A shielded aluminium busbar is a rigid high-voltage conductor built in three layers: a solid aluminium core that carries the current, an insulation layer, and an outer aluminium shield that contains electromagnetic interference and protects the part mechanically. It replaces heavy shielded copper cable between battery, distribution box, inverter and fast-charging inlet. This guide explains the structure, material choices, design rules and tests, and the aluminium materials Metline supplies for it.
Electric vehicles move hundreds of amperes at 400 V or 800 V between the battery pack, the junction or disconnect unit, the power distribution unit, the inverter and the charging inlet. Traditionally this is done with large shielded copper cables. A shielded aluminium busbar does the same job with a formed, solid aluminium conductor inside an integrated shield, so it holds its shape, packages tightly against the battery or body, and weighs much less.
The weight saving is straightforward physics. Aluminium conducts about 61 % as well as annealed copper by volume, so for the same resistance it needs roughly 1.6 times the cross-section. But it is only 30 % as dense (2.70 versus 8.9 g/cm³), so the aluminium conductor ends up at about half the mass of the copper one. Over several metres of high-voltage routing, the difference is measurable in kilograms.
A rigid busbar also removes the uncertainty of cable routing. It is bent to a fixed 3D path, clipped at defined points and terminated with machined or welded lugs, so creepage, clearance and bend radii are designed once and repeated on every vehicle.
| Layer | Typical material | Why | Key properties to specify |
|---|---|---|---|
| Conductor | 1060 (O or H temper) | Highest conductivity of the practical options; very formable | Conductivity about 61 – 62 % IACS; elongation for bending |
| Conductor | 6101 (T6, T61, T63, T64) | Higher strength and stiffness with good conductivity; holds shape and resists creep at terminals | ASTM B317 conductivity minimums from 55 % (T6) to 59.5 % IACS (T64) |
| Insulation | PA12, PVC, silicone or cross-linked polymers | Dielectric strength, temperature class, flame resistance | Wall thickness, temperature class, withstand voltage, UL 94 rating |
| Shield | 3003 aluminium tube or strip | Good conductivity, formability and corrosion resistance; easy to swage or seam | Wall thickness, continuity, transfer impedance |
The choice between 1060 and 6101 is the most important conductor decision. 1060 gives the lowest resistance and bends easily, but it is soft, so terminals need careful design to avoid creep and loosening under clamping force. 6101 in a T6x temper accepts bolted joints and vibration better and keeps a formed shape, at a small conductivity penalty. The 6101-T64 and T65 tempers are a common compromise because they keep conductivity high while adding useful strength.
Conductivity values are standard minimums from ASTM B317 (6101) and typical values for 1060; the mill certificate reports the measured figure for each lot.
Low profile, so it fits along battery trays, under floors and between modules where height is limited. A wide, thin conductor also has more surface area for heat dissipation and lower AC resistance from skin effect. Bending is easiest about the thin axis; edgewise bends need larger radii.
Bends equally well in every direction, so it suits complex 3D paths with frequent changes of direction. A round shield is also simple to make continuous and to terminate with standard sealing and shielding rings.
Start from the routing envelope. If height is the constraint and the path is mostly planar, choose flat. If the path twists through the chassis, choose round. Then size the cross-section from current, temperature rise and short-circuit duty.
Whichever shape you choose, keep the conductor solid rather than stranded where the route allows. A solid aluminium core has no interstitial air gaps, so it conducts heat outwards to the insulation and shield more evenly than a stranded cable of the same area, and it avoids the crimping problems that stranded aluminium can suffer at terminals. Stranded or laminated flexible sections are then used only where movement must be absorbed, for example between a battery pack and a body-mounted component, and joined to the rigid busbar by welding.
