Sourcing Constantan foil from China

Constantan foil duty and classification

Read from the UK Trade Tariff on 2 October 2026, heading 7410 covers copper foil no thicker than 0.15 mm, excluding any backing. For Constantan supplied as copper-alloy foil, the relevant lines are 7410 12 00 00 without backing and 7410 22 00 00 with backing.

Both lines carry 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing duty, suspension or import control against either line. The table repeats these codes to show roll and sheet supply forms; they are not separate tariff subdivisions. Import VAT is normally 20%; see duty and VAT.

Include the commodity code on the import declaration. Give your customs broker the composition certificate, metal thickness, backing details and product drawing to confirm classification using our commodity code guide. See the Manganin foil guide for related resistance-alloy sourcing within this heading.

Specify Constantan by electrical behaviour

Constantan is a copper-nickel resistance alloy. Do not buy on the trade name alone. Specify composition, resistivity at the agreed test temperature, temperature coefficient of resistance over the intended operating range, temper, thickness tolerance, width and usable roll length. State whether the foil is for resistance elements, strain gauges or thermocouple work.

For bonded foil, specify backing material, adhesive, bond strength and compatibility with your etching or joining process. Ask for batch test results and retain an approved sample. Compare samples after your own forming, bonding and thermal process, rather than accepting a room-temperature resistance reading alone.

UK REACH generally applies to substances on their own, in mixtures and in articles. Obtain composition and surface-treatment information, then review the obligations for the supplied form and intended use. Treat electrical performance testing and substance compliance as separate purchasing checks.

Worked duty example

Illustrative example, not a quote: A trial batch of unbacked Constantan foil rolls; illustrative values under 7410 12 00 00, invoiced at £2,200 free on board, with £100 of freight and insurance to the UK. The customs value is £2,300. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £2,300, so it is £460. With no duty, the only import tax is the VAT, which a VAT-registered importer can usually reclaim. The import duty and VAT guide explains each step.

Inspection checklist

Material: match roll labels and batch certificates to the agreed alloy composition, temper and electrical test results.

Dimensions: measure metal thickness across the width and along sampled lengths; check slit width, edge burrs, camber and flatness.

Electrical behaviour: test resistivity and resistance change with temperature using the agreed method; compare processed samples with the approved sample.

Surface and packing: inspect for pinholes, creases, oil, oxidation and backing separation. Check sealed packing, supported cores and batch identification. Use our inspection guide to brief the inspector.

What goes wrong

A nominally matching alloy can give different resistance after processing because composition, temper or thermal history differs. Uneven thickness produces uneven resistance, while burrs and creases can spoil etched patterns or bonded elements. Agree acceptance criteria for the finished process, then compare each batch against them.

Backing or adhesive changes can cause lifting during etching or heating. Poorly supported rolls arrive dented, and slit edges may tear during unwinding. Record approved backing details, inspect packing before dispatch and keep batch traceability through conversion.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For repeat volumes, see container programmes.