UL 796F Ed. 4-2021

Flexible Materials Interconnect Constructions - Published Date: November 17, 2025

1.1 These requirements apply to flexible material printed wiring board constructions (FMIC’s) for use as components in flexible, flex-to-install, rigid, and multilayer rigid-flex composite applications with and without stiffener and adhesive materials in devices or appliances.  1.2 Together with the Standards mentioned in the Supplementary Test Procedures, Section 3, these requirements provide data with respect to the physical, electrical, flammability, thermal, and other properties of the FMIC under consideration and are intended to provide guidance to the fabricator, end product manufacturer, safety engineers and other interested parties.  1.3 Compliance with these requirements does not indicate the product is acceptable for use as a component of an end product without further investigation.  1.4 The singlelayer and multilayer flexible, flex-to-install, and multilayer rigid-flex composite constructions addressed by these requirements consist of conductors affixed to base material, with mid-board interconnections, and cover materials.  1.5 The suitability of additional stiffener and adhesive materials, not evaluated in accordance with Stiffener and adhesive (external bonding) materials, 10, the Stiffener bond strength test, 12, and Flammability tests, 15, are subject to the applicable end-use product construction and performance requirements. See Additional stiffener and adhesive (external bonding) materials, 12, for marking requirements for FMIC’s provided with additional stiffener and adhesive materials not investigated.  1.6 The requirements for rigid printed wiring boards are in the Standard for Printed Wiring Boards, UL 796.