Cracking the Code of Complex PCBA Testing—Why EMI Is the Silent Threat No One Talks About

On today’s electronics manufacturing floor, testing isn’t just a checkpoint; it’s a battlefield. Printed circuit board assemblies (PCBAs) have become smaller, denser, and exponentially more complex, packing advanced functionality into spaces no thicker than a fingernail. That complexity is pushing traditional in-circuit testing (ICT) systems to their limit.

Industry experts highlight five major hurdles facing PCBA test engineers today—from high-impedance nodes to the rise of supercapacitors. But there’s another quiet disruptor hiding in plain sight: electromagnetic interference (EMI). As manufacturing scales, EMI isn’t just a systems design problem - it’s becoming a testing bottleneck too.

Let’s take a look inside the modern PCBA test process, where efficiency is king, accuracy is critical, and even invisible interference can grind production to a halt.

Mini Boards, Major Headaches

The trend toward miniaturization is transforming consumer electronics, automobiles, and energy industries—but it’s wreaking havoc on test access. Today’s PCBs are crowded with thousands of components, often leaving no physical room for traditional test points. This puts enormous pressure on test coverage.

To keep up, manufacturers are relying on larger panel testing and more sophisticated algorithms. Automated cluster formation tools now simulate the behavior of passive components, even when direct contact isn’t possible. These tools save hours of manual test planning and allow even entry-level engineers to achieve comprehensive coverage.

Still, with so much functionality squeezed into tight quarters, another problem starts to emerge: electrical noise.

When the Nodes Push Back

Modern PCBs rely heavily on high-impedance nodes to minimize power consumption and enhance signal fidelity. But those same nodes are test-resistant. A standard short test—used to detect unpowered shorts between components—takes three times longer on a high-impedance node due to its sensitivity and stabilization needs.

To address this, some testing platforms now use a binary identification method, grouping nodes to streamline detection. In one test scenario with 100 nodes, a process that once took 100 cycles was reduced to just seven. That’s a massive efficiency gain. Still, the underlying problem remains: the rise in impedance and vulnerability to even slight disturbances, such as EMI.

Supercapacitors and the Power Surge Problem

Another growing challenge is the emergence of supercapacitors, which are commonly found in electric vehicles and industrial systems. These high-capacity energy storage units (ranging from 1 to 100 Farads) require precise charge-discharge cycles during testing. One misstep can damage the board—or the tester.

Their increasing presence in PCBAs adds complexity and requires test protocols with extreme precision. They also introduce more opportunities for interference, especially during high-current discharges or rapid transitions.

The Trouble with Trickle Currents

Low-current measurements are another hidden minefield. Devices in standby or sleep modes rely on microamp-level currents, which are notoriously difficult to measure accurately in environments filled with digital noise. In cars, a misread sleep current in an engine control unit (ECU) can drain a battery or, worse, cause a safety system to fail.

That’s where EMI rears its head again. Even the slightest noise—undetectable by the naked eye—can skew results. For test engineers seeking to detect ultra-low leakage currents, shielding alone may not be sufficient.

The EMI You Can’t Shield Against

Most manufacturers address EMI using external solutions, such as Faraday cages, filters, or additional shielding. But these are reactive solutions—band-aids, not cures. And in test environments, they’re often bypassed entirely to allow equipment access or speed up throughput.

That’s where Slip Signal Technologies comes in.

We developed a novel way to prevent EMI, not with filters, but at the circuit logic level.  Our technology changes how signals are generated, smoothing out the electromagnetic signature before it even leaves the board. The result: less radiated noise, cleaner signal environments, and—critically—less test interference.

Testing Tomorrow’s Boards Today

The future of electronics isn’t just about smaller devices—it’s about more innovative processes. That means faster algorithms, automated test design, and rethinking how we manage interference, rather than just patching over it.

Manufacturers who treat EMI as a testing variable—not just a design afterthought—stand to gain not just in yield, but in speed, quality, and long-term reliability. And as Slip Signal shows, the best way to eliminate EMI is to stop it before it starts.