Copper busbar coating product industry knowledge details

Copper busbar coating refers to a composite conductive component formed by covering the surface of the copper bar with a layer of polymer insulating material through electrostatic spraying or fluidized bed dipping process. Its core structure is that the internal copper conductor is closely adhered to the external coating. It maintains the excellent conductive properties of the copper material while providing reliable electrical insulation, corrosion resistance and mechanical protection functions. Different from dipped PVC or heat-shrinkable sleeves, the powder coating process represented by Busbar Coating Powder uses solid powder as the coating material, which is adsorbed on the surface of the grounded copper bar under the action of static electricity. After solidification at high temperature, a continuous, dense, cross-linked thermosetting insulation layer is formed. Its adhesion and temperature resistance are better than those of thermoplastic coatings. Distinguished from the material system, Epoxy Coating Powder Busbar uses epoxy resin-based powder, which forms a three-dimensional network structure after curing, has high dielectric strength and chemical corrosion resistance, and is suitable for medium and high-voltage electrical equipment; Powder Coated Bus Bars is a broader category, covering a variety of powder systems such as epoxy, polyester, polyurethane, etc., and can be selected according to the temperature, humidity and chemical corrosion risk of the application environment.

 

In terms of structural form, Copper BusBar Powder Coating can be applied to straight copper bars, L-shaped/Z-shaped/U-shaped bent copper bars and special-shaped stamped copper bars. The coverage of the coating can be full insulation (whole package) or selective insulation (only specific sections are coated, and both ends are exposed for connection). For scenarios that require bending of wiring, the Epoxy Powder Insulated Bending Copper Busbar represents a process route that involves bending and then powder coating. The challenge is that the coating needs to maintain good flexibility and adhesion at the bending location. The cured thermosetting epoxy coating itself is not flexible, so the bending must be completed before coating. In terms of connection method, the Insulated Coating Tinned Solid Copper Busbar Connector combines tin plating with powder coating - the copper bars are first tinned at the ends to improve contact performance, and then powder-coated insulation is applied to the middle span area, and the exposed tinned areas at both ends are used for bolt connections.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The manufacturing of copper busbar powder coating starts with copper bar processing. The copper strip or plate is formed into the required shape through processes such as punching, bending, and drilling. All edges need to be chamfered or deburred (the chamfer radius is usually 1~2mm). Sharp edges may not only cause the coating to produce a Faraday cage effect during electrostatic spraying and make it difficult to cover, but will also become an electric field concentration point in subsequent use, increasing the risk of partial discharge. The processed copper bar enters the pre-treatment process - first use alkaline degreasing agent cleaning or ultrasonic cleaning to remove oil stains and processing residues on the surface, then rinse with pure water, and then perform chemical conversion treatment (such as phosphating or chromate passivation) to form a micron-level conversion film on the surface of the copper bar. This film layer can increase the adhesion and corrosion resistance of the powder coating. After the pre-treatment is completed, the copper bars must be thoroughly dried, and there should be no moisture or contaminants remaining on the surface.

 

Then enter the powder coating process. Spraying is carried out in a dedicated spray booth, and the workpiece is transported to the spray booth through a hanging chain and grounded. Busbar Coating Powder is sprayed through an electrostatic spray gun. The powder particles are charged under the high-voltage electrostatic action of the spray gun and are adsorbed by the grounded copper bar. For copper bars with complex shapes, the angle and distance of the spray gun need to be adjusted to ensure that the powder can enter hard-to-reach areas such as the inside of bends and deep holes. The spraying thickness is achieved by controlling the moving speed of the spray gun, powder output and electrostatic voltage. Usually, a coating thickness of 60~150μm can be obtained in one spraying. For the Epoxy Powder Insulated Bending Copper Busbar, since the copper row has been bent before coating, the Faraday shielding effect is prone to occur in the concave area inside the bend - charged powder particles are preferentially attracted to the protruding edges and have difficulty entering the recessed area. This requires adjusting the spray gun position or using a friction electrostatic spray gun to improve the coverage effect.

