Sourcing thyristors from China

Thyristor duty and classification

Read from the UK Trade Tariff on 29 September 2026, non-photosensitive thyristors under 8541 30 00 00 carried 0% duty for goods from China. The supplied tariff record lists no anti-dumping or countervailing duty, suspension or attached import control for this line. Import VAT at 20% still applies.

Heading 8541 covers semiconductor devices and other listed electronic components. The thyristor line also covers non-photosensitive diacs and triacs. The table shows package variants sharing the same commodity line, rather than separate tariff subdivisions. See rectifier diodes for the wider heading. For Schottky devices, see our Schottky diode sourcing guide. For Zener devices, see our Zener diode sourcing guide.

Confirm the commodity code using the device datasheet, function and photosensitivity. Describe the actual semiconductor device on the order and invoice; a finished controller needs its own classification review. For the reverse trade direction, see our guide to exporting UK semiconductors to China.

Blocking voltage, gate triggering and mounting

Specify the exact manufacturer and part reference, repetitive blocking voltage, on-state current, surge capability, gate trigger current and voltage, holding current and operating temperature range. State the test conditions beside each acceptance criterion. Agree whether substitutions are permitted before ordering.

Match the package outline, terminal arrangement, mounting method and thermal interface to your assembly. For stud-mounted or press-pack devices, agree the mounting instructions and mechanical acceptance criteria. Ask for batch-linked material declarations and test evidence.

For finished equipment subject to hazardous-substance restrictions, the manufacturer must determine whether its product complies, even where suppliers confirm component compliance. Government waste-electrical guidance says components supplied to a business for building a finished product are not electrical and electronic equipment products.

Worked duty example

Illustrative example, not a quote: Illustrative batch of packaged thyristors for a small electronics business under 8541 30 00 00, invoiced at £1,500 free on board, with £430 of freight and insurance to the UK. The customs value is £1,930. Duty at 0% is £0. Import VAT at 20% is charged on the customs value plus duty, £1,930, so it is £386. 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 device markings, manufacturer references and batch identifiers to the order, packaging and test records.

Electrical behaviour: sample-check blocking leakage, gate triggering, holding current and on-state voltage against the agreed datasheet conditions.

Mechanical fit: check terminal arrangement, package dimensions, mounting surfaces and signs of bent leads, cracked encapsulation or corrosion.

Packing: check protective packaging, separated batches and transit damage on arrival. Agree sampling and release criteria through quality inspection.

What goes wrong

A substitute can fit the board yet require more gate current than the drive circuit supplies. Incorrect terminal arrangements, excessive leakage or unsuitable holding current can cause failed triggering or unwanted conduction. Test samples in the intended circuit before approving the production batch.

A current rating without its thermal conditions can mislead the buyer. Poor mounting contact can produce overheating even when basic bench checks pass. Treat mixed markings or missing batch records as reasons to investigate before releasing stock.

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.