Insulated, Tinned & Heat-Shrink Flexible Busbars

Carsai manufactures custom insulated flexible busbar products for battery systems, transformers, switchgear, busducts, inverters, energy storage equipment and other high-current electrical assemblies.

A flexible busbar carries high current while accommodating vibration, thermal expansion and small installation tolerances. Adding insulation helps protect the conductor from accidental contact and short circuits, while tin plating can improve the corrosion resistance and connection condition of exposed copper terminals.

We manufacture flexible copper and aluminum busbars according to customer drawings. Available options include multilayer copper foil conductors, tinned terminal areas, heat-shrink sleeves, PVC insulation, epoxy coating and customized exposed connection surfaces.

Customers can specify:

• Copper or aluminum conductor
• Conductor width and total thickness
• Number and thickness of layers
• Flexible-section length
• Terminal shape and hole pattern
• Tin, nickel or silver plating
• Insulation material and color
• Covered and exposed areas
• Operating voltage
• Continuous and peak current
• Required production quantity

For an overview of all multilayer, braided, aluminum and high-current designs, visit our Flexible Busbar Manufacturer page.

What Is an Insulated Flexible Busbar?

An insulated flexible busbar is a flexible high-current conductor covered with an electrically insulating material while retaining exposed terminal areas for connection.

The conductor may consist of:

• Stacked copper foils
• Thin copper laminations
• Aluminum layers
• Braided copper
• A flexible section combined with rigid terminals

The insulation normally covers the active conductor area, while the mounting terminals remain exposed so they can make direct electrical contact with the connected equipment.

An insulated flexible copper busbar can help reduce the risk of accidental contact between nearby conductive parts. It is particularly useful inside compact electrical equipment where phase spacing or clearance between components is limited.

Depending on the market, buyers may describe the same product as a flexible insulated bus bar, flexible insulated busbar, insulated flexible bus bar or insulated copper flex bar.

These phrases generally refer to the same product family, but the required insulation method can vary significantly between applications.

Why Flexible Busbars Need Insulation

Bare flexible busbars may be suitable inside controlled equipment where the conductors are physically separated and protected by the enclosure.

Insulation may be preferred when:

• Busbars are installed close to other conductive parts
• Several phases are positioned in a compact space
• The conductor passes near a metal enclosure
• Maintenance personnel may access the equipment
• Battery modules contain exposed positive and negative connections
• Vibration could cause nearby conductors to move
• Additional protection against accidental short circuits is required

Insulation can also provide visual identification. Different colors may be used to distinguish phases, polarity or circuit functions.

Common examples include:

• Red and black for positive and negative battery conductors
• Brown, black and grey for AC phases
• Green or green-yellow for grounding conductors
• Customer-specified colors for assembly identification

Color alone does not determine insulation performance. The material, thickness, operating temperature and voltage rating must match the application.

Insulated Flexible Copper Bar Construction

An insulated flexible copper bar is usually manufactured from several thin copper layers.

The terminal ends are consolidated into stable mounting areas, while the center remains flexible. Insulation is then applied over the required conductor sections.

A typical structure may include:

1. Multiple copper foils or laminations
2. Compressed or welded terminal areas
3. Customized mounting holes
4. Tin-plated exposed terminals
5. An insulated flexible section
6. Defined transition areas between insulation and bare terminals

The copper layer quantity influences both current capacity and flexibility.

More thin layers generally produce a softer conductor, while fewer thick layers create a stiffer connection. The insulation must allow these layers to move without cracking, separating or severely restricting the intended flexibility.

The transition between the insulated area and the terminal is particularly important. If the insulation ends at a sharp bend or high-movement point, repeated movement may damage the covering.

Heat-Shrink Flexible Busbars

A heatshrink flexible busbar uses heat-shrink tubing to cover the conductive section.

During production, a suitable sleeve is positioned over the busbar and heated so it contracts around the conductor. The mounting terminals usually remain exposed.

