IPC-A-610J Section 1.8.18 – Non-Common Conductors
IPC-A-610J Section 1.8.18 defines the acceptability requirements for non-common conductors—any conductors, pads, leads, or traces that belong to different electrical nets and must remain completely isolated in a finished assembly.
This section is fundamental to ensuring that no unintended electrical connection occurs between isolated points that could compromise functionality, safety, or long-term reliability.
Non-common conductors include adjacent component leads, neighbouring pads, parallel copper traces, terminals of different circuits, and any other conductive features that are not intended to share continuity.
The primary objective of this section is to prevent conditions that create actual or potential short circuits, especially in dense SMT assemblies and safety-critical electronics. According to IPC-A-610J, assemblies are considered acceptable only when isolation between non-common conductors is fully maintained, with no bridging, solder spread, deformation, or conductive contamination.
Typical non-conformances include solder bridges, bent leads touching adjacent leads, copper slivers, solder balls lodged between pins, lifted conductors that reduce spacing, and any foreign material that may electrically connect isolated features. Even if a short has not yet occurred, any condition that could lead to reduced insulation resistance or conductive migration is classified as a defect.
This section reinforces that spacing must comply with PCB design rules, creepage and clearance requirements, and customer-specific specifications. Inspectors evaluate these conditions visually, through AOI, or microscopy for fine-pitch devices. For Class 3 electronics—automotive, aerospace, medical, industrial—the expectations are especially stringent due to the high reliability demanded.
Ultimately, Section 1.8.18 ensures that electrical isolation, mechanical integrity, and contamination control are preserved throughout manufacturing. By preventing unintentional connectivity between independent conductors, it safeguards performance, reduces field failures, and supports robust product reliability across all electronic assembly classes.