 

After spraying, the copper bars enter the curing oven. Powder coatings melt, level and chemically cross-link at high temperatures, transforming from a physically bonded powder layer into a chemically bonded thermoset coating. Curing temperature and time depend on the powder formulation. Typical epoxy powder curing conditions are 180°C to 200°C for 10 to 20 minutes. During the curing process, if the temperature is too low or the time is too short, it may lead to incomplete cross-linking and insufficient mechanical and insulating properties of the coating; if the temperature is too high or the time is too long, the coating may become discolored, brittle, or produce bubbles. The cured copper bar is taken out of the oven and cooled naturally in clean air or forced air cooling to room temperature.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Coating surface condition. The surface of the cured powder coating should be smooth and even, with no orange peel, no sagging, no bubbles, no pinholes, and no foreign matter inclusions. For the flat area of ​​Copper BusBar Powder Coating, the surface roughness is usually controlled within the range of Rz 10~30μm, which ensures sufficient insulation strength without being too rough to cause dust accumulation. The coating at edges and corners should completely cover the copper matrix without exposing copper. In these areas where electric field concentration is prone to occur, the coating thickness should not be less than 60% of the thickness of the flat area.

 

Coating performance at bends. For Epoxy Powder Insulated Bending Copper Busbar, the bending part is a key location to test the flexibility and adhesion of the coating. Under the premise that the bending radius is large enough (not less than 3 times the thickness of the copper bar) and the bending is completed before coating, the cured coating should have no microcracks on the outside of the bend and no peeling or wrinkling on the inside of the bend. When observing with a magnifying glass, the coating color of the bending area should be consistent with that of the flat area, without any whitishness. When the cross-hatch adhesion test is performed on the bent parts, the coating on the edge of the square should not fall off in a large area.

 

Boundary quality of exposed end area. For products that need to be exposed at both ends and insulated in the middle, the boundary between the exposed area and the insulating area should be clear and straight. The end face of the coating should be perpendicular to the surface of the copper bar and the thickness should be evenly transitional without any inversion or sagging. No coating creeps into exposed areas at the boundaries, and no exposed areas are accidentally covered by coating. The length of the exposed area should be at least 3~5mm longer than the minimum length required for the bolt connection, leaving enough space for bolt washers and nuts. For the Insulated Coating Tinned Solid Copper Busbar Connector, the tinned layer in the exposed area should be complete and continuous, and the surface of the tin layer should be silver-white matte without oxidation, discoloration or scratches.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copper busbar coating is widely used in medium and high voltage switch cabinets, wind power converters, rail transit traction systems and high voltage distribution boxes of electric vehicles. In 10kV to 35kV medium-voltage switchgear, the main busbar needs to withstand high power frequency withstand voltage and lightning impulse voltage. The distance between phases and the distance to ground of bare copper bars need to be larger to meet the insulation requirements. After using Epoxy Bus Bar Coating, the surface of the copper bar is covered with an epoxy coating with high dielectric strength, which can effectively reduce the distance between phases and realize the miniaturization design of the switchgear. In wind power converters, the salt spray and humid environment inside the cabin places higher requirements on the corrosion protection of copper busbars. Although the Tinned Copper Busbar can provide certain corrosion protection, the tin-plated layer may still suffer from pitting corrosion in the long-term salt spray environment. The powder coating, as a thicker organic insulation layer, can more effectively isolate the corrosive medium.

 

At the same time, the coating surface is smooth and difficult to accumulate dust, reducing the risk of surface discharge caused by contamination. In the field of rail transit, in the traction converter cabinet at the bottom of the train, the copper bars are subjected to continuous vibration and temperature cycles during operation, and may be exposed to snow melting salt spray and road dust. Powder Coated Bus Bars have become the preferred insulation solution for electrical equipment installed under the train due to their good adhesion and chemical resistance. In the high-voltage power distribution box (PDU) of electric vehicles, the Insulated Coating Tinned Solid Copper Busbar Connector combines tinned contact surfaces with powder-coated insulation - the connection area remains tinned to ensure low contact resistance, while the non-connection area is powder-coated to prevent insulation breakdown between high-voltage circuits. At the same time, the thickness and color of the coating can also be used to distinguish circuits of different voltage levels (for example, orange is used for high-voltage DC circuits). In addition, inside the energy storage container, the high-voltage connection copper bars between battery clusters use the Busbar Bonded Powder Coating process. The firm bonding between the powder coating and the copper bars ensures that the coating will not fall off or produce partial discharge in a long-term vibration environment.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If you need Copper Busbars at Coating selection suggestions, our coating engineers can provide complete process solutions and sample verification support based on your voltage level, installation environment and cost goals.