This video from NRS Brakes explains how the friction material is secured to a backing plate using glue and mechanical attachment. The video covers how glue requires extra manufacturing steps to bond the two components and the disadvantages. Also, the video shows how mechanical attachment can improve the final product while simplifying production.
Mechanical attachment for brake pads should be treated very seriously as it is very similar to rebar in concrete. Just like rebar-reinforced concrete, you cannot see the mechanical attachment in a brake pad. Mechanical attachment is required on specific applications for high loads where adhesive alone would lead to pad failure in OEM testing. NRS is a mechanical retention feature that enables the steel to be coated prior to pressing friction composites such as ceramics, metallic or organics via flash molding, positive molding or cold-fusion technology. NRS is effective under all these conditions regardless of the friction material.