Case study: Yamaha achieves 100% high-frequency PCB characterization using PXI modular instruments
Author : Matt Campbell | Product Marketing Manager | Keysight Technologies
01 May 2022
When factory automation specialist, Yamaha Fine Technologies needed a solution for measuring the components on PCBs, including providing consistent probing for sensitive RF measurements across various types of RF devices, it looked to combine its own micro prober PCB testing machine with PXI modular instrumentation.
This case study was originally featured in EPDT's 2022 PXI for T&M supplement in the May 2022 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.
As Matt Campbell, Product Marketing Manager at electronics design, validation & test expert, Keysight Technologies explains here, this resulted in the industry’s first high-frequency PCB (printed circuit board) solution for testing 100% of board components, providing the flexibility needed to configure measurement set-up to meet testing requirements and accelerating the testing process.
Yamaha Fine Technologies is a leading developer of factory automation and production line machines, including test solutions for the printed circuit board (PCB) industry. Modern PCBs constructed from flexible liquid crystal polymer (LCP) and polyimide (MPI) substrates present unique test challenges for electronics manufacturers. The PCBs require precise high-frequency measurements of high-speed transmission lines on the circuit boards. Yamaha needed a process to combine high-frequency measurements with automated PCB test to support 5G equipment reliability.
Traditional RF (radio frequency) characterization for circuit boards involves removing and measuring test coupons. Coupons are pieces of the board designed for removal and testing without impacting the main PCB. The results vary when you manually test coupons, depending on the operator’s skill and the contact of probes on the boards.
Inconsistent results cause unacceptable uncertainty with the small margin of error associated with high frequencies. Testing only coupons does not guarantee the integrity of the entire board. Manufacturers of next-generation high-frequency circuit boards require 100% traceable measurements of every PCB component.

Keysight_Yamaha Fine Technologies_PXI PCB characterization_Case Study Image
The challenge
Measuring a test coupon separate from the primary circuits will not give you the S-parameter characteristics of the actual circuits. You need to measure the circuits on the PCB to ensure their RF performance.
Testing the PCB results in the following challenges:
• Simultaneously contacting the board at multiple points — two points for single-end lines and four points for differential lines.
• Specialised fixtures require stable connections for the small contact points and unique circuit designs.
• High-frequency board materials such as LCP and MPI can warp, requiring stabilisation for accurate measurements.
• Quickly characterizing a wide variety of boards and components requires a flexible multiport network analyser that can easily remove fixtures.

Figure 1. Yamaha micro prober system with Keysight M980xA PXI VNA
PCB probing systems give you access to board components quickly and consistently. Adding high-frequency measurements to probing systems is the next logical step for testing modern PCBs.
The solution
The Yamaha Series MP502/MP502-A micro prober provides accurate probing across a wide variety of substrates. The micro prober clamps and applies tension to the corners of the substrate, enabling precise measurements, even on modern, flexible boards like LCP and MPI.
By combining the Keysight M980xA PXI vector network analyser with its own micro prober, Yamaha was able to provide a complete high-frequency characterization solution (see Figure 1).
Keysight’s M980xA PXI vector network analyser measures essential frequency characteristics such as insertion loss and return loss, with options for advanced measurements like time domain reflectometry (TDR).

Keysight M980xA Network Analyzer
The Keysight multiport network analyser measures multiple devices simultaneously as the Yamaha micro prober accurately places the probes on the board. The system restricts probe movement on the Z-axis to µm, minimising measurement uncertainty from any cable movement.
The results
The micro prober supports many different types of fixtures for a wide range of PCB devices. With the M980xA’s automatic fixture removal, you can quickly de-embed fixtures from your measurements as you exchange them for different components. It enables you to easily perform your measurements automatically to accelerate the testing process and reduce operator error. And you can store the measurement results with the PCB’s ID for full traceability.
The modular PXI network analyser gives you the flexibility to configure your measurement set-up to meet your test requirements. You can avoid test system downtime by easily exchanging individual PXI modules that require servicing. And you need only buy as many PXI modules as necessary and upgrade at any time.
By working with Keysight and using its PXI modular instrumentation, Yamaha can now offer the industry’s first high-frequency PCB solution for testing 100% of the components.
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