Automatic testing machines have a demanding job testing semiconductors, MEMS, and electronic boards 24/7. When  a leading global designer and manufacturer of test machines  introduced a new 8x flying probe tester, they needed a motion control solution robust enough to handle an annual throughput of up to 800,000 but small enough to work with miniature components.

Read this case study to learn about:

  • Achieving high probe positioning accuracy and repeatability for micro-components
  • Increasing machine throughput with X-Y-Z synchronized motion control
  • Enabling ultra-compact board design while still providing high power

Machine requirements

When the company began developing the FP4080, a high-speed, high-performance, automatic 8x flying probe tester, it needed the right motion solution to support the demands of high-volume production, including annual test capacity of up to 800,000 boards.

The new device required high probe-positioning accuracy (20μm) and repeatability (5μm) to test high-density boards with micro-pads smaller than 50μm and miniaturized components commonly used in electronic products such as smartphones, tablets, laptops and embedded PCs, routers, wearable devices, flexible circuits, and home automation devices.

The device has eight flying probes on the top and bottom, and uses linear motion technology, with linear optical encoders installed on each X-Y-Z axis, to provide the necessary acceleration and speed of up to 180 touches per second. The device was designed to operate continuously in the production environment 24/7, with minimal maintenance. Its twelve drives had to fit into a small space to reduce the machine footprint.

Motion control solution

Elmo’s nano Gold Twitter drive was chosen for the probe. Weighing only 18-22 g (<1 oz), its ultra-compact size made it possible for the customer to develop a special board for up to 12 drives that could fit into the small space while still providing high power—550 qualitative watts per drive. The installation of two boards with 12 axes each reduced the machine footprint and created a highly compact design.

The drives’ small size made it possible to install them close to the motors, which reduced EMI. Gold Twitter drives also incorporate Elmo’s proprietary Fast and Soft Switching (FASS) technology resulting in >99% efficiency with negligible EMI, eliminating the need for bulky EMI filters in the cabinet. The drive algorithm enables extremely fast motion without vibrations, and advanced schedule and fixed filtering such as low pass, notch, lead/lag and general bi-quad further improve the machine stability.

The current control was achieved through an advanced and extremely fast vector control algorithm (2000:1 dynamic range) and current loop gain scheduling that could compensate for bus voltage variations. The position and velocity control were achieved with advanced algorithms for fast settling in PTP applications and by using velocity gain scheduling based on high order filters for ultimate velocity loop performance.

Platinum Maestro controller coordinates all movements on the EtherCAT network. The top-of-the-line controller incorporates a high-level, computational multi-core system with limitless memory and on-board additional hardware peripherals. Platinum Maestro supports “Motion without Programming” using Structural Smart Building Blocks (IEC61131-3 and CPP) and enables two-way meta data transfer between the host and the controller. Platinum Maestro utilizes extremely efficient EtherCAT networking, with a cycle time down to 100µs and provides full redundancy support and EtherCAT Slave Network support for network bridging. No license is needed, leading to significant savings on production costs.


Elmo’s X-Y-Z synchronized motion is 23% faster than the customer’s previous solution, increasing the throughput by 23% as well.

The enhanced servo performance improved the overall machine stability, enabling the granite weight table’s thickness to be reduced by 500 kg.

All modules are now integrated within the machine and no external EMI filters are needed. This drastically reduces machine footprint and allows easy maintenance.

The company further saved on development costs, thanks to Elmo’s free Application Studio software (EASII), which is loaded with dozens of tools, visualizations and time-saving features. “Due to the intuitive design and logic of the EASII, a task that I would normally give to a senior and experienced motion control engineer, can now be perfectly done by a junior engineer that is new to my team,” concluded a team leader.

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