1 Scope

1.1 These requirements apply to rigid printed wiring boards and flexible printed wiring board for use as components in devices or appliances. Compliance with these requirements does not indicate that the product is acceptable for use as a component of an end product without further investigation.

1.2 The flexible printed wiring boards covered by these requirements consist of conductors affixed to insulating base film, with or without a cover material, with midboard connections.

1.3 These requirements do not cover flexible printed wiring boards of laminated-film construction in which the conductors are parallel to each other and are completely covered by the base film with only point-to-point end connections.

1.4 Flexible material constructions and multilayer rigid flex composite interconnect constructions with and without stiffener and adhesive materials shall be investigated in accordance with the Standard for Flexible Materials Interconnect Constructions, UL 796F.

Summary of Topics

This revision of ANSI/UL 796 dated November 17, 2025 includes the following changes in requirements:

– Update Testing Coupon; 2.37A, 2.39A, Figure 10.1 – Figure 10.1B, Figure 10.3 – Figure 10.3B, 10.11.2 – 10.11.4, 10.14.4, 23.2, 23.6

– Update multiple terms and definitions in Glossary; 2.11, 2.67, 2.68, 2.116 (deleted), 2.117, 2.119

– Update Bond Strength Testing at Nominal Thicknesses in Base Materials; 9.1.4

– Add missing sample thickness tolerance for UL/ANSI Type materials in Table 9.1;

– Update alternate metal-clad base materials; 9.2.4

– Clarify conductor requirements; 10.3 (title), 10.3.1, 10.4.1, 10.12, 10.12.1

– Clarify conductive coin size determination; 10.15.1, 10.15.2

– Clarify sample fabrication process requirements; 12.1.1 (deleted), 12.1.1, 12.1.5

– Clarify HDI PWB requirements; 17.4.2, Table 19.1

– Clarify metal base PWB requirements; Table 20.2, 20.1.10

– Clarify the test program for adding alternate manufacturing locations; Table 22.1

– Clarify requirements for embedded components; Table 22.9