Debunking the More Layers, Better Misconception in Laminated Busbars

With the rapid development of new energy, power electronics, and industrial automation, laminated busbars are widely used in energy storage systems, inverters, new energy vehicles, power modules, and rail transportation due to their low inductance, high integration, and good EMC performance. Especially in high-frequency, high-power equipment, laminated low-inductive busbars have gradually replaced traditional cable connections, becoming an important component of modern power systems.

 

However, a common misconception persists in the industry: that more layers in a laminated busbar necessarily mean better performance. In reality, a laminated design is a systematic engineering project that requires comprehensive consideration of inductance, heat dissipation, structural space, cost, and application scenarios. There is no absolute conclusion that "more layers equals more advanced."

 

 

 

Laminated busbars are typically composed of multiple layers of conductive copper busbars and insulating media, bonded together using a hot-pressing process. They are typical multi-layer composite structure connection bars. By optimizing the distance and layout between the positive and negative terminals, stray inductance in the circuit can be significantly reduced, improving system operational stability. Currently, mainstream specifications in the industry mainly range from 2 to 6 layers, with different layer numbers corresponding to different application needs:

 

2-layer structures are typically suitable for low- to medium-power equipment, offering advantages such as mature manufacturing processes, lower costs, and simple installation. They are commonly found in basic Power Distribution Unit Busbars, low-voltage inverters, and general industrial power distribution systems.

 

3-layer structures are one of the most widely used solutions. Three-layer laminated busbars achieve better current distribution and electromagnetic shielding, offering high cost-effectiveness in medium-power equipment. They are widely used in energy storage inverters, UPS systems, and new energy auxiliary control modules.

 

Structures with 4 or more layers are more often used in high-frequency, high-power, and complex topology scenarios, such as Laminated Busbars in High Power Converters, IGBT Laminated Busbars, and large-scale energy storage PCS systems. Their core advantages lie in lower stray inductance, stronger EMC capabilities, and higher system integration.

 

 

 

I. Changes in Electrical Performance

With an increase in the number of layers, a tighter coupling structure can be formed between the positive and negative conductors, thereby reducing stray inductance. This is particularly important for high-frequency SiC devices and high-speed switching IGBT modules.

 

Customized Laminated Busbars for IGBTs typically focus on optimizing the interlayer structure of the busbar to reduce voltage spikes and EMI interference generated during switching.

 

However, increasing the number of layers does not necessarily mean unlimited performance improvement. Too many layers can lead to increased interlayer parasitic capacitance, which, if parameters are not properly matched, may negatively impact system stability. Therefore, when designing a Laminated Busbar for a Three-Level Inverter, inductance and capacitance parameters must be balanced simultaneously.

 

II. Changes in Heat Dissipation Capacity

Multilayer structures can expand the heat conduction path and heat dissipation area, thus multilayer busbars typically have a lower temperature rise under the same current-carrying conditions.

 

In high-current scenarios such as High Voltage Explosion-Proof Inverter Busbars, multilayer structures can effectively reduce local hot spots and improve long-term operational stability.

 

However, at the same time, increasing the number of layers also leads to an increase in overall thickness, occupying more installation space. Therefore, in compact devices, the internal layout needs to be comprehensively considered.

 

III. Improved System Integration Capabilities

One of the biggest advantages of laminated busbars is their high degree of integration. Compared to traditional wiring harnesses, multi-layer structures can simultaneously integrate multiple power loops, signal loops, and grounding systems, reducing connection nodes and improving system reliability.

 

For example:

Laminated Bus Bars for Distributing Power Backplanes can be used in server and industrial power systems.

Laminated Bus Bars for Router Backplane Distribution are suitable for internal power supply in communication equipment.

Laminated Bus Bars for Cellular Base Station Power Distribution are widely used in 5G base stations and communication power supplies.

In complex cabling environments, Laminated Busbars for Complex Busbar Installations effectively reduce space requirements and simplify the installation process.

 

IV. Structural Stability and Anti-interference Capability

Multi-layer structures can form a more complete electromagnetic shielding loop, thereby improving the system's anti-interference capability.

