High-Purity Silicon (99.99% or Greater)

The dividing line is 99.99% silicon content by weight. Material at or above that threshold falls under 280461 (tariff line 2804610000) and is generally electronic or solar grade. Material below 99.99% falls under 280469, which is further split between 99–99.99% purity and below 99% purity, the latter being metallurgical-grade silicon used in aluminum alloys and chemical synthesis.

Malaysia is the top supplier, followed by Germany and Taiwan. Japan and Laos also appear among notable sources. Given the global polysilicon supply chain's complexity, importers often need to document the country of origin carefully to assess Section 301 tariff applicability.