PCBs
Figure 2. An adaptable ICT platform meets the varied demands of manufacturing seamlessly Enhancing test coverage
When the TestJet technique was introduced in the 1990s, it was a real breakthrough for increasing coverage of in-circuit tests. But today’s PCBAs are inadequately covered by capacitive probe measurement techniques, including TestJet, opening the door to Vectorless Test Enhanced Probe (VTEP) technology.
Vectorless technology The use of VTEP improved ICT coverage, especially on boards with hard-to-test packages such as BGAs, micro-BGAs, and SMT edge connectors. Today’s nanoVTEP technology provides faster test throughput, essential for high-volume manufacturing, and lower-cost fixtures. Finally, the higher fault coverage of nanoVTEP enables reliable and efficient solutions for PCBA testing.
Boundary scan test As technology evolves, complex interconnects, limited access points, and increasing component density make chipset testing more challenging. For instance, densely populated server boards with higher clocking frequencies require additional design considerations to preserve
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signal integrity and minimise undesirable distortion. Close-running parallel traces may generate electromagnetic interference, while test pads on a high-speed path may result in reflections and signal degradation. PCBAs have low ICT coverage because of limited electrical access. A boundary scan test enables a manufacturer to check a PCBA’s functionality without having full access to its internal circuitry to ensure accurate and reliable testing. The prerequisite is that the manufacturer needs to design the PCBA according to the IEEE 1149.1 standard, which requires boundary test cells connected to each pin. Using IEEE 1149.1 standard information, the manufacturer can easily verify the overall functionality of a PCBA without needing to check on its components.
high-volume manufacturing environments
In high-volume manufacturing environments, the efficient and reliable production of a PCBA is crucial to meeting market demands and maintaining competitiveness. With assembly equipment speeds surging and beat rates now often measured in seconds, the in-circuit tester risks becoming the bottleneck.
This situation presents a dilemma for manufacturers: either expand test capacity by adding more equipment or reduce test durations to align with the target beat rate. Both options present challenges. Adding more equipment is costly, demands additional fixtures, and may not be feasible because of spatial constraints in production facilities. Conversely, trimming tests necessitates extra programme maintenance and diminishes the ICT system’s ability to detect defects effectively.
A better approach is to increase the tester’s execution speed until it is no longer the bottleneck on the production line. Some ICT systems have evolved to support concurrent testing of more than one component. This process involves duplicating instrumentation in the test system so that the test executive can test multiple components in parallel, typically on boards manufactured as part of a panel. In traditional setups, in-circuit testers typically limit testing to up to four boards at a time. However, high-volume manufacturing environments, where efficiency and throughput are critical, demand the ability to test a larger number of boards simultaneously. Massively parallel
board testing can test multiple boards at the same time using multiple testing cores. By implementing parallel testing, where we assess multiple units simultaneously, we reduce the time needed to test each unit. This advancement significantly boosts testing throughput and efficiency across the board, optimising the testing process.
Conclusion
Over time, ICT systems have undergone significant evolution to tackle the technological and business hurdles of contemporary PCB manufacturing. Their functionalities have expanded considerably since their inception. Enhanced methodologies like reduced access testing, integration of boundary scan, nanoVTEP technologies, embedded testability tools, parallel testing abilities, functional testing capabilities, and adaptable system configurations have prolonged the relevance and utility of ICT systems.
Consequently, ICT remains one of the primary tools that high-volume PCBA manufacturers use to identify defects in manufacturing processes and components.
https://www.keysight.com/ Components in Electronics March 2025 41
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