Analysis of stabilizers in electroless nickel baths

Sensitive determination of lead, antimony, bismuth, or iodate by voltammetry/polarography

Many industrial production processes use electroless nickel (EN) plating to prevent wear and corrosion. In the semiconductor industry, EN plating is an essential production step, where the ENIG (electroless nickel, immersion gold) and ENEPIG (electroless nickel, electroless palladium, immersion gold) processes are used for the PCB production. Stabilizers play an important role in electroless nickel plating solutions as they control the plating rate and prevent uncontrolled plate out (decomposition) of the bath. However, it is important to hold the stabilizer concentration at an optimal level. Too low stabilizer levels negatively affect the deposition rate and bath stability. Too high levels can poison the deposition at the edges or stop the plating reaction. Monitoring of the stabilizer concentration is therefore essential for an optimal plating process.

Historically, lead has been used as a stabilizer in electroless nickel baths. Because of restrictions, such as RoHS, on heavy metals in consumer goods, and particularly electronics, alternative stabilizers have become more popular. Common alternatives are antimony, bismuth, or iodate. Anodic stripping voltammetry/polarography is ideal to determine the concentration of all three stabilizers, even in the low mg/L range. Other bath components do not interfere with this selective analysis.

With an 884 Professional VA Analyzer, determination of the stabilizer concentration is straightforward. Samples can be directly measured after dilution. To learn more about the method, download our free Application Notes on this analysis:

> Lead in electroless nickel baths

> Iodate in electroless nickel baths

> Antimony and bismouth in electroless nickel baths

> Download pr in English

Surface finishing, electroplating baths