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, 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 new edition of ANSI/UL 796 includes the following changes:

Revisions to the Definitions to Align with Industry Use

Clarify Stabilization Period Requirements

Clarify the Title of Table 9.3 Based on Changes in UL 746E

Update Reference for Figure 10.1

Clarify the Multiple Types of Multilayer Printed Wiring Boards and Define the Hybrid PWB Requirements in New Section 18

Move the Current Requirements for HDI Printed Wiring Boards to New Section 19

Clarify Current Requirements for Metal Base Printed Wiring Boards

Relocate Figures 21.1 – 21.15 to new Annex A

Clarify Microsection Analysis Process Based on Changes to the Referenced IPC Test Method

Clarification of Requirements for Solder Limit Evaluation for Laminates and PWBs

Add Evaluation for Conductive Coins

Clarify Conductor Pattern Requirements in Clause 10.7.1 and Figure 10.1

Clarify Thermal Stress Conditioning for Conductive Paste Adhesion Test

Editorial Update: Correct the spelling of Dessicator to Desiccator. (all instances)