Heat-shrink insulation offers several advantages:

• Relatively uniform conductor coverage
• Multiple material and thickness options
• Different colors
• Good suitability for prototypes and custom batches
• Clear exposed terminal areas
• Easy identification of polarity or phase
• Protection against accidental contact

The sleeve must be selected according to:

• Operating voltage
• Required dielectric performance
• Busbar dimensions
• Shrink ratio
• Conductor temperature
• Ambient temperature
• Flame-retardance requirement
• Required flexibility
• Chemical or environmental exposure

The original tube diameter must be large enough to pass over the terminals before shrinking. This can become difficult when the terminals are much wider than the flexible conductor.

In such cases, another insulation method or a specially selected heat-shrink size may be required.

PVC and Other Sleeve Insulation

PVC sleeves can be used to cover straight or moderately formed flexible conductors.

Compared with coating processes, a sleeve may offer:

• Defined insulation thickness
• Replaceable tooling for different sizes
• Different color options
• Efficient coverage of longer conductors
• Clean exposed connection areas

However, the sleeve geometry must match the busbar closely enough to avoid excessive movement or gaps.

Possible sleeve materials may be selected according to voltage, temperature, flexibility and environmental requirements.

The drawing should identify:

• Sleeve material
• Wall thickness
• Insulated length
• Distance from mounting holes
• Exposed terminal length
• Required color
• Marking or labeling requirements

Epoxy and Powder-Coated Flexible Busbars

Epoxy or powder coating can create a durable insulating layer over selected parts of a flexible busbar.

These coatings may be suitable where the product needs:

• Close-fitting insulation
• Controlled exposed terminal zones
• Resistance to abrasion
• A clean integrated appearance
• Protection around complex formed shapes

Coating a flexible conductor requires careful process selection. A coating that is suitable for a rigid busbar may crack or separate if applied to an area that repeatedly bends.

For this reason, highly flexible areas may require a more flexible coating formulation, a sleeve or a design that limits movement after installation.

The customer drawing should clearly show which surfaces must remain free from coating. Mounting holes and electrical contact surfaces normally need masking.

Tinned Flexible Copper Busbars

A tinned flexible copper busbar has tin plating applied to all or part of its copper surface.

Tin plating and insulation perform different functions:

• Tin plating protects and prepares the conductive surface.
• Insulation electrically covers areas that should not remain exposed.

Many products use both. For example, the complete copper conductor may be tin plated before a heat-shrink sleeve is added, leaving only the tinned terminal areas visible.

Tin plating can be applied to:

• The complete copper conductor
• Only the terminal ends
• Only the contact faces
• Selected areas defined in the drawing

A search for tin plate flexible busbar normally refers to a tin-plated flexible busbar. The technically clearer product description is “tin-plated flexible busbar” or “tinned flexible copper busbar.”

The required tin thickness should be specified when the project has a defined plating standard. Selective plating may also be used when only the connection areas require surface protection.

Tinned Copper Flexible Jumpers

A tinned copper flexible jumper is a short flexible connection used to bridge two terminals, busbars or electrical components.

It may be manufactured from multilayer copper foil or copper braid and can include insulation over the central flexible section.

Common applications include:

• Battery module connections
• Transformer terminals
• Circuit breakers
• Contactors
• Fuses
• Busduct interfaces
• Grounding and bonding points
• Inverter output terminals
• Switchgear assemblies

Custom jumper options include:

• Straight terminals
• Bent or offset ends
• Different terminal widths
• Round or slotted holes
• Single- or multiple-hole terminals
• Fully tinned copper
• Selectively tinned terminal areas
• Heat-shrink or PVC covering
• Phase and polarity identification

Partial Insulation Versus Full Insulation

Most busbars cannot be completely covered because their electrical contact surfaces must remain exposed.

“Fully insulated” generally means that all non-contact conductor areas are covered, while mounting terminals remain accessible.

Partial insulation

Partial insulation covers selected sections, such as the center of the busbar, while leaving larger areas exposed for forming, mounting or cooling.

It may be selected when:

• Only one area is close to another conductor
• The terminals require a large exposed surface
• The conductor needs to release heat
• The product must remain highly flexible

Full conductor insulation

Full conductor insulation covers nearly the entire busbar except for the contact faces and mounting holes.

