SLS Plastics

Plating on SLS Plastic

Selective laser sintering (SLS) is a technology used by 3D printers that takes tiny particles of plastic, ceramic or glass and fuses them together with heat from a high-powered laser. The result is a solid, three-dimensional object.

Many benefits make SLS plastic a popular material choice, including high production speed, low costs, durable parts that stand up against environmental conditions, complex geometric capabilities and more. Adding plating on SLS plastic parts provides even more benefits, including:

• Better chemical resistance: The metal around the component acts as a protective barrier against chemicals that could otherwise cause damage or corrosion of the part’s material properties.
• Additional strength: Both tensile and flexural strength increase from plating on SLS plastics. The increase in each type varies, but you can expect it to be several times the original strength of any SLA plastic component.
• Improved heat deflection: Some applications with these additive manufactured parts include hot conditions that the components need to withstand. Plating allows for deflection and strength even in high temperatures.
• Enhanced aesthetic value: While not crucial for many industrial and functional applications, plating does often improve a component’s appearance by giving it a shiny exterior. This benefit comes without the cost increase of manufacturing an entirely metal part.

Many plating companies won’t work with plastics due to the complexity and precision required for the process, and this is even more true of 3D-printed parts. When you choose SPC for your plating needs, we’ll work with your SLS plastic parts and offer you customization over the type of metal you want plating them and the process you want us to use — electroless plating or electroplating.

Before the Process of Plating SLS Plastic Parts

The process cannot begin before the plastic part is properly molded so that it is suitable for plating. Molding alleviates stress on the component and eliminates any surface imperfections that may have existed and caused quality problems. The molded part needs to meet specific parameters in its polishing, melt temperature and resin drying.

The next step before electroless plating can begin is to decide what type of plating you want from two categories: all-over plating or selective plating. All-over plating is the more cost-effective version because it requires a lower level of precision. Metal is deposited over the entire substrate surface at a thickness ranging anywhere from 40 micro-inches to 2,000 micro-inches.

When we perform selective plating, we deposit metal onto only a specific part of the surface, specified by our customer. For some applications, the whole surface cannot be covered. The parts are not exposed to any aggressive chemicals throughout the process because we want to prevent unwanted variation of texture or color. Using selective plating, we can reach a thickness level anywhere from 40 micro-inches to 400 micro-inches. Because the process requires a higher level of precision, it typically costs more than all-over plating.

Electroless Plating on SLS Plastic

Electroless plating is crucial to plating on SLS plastic even if you follow it up with electroplating for additional thickness or other qualities. Since the composition of plastic is non-metallic, the plastic substrate must be metallized before electroplating so it has higher adhesive properties. In electroless plating, metal is deposited onto the plastic substrate surface in a plating bath without any introduction of an electric current.

Many steps, though somewhat variable from job to job, can be included in the process:

• Cleaning: One of the first steps to electroless plating is making sure all fingerprints and debris like dirt are thoroughly cleaned off the surface of the substrate. A mild alkaline cleaner usually gets the job done, but sometimes wetting is required with a chromic acid or other solution.
• Pre-dipping: The plastic parts are then pre-dipped into a solvent before etching so the surface of any highly stressed or poorly molded part is improved. Additionally, the surface of parts that are hard to etch can become swelled through this step, which allows the etchant to more easily access all surface area.
• Etching: Usually consisting of sulfuric acid or chromium trioxide solutions, etchants increase the substrate surface and make liquid absorption over the component easier. This process also creates microscopic openings that facilitate metal-deposit bonding.
• Conditioning: Conditioning is an optional part of the process that can happen once etching is complete. Application of conditioner to the plastic promotes uniform absorption once the activation stage is taking place. Professionals completing the conditioning process must be careful not to over-condition.
• Neutralizing: Rinsing will always take place after etching to remove excess acid and other foreign substances. After the rinsing, a neutralizer may be applied to further insure elimination of any excess etchant. It can be made of sodium bisulfate or similar products that have been designed specifically to remove etchants.
• Pre-activating: Pre-activators are designed to enable and enhance absorption once the activation step is reached, but they must be applied with extreme caution when a conditioner is also present, since excessive conditioning could occur on the substrate’s surface.
• Activating: Next, a liquid activator with a low concentration of precious metal is introduced. It acts as a catalyst during the plating process. It also allows for significantly lower drag-out costs. The metals typically found in activators include platinum, palladium and gold.
• Accelerating: Accelerators remove extra stannous hydroxide, enabling the activator to fulfill its catalyst role more effectively. Accelerators also prevent a skip-plating occurrence.
• Bath immersion: Once the plastic parts are rinsed, we place them in an electroless bath, which deposits a thin metal coating onto them. Nickel is the most common metal chosen, often for conductivity and durability, but copper plating is less resistant to blistering, which makes it more popular for automotive parts.

Electroplating on SLS Plastic

Next, some people choose electroplating on their SLS plastic to increase thickness for higher corrosion resistance, durability and abrasion protection. While electroplating adds additional cost to the overall job, the qualities it provides on the substrate are important for greater functionality in many industrial applications. With the introduction of an electric current into the plating bath, deposition rate can increase by up to 10 times. Electroplating is not ideal for substrates with deep recesses.

Electroplating involves a specially designed electrolytic solution, commonly called a bath. The coating (plating metal) is connected to an anode, or positively charged electrode, of an electrical circuit. The substrate (SLS plastic material) is placed at a cathode, or negatively charged electrode. Both parts are immersed in the bath and the anode is supplied with a DC current that oxidizes the metal atoms and dissolves them. The dissolved ions are reduced at the cathode and plated onto the substrate.

• Nickel: For corrosion and wear resistance and a bright, metallic appearance, many people choose to plate their SLS plastic with nickel. Alloys often include metals like tungsten, tin and others, which increases the deposit hardness and further enhances the piece’s resistance.
• Copper: Most commonly chosen for its superior electrical conductivity that effectively metallizes non-conductive surfaces, copper plating also provides a heat stop-off for masking. It has a low cost compared to silver, gold and other precious metals.
• Gold: Gold improves the appearance of plated components and offers electrical conductivity, corrosion resistance and more. The heat resistance it gives a substrate makes the component usable in high-temperature applications.

Why Choose SPC to Complete Plating on Your SLS Plastic?

Plating, especially on 3D-printed plastic surfaces, is a delicate and complex process. You want professionals you can trust completing the work, which is why we encourage you to reach out to us at SPC. Our family-owned company has been creating innovative surface-treatment solutions since 1925. We strive to stay on top of metal-finishing technology and its evolution over the years, which helps us stay ahead of the competition in development, service, customer satisfaction and more. We want to bring our customers the best solutions at the lowest costs.

At SPC, our staff members make a positive difference in the caliber of work we can provide. We only hire the best and most educated, from our chemical engineers and scientists to our representatives and other industry professionals. Our staff members are constantly learning so we can become the best team possible. We also uphold social responsibility, which manifests in several ways. We emphasize a positive impact on communities and strive to make them smarter while also protecting the environment. Less waste and pollution in our plant means a better planet.

If you’ve decided plating on your SLS plastic is the right move, we’re here to help. We’ll assist you in making a decision about electroless plating versus electroplating and we’ll also provide several options for the plating material so you can get the right choice for your unique application. Once you’ve reached out to us, our highly trained representatives will get back to you within a single business day to deliver a free quote on the project.

We’re committed to differentiating ourselves, our products and our service. Contact us to see for yourself!

Additional Resources:

• Common Metals for Electroplating Plastics
• Plating Defense Against Corrosion
• Plastic Materials Electroplating Substrates