 

In the fields of new energy vehicles, electric drive systems, and rail transportation, Motor Controller Busbars and Subway Laminated Busbars have high EMC performance requirements. Multi-layer symmetrical structures can effectively reduce current imbalance problems and improve the long-term stable operation capability of equipment.

 

For rail transit and high-power traction systems, Composite Busbar for Train Power Supply Four-quadrant Power Modules also need to withstand dynamic impacts, withstand high temperatures, and maintain high insulation performance.
 

 

While higher-layer busbars offer superior performance, manufacturing complexity increases accordingly.

 

Two- to three-layer products have relatively mature processes, high yield rates, and controllable processing costs.

 

Four-layer and higher products place higher demands on copper foil thickness control, insulation lamination precision, hot-pressing processes, and symmetrical layout. This is especially true for specialized structures like partially laminated busbars, which require extremely high precision in processing local insulation and conduction areas.

 

Furthermore, multi-layer structures mean:

Increased raw material consumption;

More complex lamination processes;

Stricter testing standards;

Longer production cycles.

 

Therefore, high-layer solutions are not necessarily suitable for all projects.

 

 

For small to medium power equipment with a power output below 100kW, two to three layers are usually sufficient. These scenarios include basic applications such as general energy storage systems, small UPS systems, and Uninterruptible Power Supply (UPS) system busbars.

 

For medium-to-high power systems (100kW to 500kW), a 3-to-4 layer structure is more suitable to balance inductance performance, heat dissipation, and manufacturing costs.

 

For high-power systems exceeding 500kW, high-frequency SiC converters, and large energy storage systems, a 4-to-6 layer structure is typically required to meet requirements for lower inductance, higher EMC capabilities, and stronger heat dissipation.

 

Examples include:

Laminated busbar for electric cars;

High Voltage Explosion-Proof Inverter Busbar

Large-scale energy storage PCS systems;

High-voltage frequency converters;

New energy vehicle main drive systems.

 

In complex circuits such as multi-level topologies, a 3-to-5 layer structure is often required for the laminated busbar for three-level inverters to achieve symmetrical current paths and stable current sharing control.

 

 

 

Misconception 1: More layers necessarily mean better performance

In reality, the number of layers is the only parameter affecting performance.

Copper busbar thickness, insulation material, circuit layout, conductor spacing, and processing precision all directly impact the final performance.

Blindly increasing the number of layers not only increases costs but may also affect equipment stability due to changes in parasitic parameters.

 

Misconception 2: Low-layer products are "low-end solutions."

In fact, for many small and medium power devices, 2- to 3-layer structures are the most mature, stable, and cost-effective solutions.

A well-designed three-layer laminated busbar can fully meet the needs of most conventional industrial applications.

 

Misconception 3: Products with the same number of layers have the same performance

Even with the same number of layers, significant differences can still exist between different designs.

For example, the copper foil arrangement, insulation material, hot-pressing process, and conductor symmetry all directly affect busbar performance.

The actual performance of high-quality copper busbars is often far superior to that of ordinary structure products.

 

 

 

With the continuous development of SiC devices, high-frequency inverter technology, and energy storage systems, laminated busbars are evolving towards higher frequencies, higher integration, and greater refinement.

 

In the future, high-end electronic fields such as Laminated Bus Bars for Supercomputer Circuit Boards or Backplanes will further drive the development of busbars towards high density, miniaturization, and customization.

 

At the same time, dedicated busbar designs for new energy vehicles, power electronics, and communication equipment will become more segmented, with the industry placing greater emphasis on "application adaptation" rather than simply pursuing an increase in the number of layers.

 

 

The core value of laminated busbars lies not in "more layers," but in their ability to accurately match equipment requirements.

 

A reasonable layer design should comprehensively consider:

Equipment power;

Switching frequency;

EMC requirements;

Heat dissipation capacity;

Installation space;

Manufacturing cost;

Long-term operational stability.

 

Only through scientific design based on actual application scenarios can the performance advantages of Laminated Bus Bars, passive electronic components, be truly realized, achieving the optimal balance between system efficiency, reliability, and cost.