STMicroelectronics is the manufacturer of the popular STM32 microcontroller family. While ST is headquartered in Geneva, assembly and test occurs at facilities in China (Shenzhen) and Malaysia (Muar). China-origin ST parts face approximately 60% effective rate (Section 301 50% + Section 122 10%). COO varies significantly by part number — STM32F1/F4 series are commonly assembled in Malaysia (Muar) at 10% total duty, while other variants assembled in China (Shenzhen) face 60%. Always verify COO for specific part numbers using the calculator. STM32 lead times are currently 24–29 weeks.
STMicroelectronics is headquartered in Switzerland/France/Italy, but most components are manufactured in China, Malaysia, Morocco, Italy, France. For US customs purposes, the COO is where the component is manufactured — not where the company is based. Declaring Switzerland/France/Italy as COO when parts ship from China is a customs violation.
| Country | Sec 122 | Sec 301 | Total |
|---|---|---|---|
| China | 10% | 50% | 60% |
| Malaysia | 10% | — | 10% |
| Morocco | 10% | — | 10% |
| Italy | 10% | — | 10% |
| France | 10% | — | 10% |
* Section 301 rates shown for electronics HTS chapters (8541–8542). Rates vary by product.
| HTS Code | Description |
|---|---|
| 8542.31.0000 | STM32 microcontrollers |
| 8542.31.0000 | STM8 microcontrollers |
| 8541.29.0000 | ST power MOSFETs |
| 8542.39.0000 | ST motor drivers and power ICs |
STMicroelectronics operates a vertically integrated manufacturing model spanning front-end wafer fabrication in Europe and back-end assembly in Asia. Wafer fabrication for STM32 microcontrollers and power semiconductors occurs at fabs in Catania and Agrate Brianza (Italy) and Crolles and Tours (France), using process nodes from 40 nm down to 28 nm FD-SOI. However, die assembly, packaging, and final test — the steps that determine country of origin for US CBP purposes — are overwhelmingly performed at ST's back-end facilities in Shenzhen (China) and Muar (Malaysia). For a significant portion of STM32 variants, China is the declared COO, triggering Section 301 liability in addition to the universal Section 122 surcharge.
STM32 microcontrollers and STM8 8-bit MCUs classify under HTS 8542.31.0000 (electronic integrated circuits — processors and controllers). Power MOSFETs, IGBTs, and gate drivers classify under HTS 8541.29.0000 or 8541.40.9500. Motor driver ICs and power management devices fall under 8542.39.0000. For China-origin ST parts, the applicable tariff stack is: 0% MFN base rate + 50% Section 301 List 3 (semiconductors) + 10% Section 122 global surcharge = 60% effective rate. For Malaysia-origin parts (Muar facility), the Section 301 does not apply, yielding a 10% effective rate. Sourcing engineers should verify COO at the lot/date code level, as the same STM32 part number may ship from either location depending on allocation.
ST's Bouskoura facility in Morocco is a meaningful but smaller back-end site primarily serving automotive and industrial customers. Morocco-origin ST components face only the 10% Section 122 surcharge with no Section 301 overlay, making them the most favorable for US importers among ST's back-end locations. However, Morocco-packaged ST parts are a minority of overall supply — buyers should not assume Morocco COO without explicit factory documentation (Form A or ST country of origin certificate) on the shipment.
The 60% blended duty rate on China-origin STM32 parts creates a material landed cost differential versus Malaysia or Morocco COO equivalents. For a standard STM32F4 series MCU priced at $3.00 EXW, a China COO shipment adds $1.80 in duty (plus MPF of $32.71 minimum per entry). Procurement teams running high-volume STM32-based designs should request COO certificates from ST before placing blanket orders, negotiate for preferential allocation from non-China back-end sites, and evaluate whether STM32 alternatives manufactured in non-Section 301 countries (such as RA series from Renesas in Japan or LPC series from NXP in Malaysia) provide a viable supply chain hedge.
STM32 parts experienced severe shortages in 2021–2023, with lead times exceeding 52 weeks at peak. As of Q1 2026, most STM32 lines have normalized to 20–30 weeks for standard catalog parts, with some G0 and F1 family devices available from distributor stock. ST's dual-source strategy across China and Malaysia back-end sites means lead times can vary by COO — Malaysia-allocated parts sometimes command a premium on spot markets due to lower tariff liability. Buyers should factor the 60% effective tariff into safety stock calculations for China-COO STM32 devices, as the duty cost can exceed the component cost itself on lower-priced variants.
Enter any STMicroelectronics part number to get the COO, HTS code, and full duty calculation including MPF and HMF.
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