Boundary Scan Interconnect Testing Essentials for Populated Circuit Board Assemblies
Boundary scan interconnect testing turns silicon multiplexers into virtual probes to verify fine-pitch BGA solder joints without physical test pads.
SerDes Boundary Scan
High-Speed Testing
Extended boundary-scan test methodologies designed under the IEEE 1149.6 standard allow for the verification of high-speed serializer-deserializer channels on assembled boards using alternating current (AC) signal patterns. Deploying serdes boundary scan allows test systems to locate structural defects on differential signal lines that operate at gigabit-per-second speeds. These lines utilize series capacitors that block conventional direct-current (DC) boundary-scan testing.
This standard-based testing generates transient test signals that cross the coupling capacitors to verify trace continuity. The methodology bypasses the limitations of traditional test nodes to assess the high-speed differential signal paths.
AC-Coupling Diagnostics
Conventional boundary scan relies on static logic levels that are blocked by the series capacitors used in high-speed transmission lines. The ac-compliant scan cells generate pulse patterns that pass through the capacitors and are captured by the receiver’s scan registers. This testing catches solder voids, short circuits, and trace open faults on these critical high-speed signal paths.
Accurate diagnostics prevent complex high-frequency signal failures from escaping to the customer.
Diagnostic Performance
Software algorithms analyze the scan data to pinpoint the failing trace or open capacitor. This precise diagnosis eliminates manual probing with high-bandwidth oscilloscopes. Test systems execute these scan routines in seconds during production.