What Is Porosity in Electroplating?

In many applications, the electroplated surface of a product needs to be smooth and consistent to ensure proper functionality. In the telecommunications industry, especially, imperfections on the surface of a connector can lead to electrical resistance and poor performance.

Modern electroplating methods allow for the production of high-quality finished parts. However, a range of variables can still lead to imperfections on a finished product. One of the main types of imperfection affecting electroplated products is porosity.

What Is Porosity?

Porosity refers to the presence of microscopic defects in an electroplated product’s metal coating. These defects are small holes that typically appear with coating thicknesses of less than 1.25 microns. The pores can reach down to the base material or stop at an underplate if one is present. Porosity can affect many kinds of metal coatings, but gold may be particularly susceptible.

Although you can’t see porosity on the surface of a product on your own, it is possible to view the pores through a Scanning Electron Microscope (SEM). The number of pores that can exist on a product’s surface is up for debate, although pores typically make a bigger difference in harsh environments.

Causes of Porosity

Several problems that occur before, during and after electroplating can cause porosity. Common causes of porosity include:

  • Existing defects in the substrate surface
  • Imperfect stamping and forming processes
  • Insufficient thickness of the coating
  • Damage that occurs after plating

Because porosity is related to coating thickness, it is important to understand how metals are deposited on a substrate during electroplating. After placing the base material in an electroplating solution, the metal coating adheres to the substrate’s surface at multiple sites. The plating then spreads out from those sites to coat the surface of the object gradually as thickness increases. As a result, thin coatings may fail to cover the surface entirely or result in porosity.

How Does Porosity Affect Products?

The impact porosity has on an electroplated product depends on its intended application and whether it has an underplate. The biggest problems caused by porosity in electroplating are corrosion and corrosion creep, which occur when pores reach down to the base metal and allow corrosion products to travel through and contaminate the surface. Harsh application environments and the presence of chlorine and sulfur can increase corrosion creep in porous plated products.

In addition to causing corrosion, pores can also affect other characteristics of a final product, decreasing its strength and ductility.

How Do I Prevent Porosity in My Products?

If you think porosity could decrease your product’s durability and usability, you can prevent it from occurring and limit its negative effects by:

  • Reducing substrate surface roughness: Imperfections and roughness on the surface of the object you hope to electroplate onto can lead to increased porosity. This means you can prevent the formation of pores by polishing the surface thoroughly before electroplating.
  • Choosing to apply an underplate: An underplate cannot prevent pores from forming, but it can prevent corrosion creep. When pores stop at the underplate layer, corrosion products from the base material cannot escape to tarnish the surface.

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Contact SPC to Learn More

Plating defects such as porosity should not affect your ability to get the high-quality plated parts you require. To learn more about how Sharretts Plating Company works to prevent porosity when electroplating, reach out to us today.