Sourcing digital isolator ICs from China

Zero duty on digital isolator ICs

Heading 8542 covers electronic integrated circuits. This guide concerns digital signal isolation chips, rather than assembled isolation boards. The table shows classification routes to check, not interchangeable codes: the chapter-note categories depend on the device's construction, and the parts line applies to parts rather than complete chips. See the integrated circuits and chips guide for the wider heading.

Read from the UK Trade Tariff on 30 September 2026, every supplied line carried 0% duty for goods from China. The supplied snapshot lists no anti-dumping or countervailing duty, suspensions or attached import controls. Zero customs duty does not remove import VAT; see UK import duty and VAT.

Give your customs broker the manufacturer's datasheet, package construction and description of the isolation function. Confirm the commodity code before shipment, especially where the device combines isolation with other functions or arrives on an assembled board.

Specify the isolation barrier and signal behaviour

Order by manufacturer and full part-number suffix. Specify channel count and direction, supply voltage on each side, input thresholds, data rate, propagation delay, channel skew and operating temperature grade. Record the required output state when an input supply disappears. A matching footprint alone is insufficient for approving a substitute.

Separate continuous working voltage from the short-duration isolation withstand rating. Specify basic or reinforced insulation, package width, creepage and clearance, and immunity to rapid common-mode voltage changes. Ask for the manufacturer's isolation qualification reports matched to the exact package and suffix. Agree sample tests using the intended circuit and supply sequence.

For Great Britain, official guidance excludes component parts sold between businesses from the hazardous-substance regulations. Confirm the requirements applicable to the finished assembly with the relevant authority, and obtain part-specific material declarations. Waste-electrical-equipment guidance also distinguishes components supplied to businesses for building finished products from equipment products. Agree the evidence needed through testing and certification.

Worked duty example

Illustrative example, not a quote: 5,000 digital isolator chips on reels, illustrative only; classification assumed confirmed under 8542 39 90 00, invoiced at £12,000 free on board, with £600 of freight and insurance to the UK. The customs value is £12,600. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £12,600, so it is £2,520. 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

Identity: match chip markings, package dimensions, pin orientation, reel labels, date codes and lot numbers to the ordered suffix and traceable manufacturer records.

Isolation: match qualification reports to the supplied package and grade; have a competent laboratory perform the agreed barrier tests using the manufacturer's method.

Signal behaviour: check channel direction, timing, output default state and operation when either supply starts, stops or falls below its operating range.

Handling: check sealed moisture-barrier bags, desiccant, humidity indicators and storage records; inspect leads and solderability, and retain samples from each lot.

What goes wrong

A substitute may fit the board but reverse a channel, change the output default state or introduce excessive delay. A headline isolation withstand rating can also conceal a different continuous working-voltage rating or package spacing. Approve substitutions against the complete datasheet and intended circuit, rather than a supplier's cross-reference alone.

Broker stock can contain remarked grades, recycled chips or mixed lots. Visual inspection cannot establish barrier integrity or performance at temperature. Check traceability, compare samples with known genuine stock and run the agreed electrical tests. Damaged dry packaging and poor handling can cause failures during assembly.

Cambridge China Bridge sources these products for UK businesses, checking the factory and the documents before shipment. See factory verification. For components and parts, see sourcing for manufacturers.