The Essential Guide to PCB Flying Probe Testing

Before leaving the production facility, bare printed circuit boards (PCB) and PCB assemblies (PCBA) undergo various tests to identify electrical and circuitry issues such as shorts, openings, capacitance, and resistance. Passing these tests ensures the final products’ reliability and functionality. In PCBA, the predominant testing methods include the Flying Probe Test and the In-Circuit Test.

Understanding the Flying Probe Test (FPT)

Flying Probe tests, also known as “fixtureless in-circuit testing,” utilize probes guided by software to evaluate PCB features. This method offers flexibility, making it ideal for low-volume production and PCBs in the developmental stage.

Emerging Advanced Features:

• PDM Unit (Phase Difference Measurement Unit): Transmits signals to measure phase differences, reducing the need for unnecessary isolation tests.
• HVS Test (High Voltage Stress): Applies high voltage to uncover hidden problems without damaging the boards during testing.
• Micro Shorts Detection: Prevents burning out of components with micro shorts when sudden high voltage is applied.

The Testing Process

The testing process involves developing a comprehensive test program detailing PCB specifications, components, and testing locations. Probes inspect every section of the board to verify both board and component functionality.

Strengths and Weaknesses:

Strengths: Adaptability to various PCBA layouts and designs.
Weaknesses: Relatively slow operation due to probe movement between test points.

Enhancing Test Accuracy

To enhance test accuracy and prevent board damage, consider focusing on the following PCBA components:

• Fiducials: Provide reference points for probe placement.
• Board Rail: Maintain a sufficient border edge for accurate machine placement.
• Component Legs: Ensure dedicated probing areas around component legs to avoid damage.
• Vias: Probing near vias should adhere to non-tented specifications in PCB design.
• PCB Size: Optimize test access point proximity for efficient testing of larger PCBs.

Choosing a Flying Probe Tester

When selecting a Flying Probe Tester, prioritize critical specifications to meet your testing needs effectively.

We trust this comprehensive guide has provided valuable insights into PCB flying probe testing, assisting in your understanding and selection of suitable testing solutions.