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Process control of electroless nickel plating baths with Hg-free sensors

May 15, 2023

Article

Electroless nickel (EN) plating is known for its superior corrosion and wear resistance, low cost, uniform thickness, and ability to plate on large and complex substrates. EN plating is a widely used surface treatment method in many industries such as aerospace, construction, and electronics—particularly in the manufacturing process of PCBs (printed circuit boards). To ensure that a high-quality coating is produced and the desired specifications are met, several parameters must be monitored during the electroless nickel plating process. This article describes how mercury-free sensors from Metrohm can be used to monitor the concentration of stabilizers (e.g., Pb, Sb(III), and Bi) in electroless Ni plating baths.

Overview of the electroless Ni plating process

Electroless nickel plating is known as a chemical or autocatalytic plating process. EN plating is based on the deposition of nickel alloys on different substrates without the use of electric current. The process takes place in a specific Ni plating bath, such as that in Figure 1. An electroless nickel plating bath typically contains several key components including Ni salts, reducing agent, pH adjuster, stabilizers, and complexing agent. The specific composition of the bath may vary—additional components may be added to achieve specific coating properties or to improve the efficiency of the plating process [1].

Example of an electroless Ni plating bath.
Figure 1. Example of an electroless Ni plating bath.