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Common Mistakes in Laminated Busbar Selection and How to Avoid Them

07/01

2026

By A&JLINK Engineering Team · Last updated  July 2026 · 8 min read
The short answer
The five busbar selection mistakes that cause the most field failures — and how to avoid them.
  • ✓Selection, not defect. A selection mistake is a part specified wrong — even when it was manufactured exactly to drawing.
  • ✓The big five. Buying by price alone, ignoring inductance, overlooking thermal and current ratings, wrong insulation, and copper-vs-aluminum mismatch.
  • ✓Why it matters. Most busbar failures trace back to a decision made before the design was locked, not to a material defect.
  • ✓The fix. Judge on total cost of ownership and duty-cycle fit, then run every choice through a short pre-purchase checklist.
A laminated busbar looks simple — a few copper layers and some insulating film — but the decisions that determine whether it works are made before anyone orders a part. When a busbar overheats, a joint loosens, or a design fails a short-circuit test, the root cause is usually a selection mistake made weeks or months earlier.
This article walks through the most common busbar selection mistakes, why they happen, and how to avoid them. It is the mirror image of the laminated busbar selection guide we keep at the top of our technical resources: where that guide shows how to choose correctly, this one shows where choosing goes wrong.
Scope: this article covers the common errors made when selecting a laminated busbar and how to prevent them. It is about choosing the right part, not the right supplier — for how to evaluate suppliers rather than parts, see our how to choose a laminated busbar manufacturer selection guide.
A laminated busbar is the backbone of low-inductance power distribution, and selecting it correctly starts with recognizing the traps. Our complete overview covers what a laminated busbar is, its key advantages, full technical specifications, industry applications, and a technical-guides hub — this article is the "avoid the traps" companion to that page.

1. What Is a Laminated Busbar Selection Mistake?

A selection mistake is any choice that fails against the busbar's real operating duty. It is distinct from a manufacturing defect: a defect is a part that was made wrong, while a selection mistake is a part that was specified wrong — even if it was made exactly to drawing.
The distinction matters because it changes where the fix belongs. A defect is corrected at the supplier; a selection mistake is corrected at the design stage, before money is spent on tooling or inventory. The five errors below are the ones engineers and buyers most often repeat, because each one feels justified in isolation and only fails when viewed against the full duty cycle.

2. Mistake 1: Choosing Only by Price

The most common selection mistake is treating the busbar as a commodity and buying on unit price alone. On the surface this is defensible — procurement is rewarded for cost reduction. But a busbar is not a cable or a bolt; its value is in how it performs across the system's life, not in its per-piece cost.
The right lens is total cost of ownership. A cheaper busbar that runs hotter, needs rework, or fails a qualification test costs far more over the life of the product than a properly engineered one. Price should be compared only between parts that meet the same electrical, thermal, and mechanical specification — otherwise the comparison is meaningless.

3. Mistake 2: Ignoring Inductance Requirements

Loop inductance is the parameter most often omitted from a busbar specification, and it is the one most likely to bite later. In fast-switching power electronics, high loop inductance produces voltage overshoot and ringing that stresses semiconductors and can cause spurious failures.
A laminated busbar controls inductance through geometry: positive and negative layers are stacked tightly with a thin insulator between them, canceling the magnetic field and collapsing the loop area. If inductance is not specified, the busbar may be built with generous layer spacing that is easy to manufacture but electrically poor.
For a deeper treatment of where inductance comes from and how to control it, see our guide on parasitic inductance in laminated busbars.

4. Mistake 3: Overlooking Thermal and Current Ratings

A busbar that meets the steady-state current on paper can still fail if the thermal duty was underestimated. Two numbers are routinely confused: the continuous current rating and the short-circuit withstand requirement. Sizing for one while ignoring the other is a classic error.
Temperature rise at the joints is where the real risk lives. Even a well-sized conductor can develop hot spots at bolted connections if contact pressure, plating, or surface finish are not controlled. The busbar must stay within the insulation's thermal class across the full ambient range and the worst-case duty cycle, not just the nominal case.

