Each component type in a mixed shipment must be classified individually — there is no single 'catch-all' HTS heading for miscellaneous electronic components. Importers should work with a customs broker to build a classification matrix keyed to manufacturer part numbers before the first shipment, and update it whenever new component types are added to the procurement list. Commingling unclassified components in a single line item is a common audit trigger.

Yes — quartz crystals (piezoelectric) and crystal oscillator modules occupy specific HTS subheadings under Chapter 85 that are distinct from general electronic components. The distinction between an unpackaged quartz blank, a packaged crystal resonator, and a complete oscillator module (which includes active circuitry) is particularly important, as each stage of assembly may fall under a different heading with a different duty rate.