In-Circuit Test The Triumph of Adapter-Free Testing

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dataTec AG

SIMTOS (Seoul International Machine Tool Show)

In the section Legendary Stories, we take a look at remarkable events in the industry. In this episode, it's about a small company that challenged the rigid bed of nails with the first European flying probe tester and redefined flexibility in manufacturing.

Before an electronic product leaves the factory, it is tested. In the mid-1980s, this meant an in-house testing department would spend weeks programming test software, while a mechanical workshop milled an adapter, the so-called bed of nails, which ultimately had to fit the circuit board to the millimeter. Hundreds of spring-loaded contact pins simultaneously probed every measurement point. It was fast and precise. However, it was also a nightmare for anyone who did not produce ten thousand identical circuit boards.

Because if the design changed, a new bed of nails had to be built. That meant a new adapter, thousands of euros in costs, and weeks of waiting time. For prototypes, small series, and the growing number of EMS providers with constantly changing orders, this was an economic catastrophe.

The Bed of Nails Consumes Money and Time

An ICT test adapter (In-Circuit Test) was and still is a masterpiece of precision mechanics. For an average circuit board with 500 test points, a specialist drilled, milled, and assembled a carrier plate, where each individual pin had to be guided, spring-loaded, and precisely aligned with the corresponding test point. The costs were in the four-digit, sometimes even five-digit range. Delivery times were also not fast, with developers having to wait four to eight weeks for their test adapter. It was only economical if large quantities ran through the same adapter.

However, in the late 1980s, electronics manufacturing underwent a fundamental change. Surface Mount Technology (SMT) reduced batch sizes, accelerated product cycles, and increased product diversity. Suddenly, no one was ordering the same board for a year anymore. The rigid bed-of-nails test was too slow for the new flexibility. The market needed a system that could adapt to each new circuit board solely through software. No mechanics and no waiting time. The answer was: Flying Probe.

Japan First, Europe Follows

In 1987, the Japanese Takaya Corporation introduced the APT2200, the world's first flying probe tester. The principle was as simple as it was revolutionary: instead of a fixed bed of nails, two to four fine probes moved along precision axes across the circuit board, from test point to test point, software-controlled, without any mechanical adapter. Although the test was slower than with the bed of nails, it could be set up in minutes instead of weeks. However, it took seven years before a European company mustered the courage and the necessary expertise to develop its own flying probe tester. This company was not located in Munich, Stuttgart, or Grenoble but in Strambino, a small town of 3,000 inhabitants in Piedmont, an hour's drive north of Turin, and it was called Seica.

From Test House to Pioneer

Antonio Grassino had worked for twelve years in the electrical test department of Olivetti, the Italian office machine giant, which in the 1980s was still one of the great innovators in the electronics world. In 1986, he resigned. Armed with his experience, he founded a testing house in Strambino, specializing in the development of complex functional test programs for customers in avionics and telecommunications.

The service soon fostered the ambition to develop its own testing systems. In 1990, Seica developed a modular in-circuit test system based on a modular design principle. The hardware and software platform evolved with the requirements, eliminating the need for a new system for every test type. With models such as the legendary Pilot S20, the company proved by the late 1990s that the technology was ready for the global market.

It was a radical approach because the major ATE (Automatic Test Equipment) manufacturers of the time relied on closed systems: one device for in-circuit testing, another for functional testing. Nothing was compatible. In 1994, Seica took the decisive step and added a mechatronic dimension to its modular platform. The result was the first European flying probe tester and, according to Seica, the world's first system of its kind with true in-circuit capability. It was introduced in 1995.

Eight Probes, One System

The first Seica system, the so-called Pilot, relied from the beginning on an architecture designed to keep development efforts low: the same software platform for bed-of-nails and flying-probe tests, the same measurement modules, the same user interface. Anyone who could program a Seica ICT could also operate the flying prober.

The mechanics were the centerpiece. It consisted of precision linear axes that placed spring-mounted probes onto the test points with an accuracy of a few micrometers, double-sided, with up to four probes per side. Later generations, such as the Pilot V8, featured up to eight simultaneous probes. A unique feature was the vertical orientation of the circuit board within the system, which simplified double-sided contact. This was complemented by capacitive probes for bare-board tests, boundary-scan integration, and even thermal testing functions.

The software was key: It translated the PCB's CAD data directly into movement commands for the probes. No adapter and no manual calibration were necessary. The circuit board was placed on a base plate or mounted in a frame, and the system probed point by point. A full test took minutes instead of seconds, but setup time had been reduced to nearly zero.

From Strambino to the World

Seica was internationally oriented from the very beginning. As early as the early 1990s, the company worked closely with U.S. companies such as Computer Automation, GenRad, and Teradyne, the dominant players in the industry at the time. In 1995, the same year the first flying probe tester was launched, Seica established a branch in Beijing with Smart Technology. Offices followed in Paris and near Boston in 2000, in Suzhou in 2004, and in Munich (Germany) in 2008.

Today, Seica has installed over 1,000 systems worldwide. Flying probe testing remains the core product, as no other technology combines flexibility, cost-effectiveness, and testing depth as efficiently for small series and prototypes. The modular architecture from the past, the VIP platform (Versatile Interface Platform), still supports the current systems today. Thirty years later, flying probe testing is indispensable in electronics manufacturing. No prototype leaves the line without being probed by fine measuring tips. No EMS provider with varying orders can do without it. And every time a developer tests a new circuit board for the first time without having to wait weeks for an adapter, they benefit from an idea that originated in Japan in the 1980s and found its European master in Italy in 1994.