5. Mistake 4: Wrong Insulation or Coating Choice

Insulation is chosen for dielectric strength, temperature class, and long-term stability — but it is often specified last, after the conductor is already fixed. The result is an insulation that is either over-specified (paying for capability that is not needed) or under-specified (failing creepage and clearance at the system's voltage and pollution degree).
The choice also extends to the contact surfaces. Plating — tin, nickel, or other finishes — determines how well a joint resists oxidation and holds low contact resistance through thermal cycling. Insulation coordination should be evaluated against IEC 60664-1, and the thermal endurance of the insulating film against IEC 60216, rather than picked from habit.

6. Mistake 5: Mismatched Material (Copper vs Aluminum)

Copper and aluminum are both legitimate conductor choices, but they are not interchangeable. Copper offers higher conductivity and mechanical robustness; aluminum is lighter and lower-cost but requires a larger cross-section and careful handling of oxidation at joints.
The mistake is choosing on a single dimension — usually weight or price — without accounting for the knock-on effects. An aluminum busbar may need more space, a different joint strategy, and plating at every contact surface to prevent galvanic issues where it meets copper or tin. The material decision should follow the current, space, and weight targets of the application, not a preference.

7. How to Avoid These Mistakes: A Pre-Purchase Checklist

Every selection mistake above is preventable with a short, deliberate review before the order is placed. Run the busbar specification through these checks:
  • ☐Duty cycle, not catalog. Are current, voltage, and temperature rise tied to the actual operating profile, including transients and short-circuit withstand?
  • ☐Inductance stated. Is a loop-inductance target specified, with layer spacing and geometry that deliver it?
  • ☐Thermal margin. Does the busbar stay within the insulation's thermal class at worst-case ambient and current?
  • ☐Insulation and plating correct. Is insulation coordinated to the system voltage and pollution degree (IEC 60664-1), and are contact surfaces plated for stable low resistance?
  • ☐Material matched to application. Was copper vs. aluminum chosen against current, space, weight, and cost targets — not habit?
  • ☐Total cost, not unit price. Is the decision based on cost over the product's life, not the per-piece number?
If the answer to any of these is uncertain, the specification is not ready to order.

8. Frequently Asked Questions

What is the most common laminated busbar selection mistake?
Choosing by unit price alone. A busbar's value is in how it performs across the system's life, so the correct comparison is total cost of ownership between parts that meet the same specification — not the lowest sticker price.
Why does inductance matter in busbar selection?
High loop inductance produces voltage overshoot and ringing in fast-switching circuits, stressing semiconductors and causing spurious failures. A laminated busbar controls inductance through tightly stacked layers, but only if a target is actually specified.
How do I choose between copper and aluminum?
Match the material to the application's current, space, weight, and cost targets. Copper favors conductivity and robustness; aluminum favors weight and cost but needs a larger cross-section and careful joint plating. Neither is universally better.
What should I check before ordering a laminated busbar?
Run the specification through a pre-purchase checklist covering duty cycle, inductance, thermal margin, insulation and plating, material choice, and total cost of ownership. If any item is uncertain, resolve it before ordering.

9. Summary

Most laminated busbar failures are not manufacturing defects — they are busbar selection mistakes made earlier, when a choice felt justified in isolation but failed against the full operating duty. Choosing by price, ignoring inductance, underestimating thermal duty, picking the wrong insulation, and mismatching materials are the five errors that recur most often.
The antidote is a short, disciplined review before ordering: tie every parameter to the real duty cycle, specify inductance and thermal margin explicitly, coordinate insulation to the system voltage, match material to the application, and judge on total cost of ownership rather than unit price.
Get a Laminated Busbar Specified Correctly from the Start
Send us your current, voltage, and duty-cycle requirements — our engineers will review feasibility and come back with design recommendations.
Talk to an Engineer

References & Standards

  1. IEC 60664-1 — Insulation coordination for equipment within low-voltage supply systems. International Electrotechnical Commission. webstore.iec.ch
  2. IEC 60216 — Electrical insulating materials – Thermal endurance properties. International Electrotechnical Commission. webstore.iec.ch
  3. IEC 61439-1 — Low-voltage switchgear and controlgear assemblies. International Electrotechnical Commission. webstore.iec.ch

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