. Considering the nature of the plating, which can be briefly divided into non-noble and noble platings, different methods were used to improve performance, based on critical failure mechanisms. To measure the lifetime in experiments, the samples were tested under various conditions in the wear and fretting corrosion test. A model was proposed and validated to forecast the lifetime of the non-noble plating under various oxygen partial pressures. A methodology to predict the wear process of the noble plating was developed and then verified with experimental results. According to the results of the investigation in this dissertation, a great improvement of the platings in the lifetime and performance had been achieved. The dissertation had been submitted to the Faculty of Georesources and Materials Engineering, RWTH Aachen for assessment on 28.05.2020.