Electroplating is used by manufacturers in a wide range of sectors to add a finishing touch to their products. Electroplating has various advantages for the end product, including a stronger surface, corrosion resistance, wear resistance, and an overall enhancement in appearance. If you’re familiar with electroplating, you’re surely aware that the process entails submerging the substrate in a chemical bath containing metal ions such as gold, copper, nickel, or silver.
The introduction of direct current immediately follows the application of the coating through electrodeposition. A metal coating is applied to the surface of another metal object during the plating process. These metals can conduct electricity, which is necessary for the coating’s adherence. But what if you need to plate metal onto a non-conductive material’s surface?
Understanding non-conductive material
Non-conductive materials, commonly known as insulators, are substances that inhibit or obstruct electron flow. Because the atoms inside these insulators lack the additional electrons required to carry an electric charge, they display this property, making it extremely difficult to pass a charge through the material. Paper, glass, rubber, porcelain, ceramic, and plastic are examples of non-conductive materials.
Glass, ceramic, and plastic are standard in various sectors, and they are frequently plated with metal to change their appearance and physical properties. Plating non-conductive materials can also be found in multiple consumer products, such as kitchenware, toiletries, bathroom items, apparel, and bottle caps.
Electroplating onto non-conductive materials
Today’s manufacturing sector knows a lot more about plating onto non-conductive materials than it did when it first started, and the technique has improved over time. When plating onto non-conductive materials, though, it’s not uncommon to run into issues. Several aspects must be considered to ensure a high-quality output, the most important factors relating to product design and plating methods.
- While this is a self-evident concept, it is important to remember because it impacts the electroplating process. The classic electroplating procedure is functionally unable to plate due to the substrate material’s inability to conduct electricity. As a result, the first layer to be deposited on a part must be done using an electroless plating process. This stage is difficult in and of itself since it has a considerable impact on the product’s handling during the design and plating procedures.
- Designing a product for the plating process is one of the most difficult aspects of non-conductive material plating. Because non-conductive materials can’t be plated with electricity, their design must accommodate electroless plating. The following elements and factors must be included in a product design to ensure good plating.
- Wall thickness: The product’s walls should be no more than 3.8 millimetres thick. Thicker walls restrict airflow, causing uneven cooling and warping or shrinking of the part. Ribs can add strength to a component instead of thicker walls, which has the added benefit of keeping the product weight low.
- Minimal variation: The product’s cross-sectional dimensions should remain consistent throughout. Use smooth curves instead of using harsh edges, curves, corners, and recesses when creating a product. Deep grooves can be difficult to access, and sharp corners might cause plate accumulation or flash, compromising the product’s final fit and look.
- Trapping of process chemicals is one of the most serious issues encountered during the plating process. These chemicals can get trapped in or on the product surface during cleaning, washing, or electroplating procedures and leak out at a later stage, causing damage or hindering layer adhesion. To avoid this, construct portions that drain faster — for example, if a design has a blind hole, make it a through-hole or make it larger to aid the liquid draining process.
- Mould design is very important for plastic parts. It’s critical to design the product mould so that the completed item can be ejected without using a mould release agent. Mould release agents, such as silicon, can adhere to the surface of the plastic and prevent the plating from adhering to the part. Instead of utilising such agents, basic procedures such as polishing the mould’s surface can make ejection easier without using hazardous chemicals.
Challenges with electroplating on non-conductive materials (plastic and ceramic)
While plating onto non-metallic materials like ceramics and plastics has numerous advantages, it can be a more challenging operation than plating into metal. Some of the factors to keep in mind while plating non-conductive materials are listed below.
- Cleanliness: Maintaining the cleanliness of the substrate material is critical for a high-quality end product; contaminated surfaces can result in poor adhesion and surface flaws, among other issues. To do this, the material is chemically cleaned before plating, with chemical baths used to remove surface impurities from exposed areas. The base isn’t the only thing that needs to be kept clean — plastic moulds, racks, baths, and other equipment used in the production and plating processes should also be kept clean to avoid pollutants getting into and on the product.
- Draining and drying the product between each phase is critical, so draining should be designed into the product. Trapped chemicals can leak out during the plating process, resulting in a low-quality plate or poor adhesion between plating layers.
- Moisture can also be a problem during plating, as trapped moisture pockets in plastic parts can cause surface flaws, including blisters and splay.
- Due to excessive temperatures or currents, non-conductive materials may distort or shatter at various phases of the plating process. These problems can also be caused by handling errors.
While these difficulties are distinct from those encountered when electroplating conductive materials, they are reasonably simple to overcome when working with a professional plating company that specialises in electroplating non-conductive materials and is knowledgeable about the process’s complexities.
Electroless plating as an alternative for non-conductive materials
The electroless plating procedure is the key to electroplating non-conductive materials. Electroless plating uses an electric current to deposit a thin layer of metal. Electroless plating uses no electricity to deposit a light coating of metal. Instead, the electroless plating technique uses an autocatalytic reaction to apply the coating. The steps to electroless plating include-
- Any oils, greases, or particles on the surface of the substrate must be removed before applying any chemicals; any of these could interfere with the etching or plating process, resulting in a sub-standard coating. Cleaning often entails using multiple acids and bases, followed by several rinses to remove any chemical residues.
- After the material’s surface has been cleaned, etching is used to prepare it for plating. This method involves immersing a plastic or ceramic workpiece in a chrome-sulfur etching solution, which eats away at the substrate’s surface. This procedure adds texture to the piece’s surface, making it easier for the metal to attach to the substrate. After finishing this step, thoroughly clean the substrate to remove any excess chromic acid.
- After etching, the item is immersed in an electrolyte bath of palladium and tin salts. The object is then electroplated with a nickel or copper electroless plating solution. As a catalyst, the palladium and tin salt solution causes a reaction that drives the nickel or copper to form a thin layer on the substrate.
- If you don’t want to use an electrolyte bath, you can apply conductive paint over the substrate’s surface.
- After the electroless layer has been completed, a thin coating of copper metal is electrodeposited on the workpiece’s surface.
Plating onto non-conductive materials is a difficult procedure with a lot of variables to consider. Working with an experienced plating company like Smart Microns, on the other hand, can make things a lot easier.