IPC/WHMA-A-620 Explained: Class 1, 2, and 3

IPC/WHMA-A-620 is the joint IPC and Wire Harness Manufacturers Association acceptability standard for cable and wire harness assemblies. It's the closest thing the industry has to a universal workmanship rulebook.

The standard defines three product classes. Class 1 is general electronic products where the primary requirement is function. Class 2 covers dedicated service electronic products where extended life and uninterrupted service are desired — most industrial and commercial harnesses live here. Class 3 covers high-performance electronic products where continued performance or performance-on-demand is critical: aerospace, medical life-support, defense.

A-620 covers everything: wire preparation, crimping, soldering, splicing, connectorization, marking, molding, testing, and inspection. Each subject has acceptable / process indicator / defect criteria for each class. Class 3 criteria are tighter across the board.

For most commercial builds, Class 2 gives you a rigorous baseline without the documentation overhead of Class 3. For aerospace and medical, Class 3 is table stakes. When your customer doesn't specify, ask.