Definition

UL 94 classifies plastics based on flammability characteristics. Critical for PCB base materials, with ratings including V-0 (self-extinguishes within 10 seconds, no flaming drips - standard for FR-4), V-1 (self-extinguishes within 30 seconds), V-2 (allows non-flaming drips), and HB (slow-burning horizontal test). When you specify FR-4, you're getting UL 94 V-0 rated material. For consumer products, UL 94 V-0 is typically required. Check with your certification requirements - some applications accept V-1 or V-2 ratings.