“Optimum process performance cannot be obtained without careful control of the plating bath chemistry.”

There are numerous factors that are necessary to obtain an acceptable plated part. Bath chemistry is one of the most critical ones. As quality requirements become more stringent for plated parts, plating has evolved into a more exact science. This is especially true for mission critical components.

Chemistry for Plating Processes
Chemical Analysis and Adjustments at AEP

Some parts must meet porosity or salt spray requirements, while others must be R0HS compliant with lead contaminations being carefully controlled. Precious metal plating baths must be monitored to meet hardness and purity standards.
Most bath parameters, including pH, metal concentration and impurities are analyzed on a consistent basis. The data is recorded and plotted while calculating upper and lower control limits. Lab software has become a very useful tool to monitor variables and determine what type of chemical additions a bath may require.

Once the optimum concentration of chemicals in a plating bath is determined, it is important to analyze and maintain that concentration. Some of the methods utilized to perform the analysis include:

Volumetric Methods – most notably titration, where the concentration of the analyzed component is generally determined by a color change when adding a reagent.

Gravimetric Methods – a component is separated from other components often by precipitation. The precipitate is then analyzed for concentration.

UV-Vis Spectroscopy – substance analysis by the measurement of emitted light compared to the light that is absorbed. When atoms are excited, they emit light. These wavelengths are distinct for each element and can be analyzed.

Atomic Absorption – this method uses a flame to convert a sample aerosol into an atomic vapor that absorbs radiation from a light source emitting a spectrum specific to the element being analyzed.

When plating parts that are used for high reliability connections, such as the many components we plate at American Electro Products, it is imperative that they meet all necessary specifications on a consistent basis. These critical applications include aerospace, automobile, medical and military. As you can imagine, there is no room for error. The part must perform as designed throughout its lifecycle. Further, downstream corrective action costs escalate quickly. Maintaining bath chemistry at optimum levels is a major ingredient in achieving the quality required by these industries. It is also an important factor to maintaining Nadcap certification, which also includes strict documentation procedures.