| Aspect | Single-core | Integrated dual-core |
|---|---|---|
| Conductor layout | Positive and negative routed as separate busbars | Positive and negative inside one shielded body |
| Routing | Two paths, more flexible | One path, more compact |
| Space | Needs room for two runs and their clearances | Better for tight packaging |
| EMC | Each conductor shielded individually | Close pairing reduces the loop area, which helps emissions |
| Parts count | Two sets of clips, seals and terminations | Fewer clips and seals; less insulation material |
| Best for | Platform variants with differing layouts | High-volume platforms with fixed packaging |
Dual-core designs need careful attention to insulation between conductors, because the full system voltage now sits across a thin internal barrier, and to heat, because two current-carrying conductors share one shield. Single-core designs are easier to service and to adapt between vehicle variants.
| Requirement | What it means | Common test approach |
|---|---|---|
| Conductor conductivity | Resistance per metre within design limit | Eddy-current or four-wire resistance per ASTM B193 |
| Shielding effectiveness / transfer impedance | How well the shield keeps switching noise inside | Triaxial method (IEC 62153-4-3) or line-injection methods; limits set by the OEM |
| Withstand voltage and insulation resistance | No breakdown between conductor and shield | DC or AC high-voltage test for a set time |
| Temperature rise | Steady-state heating at rated current | Thermocouple test at rated and peak current |
| Flammability | Insulation does not sustain burning | UL 94 or FMVSS 302 style tests on the insulation |
| Vibration and thermal shock | No cracking of shield, insulation or terminals | Random vibration and temperature cycling to OEM profile |
| Crush and abrasion | Shield protects the insulation from damage | Defined load and abrasion cycles, then withstand test |
| Salt spray | Shield and terminations resist corrosion | Neutral salt spray per ASTM B117 or ISO 9227 |
Exact figures, such as a minimum shielding effectiveness in dB across a frequency band, a maximum transfer impedance in mΩ/m or a withstand voltage, come from the vehicle maker's specification or from standards such as ISO 19642 and LV 216 for high-voltage conductors. Write them on the drawing; they decide shield wall thickness and insulation thickness more than any other factor.
Main positive and negative links between modules, the battery junction box (BJB) and the battery disconnect unit (BDU).
Short, rigid links from the PDU to the inverter, DC-DC converter and auxiliary loads.
High-current runs from the charging inlet to the battery, where peak current and temperature rise are highest.
Connections to the traction inverter where switching noise makes shielding essential.
Stationary storage racks, electric buses and trucks, where long high-current runs make the weight saving larger.
Traction and hotel-power links in vehicles that need compact, robust high-voltage routing.
Metline is an aluminium supplier. For shielded busbar programmes we supply the aluminium inputs, cut and prepared to your drawing, to busbar and harness makers who add insulation, form the assembly and terminate it. Consistent conductivity and temper from lot to lot matter as much as the nominal grade, because they set both resistance and bending behaviour on your line:
Insulation compounding, assembly and validation remain with the busbar maker or vehicle supplier.
For the same electrical resistance an aluminium conductor needs about 1.6 times the cross-section of copper but weighs roughly half as much. As a rigid busbar it also holds a fixed route, packages tightly and reduces clips, conduit and assembly variation.
1060 gives slightly higher conductivity and bends easily but is soft at bolted joints. 6101 in T6x tempers is stronger, resists creep and vibration better and keeps its formed shape, with conductivity minimums of 55 – 59.5 % IACS depending on temper.
Peak current capability depends on cross-section, duration, cooling and allowed temperature rise, not on the material alone. Busbars for fast charging are routinely sized for several hundred amperes; confirm by calculation and a temperature-rise test at your duty cycle.
An aluminium alloy such as 3003 conducts well enough to give effective shielding, forms easily around the insulation, resists corrosion and keeps the whole assembly light. It also protects the insulation against abrasion and crushing.
Yes, within defined minimum bend radii. Too tight a bend can crack the shield or thin the insulation, so bends are designed with the conductor temper, insulation thickness and shield wall in mind and validated with a withstand test afterwards.
Metline supplies the aluminium materials: 1060, 1350 and 6101 conductor rod and flat bar, 3003 shield tube and strip, cut and prepared to drawing with mill certificates, shipped worldwide.
Send conductor size, alloy, temper and shield dimensions. Our team will confirm availability, certification and a delivered quote.