It may be preferred in compact battery packs, enclosed distribution systems or equipment with closely spaced conductors.

The final decision should consider voltage, temperature rise, clearance, flexibility and assembly method.

Applications

Battery packs and energy storage systems

Insulated flexible busbars can connect battery modules, contactors, fuses, disconnects and power-distribution units.

Insulation is especially valuable where positive and negative conductors are positioned near metal frames or adjacent battery modules.

Tin-plated terminals can also provide protected connection surfaces for repeated battery-system assembly.

Transformers

Transformer flexible links may require insulation where phase spacing is limited or conductors pass near grounded metal structures.

The flexible section helps absorb vibration, while insulation provides additional electrical separation.

Switchgear and busducts

Insulated flexible connectors may be installed between busbars, circuit breakers, transformers and busduct terminals.

Phase colors and controlled exposed terminal zones can simplify installation and inspection.

Inverters and power converters

Power-electronic equipment often contains compact high-current DC connections. An insulated flexible conductor can help route power between capacitors, modules and external terminals while reducing accidental-contact risk.

Design Considerations

An insulation system should not be selected only from the operating voltage.

The design should also consider:

• Continuous current
• Conductor temperature
• Ambient temperature
• Allowable temperature rise
• Required movement
• Bend radius
• Insulation thickness
• Creepage and clearance
• Exposure to oil, moisture or chemicals
• Flame-retardance requirements
• Assembly and maintenance access
• Terminal-plating compatibility

Insulation can reduce heat dissipation compared with a bare conductor. Therefore, the conductor cross-section may need to be reviewed when a previously bare busbar is changed to an insulated design.

Manufacturing and Inspection

A typical production process includes:

1. Reviewing the drawing and insulation specification
2. Confirming conductor material and cross-section
3. Cutting and stacking copper or aluminum layers
4. Forming or consolidating terminal areas
5. Punching or machining mounting holes
6. Producing required bends and offsets
7. Deburring and cleaning
8. Applying tin or other plating
9. Masking exposed terminal areas
10. Adding the sleeve, heat-shrink or coating
11. Inspecting insulation position and coverage
12. Checking dimensions and terminal surfaces
13. Protecting exposed contact areas during packing

Inspection items may include:

• Overall dimensions
• Flexible-section length
• Hole diameter and spacing
• Terminal flatness
• Plating coverage
• Insulation thickness
• Insulation length
• Distance from insulation to mounting holes
• Surface defects
• Color and marking
• Exposed contact-area dimensions

Information Needed for a Quotation

To quote an insulated and tinned flexible busbar, please provide:

• 2D or 3D drawing
• Copper or aluminum grade
• Continuous and peak current
• Operating voltage
• Conductor width and total thickness
• Individual layer thickness
• Number of layers
• Flexible-section length
• Terminal dimensions
• Hole size and spacing
• Plating type and thickness
• Insulation material
• Required insulation color
• Covered and exposed areas
• Operating temperature
• Order quantity
• Annual demand

If the final drawing is unavailable, we can initially review a sketch, sample or installation photograph.

Frequently Asked Questions

Are tinned and insulated busbars the same product?

Not necessarily. Tin plating is a conductive surface treatment, while insulation covers conductive areas. One busbar can use either treatment or both.

Can the whole copper busbar be tin plated before insulation?

Yes. The complete copper conductor can be plated first and then insulated, leaving the required terminal areas exposed.

Does insulation reduce busbar flexibility?

It can. The effect depends on the insulation material, thickness and flexible-section design. These factors should be considered together.

Can the two terminals have different exposed areas?

Yes. Each end can have a different terminal length, shape, hole pattern and plating area.

Can you provide different insulation colors?

Yes. Available colors depend on the selected sleeve, heat-shrink or coating material and order requirements.

Can you produce prototypes?

Prototype and small-batch production can be evaluated before regular-volume manufacturing.

Request an Insulated Flexible Busbar Quotation

Carsai manufactures insulated, tinned and heat-shrink flexible busbars for batteries, transformers, switchgear, busducts and power-conversion equipment.

Send your drawing with the required insulation type, exposed terminal areas, plating, operating voltage, current, dimensions and quantity.