UL 94 - Flammability Rating in PCBs

Author - Laura Biddiscombe

UL 94 is the Standard for Safety of Flammability of Plastic Materials for Parts in Devices and Appliances. It is a plastics flammability standard released by Underwriters Laboratories of the USA. The standard enables testers to classify plastics according to how they burn in various orientations and thicknesses.

From lowest (least flame-retardant) to highest (most flame-retardant), the classifications are:

• HB: slow burning on a horizontal specimen; burning rate < 76 mm/min for thickness < 3 mm and burning stops before 100 mm
• V-2 burning stops within 30 seconds on a vertical specimen; drips of flaming particles are allowed.
• V-1: burning stops within 30 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
• V-0: burning stops within 10 seconds on a vertical specimen; drips of particles allowed as long as they are not inflamed.
• 5VB: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may develop a hole.
• 5VA: burning stops within 60 seconds on a vertical specimen; no drips allowed; plaque specimens may not develop a hole.

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In general, VersaLogic products are designed to meet certain safety standards, including UL 60950, CE emissions and immunity standards, and FCC Class A.

However, VersaLogic boards are components and not intended for stand-alone use. They are not tested and certified to meet those standards, as most safety certifications apply to complete products.

The UL mark on VersaLogic PCBs certifies a flammability rating of UL 94 V-0. This certification applies to the PCB only. _____________________________________________________________________________________________________

Requirements for V-0

• The specimens may not burn with flaming combustion for more than 10 seconds after either application of the test flame.
• The total flaming combustion time may not exceed 50 seconds for the 10 flame applications for each set of 5 specimens.
• The specimens may not burn with flaming or glowing combustion up to the holding clamp.
• The specimens may not drip flaming particles that ignite the dry absorbent surgical cotton located 300 mm below the test specimen.
• The specimens may not have glowing combustion that persists for more than 30 seconds after the second removal of the test flame.

 For more information on flammability ratings for any of our product lines please contact Sarsen Technology on +44 1672 511166 or send us an email - info@sarsen.net