What is UL?
Founded about 120 years ago in the United States, Underwriters Laboratories
(UL) is an independent facility for testing the safety of new products and
technologies. Today, it has sites around the world that focus on product safety.
It tests products, certifies manufacturers, and manufactures and updates safety
standards for a wide range of industrial and commercial sectors.
For PCB boards, the main standards are UL 796, specific PCB standards, and
UL 94 for flammability testing of all plastics. These specify the number of
performance tests to measure the long-term reliability and fire safety of the
PCB. If the board meets these standards, it is marked with the UL logo,
manufacturer logo, and board type. So for Eurocircuits, we see the UL logo on
the left, then the UL trademark of Eurocircuits, and the last ML for
When do you use the UL mark?
As long as safety, especially flammability is a key issue, UL marking is
required. For European OEMs, any board that enters the United States usually
needs it. This requirement can be set by the OEM or the end customer.
What does the UL mark mean?
The base material meets the flammability level specified in UL94. For FR4,
the required level is UL94 V0. This means that when a vertical sample of
material is introduced into the test flame and then removed, it will
self-extinguish within 10 seconds. It does not drip out the burning
All Eurocircuits FR4 materials meet UL 94 V0 requirements. For boards that
require UL marking, we use Isola and Nan Ya materials.
The base material meets the specified electrical breakdown (tracking) or
comparative tracking index (CTI) values. This is a voltage difference that can
be destroyed by the insulation properties of the substrate, leading to safety
and performance issues. Isola and Nan Ya FR4 materials meet Class 3 (175 - 249
Eurocircuits UL Specifications
Our UL certification E332411 can be found on the UL website. (UL query URL:
The UL logo is free.
For more information about which boards provide UL certification, you can
contact us by phone or email to get relevant information.