UL Symbol The "Insurance Institute" logo, UL stands for Underwriters Laboratories, INC. This is a large-scale experimental and experimental organization formed by the United States insurers. Founded in 1894, the United States now has five test centers, specializing in the various goods sold in the United States market, in its "flame-proof" and "security" checks. However, UL has never been involved in the quality of the product itself. Many companies often add the words “quality meets the UL standards†in their advertising materials. This is a mistake that is also a joke of “half amateursâ€. Products sold in the Far East are controlled by UL at the inspection center in Santa Clara, California. For circuit boards and electronic products, if UL's approval is not obtained, it will be almost impossible to make appearances in the U.S. market. There are several types of UL general business services, namely: a. Listing services; b. Classification service; c. Component approval service (Recognition) The manufacturer's logo (Logo) is usually filled on the circuit board solder surface itself, and a special symbol is applied to UL. UL also manages its flame resistance in a variety of industrial products with well-written written specifications. Related to the PCB are: "UL 94" (Test for Flammability), and "UL 796" (PCB printed circuit board and flame retardancy).