Other Inorganic Compounds; Phosphides, Gallium Arsenide Wafers, and Amalgams

Undoped GaAs wafers are specifically called out at 2853909010. Once a wafer is intentionally doped (e.g., with silicon or zinc to create n-type or p-type material), it may shift classification to Chapter 38 (semiconductor-grade materials) or remain in Chapter 28 depending on the degree of processing and applicable chapter notes. CBP has issued rulings on this distinction, and importers of doped wafers should seek a binding ruling if classification is uncertain.

Copper phosphides containing more than 15% phosphorus by weight (2853901000) are primarily used as deoxidizing master alloys in copper and bronze casting. They are a niche but essential input for foundries and electrical conductor manufacturers. Import volumes tend to track copper alloy production cycles rather than semiconductor demand.