UL 796 PDF

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-lay film 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.

1.5 The evaluation of printed wiring boards that are produced using additive manufacturing (AM) processes, commonly referred to as 3D printing, are to be evaluated under the appropriate clauses of this Standard based on the board application.

1.6 For constructions and materials not specifically addressed in this Standard:

1. • The printed wiring board should provide safeguards not less than that generally afforded by this document and the principles of safety contained herein. This includes printed wiring boards with technologies, materials, or methods of construction, including the manufacturing process, not specifically addressed in this document.
2. • Propose for discussion with the Technical Committee the need for additional detailed requirements to address a new situation in a timely manner.

SUMMARY OF TOPICS:

This revision of ANSI/UL 796 dated October 4, 2023 includes the following changes in requirements:

• Addition of constructions not currently covered; 1.5, 1.6

• Clarification of requirements; 1.2, 2.68, 2.92, 17.6.2, Table 20.1

• Modify reference to IPC test pattern artwork in Figure 10.1.

• Additional Considerations for flame only multi-layer PWBs ; 16.2.1

• Clarification of missing requirements for hybrid PWBs; 18.4A

• Clarification of ceramic PWB requirements; 20.1.2