Laminated Copper Busbar

Every switch transition in a power loop dissipates energy stored in stray inductance as voltage overshoot: V = L x di/dt. A laminated busbar collapses L by running the DC+ and DC- planes face to face across a 5-10 mil dielectric film, so the loop area shrinks and the overlapping magnetic fields cancel each other. The result is single-digit-nanohenry loop inductance without extra snubber capacitors. Our low-inductance design guide shows the loop-area math; for the capacitor side of the same loop see the capacitor bank busbar and inverter DC-link busbar pages.

Pick the inter-layer film by continuous temperature, dielectric constant (ASTM D150), dielectric strength (ASTM D149) and UL 94 flammability:

Nomex and Kapton serve high-temperature drives; PET is the cost-controlled choice for room-temperature inverters; FR-4 and epoxy powder add rigidity and a V-0 rating. See busbar insulating films.

The cut edge decides long-term life in your environment:

• Open edge - lowest cost, for dry, controlled cabinets protected by the enclosure.
• Pinched edge - the stack is crimped closed for dust and light-moisture resistance.
• Epoxy-filled edge - resin seals the stack against humidity, chemicals and wash-downs.

For heat beyond natural convection, we laminate an aluminium cold plate with machined coolant channels straight into the stack - see thermal management. Hi-pot and leakage checks are explained at partial discharge testing. Send a drawing through the custom busbar design service.

A laminated copper busbar cancels inductance by running conductors face to face across a thin dielectric; the number of layers and the dielectric gap set how far that cancellation goes. Values below are planning estimates for a hot-pressed C11000 stack quoted across industrial, inverter and traction use, assuming a 300 mm run unless noted.

These numbers are planning estimates for a tin-plated C11000 stack; the spike column follows ΔV = L × di/dt with the edge rate planned between 1.5 and 3 A/ns depending on device family. Laminated busbar dielectric materials are chosen for the voltage class and operating temperature — PET up to around 130 °C continuous, Nomex for higher temperature, epoxy film for the tightest gap. Laminated busbar edge sealing is what keeps the dielectric out of moisture and contamination, and a well-sealed stack typically meets the humidity class the enclosure calls for. The low-inductance busbar design notes explain the gap-versus-nH relationship, and the dielectric selection guide compares the film options.

Because a laminated copper busbar is a generic build rather than a dedicated DC link, the terminal geometry can be cut to a wide range of module and device packages. The list below is the broader package families we routinely tool laminated tabs for, with the terminal patterns most often specified across industrial, renewable and traction builds; tab current density is planned near 1.0 A/mm² continuous.

Quote us the module datasheet; the DFM step locks tab width, pitch and stand-off height against that drawing. Where the terminal lands on a non-module device — a capacitor, a fuse or a terminal block — we tool the tab to that device drawing instead. Plating on the tab face is tin as standard, with silver on request for higher-pressure joints. The custom design process page describes the review cycle, and the laminated busbar design guide lists the stack and gap options available at tooling. Conductor thickness is typically 0.5 to 2 mm per layer, and a two-layer stack is the default when the current rating stays below about 400 A per phase. A three-layer stack is quoted when the rating climbs toward 800 A, and a four-layer sandwich is the typical choice above 1000 A per phase or for fast-edge duty.