Surface Finishing Tutorial
#290 Electroplating on Other Types of Metals
Category : Electroplating
May 8, 2017
The following table describes the characteristics and precautions specific to other metals being plated that were not introduced in the previous lessons.
| Metal | Characteristics and precautions |
| Zinc alloy | Zinc die-casting applications are popular. Precision casting makes this material suitable for complex shapes of components. In recent years, zinc die-casting has been a popular choice for electrical components and communication equipment parts because the advancement of molding technology has made the production of high precision yet ultra thin die-casting possible. Since it is a metal, electromagnetic shielding properties of zinc die-casting are superior to those of the plastic materials.
Prior to plating, the following tasks are required: pre-rinsing process (cleaning by solvent or emulsion) to eliminate dirt and smudges, as well as the strike plating using a cyanide bath. |
| Magnesium alloy | It is an ultra-lightweight material substituting aluminum and plastics. Its specific weight is 1.8 g/cm3, which is approximately two-thirds of the aluminum. The applications include mobile IT equipment, such as mobile phones and laptop casing. Since it is easy to recycle, it has been becoming a popular material for home electronics and audiovisual equipment. This material featuring lightweight, recyclable, and electromagnetic shielding properties is expected to be more common in the future.
Precautions for plating this material are almost similar to aluminum. However, special processes are adopted for activation and zinc substitution since magnesium is more reactive than aluminum. Strike plating is also required. In reality, most of them are die-cast products. Therefore, the plating surface tends to have a number of pinholes resulting in the reduced corrosion properties. Many of them are usually painted after the chemical conversion coating process, including chromate treatment. |
| Ferrite | Magnetic ferrite is used for magnetic necklaces, acupressure magnetic patches, and electronic components. The surface must be conditioned to have a smooth texture. Before electroplating, electroless nickel plating must be applied after the special pretreatment. |
| Stainless steel | The surface of stainless steel is covered by a passive film. This film must be removed before the plating process. As the activation treatment, the stainless steel product is immersed or electrolyzed in a nickel chloride bath where they will be coated with nickel plating. Next, the product is treated with electroplating. |
| Molybdenum | Plating is required for improving the soldering performance. However, a conventional plating method does not provide sufficient adhesion properties. |
| Beryllium | This lightweight and highly rigid material outperforms aluminum. Together with titanium, it is adopted in mechanical components. Since this metal is as reactive as magnesium, it is difficult to apply pretreatment. Some reports indicate that special processing may add better adhesion properties, but this material is generally difficult to work with. |
| Titanium | This material is known to have higher corrosion resistance as its surface is covered with a strong passive film. Plating may be applied in order to add conductivity or aesthetic appearance. In such a case, a special pretreatment process is required. |
| Sintered alloy | Sintered alloy is generally made of steel or copper powders. The porous characteristics of the sintered alloy make it difficult to be plated although such feature is effective in retaining lubrication oil. How to remove process liquid trapped in the holes is extremely important. Depending on the application, some of the sintered products have their pores impregnated, and this is easier than removing the residual liquid. |
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