Materials for High and Low Voltage Small Busbars

Copper and aluminum are the primary conductive materials for small busbars, with insulation materials varying by voltage level and application.

Conductive Materials

Copper is the most commonly used material for both high and low voltage busbars due to its excellent electrical conductivity, thermal performance, and mechanical strength. It is ideal for high-current applications and provides low resistance, which minimizes voltage drop and heat generation . Aluminum is also widely used, especially where weight reduction is important, such as in automotive or aerospace applications. While its conductivity is lower than copper, aluminum is lighter and more cost-effective, making it suitable for low to medium current busbars . For high-frequency or high-power converters, thicker copper or laminated busbars may be used to reduce parasitic inductance and improve current handling, particularly in systems using wide-bandgap semiconductors like SiC or GaN .

Insulation Materials

High Voltage Busbars (≥1 kV) require high-grade insulation to prevent electrical breakdown. Common insulation materials include:

• Epoxy resin and polyester for solid insulation
• Laminated materials such as Nomex®, Tedlar®, Mylar®, Kapton®, Ultem®, or combinations like Mylar/Tedlar for laminated busbars These materials provide thermal stability, mechanical strength, and dielectric protection, which are critical for voltages up to 110 kV . Chamfered edges and careful structural design help reduce electric field concentration and improve safety . Low Voltage Busbars (<1 kV) typically use more flexible and cost-effective insulation, such as PVC, polyvinyl chloride, heat shrink tubing, or epoxy powder coating. These materials are sufficient for voltages commonly found in industrial and commercial systems (220–380 V) and allow for easier shaping and assembly .

Design Considerations

• Cross-sectional area is determined by current density guidelines (e.g., 1.5–2.5 A/mm² for copper in continuous duty) to ensure safe operation and minimize hotspots .
• Rigid busbars are solid copper or aluminum bars, while flexible busbars may use laminated layers or braided segments to accommodate mechanical movement and reduce stress .
• Laminated busbars combine conductive layers with insulation to reduce inductance, improve high-frequency performance, and allow integration of components like sensors or capacitors .

Summary

For small busbars, copper is preferred for high conductivity, while aluminum is used for weight-sensitive applications. High voltage systems require robust insulation like epoxy or laminated materials, whereas low voltage systems can use PVC or heat-shrink coatings. Proper sizing, insulation, and design ensure safe, efficient, and reliable operation across both high and low voltage applications .