Product classification
HS code for Soldering flux: 3810.90
Fluxes and other auxiliary preparations, for soldering, brazing or welding, or preparations used as cores or coatings for welding electrodes or rods.
Classification of soldering flux under HS 3810.90
Soldering flux and other auxiliary preparations for soldering, brazing, or welding are classified under HS code 3810.90. This classification is found within Chapter 38, which covers miscellaneous chemical products. The logic for this classification is based on the chemical nature of the product and its role as a processing aid. Flux is essential in metal joining processes because it removes oxides from the surfaces of the metals to be joined, prevents further oxidation during the heating process, and promotes the flow of the filler metal. HS code 3810.90 is a residual category for preparations that do not fall under the more specific 3810.10, which is for pickling preparations for metal surfaces. It includes a variety of forms, such as pastes, liquids, and powders, and can be based on rosin, organic acids, or inorganic salts. Correct classification is vital for compliance with chemical safety regulations.
- Covers
- Rosin-based soldering flux
- Acid-core soldering flux
- Soldering paste containing flux
- Brazing powders and fluxes
- Welding electrode coatings (auxiliary)
- Also under 3810.90
- Kester Flux
- Alpha Assembly Solutions Flux
- Indium Corporation Flux
- Lincoln Electric Flux
- ESAB Welding Flux
Codes often confused with 3810.90
Common mistake. Soldering flux is often confused with HS code 3810.10, which is strictly for pickling preparations used to clean metal surfaces before processing. While both involve surface treatment, 3810.90 is specific to the act of soldering or welding. Additionally, flux-cored solder wire is often misclassified here, but it should actually be classified under 8311 or 8003 depending on the metal composition.
Top exporters and importers of HS 381090 (the code used for soldering flux), 2025
In 2025, the largest exporter of HS 381090 (the code used for soldering flux) in UN Comtrade data was Germany, with 18% of world exports; the largest importer in UN Comtrade data was China, with 11% of world imports. Countries that did not report 2025 data are estimated from partner records, which can understate them.
Figures cover everything classified under HS 381090, not only soldering flux.
Top exporters 2025 · share of world exports
- 1 Germany $164M 18% of world exports
- 2 Japan $159M 17% of world exports
- 3 China $86M 9.4% of world exports
World total: $921M Reported figures on UN Comtrade ↗
Top importers 2025 · share of world imports
- 1 China $120M 11% of world imports
- 2 Malaysia $105M 9.7% of world imports
- 3 Philippines $78M 7.2% of world imports
World total: $1.1B Reported figures on UN Comtrade ↗
How these figures are built
109 countries reported 2025 trade to UN Comtrade in HS 2022, and their own totals are used. Countries that did not report are estimated from what other countries recorded trading with them. Those estimates miss trade with other non-reporting countries, so they can be low, and a non-reporting country can rank higher than shown or be missing from the list. World totals add both and leave out trade between two non-reporting countries. Figures are in current US dollars; reported imports are mostly valued CIF and exports FOB, and exports include re-exports. The UN Comtrade links show the underlying records; they can also list a few reporters left out here (regional groups and older HS editions).
Source: UN Comtrade (United Nations Statistics Division), 2025 annual data.
Brazil NCM code for soldering flux
Brazil classifies soldering flux under NCM 3810.90.00: HS 3810.90 with 00 added.
Source: Siscomex NCM table, updated Oct 2026. The Portuguese text on each NCM page is the official one.
Questions about soldering flux
What is the HS code for Soldering flux?
The HS code for Soldering flux is 381090 (Fluxes and other auxiliary preparations; for soldering, brazing or welding, or preparations used as cores or coatings for welding electrodes or rods). The HS code for soldering, brazing, or welding flux preparations is 3810.90.
How do I classify Soldering flux for customs?
Soldering flux is classified under HS code 381090 — Fluxes and other auxiliary preparations; for soldering, brazing or welding, or preparations used as cores or coatings for welding electrodes or rods. This is a 6-digit subheading level code.
Is solder wire included in this HS code?
No, solder wire (even if it contains a flux core) is classified under the heading for the base metal, such as 8003.00 for tin or 8311 for base metal electrodes.
Which countries are the top exporters of soldering flux (HS 381090)?
In 2025, the top exporters of HS 381090 (the code used for soldering flux) in UN Comtrade data were Germany ($164M, 18% of world exports), Japan ($159M) and China ($86M). World exports came to about $921M, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Which countries are the top importers of soldering flux (HS 381090)?
In 2025, the top importers of HS 381090 (the code used for soldering flux) in UN Comtrade data were China ($120M, 11% of world imports), Malaysia ($105M) and the Philippines ($78M). World imports came to about $1.1B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.
Is the HS code for Soldering flux the same in all countries?
The base HS code 381090 for Soldering flux is internationally standardized for the first 6 digits across 200+ countries. Individual countries may add additional digits for national tariff lines and specific classifications.
What is the NCM code for soldering flux in Brazil?
In Brazil, soldering flux (HS 381090) is classified under NCM 3810.90.00.